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Age-related decline of muscle power (powerpenia) featured article

Around age 50, muscle strength—the ability to exert force or lift a heavy resistance—drops by about 3% per year, while muscle mass falls by about 1% per year.

The fix to this is simple: Resistance training and an adequate protein intake. Engaging in strength training 2–3 times per week and consuming 1.2–1.6 grams of protein per kilogram of body weight per day can help one maintain—and even build—muscle mass and muscle strength as they age.

It's not inevitable that we lose muscle as we get older. But it takes work.

These drops in muscle strength and mass might seem drastic, but muscle power might experience even more drastic changes.

In fact, muscle power is so important that researchers have proposed a new term for the age-related loss of muscle power: powerpenia (a friendly nod to the more well-known term sarcopenia, which refers to the age-related loss of muscle mass).

[image id='aging and muscle loss'...

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Why It's Never Too Late to Start Building Muscle

Posted on January 21st 2025 (5 months)

In this clip, Dr. Rhonda Patrick highlights muscle's role in aging, metabolic health, and how exercise and protein combat age-related muscle loss.

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The 4 Most Important Players for Muscle Mass - Rhonda Patrick

Posted on January 21st 2025 (5 months)

In this clip, Dr. Rhonda Patrick outlines key factors for building and maintaining muscle mass.

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The Science of Protein and Its Role in Longevity, Cancer, Aging, and Building Muscle

Posted on December 3rd 2024 (7 months)

Dr. Rhonda Patrick dives into the science of protein and discusses intake requirements, its ties to longevity, and debunks several protein-related myths.

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News & Publications

  • Regular infrared sauna use increases blood vessel density in aged muscles by 33%, though muscle size, strength, and protein synthesis remain unchanged. pubmed.ncbi.nlm.nih.gov
    Aging Heat Stress Muscle Sauna Protein

    Scientists have speculated that regular heat exposure, such as that experienced in a sauna, might help aging muscles adapt in ways that preserve strength and mass. A recent study found that older adults who engaged in infrared sauna sessions regularly experienced a 33% increase in the number of small blood vessels surrounding their muscle fibers.

    Researchers asked 14 healthy older adults (65 to 85 years old) to sit in an infrared sauna (60°C, 140°F) for 45 minutes, three times weekly, for eight weeks. They collected muscle biopsies before and after the heat exposure to measure capillarization—the number of capillaries around each muscle fiber—as well as muscle size. They also tracked muscle protein synthesis using amino acid infusions and ultrasound imaging to assess how well blood flowed through muscle tissue after eating. Finally, they measured leg strength using a one-repetition maximum test.

    After eight weeks of heat therapy, participants had 31% to 33% more capillaries surrounding both type I and type II muscle fibers. However, muscle blood flow, protein synthesis rates, leg strength, and muscle size did not improve. Body weight, body composition, and walking speed also stayed the same. The only physical performance measure that improved was handgrip strength, which increased slightly. Interestingly, systolic blood pressure dropped by 2%, while diastolic pressure and resting heart rate were unchanged.

    These findings suggest that passive heat treatment can increase blood vessel density in older muscle tissue, but this change alone doesn’t improve nutrient delivery, muscle building, or strength. Heat exposure might support muscle health in other ways, but it doesn’t appear to be a replacement for resistance or aerobic exercise. Learn more about the benefits of heat exposure in Aliquot #96: Thermal Stress, Part I: The Science Behind Heat Stress and its Positive Effects on Health.

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  • Once-weekly, low-volume resistance training boosts physical functioning, energy, and social engagement in older adults while reducing pain by up to 40% and improving strength by 30%. www.sciencedirect.com
    Exercise Aging Muscle

    Resistance training is a powerful tool for improving the health and well-being of older adults, but many guidelines focus on higher training volumes that may be difficult for some to achieve or maintain. A recent study found that once-weekly, low-volume resistance training boosted physical functioning, energy, and social engagement in older adults, reducing pain by up to 40% and improving strength by 30%.

    Researchers assigned 31 older adults (average age, 66) to one of four groups. Participants trained once a week for six weeks, doing leg press exercises with either a slower, controlled pace or a more explosive effort and using lighter or heavier weekly exercise “doses” (either three or five sets of five repetitions). The researchers assessed the participants' quality of life, functional capacity, strength, and body mass at baseline and weeks 3 and 6.

    They found that participants moved more easily, felt more energetic, and reported less pain after the intervention. Their balance and strength improved, and many participants reported more frequent physical activity—an average increase of 25%—and a 20% improvement in mental health. Most participants (85%) continued exercising after the study, and 95% said they would recommend the program. Many valued the structure and support, with 75% finding the shorter three-by-five routine practical and sustainable.

    These findings suggest that lower-dose, once-weekly resistance training interventions can produce meaningful health improvements in older adults. One of the principal benefits of resistance training is building muscle, which is critical for maintaining health during aging. Learn how it’s never too late to start building muscle in this clip featuring Dr. Rhonda Patrick.

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  • Short-term creatine monohydrate use, even without exercise, may boost lean body mass, particularly in women. www.mdpi.com
    Exercise Muscle Supplements

    Creatine monohydrate—one of the most widely studied and popular supplements—has a well-earned reputation for helping increase lean body mass, but some of those gains may come from changes in body water rather than actual muscle growth. A recent study found that creatine monohydrate alone, even without exercise, can boost lean body mass in the short term—especially in women.

    Researchers randomly assigned 63 healthy adults to take either 5 grams of creatine monohydrate daily or nothing. After a one-week “wash-in” period with the supplement, everyone began a 12-week resistance training program. The researchers measured lean body mass using a body scan before and after the wash-in and after the training program.

    After one week of taking creatine without exercising, those who used the supplement had gained about 0.5 kilograms (roughly 1.1 pounds) more lean body mass than the control group—a difference most apparent in women. Once training began, both groups gained about 2 kilograms (4.4 pounds) of lean body mass over 12 weeks, but creatine users did not gain more than those who did not take it, indicating the supplement gave an early bump in lean body mass but did not enhance long-term gains from resistance training.

    These findings suggest that short-term creatine use can raise lean body mass measurements, likely by increasing body water. The investigators posited that higher doses or different timing strategies may be necessary to see continued benefits beyond that initial increase. Learn more about creatine in this episode featuring Dr. Darren Candow.

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  • Post-exercise infrared sauna use contributes to a 25% increase in jump height and a 6.8% peak power boost in female athletes—a potential tool for enhancing power production. pmc.ncbi.nlm.nih.gov
    Exercise Performance Muscle Sauna

    Infrared saunas are gaining in popularity among athletes as a recovery tool, but their effects on strength training adaptations remain uncertain. While traditional saunas can impair performance, infrared saunas may offer a more effective and comfortable recovery option. A recent study found that using infrared saunas after exercise enhances power production but doesn’t influence muscle growth.

    Forty female team sport athletes participated in the study, with half using an infrared sauna after training sessions for six weeks. Sauna sessions were done three times weekly for 10 minutes at 50°C (122°F) following their training. All participants underwent body composition measurements and physical performance tests, including sprint tests, jumps, and leg press exercises, before and after the training period.

    Both groups improved in neuromuscular performance and muscle size. However, the infrared sauna group showed greater jump height and peak power improvements, with a 25% increase in jump height and a 6.8% increase in peak power. Five-minute sprint times were also faster in the infrared sauna group, though not statistically significant. While both groups gained lean mass, the infrared sauna group experienced small body mass and fat mass increases. There were no marked differences between the groups in muscle hypertrophy or other body composition changes.

    These findings suggest that post-exercise infrared sauna use enhances power output over time but doesn’t affect muscle growth. Learn more about the benefits of infrared and traditional sauna use in our overview article.

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  • Curcumin, a compound derived from turmeric, aids in reducing muscle damage and soreness after intense exercise, potentially speeding up recovery. www.tandfonline.com
    Exercise Performance Inflammation Muscle Curcumin Polyphenol

    Intense exercise—especially eccentric movements like downhill running or heavy weightlifting—can cause microscopic muscle damage, inflammation, and soreness. While this process is part of adaptation, excessive damage can delay recovery and hinder performance. A recent study found that curcumin, a compound derived from turmeric, may help reduce muscle damage and soreness, potentially speeding up recovery.

    Researchers analyzed the findings of 11 studies on curcumin and exercise-induced muscle damage. The various studies focused on healthy adults who exercised regularly and took curcumin before, during, or after workouts.

    The analysis revealed that curcumin supplementation may ease muscle soreness, reduce inflammation, and improve recovery after strenuous exercise. However, the benefits depended on dose (which ranged from 90 milligrams to 2.5 grams), bioavailability, and timing, with post-exercise supplementation appearing most effective.

    These findings suggest that curcumin could be a useful supplement for athletes looking to minimize muscle soreness and recover faster. However, its low bioavailability may limit its effectiveness. In addition, the investigators noted that many of the studies were small, limiting their findings' applicability. Curcumin is a polyphenolic compound. Learn more about polyphenols in our overview article.

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  • Higher muscular strength and cardiorespiratory fitness can help reduce the risk of premature death in cancer patients by up to 46%. bjsm.bmj.com
    Exercise Cancer Muscle Mortality Cardiovascular

    Cancer remains one of the leading causes of death globally, with millions of new cases and deaths each year. Despite treatment advancements, cancer patients are at a greater risk of death due to muscle loss, heart complications, and inadequate physical activity. A recent study found that higher muscle strength and cardiorespiratory fitness reduce the risk of death in cancer patients, with a 31% to 46% lower likelihood of premature death.

    Researchers conducted a systematic review and meta-analysis of 42 studies involving more than 47,000 cancer patients across various types and stages to examine how muscle strength and cardiorespiratory fitness influence survival rates. They sought to determine whether higher fitness levels were associated with better outcomes in terms of overall and cancer-specific death.

    Their analysis revealed that patients with higher muscle strength or cardiorespiratory fitness were 31% to 46% less likely to die prematurely from any cause than those with lower fitness levels. Each increase in muscle strength was associated with an 11% lower risk of all-cause mortality. Furthermore, patients with advanced cancer stages, as well as those with lung and digestive cancers, saw significant reductions in death risks—ranging from 8% to 46% lower for all-cause mortality. Increments in cardiorespiratory fitness were particularly important, with each improvement in cardiorespiratory fitness linked to an 18% reduced risk of dying specifically from cancer.

    These findings suggest that boosting muscle strength and cardiorespiratory fitness can improve cancer patients' survival rates. Given the strong connection between physical fitness and mortality risk, health professionals should prioritize fitness assessments for cancer patients as part of their treatment strategies. Learn more about the role of exercise in cancer prevention and recurrence in this episode featuring Dr. Kerry Courneya.

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  • Fat deposits in muscles increase the risk of major cardiovascular events by 53%. pubmed.ncbi.nlm.nih.gov
    Muscle Cardiovascular

    Fatty deposits that run through a steak—known as marbling—improve the meat’s quality, making it more tender, juicy, and flavorful. However, evidence indicates that fatty deposits in human muscles may have adverse health effects. A recent study found that higher fat levels within muscles were associated with a 53% increase in the risk of major cardiovascular events, such as heart attacks or heart failure.

    The study included 669 people undergoing routine cardiac evaluations. Researchers assessed their coronary flow reserve, which measures the capacity of the coronary arteries to increase blood flow during stress or exertion. They also measured body mass index (BMI—a proxy for body fatness), skeletal muscle mass, and fat levels beneath the skin and within the muscles. They monitored the participants for major cardiovascular events for about six years.

    The researchers found that higher BMI, lower muscle mass, and more fat inside the muscles were linked to reduced blood flow in the coronary arteries, but fat under the skin was not. For every unit decrease in blood flow, the risk of a major cardiovascular event increased by 78%, and for every 10 cm² increase in fat inside the muscles, the risk increased by 53%. In contrast, larger muscles and more fat under the skin were associated with an 11% and 6% reduction in the risk of a major cardiovascular event, respectively.

    These findings suggest that higher muscle fat content increases the risk of major cardiovascular events. Evidence suggests that exercise reduces muscle fat content, potentially explaining how exercise reduces cardiovascular risks. Learn more about how exercise protects the heart in this episode featuring Dr. Ben Levine.

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  • Combining creatine with dextrose accelerates muscle creatine accumulation and maintains elevated levels, potentially boosting muscle mass and performance. www.degruyter.com
    Exercise Muscle Supplements

    Creatine helps supply energy to muscles during high-intensity exercise and is commonly used to boost performance and muscle mass. However, determining the most effective creatine supplementation protocol has proven challenging. A recent study found that combining creatine with dextrose for five days rapidly increases muscle total creatine, with continued consumption maintaining this high level.

    Researchers provided healthy young men with one of four creatine supplementation protocols: Group 1: Four doses of 5 grams of creatine daily for five days, followed by 5 grams daily for 28 days.
    Group 2: Four doses of 5 grams of creatine plus 95 grams of dextrose daily for five days. Group 3: Split from Group 2 after the initial five days:
    Group 3A: 5 grams of creatine daily for 28 days.
    Group 3B: 5 grams of creatine plus 95 grams of dextrose daily for 28 days. Group 4: Four doses of 5 grams of creatine with 14 grams of protein, 7 grams of phenylalanine, 7 grams of leucine, and 57 grams of dextrose daily for five days, followed by a single daily dose of the same combination for the next 28 days.
    The researchers collected muscle biopsies from the participants at baseline, after five days, and after 33 days.

    They found that muscle total creatine increased in Groups 1, 2, and 4 after five days. The largest increase occurred in Group 2, reaching an average maximum of 150 mmol/kg. However, after 33 days:
    Group 1 total creatine increased further to approximately 150 mmol/kg.
    Group 3A showed a tendency to decline.
    Group 3B remained unchanged from the level observed at five days.
    Group 4 remained unchanged from the level observed at five days and was lower than Group 1. Creatine transporter gene expression changed slightly in all groups. However, the more creatine levels increased after five days, the smaller the change in this gene’s activity.

    These findings suggest that combining creatine with dextrose for five days rapidly increases total muscle creatine. Continued consumption of creatine with dextrose helps maintain this high level. While ingesting creatine alone also boosts total muscle creatine, it takes longer to reach levels similar to those in combination with dextrose. Learn more about creatine in this episode featuring Dr. Rhonda Patrick.

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  • Mechanical stresses and myokines produced by muscles during exercise synergistically promote nerve growth and connectivity. onlinelibrary.wiley.com
    Exercise Muscle Neurodegeneration

    Muscle contraction, the hallmark of exercise, releases signaling molecules called myokines that influence cell function throughout the body. However, the mechanical forces it generates may also play a role. A recent lab study found that biochemical and mechanical signals from contracting muscle work synergistically to promote nerve growth and maturation.

    Researchers grew muscle cells on a specialized gel that mimicked the movements of contracting muscles. Then, by adding tiny magnetic particles, they stretched the cells to simulate exercise. They assessed how these forces and the myokines released by the muscle cells influenced the growth of nerve cells.

    They found that nerve cells grew and migrated more readily when exposed to myokines from contracting muscle cells, with more robust effects at higher levels of muscle activity. Stretching the nerve cells mechanically produced similar growth, but further analysis demonstrated that chemical signals were more effective in activating genes related to nerve growth and forming connections.

    These findings suggest that exercise influences nerve health through biochemical and mechanical pathways, providing new insights into how muscle activity supports the nervous system. Myokines also exert anti-cancer effects. Learn more in this episode featuring Dr. Rhonda Patrick.

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  • High-protein, low-calorie diets—whether animal or plant-based—lead to an average weight loss of ~18 pounds and improved glucose metabolism in people at risk for type 2 diabetes. dom-pubs.pericles-prod.literatumonline.com
    Diet Obesity Diabetes Muscle Protein Weight Loss

    The global obesity epidemic is driving a marked increase in the incidence of type 2 diabetes, and some experts estimate that by 2024, more than 780 million adults worldwide will develop the disease. A recent study found that high-protein, low-calorie diets promote weight loss and improve cardiometabolic markers in people at risk for type 2 diabetes.

    The study involved 117 adults with either prediabetes or type 2 diabetes and a body mass index (BMI) over 27.5—considered overweight or obese. Participants consumed an animal- or plant-based high-protein diet that provided 35% of their total calories for six months. The remainder of their calories came from fat (30%) and carbohydrates (35%).

    Participants in both groups saw similar improvements in body composition, including an average weight loss of approximately 8 kilograms (~18 pounds) and reduced visceral (abdominal) fat. Glucose metabolism indicators, such as fasting glucose and glycated hemoglobin levels, improved equally in both groups, as did lipid levels, liver enzymes, and inflammatory markers.

    These findings suggest that high-protein, low-calorie diets—whether animal- or plant-based—can improve body composition, glucose metabolism, and other cardiometabolic markers in people with prediabetes or type 2 diabetes.

    Dietary protein supports muscle hypertrophy and maintenance—critical aspects of glucose metabolism. Learn how to optimize protein intake to support muscle health when following a plant-based diet in this clip featuring Dr. Luc van Loon.

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  • Resistance training in one arm can help preserve muscle strength and size in the opposite, immobilized arm, a phenomenon known as cross-education effects. journals.physiology.org
    Exercise Muscle Strength

    Injuries often leave one limb immobilized, driving a rapid decline in muscle strength and size. But what if training the opposite limb could help preserve the strength of the immobilized one? A recent study found that targeted exercise of one arm can help maintain strength and size in the opposite immobilized arm, offering potential benefits for rehabilitation.

    Researchers immobilized the nondominant forearms of 16 adult participants for four weeks using a cast. Then, they randomly assigned them to a resistance training or non-exercising group. Participants in the training group performed eccentric wrist flexion exercises with the non-immobilized arm three times a week. Both groups underwent testing before and after the intervention to measure muscle strength, thickness, and cross-sectional area using ultrasound and computed tomography.

    The researchers found that those in the training group experienced only a 2.4% reduction in strength in the immobilized arm compared to a 21.6% reduction in the non-training group. In addition, the training group saw a 1.3% increase in muscle size of the immobilized forearm, while the non-training group showed a 2.3% decrease. They also observed strength gains in the non-immobilized arm, with a 30.8% improvement in the training group compared to a 7.4% decline in the non-training group.

    These findings suggest that engaging in targeted resistance training of the non-immobilized limb can help preserve the size of an immobilized limb and maintain strength across different types of muscle contractions. The researchers posited that the immobilized arm retained more muscle mass and strength due to neural adaptations from training the opposite arm, a phenomenon known as cross-education effects. Interestingly, sauna use can also help maintain muscle mass during periods of disuse due to immobilization. Learn more in our overview article.

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  • Increasing resistance training volume overcomes non-responsiveness in muscle growth in older adults, driving significant size and strength improvements. pubmed.ncbi.nlm.nih.gov
    Exercise Aging Muscle

    As we age, our muscles' response to resistance training diminishes to varying degrees, with some people responding and others not. This non-responsiveness can make maintaining muscle mass and strength challenging in later years. A recent study found that increasing resistance training volume—the number of sets performed—overcomes non-responsiveness in older adults.

    The study involved 85 older adults (average age, 68) who completed a 10-week resistance training program. Participants followed a low-volume protocol (one set) for one leg and a high-volume protocol (four sets) on the other leg while performing knee extensions twice weekly. Researchers measured their muscle size and assessed their leg strength before and after the intervention.

    They found that 51 participants didn’t respond to the low-volume training. However, they experienced considerable muscle size and strength improvements when they increased their volume. Responders—those who saw muscle gains from the one-set protocol—also benefited from the higher volume, but their strength gains were similar regardless of volume.

    These findings suggest that older adults who don’t see improvements from resistance training can achieve meaningful gains by increasing the number of sets performed. Learn more about resistance training in this clip featuring Dr. Brad Schoenfeld.

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  • Resistance exercise activates muscles' cellular "housekeeping" processes, ridding cells of harmful waste products. pubmed.ncbi.nlm.nih.gov
    Exercise Muscle Autophagy

    Cellular processes are messy. They produce copious amounts of harmful waste products and damaged parts that can accumulate inside the cell, creating havoc and even cell death. A recent study found that resistance training activates critical cellular cleanup processes in muscles, facilitating waste disposal and supporting muscle cell health.

    The study had two phases: an acute exercise phase with intense workouts to trigger an immediate muscle response and a six-week adaptation phase to see how muscles adjust to repeated mechanical stress. In the acute phase, participants performed resistance exercises, including leg extensions, leg presses, and drop jumps, using heavy weights and incorporating eccentric movements. During the adaptation phase, they performed the exercises at a lower intensity twice a week, allowing the muscles to adapt to the consistent workload gradually. Researchers took muscle samples before and after these sessions at the start and end of the study, analyzing changes in critical proteins and focusing on a cellular protein called BAG3.

    BAG3 facilitates a cellular cleanup process called chaperone-assisted selective autophagy, or CASA. Unlike ordinary autophagy, which generally recycles various cell parts, CASA specifically targets and breaks down damaged or misfolded proteins with the help of unique proteins called chaperones. BAG3 is one of these chaperones. Under resting conditions, two phosphorous molecules tether BAG3 in place, keeping it inactive.

    However, the researchers found that when cells experienced mechanical stress, the phosphorous molecules released BAG3, activating it and allowing it to perform its chaperoning job. Notably, BAG3 release was essential for eliminating damaged mitochondria—a process called mitophagy—in skeletal muscles.

    These findings suggest resistance exercise supports cellular health and mitophagy by boosting in-house cleanup processes. Learn more about mitophagy in this clip featuring Dr. Guido Kroemer.

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  • Collagen supplementation doesn't boost muscle or connective tissue synthesis after resistance training. pubmed.ncbi.nlm.nih.gov
    Exercise Muscle Supplements

    Resistance training remodels muscle fibers and connective tissues, driving muscle mass and strength gains. This phenomenon has led to the plausible theory that enhancing collagen synthesis could boost functional strength. However, recent research suggests otherwise. A study found that collagen supplementation was no more effective than a placebo at promoting muscle fiber and connective tissue synthesis.

    In this small study, 25 young men performed strenuous resistance exercise training for one week. About half of the men took 15 grams of hydrolyzed collagen peptides twice daily during the intervention, while the other half took a placebo. Researchers measured their muscle fiber and connective tissue protein synthesis daily.

    They found that connective protein synthesis was 48% higher than muscle fiber synthesis following resistance training. Although plasma levels of collagen peptides increased among participants taking the supplemental collagen, supplementation did not increase muscle fiber or connective tissue synthesis more than the placebo. Learn more about the disappointing results of this particular role for collagen supplementation in the episode featuring Dr. Luc van Loon.

    The good news is that collagen supplementation may have benefits beyond this specific role. Collagens are major structural proteins in many body tissues, including tendons, ligaments, cartilage, skin, blood vessels, muscles, gut tissue, and dentin. They are the most abundant proteins in the body, making up about 30 percent of the total protein mass. Hydrolyzed collagen, also known as collagen peptides or hydrolysate, is made by breaking down collagen into smaller amino acid chains (called peptides) using heat or enzymes. Read more about hydrolyzed collagen in our overview article.

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  • Magnesium supplementation reduces post-workout muscle soreness and enhances recovery in both recreational runners and elite athletes. translational-medicine.biomedcentral.com
    Exercise Performance Magnesium Muscle

    Muscle contraction relies on a magnesium-dependent calcium transport system. Consequently, magnesium levels drop after exercise, increasing muscle soreness and impairing performance. A recent review found that magnesium supplementation reduces muscle soreness, improves performance, and protects against muscle damage.

    Researchers reviewed the findings of four studies investigating the effects of magnesium supplementation on muscle soreness. The studies included 73 participants (60 males and 13 females) between the ages of 19 and 27. One study focused on muscle soreness, one on running performance, and two on team sports performance.

    They found that 350 milligrams of magnesium glycinate daily reduced muscle soreness and improved recovery after resistance training. Similarly, 500 milligrams of magnesium oxide and stearate taken daily for a week reduced muscle soreness in recreational runners with low dietary magnesium intake. Markers of muscle damage decreased in elite basketball players who took 400 milligrams of magnesium daily throughout the season. Competitive cyclists experienced similar effects at the same dose.

    These findings suggest that magnesium supports muscle health and performance in recreational and competitive athletes. The review’s authors posited that physically active people need 10% to 20% more magnesium than the recommended doses taken two hours before physical activity, even during the off-season. For more information about magnesium, check out our deep-dive podcast and our comprehensive overview article.

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  • Drop set training, a resistance method involving exercising to muscle failure at decreasing weights, promotes muscle growth as effectively as traditional workouts but in less time. sportsmedicine-open.springeropen.com
    Exercise Muscle

    Drop sets are a popular resistance-training method for promoting muscle growth. They involve performing an exercise to muscle failure at a given weight, then reducing the weight and immediately continuing to muscle failure again. A recent review and meta-analysis found that drop sets promote muscle hypertrophy as effectively as traditional training but require less time commitment.

    Researchers analyzed the findings of six studies investigating the effects of drop-set training on muscle hypertrophy. They found that both drop-set and traditional training groups experienced marked muscle growth after training. The drop-set group showed slightly greater improvement than the traditional group, but the difference between the two groups wasn’t statistically significant. Drop-set training took half to one-third the time of traditional training.

    These findings suggest that drop sets are a time-efficient resistance-training strategy for promoting muscle growth. Some of the mechanisms that promote muscle hypertrophy with resistance training include mechanical tension and metabolic stress. Mechanical tension arises from muscle fiber force generation and stretch, while metabolic stress involves the accumulation of exercise-induced metabolites. Drop sets might enhance muscle hypertrophy by causing greater muscle fatigue than traditional sets, potentially activating all motor units and maximizing muscle growth. Learn more about drop sets and other time-efficient strategies for promoting muscle growth in this clip featuring Dr. Brad Schoenfeld.

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  • Heavy resistance training for a year mitigates age-related muscle function decline in retirees, extending benefits over four years. t.co
    Exercise Aging Muscle

    As people age, they often experience muscle function and size declines, adversely affecting their health and overall quality of life. However, evidence suggests exercise can forestall these effects. A recent study found that one year of supervised resistance training with heavy loads exerts lasting benefits on muscle function in older adults.

    Researchers conducted a randomized controlled trial involving 451 older adults at retirement age. They assigned participants to one of three groups: heavy resistance training, moderate-intensity training, or a non-exercising control group. They measured participants' leg extensor power, isometric leg strength, and body composition before and after the one-year intervention and again at two and four years after the study started.

    They found that participants in the heavy resistance training group maintained their baseline isometric leg strength without notable decline over the four years. In contrast, participants in the moderate-intensity and control groups experienced decreased leg strength over time.

    The heavy resistance training protocol involved a full-body workout performed three times a week, using machines in a commercial gym while under supervision. Participants spent the first six to eight weeks getting accustomed to the routine and then completed three sets of six to 12 repetitions for each exercise at about 70% to 85% of their maximum effort.

    These findings suggest that one year of heavy resistance training can help preserve muscle function in older adults, potentially mitigating typical age-related declines in muscle strength. They also highlight the importance of incorporating resistance training into exercise programs for older adults to promote healthy aging. Learn more about resistance training for older adults in this clip featuring Dr. Brad Schoenfeld.

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  • High-dose dietary vitamin D allocates excess calories to muscle growth instead of fat storage. pubmed.ncbi.nlm.nih.gov
    Vitamin D Exercise Fat Muscle

    Fat tissue produces leptin, a hormone that communicates with the brain to regulate energy balance. When fat mass increases, leptin levels in the blood also rise, signaling the brain to curb appetite and increase energy use. However, in obesity, the body’s sensitivity to leptin is reduced, blunting these regulatory effects. A recent study in mice found that vitamin D allocates excess calories to muscle growth instead of fat storage by regulating leptin and myostatin, a hormone involved in muscle growth.

    Researchers fed mice diets containing low, moderate, or high doses of vitamin D for four weeks to induce deficient, normal, and high vitamin D concentrations, respectively. Then, they measured changes in the animals' blood concentrations of leptin and myostatin and assessed their strength.

    They found that high doses of vitamin D increased leptin production and sensitivity while decreasing myostatin production. These changes elicited a greater allocation of excess calories to muscle and linear growth instead of fat storage.

    These findings suggest that high-dose vitamin D could effectively manage obesity and related conditions by redirecting calories from fat storage to muscle growth. They also highlight the interplay between vitamin D, leptin, and myostatin. Learn more about vitamin D in our comprehensive overview article.

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  • In older adults with type 2 diabetes, high-intensity resistance training decreases blood glucose levels by 12 percent and strengthens muscles by 33 percent. pubmed.ncbi.nlm.nih.gov
    Exercise Aging Diabetes Muscle

    Type 2 diabetes is a metabolic disorder characterized by high blood glucose, increasing the risk for a wide range of complications, including kidney dysfunction, vision loss, and circulatory problems. However, evidence suggests that exercise improves blood glucose control. A 2002 study found that resistance training improved blood glucose control in people with type 2 diabetes.

    The study involved 62 older adults with type 2 diabetes. Half of the participants engaged in a 16-week high-intensity resistance training program (gradually increasing in intensity), while the other half maintained their typical activities. Researchers measured participants' glycated hemoglobin levels (HbA1c, a measure of long-term blood glucose control), body composition, and muscle glycogen stores before and after the intervention.

    They found that among resistance training participants, HbA1c decreased by approximately 12 percent, muscle glycogen increased by 31 percent, and muscle strength increased by 33 percent. Those who engaged in resistance training also experienced reductions in blood pressure and body fat, and their need for diabetes medications decreased.

    These findings suggest that resistance training is a robust adjunct to type 2 diabetes treatments, effectively improving blood glucose control and metabolic health. Resistance training involves pushing or pulling against the resistance of an object, such as weights, bands, or even one’s body weight. Older adults starting a resistance training program may benefit from using lighter weights and performing more repetitions, especially if they have chronic joint problems. Learn more in this episode featuring Dr. Brad Schoenfeld.

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  • Creatine supplementation improves muscle strength and function, potentially averting functional disability in older adults. aspenjournals.onlinelibrary.wiley.com
    Aging Muscle Supplements

    Older adults often experience acquired functional disability – a newfound inability to carry out tasks necessary for independent living. This disability often arises due to the skeletal muscle wasting that can occur with acute periods of disuse, such as during hospitalization or illness. A recent systematic review found that creatine supplementation improved physical function in older adults at risk for acquired functional disability.

    Researchers analyzed the findings of randomized controlled trials that investigated the effects of creatine supplementation on physical function in older adults. Their analysis included 33 trials and more than 1,000 participants, about half of whom had a chronic disease.

    They found that creatine supplementation improved participants' handgrip strength, lean tissue mass, and upper-body muscle strength with few adverse effects. About two-thirds of the studies practiced creatine loading, with a daily maintenance dose ranging from 0.07 to 0.3 grams per kilogram of body weight. The most common dose was 5 grams daily. The investigators deemed the quality of evidence as “low” or “very low” due to study heterogeneity.

    These findings suggest that creatine supplementation prevents acquired functional disability in older adults. A possible contributor to acquired functional disability is catabolic crisis, a phenomenon defined by periods of accelerated declines in muscle mass and functional capacity. Catabolic crisis can occur at any age but is more common among older adults, for whom injuries, surgeries, or prolonged illnesses dictate long and sometimes frequent periods of physical inactivity or immobilization. These cumulative insults drive older adults toward a disability threshold from which they might not recover. Omega-3 fatty acid supplementation may reduce the risk of catabolic crisis. Learn more in this episode featuring Dr. Chris McGlory.

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  • Older adults improve muscle strength, waist circumference, and cholesterol levels by boosting protein intake and engaging in regular exercise. onlinelibrary.wiley.com
    Nutrition Exercise Diet Aging Muscle Protein

    Maintaining muscle mass as we age requires a comprehensive approach encompassing nutrition and regular physical activity. However, many older adults don’t consume adequate dietary protein and may lead sedentary lives, due to injuries, chronic illnesses, or joint problems. A recent study found that older adults who increased their dietary protein intake and engaged in regular exercise showed marked improvements in multiple health and fitness parameters.

    The study involved 97 older adults (average age, 64) with low dietary protein intake (less than 1 gram per kilogram of body weight daily) who had experienced at least one fall in the past year. Half of the participants received a daily serving of a protein-enriched soup (providing 24 to 30 grams of protein) and engaged in one hour of group exercise (aerobic and resistance) each week for 12 weeks. The other half received nutrition education training at the beginning of the study and maintained their normal activity levels.

    At the end of the study, sedentary participants showed improvements in handgrip strength only. However, the participants who consumed the protein-rich soup and exercised regularly showed improvements in waist circumference, walking distance, lower body strength, functional mobility, handgrip strength, nutritional status, serum triglycerides, HDL cholesterol, and DHEA-S.

    DHEA-S (dehydroepiandrosterone sulfate) is a naturally occurring precursor to estrogen and testosterone. These steroid hormones exert anabolic effects by enhancing the bioavailability of insulin-like growth factor-1 in muscles, facilitating muscle growth and repair.

    These findings suggest that increasing dietary protein and activity levels in older adults improves multiple health and fitness parameters. Interestingly, most of the participants in this study were female. Evidence suggests women typically consume less protein than men. In this clip, Dr. Stuart Phillips provides some insights to help older women get sufficient protein to support muscle health.

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  • Increasing protein intake during breakfast increases muscle mass, particularly in older adults. pubmed.ncbi.nlm.nih.gov
    Nutrition Diet Muscle Protein

    Although exercise is the primary stimulus for maintaining muscle mass and strength, nutritional support is essential, too, especially in the form of dietary protein. However, most people’s protein intake is skewed toward later in the day, with little to no protein at breakfast. A recent review found that older adults with higher protein intake at breakfast had greater muscle mass.

    Researchers reviewed the findings of 15 studies examining associations between protein intake and muscle mass. The various studies included cross-sectional, case-control, cohort, and randomized controlled trials involving primarily older males and females. However, one study included middle-aged females, and one included young males.

    The researchers found that consuming a high-protein breakfast (ranging between 0.27 and 0.53 grams per kilogram bodyweight) increased muscle mass, particularly in older adults. While some of the studies' findings suggested that a high-protein breakfast enhanced muscle strength, the evidence was inconsistent across all studies.

    These findings suggest that increasing protein intake at breakfast supports muscle mass maintenance. The investigators posited that increasing protein intake during breakfast could be a beneficial strategy for supporting muscle health for active adults or those in resistance training. However, individual results may vary, indicating the need for more personalized dietary recommendations. Learn more about the role of dietary protein in building and maintaining muscle in this episode featuring Dr. Stuart Phillips.

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  • Interrupting prolonged sitting with ten body-weight squats improves blood glucose levels better than a 30-minute walk. onlinelibrary.wiley.com
    Exercise Diabetes Muscle Blood Sugar

    Prolonged sitting is a prominent feature of modern life. Unfortunately, it carries considerable health risks, including impaired glucose metabolism and an increased risk of type 2 diabetes. A recent study found that interrupting prolonged sitting periods with short bursts of activity – especially frequent walks or squats – improves blood glucose levels.

    The study involved 18 men with overweight and obesity who engaged in four different activities on separate days: sitting uninterrupted for 8.5 hours, or sitting interrupted by a single 30-minute walk, ten three-minute walks (every 45 minutes), or ten three-minute squat sessions (every 45 minutes). Researchers assessed the participants' blood glucose levels using continuous glucose monitors and gauged their muscle activity, especially in the quadriceps, hamstrings, and gluteal muscles, using an electromyogram.

    They found that any form of sitting interruption reduced blood glucose levels better than uninterrupted sitting, with the frequent three-minute walks and squat exercises outperforming the single 30-minute walk. Increased muscle activity, particularly in the quadriceps and gluteal muscles, correlated strongly with these improvements.

    These findings suggest that interrupting prolonged sitting with frequent, short bouts of physical activity, especially those that engage the lower body muscles, is more effective in enhancing glycemic control than a single, longer session of activity. Evidence suggests that these short bursts of activity, often called “exercise snacks,” improve cardiorespiratory fitness and markers of immune function. Learn more in this clip featuring Dr. Martin Gibala.

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  • High-dose statin impairs mitochondrial energy output by more than 30 percent in adults with overweight. pubmed.ncbi.nlm.nih.gov
    Cholesterol Mitochondria Drug Muscle Cardiovascular

    Statins comprise a large class of drugs that lower blood cholesterol levels by blocking the production of an enzyme involved in cholesterol synthesis. Although statins are generally well tolerated, as many as 10 to 20 percent of people taking the drugs experience complications, including myopathy (muscle damage), liver damage, and cognitive problems. A recent study found that atorvastatin, a commonly prescribed statin, reduces muscle cells' energy production.

    The study involved eight inactive but otherwise healthy adults with overweight who took a high dose of atorvastatin (80 milligrams) daily for 56 days. Researchers collected muscle samples from the participants before they took the statin and then again after 14, 28, and 56 days to assess their muscle cells' capacity for energy production.

    They found that over the 56 days, the muscle cells' ability to produce energy via oxidative phosphorylation diminished by more than 30 percent. Additionally, the muscle’s capacity to use oxygen, a key indicator of cardiorespiratory fitness, dropped by as much as 45 percent. The study investigators attributed this decline to the statin’s inhibition of specific components (complexes III and IV) within the mitochondria that are vital for energy production.

    The findings from this very small study shed light on how high-dose atorvastatin therapy can significantly reduce the energy production in muscle cells, driving a decrease in muscle and aerobic fitness. They also underscore the importance of further research in larger groups to balance the health benefits of statins with their potential effects on muscle function. Learn more about statins in this deep-dive discussion with Dr. Peter Attia.

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  • Increased dietary fiber intake can help maintain muscle mass in older adults, potentially offering protection against age-related muscle loss. pubmed.ncbi.nlm.nih.gov
    Diet Aging Muscle Fiber

    Sarcopenia is an age-related condition involving the gradual loss of muscle mass and strength. Older adults with sarcopenia are at greater risk for frailty, falls, loss of independence, and early death. A 2022 study found that higher dietary fiber intake maintains muscle mass in older adults.

    Researchers assessed the physical capabilities (including balance, walking speed, and grip strength) of 981 older adults. They also measured their muscle mass using DEXA. Participants reported their dietary fiber intake and wore accelerometers to track their physical activity.

    The DEXA scans revealed that women who consumed more fiber had considerably greater muscle mass than those who ate less. Men who consumed more fiber also had greater muscle mass, but only in those without metabolic syndrome. The associations were consistent even when considering physical activity and protein consumption.

    These findings suggest that dietary fiber protects against muscle loss in older adults. Sources of dietary fiber include fruits, vegetables, whole grains, and legumes. People who follow a lower carbohydrate diet might find getting enough fiber challenging. Dr. Dominic D'Agostino provides some tips on how to get plenty of fiber even when following a ketogenic diet.

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  • A daily protein intake of greater than 1.8 grams per kilogram of body weight likely pays the greatest dividends for promoting muscle protein synthesis in trained women. onlinelibrary.wiley.com
    Exercise Diet Muscle Protein

    Robust evidence supports dietary protein intake to support muscle protein synthesis after resistance training. However, most studies investigating the effects of dietary protein have been conducted in men. A recent study found that a daily protein intake greater than 1.8 grams per kilogram of body weight optimized muscle protein synthesis in trained women.

    Researchers asked 24 young women who regularly engaged in resistance training to engage in two resistance training sessions separated by a four-hour break. After each session, the women consumed 15, 30, or 60 grams of whey protein. These amounts provided the women 1.8, 2.3, and 3.2 grams of protein per kilogram of body weight, respectively. Over 24 hours post-workout, the researchers measured the women’s muscle protein synthesis and blood amino acid levels.

    They found that 15 grams of whey protein had little effect on muscle protein synthesis. However, after consuming 30 or 60 grams of whey protein, the women’s muscle protein synthesis increased, especially in the first eight hours post-workout. Interestingly, there was little difference in muscle protein synthesis between the 30- and 60-gram doses.

    Current dietary guidelines recommend that healthy adults consume 0.8 grams of protein per kilogram of body weight per day. However, this intake level is likely too low for building and maintaining muscle mass. The findings from this study suggest that increasing the recommended amount, ensuring a daily intake of greater than 1.8 grams per kilogram of body weight, will pay the greatest dividends for promoting muscle protein synthesis in trained women. Learn more about the importance of dietary protein in this episode featuring Dr. Stuart Philips.

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  • Omega-3s protect the heart and muscles against damage incurred during endurance running. www.ncbi.nlm.nih.gov
    Exercise Heart Disease Omega-3 Inflammation Muscle

    The physical stress of marathon running can promote exercise-induced muscle damage, reducing muscle force production, elevating blood cytokines, and driving systemic inflammation. Consequently, despite having high cardiorespiratory and neuromuscular fitness, marathon runners are susceptible to lower extremity muscle injuries, cardiac dysfunction, and arrhythmia, particularly as running intensity escalates. A recent study shows that supplemental omega-3 fatty acids ameliorate some of the harmful effects of endurance running.

    The study involved 24 male long-distance runners. Half of the runners received 3,000 milligrams (mg) of omega-3s (852 mg EPA; 1,602 mg DHA) daily for three weeks, and the other half took a placebo. After the third week of supplementation, the participants performed a downhill running exercise test. The researchers measured the participants' cardiac markers, inflammatory cytokines, and blood lipids and assessed their Omega-3 Index, a measure of omega-3 concentrations in red blood cell membranes.

    They found that the participants' Omega-3 Indices increased from 3.9 to 4.8, roughly 23 percent relative to baseline when they took supplemental omega-3s. Markers of cardiac injury (troponin and creatine kinase isoenzyme MB) and the inflammatory cytokine TNF-alpha decreased. Participants' HDL cholesterol levels also increased.

    These findings suggest that supplemental omega-3s ameliorate some of the harmful effects of endurance running, possibly due to omega-3s' potent anti-inflammatory properties. Learn more about the health effects of omega-3s in this episode featuring Dr. Bill Harris.

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  • Naringenin, a citrus fruit flavonoid, preserves muscle mass in aging while enhancing exercise capacity and aerobic metabolism efficiency (animal study). medicalxpress.com
    Nutrition Aging Muscle Polyphenol

    Muscle mass declines markedly with age, with up to 8 percent muscle mass loss occurring per decade after age 30. Evidence suggests that naringenin, a flavonoid compound found in citrus fruits, maintains muscle mass in aging. Mice that ate a diet supplemented with naringenin showed improved muscle endurance and grip strength.

    Researchers supplemented the diets of young adult mice, middle-aged mice, and mice prone to muscular dystrophy (accelerated muscle loss) with naringenin. Then, they assessed naringenin’s effects on exercise capacity and aerobic metabolic levels in skeletal muscle.

    They found that young adult and middle-aged mice receiving naringenin could run farther than those that did not. Middle-aged mice also showed improved grip strength and increased calf muscle size. Mice prone to developing muscular dystrophy ran farther and showed improved grip strength.

    The researchers attributed these improvements in muscle endurance to naringenin’s capacity to increase the number of oxidative myofibers (muscle fibers that use oxygen) and improve the overall efficiency of aerobic metabolism in the body. They found that Sp1, a transcription factor that influences gene expression in muscle, likely mediated naringenin’s effects.

    These findings indicate that naringenin may preserve muscle mass in aging and disease. Other dietary components, such as omega-3 fatty acids, influence muscle maintenance, too. Learn more in this episode featuring Dr. Chris McGlory.

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  • Vitamin D increases muscle strength and mass without altering body weight in mice. www.biorxiv.org
    Vitamin D Obesity Aging Metabolism Hormones Muscle

    Vitamin D, best known for maintaining calcium balance and bone health, is critical in many physiological processes, including blood pressure regulation, immune function, and cell growth. Evidence now suggests vitamin D also influences body composition and muscle strength. A recent study in mice showed that high vitamin D intake increased muscle strength and mass without altering body weight.

    Researchers fed mice one of three diets, providing low, normal, and high doses of vitamin D for four weeks to achieve deficient, insufficient, and sufficient vitamin D concentrations, respectively. At the end of the fourth week, they assessed the animals' grip strength (a measure of muscle function) and body composition.

    They found that compared to low or normal vitamin D intake, high intake increased grip strength and lean mass and decreased fat mass without altering the animals' weights. High intake also impaired myostatin production and increased the animals' leptin sensitivity and energy expenditure without altering their activity levels.

    Leptin is a satiety hormone that signals the brain to balance energy. When body fat increases or decreases, blood concentrations of leptin change accordingly. Higher leptin levels signal the brain to reduce hunger and boost energy use. However, in obesity, the body becomes less responsive to leptin, dulling its effects on appetite and energy expenditure.

    These findings suggest that vitamin D influences body composition and metabolism by preferentially allocating calories toward muscle development and overall growth rather than fat storage. They also highlight the intricate relationship between obesity and vitamin D status. Learn more about vitamin D in our comprehensive overview article.

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  • Genes involved in muscle function, energy production and utilization, and oxygen delivery play critical roles in how exercise boosts VO2 max. bmcgenomics.biomedcentral.com
    Exercise Metabolism Genetics Muscle Aerobic

    VO2 max – the maximum rate of oxygen a person can consume during exercise – is a robust predictor of a person’s risk for chronic diseases and death. Exercise increases VO2 max, but how well a person responds to exercise training varies considerably and may be influenced by genetics. A 2017 systematic review identified nearly 100 genes that likely influence a person’s VO2 max response to exercise training.

    Researchers reviewed 35 studies investigating genetic variants in the context of supervised aerobic exercise interventions aimed at improving VO2 max. The studies were based on DNA samples from more than 4,200 people of varied genetic makeup.

    The researchers' analysis identified 97 genes that might influence a person’s VO2 max response to exercise training by modulating muscle function and efficiency, electrolyte balance, lipid metabolism, oxidative phosphorylation, energy production, and oxygen delivery. They found that people who responded more favorably to exercise training tended to have more positive response alleles – genetic variants associated with a more favorable or beneficial response to exercise training – in those genes.

    These findings highlight the influence of specific genetic variants on a person’s response to exercise training and their effect on VO2 max improvements. However, the authors cautioned that while most of the articles reviewed in their analysis primarily investigated a single or a limited number of candidate genes or markers, exercise-related traits are intricate and influenced by multiple genes working in concert. Learn how Tabata, a type of HIIT, increases VO2 max in this clip featuring Dr. Martin Gibala.

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  • High-intensity interval training counteracts muscle protein loss induced by sleep deprivation. www.ncbi.nlm.nih.gov
    Exercise Sleep Muscle Protein Aerobic

    Sleep deprivation profoundly affects the human body, negatively influencing cognitive performance, cardiovascular health, and more. Findings from a 2020 study suggest that sleep deprivation impairs muscle protein synthesis, but exercise counters this effect. People who slept only four hours per night but engaged in high-intensity interval training (HIIT) exhibited muscle protein synthesis comparable to those who slept a full night.

    Researchers assigned 24 healthy young men to one of three five-night sleep protocols: normal sleep (eight hours nightly), sleep restriction (four hours nightly), and sleep restriction with HIIT. Researchers collected muscle biopsies to assess muscle protein synthesis before and after the intervention.

    They found that the group with sleep restriction had lower rates of muscle protein synthesis than those with normal sleep and those who combined sleep restriction with HIIT.

    HIIT is a time-efficient strategy to promote cardiovascular fitness and metabolic health. Its flexibility accommodates a wide range of exercises, including walking, running, cycling, and even resistance training, making it accessible to people of different fitness levels and abilities.

    This was a small study, but the findings suggest that sleep restriction reduces muscle protein synthesis, potentially contributing to muscle loss. However, engaging in HIIT during periods of sleep restriction helps maintain muscle protein synthesis, potentially counteracting the adverse effects of sleep loss on muscle mass. Learn more about the benefits of HIIT in this episode featuring Dr. Martin Gibala

    Former FMF guest Dr. Stuart Phillips was a collaborator and participant in this study. Learn more about Dr. Phillips' research in this episode.

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  • Greater lean muscle mass linked to a 12 percent reduction in Alzheimer's disease risk, suggesting exercise can play a critical role in prevention. medicalxpress.com
    Alzheimer's Genetics Muscle

    A growing body of evidence links excess body fat to an increased risk for Alzheimer’s disease, likely due to several factors, including heightened inflammation, insulin resistance, and elevated levels of amyloid-beta (a pathological hallmark of the disease) in fat tissue. A recent study found that greater lean muscle mass reduced the risk for Alzheimer’s disease by 12 percent.

    Using Mendelian randomization techniques, researchers analyzed health data and cognitive performance of more than a million people with or without Alzheimer’s disease. Mendelian randomization is a research method that provides evidence of links between modifiable risk factors and disease based on genetic variants within a population. They calculated the participants' muscle mass based on genetic factors, often referred to as genetic proxies.

    They found that people with greater genetically proxied lean muscle mass in the arms and legs were 12 percent less likely to develop Alzheimer’s disease, even when accounting for genetic factors that may influence risk. They also demonstrated better cognitive performance.

    These findings suggest that lean muscle mass protects against Alzheimer’s disease. However, the researchers noted that whether increasing lean muscle mass can reverse the pathology of Alzheimer’s disease in people with preclinical disease or mild cognitive impairment is unclear. Learn how resistance training helps build and maintain lean muscle mass in this clip featuring Dr. Brad Schoenfeld.

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  • Vitamin D may be critical in building strong muscles and combating obesity. www.biorxiv.org
    Vitamin D Obesity Muscle

    Poor strength and muscle mass are linked with many disease states, including obesity, diabetes, and chronic inflammation. A new study in mice shows that vitamin D is critical in building and maintaining muscle. Mice with higher vitamin D levels had greater strength and muscle mass and less fat mass than those with lower levels.

    Researchers fed mice three different diets over a period of 12 weeks to induce deficient, normal, and high blood concentrations of vitamin D. They measured the animals' strength and body composition before and after each dietary intervention. They also measured levels of myostatin (a hormone that inhibits muscle growth) and leptin (a hormone that maintains bodyfat stores) in the animals' blood.

    They found that vitamin D-deficient mice had poor strength and low muscle mass. Boosting vitamin D levels to normal (20-30 ng/mL) increased the animals' muscle strength but did not increase muscle mass. However, raising vitamin D to high concentrations increased both strength and muscle mass. This increase occurred without a corresponding weight increase but with a decrease in fat mass, implying that vitamin D redistributed dietary calories from fat to muscle. Higher vitamin D concentrations were associated with reductions in myostatin levels and increases in leptin levels.

    These findings suggest that high vitamin D concentrations decrease myostatin production and increase leptin production, redirecting excess calories to muscle growth instead of fat storage. Learn more about the health benefits of vitamin D in our comprehensive overview article.

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  • Regular cycling may slow age-related muscle loss and weakness. apple.news
    Exercise Aging Fat Muscle

    A new study found that regular cycling may slow sarcopenia – the age-related loss of muscle mass and strength. Men who cycled regularly had larger, leaner gluteus muscles than inactive men.

    The study involved two groups of men: 28 who were physically inactive and had not practiced sports for an average of 27 years and 28 who were trained recreational male cyclists, had cycled more than 4,300 miles in the past year, and had been cycling for an average of 15 years. Researchers used magnetic resonance imaging to determine the volume of the participants' gluteus maximus and gluteus medius muscles, which are situated in and around the buttocks, as well as the percentage of fat infiltration within those muscles.

    They found that the inactive group tended to be heavier than the cyclists. They also found that the cyclists had larger gluteus maximus and gluteus medius muscles than the males in the inactive group. On average, the cyclists had 7 percent less fat infiltration in the gluteus maximus and 5 percent less in the gluteus medius than the males in the inactive group.

    Research suggests that physical inactivity promotes muscle fat infiltration and progressive muscle weakness, driving sarcopenia – the age-related loss of muscle tissue. However, exercise and appropriate nutritional support may forestall these muscle losses. Learn how exercise and dietary protein play roles in slowing age-related muscle loss in this episode featuring Dr. Stuart Phillips.

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  • Hydrolyzed collagen increases knee joint strength and tendon stiffness by 18 percent. www.frontiersin.org
    Muscle Bone Supplements

    A new study shows that hydrolyzed collagen strengthens knee tendons in female soccer players. Those who took supplemental collagen experienced an 18 percent gain in knee tendon stiffness, potentially reducing their risk for injury during play.

    The study involved 17 elite teenage female soccer players. Half of the players consumed a hydrolyzed collagen supplement plus vitamin C three times a week for ten weeks. The other half consumed a placebo. Both groups participated in a training regimen designed to strengthen the knee and thigh muscles. A team of researchers measured various parameters of the players' knee tendon thickness and strength before and after the intervention.

    They found that the players who consumed the supplemental hydrolyzed collagen experienced an 18 percent increase in their knee tendon stiffness. However, they experienced little change in tendon thickness, suggesting that the increase in stiffness was due to changes in the tendon’s material properties subsequent to collagen intake.

    Female soccer players are more likely to experience knee injuries than male players, due in part to greater knee joint laxity. These findings suggest that supplemental hydrolyzed collagen support training regimens to bolster knee strength in female athletes.

    Hydrolyzed collagen is a mixture of peptides derived from the protein collagen. Evidence suggests that supplemental hydrolyzed collagen consumption improves skin aging, decreases arthritis-induced pain, increases bone mineral density, and decreases hypertension. Learn more about hydrolyzed collage in our overview article.

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  • Blood flow-restricted training may increase growth hormone secretion, activate mTOR, and promote fast-twitch fiber recruitment at low intensity.(2019) journals.lww.com
    Exercise Hormones Muscle BFR

    From the publication:

    The low-pH environment induced by the metabolic accumulations is known to stimulate growth hormone (GH) secretion, which is known to possibly have an interactive effect toward MPS [muscle protein synthesis]. There is continual debate over the direct hypertrophic actions of GH toward overall MPS. […] The implementation of BFR training in 1 study has been found to elevate GH levels to ∼290. Another study has found that skeletal muscle ischemia coupled with low-intensity resistance exercise through knee extensions acutely increased GH levels, whereas reducing the maximal voluntary contraction. It is known that the implementation of Kaatsu training [blood flow–restricted training] increased the postexercise GH levels 10-fold above the control group with no blood flow–restriction.

    […]

    According to the literature, it is also known that a single bout of low-intensity resistance exercise with blood flow restriction can result in both an upregulation of the anabolic cell signaling mTOR pathway within 3 hours after exercise and a downregulation of the proteolytic transcripts for skeletal muscle at 8 hours after exercise.

    […]

    In accordance with occlusion training, it is known that compared with slow-twitch (ST) muscle fibers, the fast-twitch (FT) fibers are recruited quickly, although the intensity is low. In other words, BFR training can recruit FT fibers without regards to the widely accepted size principle in which ST fibers are recruited first with FT fibers being recruited as intensity progresses. The rationale presented throughout the literature may be due to the hypoxia conditions created by the vascular occlusion through which the additional recruitment of more motor units may take place to compensate for the deficit in overall force development. In addition, the metabolite accumulations throughout the BFR training session may also induce the increased recruitment of FT or higher threshold motor units. Several studies show through the utilization of electromyography (EMG) that during Kaatsu training, there was an increase in the recruitment of FT muscle fibers. Another study that implemented low-intensity vascular occlusion training showed early fatigue of type I fibers due to the lack of delivery in oxygen, thus showing a greater increase in the CSA [ross-sectional area] of type II fibers by 27.6% compared with type I muscle fibers increase of 5.9% during a 2-week training program at 20% of 1RM.

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  • Blood flow restriction may be effective and safe in treating muscle wasting and improving exercise outcomes in various populations. (2019) www.ncbi.nlm.nih.gov
    Exercise Muscle BFR

    From the publication:

    Evidence has demonstrated that 14 days of BFR [blood flow restriction] are more effective than isometric exercise to prevent muscle waste and weakness induced by immobilization and unloading. [repeated blood flow restriction without training vs isometric training vs no intervention]

    […]

    Several randomized controlled trials and meta‐analyses have shown that RT [resistance training] with BFR (RT‐BFR) [usually low intensity, between 20% and 40% of the 1‐RM load] produces similar muscle hypertrophy response to high intensity RT, in different populations.

    […]

    Moderate to high intensity ET [endurance training] promotes significant increases in cardiorespiratory capacity, with no or small improvements in muscle strength and hypertrophy. However, when ET [endurance training] is performed with BFR (ET‐BFR), there is a significant increase in aerobic power (i.e. maximum oxygen consumption VO2max), as well as increases in muscle strength and hypertrophy.

    […]

    BFR approach has been applied to >12 000 people in Japan across different physical conditions, such as cerebrovascular, orthopaedic, cardiac, respiratory, and neuromuscular diseases, as well as obesity, diabetes, and hypertension, with no significant side effects reported on rheological response. From 300 000 training sessions, only 0.055% of practitioners developed venous thrombus, 0.008% developed pulmonary embolism, and 0.008% of the cohort presented rhabdomyolysis.

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  • Study shows that high protein does not affect kidney function across a wide variety of metrics. journals.humankinetics.com
    Muscle Protein

    “We’ve got 40 years’ worth of data with people on [protein supplementation] now. And we’re not seeing some sort of rife wave of people who used it getting various forms of cancer, etc., which you would expect. Forty years is enough to see the effect.” - Stuart Phillips, Ph.D. on high protein supplementation

    High protein intake is often believed to be harmful to kidney function, but robust evidence indicates that this concern is unfounded. A 2000 study demonstrated that athletes with high protein consumption do not have an increased risk for kidney dysfunction.

    Researchers asked bodybuilders and other athletes to keep detailed dietary records for one week after following their normal dietary patterns for one month. Then the researchers assessed the participants' kidney function via blood tests and urinalysis. They also measured their nitrogen balance – an assessment of the net balance of protein metabolism in the body drawn from estimates of nitrogen losses that occur via urine, feces, sweat, and other means.

    They found that, on average, daily protein intake was approximately 1.97 grams per kilogram of body weight among the bodybuilders and 1.35 grams per kilogram of body weight among the other athletes. Despite their high protein intake, the participants' urinary output of creatinine, urea, and albumin was normal, as were other kidney health parameters. Both the bodybuilders and the other athletes achieved nitrogen balance when their daily protein intake exceeded 1.26 grams per kilogram of body weight.

    The current recommended dietary allowance for protein intake is 0.8 grams per kilogram of body weight (~0.36 grams per pound) per day – about 68 grams for a 150-pound adult. Nutrition experts established this guideline several decades ago, based on evidence from nitrogen balance studies, which are often inaccurate due to problems with collection and overestimation of losses. Based on findings from more recent stable isotope studies, which more accurately assess muscle protein anabolism and catabolism, evidence suggests that eating 1.2 to 1.6 grams of protein per kilogram of body weight is likely optimal for muscle protein synthesis, especially as one ages. Learn more in this episode featuring Dr. Stuart Phillips.

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  • Resistance training reverses age-related muscle loss in older women. www.sciencedirect.com
    Exercise Aging Muscle

    Resistance exercise reduces symptoms of sarcopenia – age-related muscle loss – in older women, a new study has found. Women who engaged in resistance training saw improvements in muscle size, strength, and function.

    Researchers studied the effects of resistance training in 38 women who were 70 years of age or older. About half of the women engaged in a supervised resistance training program for six months, while the other half did not. The researchers assessed the women’s body composition, strength, and capacity to perform basic fitness tests.

    They found that half of the women who engaged in the resistance training experienced remission of their sarcopenia, demonstrated by increases in muscular mass, decreases in fat mass, and enhanced muscular strength and performance in their arms and legs. The women who trained also performed better on tests of leg function and strength as well as balance.

    Sarcopenia is an age-related condition characterized by a progressive loss of muscle mass and associated strength. Because the condition begins as early as one’s 30s, a person in their 70s may have lost as much as half of their muscle mass.

    This study demonstrates that resistance training rebuilds muscle mass in older women. Having sufficient muscle mass markedly reduces a person’s risk of dying prematurely, and actively challenging those muscles, through regular physical activity and exercise, may extend a person’s life by several years. Learn more in this clip featuring Dr. Stuart Phillips.

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  • Eccentric exercises, which emphasize lowering a weight, rather than lifting it, increase muscle size and strength with fewer repetitions. link.springer.com
    Exercise Muscle

    Performing eccentric movements – the “lowering” aspect of lifting a weight – pays huge dividends in muscle size and strength, a new study has found. Study participants who lowered weights achieved similar benefits to those who lifted and lowered weights, even though they performed half as many repetitions.

    Researchers asked 53 young adults who did not regularly lift weights to perform one of three variations of a dumbbell curl twice a week for five weeks. The variations included concentric + eccentric (lifting and lowering) movements, concentric (lifting) movements only, or eccentric (lowering) movements only. One group of participants did not perform any exercises. The researchers measured the participants' upper arm muscle thicknesses before and after the intervention.

    They found that all the participants who performed the various exercises saw improvements in muscle size, strength, and force-generating capacity. In particular, muscle thickness increased by an average of 10.6 percent among those who performed concentric + eccentric movements, 9.7 percent among those who performed eccentric movements only, and 2.5 percent among those who did concentric movements only. Interestingly, the total training volume for those performing eccentric movements was roughly half that of the concentric + eccentric group.

    These findings suggest that performing eccentric movements during resistance training benefits muscle growth and strength – with less effort than concentric movements. [Learn more about eccentric and concentric exercises in this episode featuring Dr. Brad Schoenfeld.](LINK)

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  • Estradiol may act as a regulator of muscle energy metabolism and muscle cell viability: loss of estrogen in menopause may promote sarcopenia www.sciencedaily.com
    Metabolism Hormones Estrogen Muscle Apoptosis

    From the article:

    The effects of estrogen on skeletal muscles are not yet well known. The study from the University of Jyväskylä discovered that estrogen acts as an upstream regulator for the energy metabolism and viability of muscle cells.

    […]

    “These findings help to understand why menopausal women’s muscles get smaller and their muscle strength diminishes,” Dr. Laakkonen explains. Skeletal muscle is important for whole-body metabolism. Therefore, these results are important when fighting against the elevated risk of metabolic diseases associated to aging.

    In total 24 pre- and postmenopausal women participated in this muscle research on middle-aged women.

    From the publication:

    The major canonical pathways found to be differentially regulated included mitochondrial dysfunction, oxidative phosphorylation, glycolysis, and TCA-cycle, strong indicators for affected energy metabolism. The major biological processes predicted to be affected were related to cell death, apoptosis, and cell survival, as well as contractility of the muscle and glycolysis. Furthermore, E2 [17β-estradiol] was predicted to be an upstream regulator of these processes, which we confirmed by exposing myotubes to E2 in vitro.

    View full publication

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  • Testosterone treatment of older men didn`t affect functional status or cognition but increased lean body mass and had mixed metabolic effects. (2008) www.sciencedaily.com
    Hormones Cholesterol Testosterone Muscle Bone Insulin Weight Loss Cardiovascular

    From the article:

    Marielle H. Emmelot-Vonk, M.D., of University Medical Center Utrecht, the Netherlands, and colleagues conducted a randomized, placebo-controlled study to assess the effects of testosterone supplementation on functional mobility, cognition, bone mineral density, body composition, lipids, quality of life, and safety parameters in older men with testosterone levels less than 13.7 nmol/L (less than the average level in this age group) during a period of six months. The trial, conducted from January 2004 to April 2005, included 207 men between the ages of 60 and 80 years. Participants were randomly assigned to receive 80 mg of testosterone undecenoate or a matching placebo twice daily for six months.

    The researchers found that during the study, lean body mass increased and fat mass decreased in the testosterone group compared with the placebo group but these factors were not accompanied by an increase of functional mobility or muscle strength. Cognitive function and bone mineral density did not change. Insulin sensitivity improved but high-density lipoprotein cholesterol (the “good” cholesterol) decreased. By the end of the study, 47.8 percent in the testosterone group vs. 35.5 percent in the placebo group had the metabolic syndrome (a strong risk factor for cardiovascular disease and type 2 diabetes, a group of several metabolic components in one individual including obesity and dyslipidemia). This difference was not statistically significant.

    Quality-of-life measures did not differ aside from hormone-related quality of life in the testosterone group. Adverse events were not significantly different in the two groups. Testosterone supplementation was associated with an increase in the concentrations of blood creatinine, a measure of kidney function, and hemoglobin and hematocrit, two red blood cell measures. No negative effects on prostate safety were detected (some reports have suggested that testosterone therapy could increase the risk of development or progression of prostate disease or cancer).

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  • The beneficial effects of 6 months of testosterone treatment on frailty in older men were not maintained 6 months after treatment. (2010) www.sciencedaily.com
    Aging Hormones Testosterone Muscle Weight Loss

    From the article:

    Frailty is an age-related state of physical limitation caused by the loss of muscle mass and function and can lead to adverse clinical outcomes such as dependency, institutionalization and death. Testosterone levels naturally decline with aging and testosterone replacement is a common therapy. Short-term testosterone treatment in frail elderly men has been shown to improve muscle mass and strength, but until now it has been unclear whether these effects could be maintained post-treatment.

    […]

    In this study, researchers evaluated 274 intermediate-frail and frail elderly men aged 65-90 years with low testosterone levels. Study participants received either a testosterone gel or placebo for six months. Assessments were carried out at baseline, the end of treatment and six months after treatment cessation. Researchers found that the increased lean body mass, muscle strength and quality of life after six months of testosterone treatment were not maintained six months after treatment.

    “At present, the optimal duration of anabolic hormonal intervention to produce sustained benefits in treating frailty in older men is unknown,” said Wu. “To best interrupt the downward spiral into frailty a greater emphasis should be placed on a multi-disciplinary interventional approach including resistance exercise, diet and other lifestyle options, in conjunction with pharmacological agents.”

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  • Older men with higher testosterone levels may lose less muscle mass as they age. (2011) www.sciencedaily.com
    Aging Hormones Testosterone Muscle

    From the article:

    “Our study finds that men, aged 65 years and older, with higher testosterone levels lost less muscle mass, especially in their arms and legs, than men this age who had lower testosterone levels,” said Erin LeBlanc, MD, of Kaiser Permanente Northwest in Portland, OR and lead author of the study. “Men who had higher testosterone levels before they lost weight also lost less leg function and could stand up more easily from a chair than men who had lower testosterone levels before they lost weight.”

    In this study, researchers used data from 1,183 men aged 65 years or older and tested the hypothesis that higher baseline measures of sex steroids are associated with lesser declines in lean mass and maintenance of physical performance over an average follow-up of 4.5 years. Body composition was measured using dual energy x-ray absorptiometry (DXA) scans and physical performance was measured through a series of exercises that assessed grip strength, lower extremity power, walking speed and the ability to rise from a chair without the use of arms.

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  • Testosterone-deficient men on testosterone therapy lost 6.6 pounds more body fat while dieting but maintained muscle mass. (2016) www.sciencedaily.com
    Diet Obesity Hormones Fat Testosterone Muscle

    From the article:

    For the first 10 weeks, all participants were placed on a strict 600 kcal per day very-low calorie diet. They were also encouraged to abstain from alcohol and perform at least 30 minutes a day of moderate exercise. From the 11th through the 56th week, participants in both groups used a weight-maintenance diet based on the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) Total Wellbeing Diet comprising of normal foods.

    Every 10 weeks over the 56-week-long study, 49 men also received injections of 1,000mg of intramuscular testosterone undecanoate, and 51 took placebo.

    At the end of 56 weeks, both groups lost roughly 11 kg (24.2 lb). But those in the testosterone group lost almost exclusively fat, while those on placebo lost both lean and fat. The men taking testosterone lost 3 kg (6.6 lb) more body fat than those on placebo and maintained their muscle mass, while those on placebo lost 3.5 kg (7.7 lb) of muscle mass.

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  • Short-term aerobic conditioning prior to resistance training augments muscle hypertrophy and satellite cell content in healthy young men and women pubmed.ncbi.nlm.nih.gov
    Exercise Muscle Aerobic

    Aerobic exercise pre-conditions muscles for optimal returns from resistance exercise.

    Skeletal muscle contains a designated population of adult stem cells called satellite cells. These cells are typically inactive, but if the muscle is injured or stressed (as in exercise), they can be recruited to participate in the regeneration of muscle fibers. As such, satellite cells play important roles in muscle maintenance, repair, and hypertrophy, the increase in muscle size that accompanies exercise. Findings from a new study suggest that engaging in aerobic exercise prior to resistance training increases satellite cell numbers and promotes muscle hypertrophy via increased muscle capillarization.

    Muscle capillarization refers to the formation of capillaries in muscle tissue. Capillarization facilitates the delivery of oxygen, nutrients, and various signaling and growth factors to muscle tissues and plays critical roles in muscle maintenance and growth. Previous research indicates that muscle capillarization decreases with age.

    The study involved 14 healthy, recreationally active young adults (average age, 22 years). Using a specially adapted exercise bike that challenged only one leg, participants engaged in 45 minutes of progressively difficult aerobic exercise conditioning three times a week for six weeks. Previous research has demonstrated that six to eight weeks of conditioning is sufficient to promote muscle capillarization.

    Two weeks after completing the conditioning program, the participants began a 10-week resistance training program using both legs and primarily targeting the muscles of the thighs. Immediately after each resistance training session, participants received a whey protein supplement that contained leucine, a branched-chain amino acid that promotes muscle protein synthesis, which is essential for muscle gains. The investigators collected muscle tissue samples from the participants' legs before and after the interventions to assess muscle capillarization, fiber size, and satellite cell content and activity.

    They found that aerobic conditioning promoted muscle capillarization in the conditioned leg, amplifying muscle hypertrophy in response to resistance training. They noted that the number of satellite cells increased in the conditioned leg relative to the non-conditioned one. In addition, they observed a significant relationship between the degree of capillarization and hypertrophy.

    These findings suggest that engaging in aerobic exercise prior to resistance training promotes muscle capillarization, which in turn increases satellite cell numbers and promotes muscle protein synthesis and hypertrophy. Learn about other factors that promote muscle hypertrophy in this episode featuring Dr. Stuart Phillips.

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  • Potential role of passively increased muscle temperature on contractile function link.springer.com
    Heat Stress Muscle Sauna Strength

    Declines in muscle force, power, and contractile function can be observed in older adults, clinical populations, inactive individuals, and injured athletes. Passive heating exposure (e.g., hot baths, sauna, or heated garments) has been used for health purposes, including skeletal muscle treatment. An acute increase in muscle temperature by passive heating can increase the voluntary rate of force development and electrically evoked contraction properties (i.e., time to peak twitch torque, half-relation time, and electromechanical delay). The improvements in the rate of force development and evoked contraction assessments with increased muscle temperature after passive heating reveal peripheral mechanisms’ potential role in enhancing muscle contraction. This review aimed to summarise, discuss, and highlight the potential role of an acute passive heating stimulus on skeletal muscle cells to improve contractile function. These mechanisms include increased calcium kinetics (release/reuptake), calcium sensitivity, and increased intramuscular fluid.

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  • Creatine supplementation and aging musculoskeletal health link.springer.com
    Nutrition Aging Muscle

    Creatine prevents age-related muscle losses.

    Creatine is a nitrogen-containing compound that is produced in the liver and kidneys and stored in the brain and muscles. It plays essential roles in the recycling of adenosine triphosphate, or ATP. Creatine is also present in the diet in meat and seafood and is widely used as a dietary supplement to build and maintain muscle mass. Although creatine is available in many forms, the bulk of the research on the compound has centered on creatine monohydrate. Evidence from a 2013 meta-analysis suggests that creatine prevents age-related muscle losses.

    Sarcopenia, the progressive loss of skeletal muscle mass and strength that occurs with aging, begins as early as one’s 30s or 40s. By the time a person reaches their 80s, they may have lost as much as half of their total muscle mass. As a result, sarcopenia is one of the leading causes of functional decline and loss of independence in older adults. Contributing factors for sarcopenia include poor nutrition, low physical activity, and inflammation, among others. However, evidence suggests that resistance exercise can prevent or reverse sarcopenia.

    The investigators conducted a meta-analysis, a type of study that analyzes the data derived from multiple studies using objective, statistical formulas to identify a common effect. Their analysis included 13 studies that examined the effects of creatine supplementation and resistance exercise on muscle mass and other health indicators in adults over the age of 50 years.

    They found that creatine supplementation, in combination with resistance exercise, promotes muscle accretion and builds strength in older adults more effectively than resistance exercise alone. Their analysis also revealed that creatine supplementation benefits bone health by increasing bone mineral density and improving markers of bone biology.

    These findings suggest that creatine and resistance exercise work in a synergistic fashion to promote muscle mass and strength in older adults. However, the investigators cautioned that although creatine is widely considered safe for most people, its effects on people with kidney dysfunction aren’t known and further research in older adults is warranted. [Watch this clip in which Dr. Stuart Phillips discusses the benefits of creatine on muscle protein synthesis.](LINK)

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  • The secret to staying young: New research highlights power of life long exercise to keep muscles healthy www.sciencedaily.com
    Exercise Aging Muscle

    Lifelong exercise protects older adults from losing muscle mass and function with age.

    With age, muscles shrink in size and lose strength, a process called sarcopenia that can increase frailty and reduce the quality of life for older adults. In people with sarcopenia, muscle fibers contain fewer satellite cells (i.e., muscle stem cells) and progressively lose their connections to nerves, a process called denervation. Findings of a new report show that lifelong exercisers have more youthful muscles that resist denervation.

    Satellite cells are stem cells that proliferate, fuse together, and form the long tubular structures than comprise muscle fibers. Satellite cells are necessary for muscle repair and growth after exercise, a process called hypertrophy, due to their connection with cells that produce growth factors and deliver nutrients. Previous research demonstrates that exercise interventions that last several weeks can reverse muscle denervation in older adults with frailty; however, the preventive effects of lifelong exercise have yet to be investigated.

    The authors recruited 15 moderately active young men (average age, 26 years), 16 older men who were lifelong exercisers (average age, 73 years), and 15 older men who lived a sedentary lifestyle (average age, 73 years). On their first visit to the lab, participants completed a bout of heavy resistance training on only one side of their body so that the researchers could compare the effects of exercise and sedentary behavior in each person. The researchers also measured maximum muscle strength and body composition and collected a blood sample. Participants provided another blood sample two days and six days after the exercise challenge and provided a muscle biopsy sample six days after.

    Lifelong exercisers had muscles that were more resistant to fatigue during exercise compared to sedentary young and older adults. Compared with sedentary older adults, lifelong exercisers had more satellite cells in their muscles connected to type 2 myofibrils, which are important for fast-twitch muscle movement, but no difference in connection to type 1 slow-twitch myofibrils. Muscles from lifelong exercisers also expressed high levels of mRNA for acetylcholine receptors, which are necessary for preventing denervation.

    These results show that lifelong exercisers maintained a more youthful muscle profile due to increased connections with muscle- and nerve-supporting satellite cells. People who started life with a sedentary lifestyle can still reap the longevity-promoting benefits of exercise. Starting a new aerobic exercise habit, even at age 70, cuts heart disease death in half.

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  • Vitamin D supplementation may improve cardiorespiratory fitness and muscle strength (randomized controlled trial, n=74) pubmed.ncbi.nlm.nih.gov
    Vitamin D Exercise Muscle Aerobic Strength Supplements

    From the abstract:

    Cardiorespiratory fitness and muscle strength were measured before and after supplementation through maximal treadmill tests and dynamometry, respectively. Wilcoxon tests were used to compare intragroup results and the Mann-Whitney test to examine intergroup differences. There was an increase in the serum concentration of vitamin D in participants who ingested the supplementation. Cardiorespiratory fitness improved after supplementation through increases in the values of maximum oxygen consumption of 28% (p < .001). Muscle strength in left hand grip increased 18% in participants who received the supplement (p = .007). Sixty days of cholecalciferol supplementation improved cardiorespiratory fitness and upper limb muscle strength.

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  • Omega-3 supplementation improves muscle mass and function. www.sciencedirect.com
    Omega-3 Muscle Supplements

    Sarcopenia, the loss of muscle mass and function with age, reduces mobility and quality of life. Many of the diseases that are associated with sarcopenia (e.g., cancer, chronic obstructive pulmonary disease, health failure, and type 2 diabetes) are known to involve severe inflammation. Findings of a new report demonstrate an improvement in muscle mass and strength following supplementation with anti-inflammatory omega-3 fatty acids.

    Muscles require growth hormones to maintain their mass; however, in sarcopenia, inflammation reduces muscle tissue’s ability to grow in response to insulin. Long-chain omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have powerful anti-inflammatory effects. EPA and DHA reduce the production of pro-inflammatory eicosanoid compounds and increase the production of anti-inflammatory and pro-resolving compounds. Previous research exploring the effects of omega-3 supplementation in patients with sarcopenia uses a wide range of methods, making the evidence difficult to evaluate.

    The authors conducted a systematic review and meta-analysis to determine the effects of omega-3s on muscle mass, volume, and function. They searched existing literature for relevant trials, rated them for risk of bias, and selected a set of high-quality studies. The authors combined data from these studies and reanalyzed it, taking into account variations in design, omega-3 dose, and methods used to measure muscle.

    Supplementation with omega-3 fatty acids significantly increased lean body mass, skeletal muscle mass, and strength of the quadricep muscles, which are vital for good mobility. Specifically, omega-3s improved quadriceps maximal voluntary contraction, a measure of the amount of tension a muscle can generate. With one exception, all studies used EPA and DHA supplements (one used only alpha linoleic acid) ranging from 102 to more than 4,000 milligrams. Interestingly, the authors did not find a relationship between dose and effectiveness. They believe this is caused by variations in study design and methods. The data revealed that even low-dose omega-3 supplementation was sufficient to increase lean body mass.

    These data demonstrate the efficacy of omega-3 supplementation in improving sarcopenia-related outcomes. The authors suggested that future studies explore the effects of a range of omega-3 doses on muscle mass and function.

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  • Whole-body hyperthermia activates muscle hormone irisin and increases neuroprotective factors. www.sciencedirect.com
    Exercise Brain Muscle Sauna BDNF Neurodegeneration

    Exposure to high heat while sauna bathing causes mild hyperthermia – an increase in the body’s core temperature – that induces a thermoregulatory response to restore homeostasis and condition the body for future heat stressors. These adaptations to high temperatures involve increased production of brain derived neurotrophic factor (BDNF), a promoter of neuroplasticity, and irisin, a biomarker of exercise. Findings of a new report demonstrate that whole-body hyperthermia increases BDNF and irisin in healthy young adults.

    Whole-body hyperthermia is a therapeutic strategy used to treat various diseases, including cancer and depression. Previous research has shown that use of a hyperthermia chamber increases BDNF to a greater extent than light intensity exercise. Some research has suggested that BDNF production is stimulated by irisin, a hormone secreted from muscle in response to exercise. Irisin may mediate some of the beneficial effects of exercise and sauna use in humans, but additional research is needed.

    The authors recruited 20 male participants (average age, 22 years) and assessed their baseline heat tolerance using a hyperthermia protocol. Participants reclined in a hyperthermia chamber while the researchers increased the temperature of the chamber by 50 degrees F every ten minutes until the participant reached their personal heat threshold. Next, participants completed ten hyperthermia sessions tailored to their baseline conditioning, during which the hyperthermia chamber was set to a temperature of 150 to 175 degrees F. Following a three-week wash-out period, they completed ten sham treatments over two weeks, during which the hyperthermia chamber was set to a temperature of 75 to 77 degrees F.

    Participants had an average core body temperature of 102 degrees F at the end of each whole-body hyperthermia treatment. Following ten whole-body hyperthermia treatments, participants had a significant increase in circulating irisin levels (6.3 micrograms per milliliter) compared to their baseline levels (5.0 micrograms per milliliter) and compared to their irisin levels following the sham treatment (5.4 micrograms per milliliter). Whole-body hyperthermia treatment also significantly increased BDNF levels (28.3 picograms per liter) compared to baseline (25.9 picograms per liter).

    In healthy young adults, ten whole-body hyperthermia significantly increased irisin and BDNF levels. The authors noted that future studies should explore the effects of whole-body hyperthermia on adipose tissue, which also produces irisin.

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  • Muscles contain sensors for mechanical force that drive growth following exercise. www.sciencedaily.com
    Exercise Muscle

    The question of why muscles grow after exercise seems to have a simple answer - they grow by repairing themselves from the damage exercise causes. However, this theory does not explain the loss of muscle mass that occurs after long periods of rest or in microgravity environments such as those encountered in space. Authors of a new report suggest that muscle growth is regulated by structures within muscle cells that sense changes in mechanical force.

    Muscle fibers lengthen and shorten in cycles to create muscle movement. Fast muscle fiber cycling is utilized during the fight or flight response, generating nearly instantaneous motion. Over periods of several days, muscles regulate their growth based on the number of these contraction cycles. But how muscles “know” how much they have been used has yet to be elucidated.

    The sarcomere is the smallest structural unit of striated muscle (i.e., skeletal and cardiac muscle) and is composed of thin actin and thick myosin filaments, which slide against each other to create the force needed for contraction and relaxation. Titin is a protein at the core of the myosin filaments that changes shape when force is applied. Force “opens” the titin protein structure, exposing a molecular site for phosphorylation (i.e., adding a phosphate group). This phosphorylation initiates a signaling cascade that results in changes to gene expression that affect long-term growth and atrophy of skeletal muscles.

    The authors created a mathematical model to explain the mechanism of the mechanosensing function of titin. The model was divided into three parts. The first part of the model characterized the opening of the titin protein structure in response to force. The second part of the model characterized the creation and degradation of signaling molecules that are downstream in the signaling cascade initiated by titin phosphorylation. The third part of the model characterized how muscle cells compensate for the depletion of short-term adenosine triphosphate (ATP) energy stores that results from energy production through oxidative phosphorylation.

    From the modeling calculations, the authors found that titin acts as a mechanosensitive switch that is put under extreme force during resistance exercise (e.g., weight lifting) and less force during endurance exercise (e.g., jogging). The model also explained that titin phosphorylation geometrically inhibits the function of ribosomes, the cell structures that build proteins. Following exercise, some protein synthesis in the muscle is inhibited; however, after a lag of days or weeks, repeated exercise increases the rate of ribosome gene expression and synthesis. Building on this information, the model yielded that these alterations in protein synthesis are ultimately responsible for muscle hypertrophy following exercise and muscle atrophy following extended rest.

    The authors noted that this important research may identify targets for future therapies that prevent the loss of muscle mass that occurs with age and with diseases such as cancer and HIV.

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  • Time-restricted eating improves athletic performance. www.mdpi.com
    Exercise Fasting Fat Muscle Time-Restricted Eating

    Time-restricted eating involves restricting the timing of food intake to certain hours of the day (typically within an 8- to 12-hour time window) without an overt attempt to reduce caloric intake. Increasing the amount of time spent fasting each day has been used to treat metabolic diseases such as type 2 diabetes and high cholesterol, increase muscle mass, decrease fat mass, and improve exercise performance. Findings of a recent report demonstrate the beneficial effects of time-restricted eating on exercise performance in power athletes.

    Increasing muscle mass and decreasing fat mass is an important goal for many athletes because increasing their strength-to-mass ratio improves performance. While time-restricted eating is one strategy to improve body composition, previous research has shown that other types of intermittent fasting (e.g., religious fasting during Ramadan) decrease power output and endurance. Another study involving intermittent fasting with caloric restriction found similar deficits in athletic performance. The effects of long-term time-restricted eating without caloric restriction are unknown.

    The researchers recruited healthy young males who were currently practicing a power-sport at least three times per week and had been practicing for at least three years. Twelve participants (average age, 22 years) completed four weeks of time-restricted eating and four weeks of a standard meal pattern in random order with two weeks of wash-out in between. During the time-restricted eating period, participants consumed all of their food within an eight-hour window. The researchers measured body composition using X-ray and athletic performance using the Wingate test, a cycling challenge that measures power and total work.

    Time-restricted eating produced a significant increase in total work (a measure of force over a set distance) and average power output (a measure of work over time). These improvements translated to a one second reduction in sprinting time. The participants achieved this change after four weeks of time-restricted eating, but not after one week. Time-restricted eating did not improve peak power, endurance, or body composition.

    Time-restricted eating, along with regular training, improved exercise performance in athletes. Given that the difference between the current and former 400 meter running world records is only 15 hundredths of one second, the one second decrease in sprinting time produced by time-restricted eating is meaningful.

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  • Time-restricted feeding reduces weight gain and cholesterol in male mice. www.sciencedaily.com
    Cholesterol Fasting Fat Muscle Sugar Time-Restricted Eating Weight Loss Lipopolysaccharide

    A Western diet pattern, characterized by a low intake of fruits and vegetables and a high intake of sugar and processed foods, promotes the development of obesity and metabolic disease. Time restricted eating has been shown to decrease weight and improve metabolic health in humans. However, factors such as age and sex modulate both susceptibilty to obesity and likelihood of responding to weight-loss treatments. Authors of a new report found that male mice experienced greater metabolic benefit from time-restricted feeding than females.

    Time-restricted eating, the practice of limiting food intake to an 8- or 12-hour window, is an emerging therapy for the treatment and prevention of metabolic diseases. Much of the research about time-restricted eating in humans is based on research of time-restricted feeding in mice, which has elucidated many of the cellular mechanisms related to [time-restricted eating’s benefits.](​​https://journals.physiology.org/doi/full/10.1152/ajpregu.00775.2005) These two terms distinguish which population, humans or non-human animals, is practicing time-restricted food intake.

    The prevalence of obesity is on the rise in the industrialized world, a problem compounded by an increasing average age in the same populations. The accumulation of extra fat throughout life puts a person at greater risk of metabolic disease as they age. Females are more likely to gain and retain fat mass than males; however, pre-menopausal females tend to have lower rates of type 2 diabetes and cardiovascular disease due to the protective effects of estrogen. Previous research in humans has demonstrated weight loss and improved metabolic health with time-restricted eating; however, additional research is needed to understand the sex- and age-dependent effects of time-restricted eating.

    The researchers used male and female mice of two ages: three months old (equivalent to 20-year-old humans) and 12 months old (equivalent to 42 year-old-humans). They fed mice a chow diet representative of a Western diet pattern with 17 percent of calories from sugar (human equivalent of about 25 ounces of soda per day) and 45 percent of calories from fat including lard and soybean oil. Current dietary guidelines recommend limiting solid fats such as lard). Half of the mice had 24-hour access to food while the other half only had restricted access, limited to just nine hours per day. Mice continued their diet for a total of 12 to 13 weeks. After 10 weeks, the researchers measured changes in the animals' body weight, glucose sensitivity, serum cholesterol, fatty liver, muscle performance, and immune response when challenged with bacterial endotoxin.

    Although mice in the time-restricted feeding group consumed the same amount of food as mice with constant access to food, time-restricted feeding resulted in 15 percent less weight gain in young male mice and 23 percent less weight gain in older male mice. Time-restricted feeding did not significantly prevent weight gain in female mice. Male mice also experienced a greater reduction in serum cholesterol with time-restricted feeding compared to females. Both older male and female mice had lower rates of insulin resistance and fatty liver while on time-restricted feeding. This protection was likely due to changes in gene expression that increased glucose uptake by and decreased glucose output from the liver. In young male mice, time-restricted feeding preserved muscle mass, function, and performance, but not in young females. Finally, when challenged with bacterial endotoxin, older mice practicing time-restricted feeding were significantly more likely to survive septic shock than mice with 24-hour access to food, demonstrating better health and resilience.

    Time-restricted feeding improved survival of septic shock and provided protection against insulin resistance and fatty liver in both sexes; however, male mice experienced greater reductions in body weight and serum cholesterol and maintained greater muscle mass and performance compared to female mice. The authors noted that their research is of particular interest considering the increased risk of severe COVID-19 illness in those with poor metabolic health.

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  • Depression is associated with muscle loss in older adults. journals.plos.org
    Aging Depression Muscle Dementia

    Sarcopenia, the loss of muscle mass with age, is related to falling, poor oral health, and chronic disease. Sarcopenia is a progressive disorder, but early interventions with diet and exercise may improve health outcomes. Authors of a new report investigated the relationship between sarcopenia progression, depression, dementia, and hypertension.

    Body composition shifts across the lifespan, with a progression toward lower muscle mass and increased fat mass after age of 60. Because fat and muscle participate in whole-body metabolism and hormone signaling, this shift in body composition contributes to the development of age-related diseases. Previous research has reported a link between sarcopenia, cognitive impairment, and depressive symptoms in older Korean men, but research is needed in additional demographic groups.

    The authors collected data from more than 750 adults aged 60 years and older living in Japan. Participants completed surveys to measure depression and dementia status and underwent a physical examination that included the measurement of blood pressure, height, muscle mass, grip strength, and walking speed. The investigators classified participants as having sarcopenia if they had low skeletal muscle index (i.e., the ratio of the muscle in a person’s arms and legs to their height), poor grip strength, and slower walking speed. They defined pre-sarcopenia as having a low skeletal muscle index with normal grip strength and walking speed. Finally, they classified participants with a normal skeletal muscle index as robust.

    Sarcopenia was associated with increased age and depression severity, but reduced hypertension. Compared to robust participants, those with pre-sarcopenia were more likely to have depression and hypertension. However, sarcopenia was not associated with dementia, which the authors noted may have been due to the small number of participants (only 49) with dementia.

    The authors suggested that future research should explore strategies for management of depression, dementia, and hypertension in the prevention of sarcopenia.

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  • Greater muscle strength reduces depression risk. www.psypost.org
    Exercise Brain Depression Muscle IL-6

    Depression is characterized by mood alterations, such as increased sadness and irritability, and physiological changes, such as decreased sleep, appetite, and sexual desire. Previous research has reported a relationship between increased muscle strength and lower depression risk in older adults. Findings of a recent study detail the relationship between muscle strength and depression risk in young adults.

    Cytokines are proteins that participate in cell-signaling. Pro-inflammatory cytokines are increased in depression and contribute to the dysfunction of neurotransmission, hippocampal neurogenesis, and stress-related nervous system activation. Skeletal muscle cells secrete a number of pro-inflammatory cytokines, such as interleukin (IL)-6, IL-8, and IL-15. A previous study demonstrated a relationship between lower levels of inflammation in adolescents with increased muscle strength and decreased body fat, but the study did not measure depression risk.

    The authors included 600 female participants without depression (average age, 19 years) in their analysis who were part of a larger observational study of physical fitness and health in Chinese college students. Participants completed a survey to measure depression symptoms and a physical exam including the use of a dynamometer to measure grip strength, a proxy for total skeletal muscle strength. The authors collected these measures at baseline and at a one-year follow-up. They classified participants into one of four categories based on the amount of grip strength they gained over the one-year study period.

    At the one-year time point, about 11 percent of participants reported depressive symptoms. Participants who gained the most grip strength over the one-year study period had a 66 percent lower risk of depression compared to participants who gained the least grip strength. Participants with the greatest gains in grip strength tended to be younger and smoke less at baseline than participants with the least gains in grip strength. Finally, gains in grip strength were significantly related to body mass index (BMI) at baseline. Underweight, defined as a BMI less than 18.5, was more common in participants with the lowest gains in grip strength (43 percent), while overweight, defined as a BMI greater than 25, was more common in participants with the greatest gains in grip strength (23 percent).

    The authors concluded that increased grip strength is associated with a lower risk of depressive symptoms in young adults.

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  • Body fat increases the risk of death, while muscle mass decreases it. academic.oup.com
    Aging Muscle

    Body mass index (BMI) is a measure of body size that is calculated by dividing a person’s weight by their height. A wealth of research has demonstrated that having a body mass index outside of the normal range (18.5 to 25) increases the risk of death. However, body mass index does not differentiate fat and muscle mass. Authors of a new report investigated the effects of body composition on risk of death.

    Extra body fat has been shown to increase the risk of developing a number of chronic lifestyle diseases, while increased muscle (fat-free) mass has been shown to decrease disease risk. Previous research has demonstrated mixed results for the effect of body composition and risk of death, likely due to differences in study design.

    The authors combined data from seven studies with over 16,000 participants between the ages of 20 and 93 years collected between 1994 and 2008. Researchers measured body composition using bioelectrical impedance and adjusted for age and sex. They also interviewed participants about their health, lifestyle, and socioeconomic factors and tracked them for an average of 14 years.

    After adjusting for a number of demographic and lifestyle factors, the researchers found that having body fat below or above the normal range increased risk of death among the participants. Those with high body fat (37 kilograms) had a 56 percent greater risk of death, while those with highest fat-free mass had a 30 percent lower risk of death.

    The authors concluded that fat mass and fat-free mass have opposite effects on the risk of death. They noted that their study included a large number of participants and a long follow-up period, which strengthened the quality of their results.

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  • Omega-3 fatty acids may reduce muscle loss in older adults. www.ncbi.nlm.nih.gov
    Aging Omega-3 Muscle

    Sarcopenia is an age-related progressive condition characterized by the loss of skeletal muscle mass and strength. It is one of the leading causes of functional decline and loss of independence in older adults. Contributing factors for sarcopenia include poor nutrition, low physical activity, and inflammation, among others. Findings from a recent meta-analysis suggest that omega-3 fatty acids are beneficial in preventing or treating sarcopenia.

    Omega-3 fatty acids participate in a wide range of physiological processes and are essential for human health. Some evidence demonstrates that omega-3 fatty acids play roles in muscle mass synthesis and function. Omega-3 fatty acids include alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is found mainly in plant oils such as flaxseed, soybean, and canola oils. DHA and EPA are found in fish and other seafood. The human body can convert some ALA into EPA and then to DHA, but the process is very inefficient.

    The authors analyzed data from 10 randomized controlled intervention trials investigating the effects of increased omega-3 fatty acid intake on skeletal muscle mass, muscle strength, or muscle performance. More than 550 adults aged 60 years and older were included in the studies, the duration of which spanned 10 to 24 weeks. Outcomes included changes in muscle mass, muscle strength, or physical performance, assessed by walking time or the Timed Up & Go Test (TUG).

    The trials provided omega-3 fatty acids from a variety of sources, including fish oil, flax oil, and healthy dietary patterns that adhered to a low omega-6 to omega-3 ratio. Doses ranged from 0.16 to 2.6 gram per day of EPA and from 0 to 1.8 grams per day of DHA. One study provided 14.0 gram per day of ALA. The participants saw increases in muscle mass of about 0.33 kilograms (~11 ounces), and their TUG test times decreased by 30 seconds. Participants who consumed more than 2 grams of omega-3s per day saw greater improvements, with increases in muscle mass of 0.67 kilograms (~1.8 pounds). Among those enrolled in interventions lasting six months or longer, walking times improved by nearly 2 meters per second.

    These findings suggest that nutritional interventions that include dietary and/or supplemental omega-3 fatty acids improve muscle mass and physical performance in older adults. The relatively small number of trials and the varying doses, duration, and study designs limit the application of the findings, however.

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  • Curcumin maintains muscle power and reduces muscle soreness after plyometric exercise. www.tandfonline.com
    Muscle Curcumin

    Plyometric exercises involve quick, powerful movements to promote speed, endurance, and strength. Loss of muscle power and delayed onset muscle soreness commonly occur after plyometric exercise. Findings from a new study suggest that curcumin maintains muscle power and reduces muscle soreness after plyometric exercise.

    Curcumin in a bioactive compound produced by the plant Curcuma longa, a member of the ginger family. Curcumin exhibits a wide array of beneficial health effects, including anti-inflammatory, anti-cancer, and anti-diabetes properties. It is responsible for the bright yellow pigment of turmeric, a type of spice commonly used in Indian food.

    The study involved 22 healthy men and women who took either 500 milligrams of curcumin or a placebo twice daily for 10 days surrounding a single session of plyometric exercise (six days before, the day of, and three days afterward). The exercise consisted of five sets of 20 drop jumps performed from a 24-inch-high platform with a 60-second period of rest between sets. The investigators measured creatine kinase (a marker of muscle damage) and erythrocyte sedimentation rate (a marker of inflammation) in the participants' blood. The participants performed a vertical jump and provided subjective assessments to gauge muscle soreness pre-supplementation, 24-hours and immediately pre-exercise, immediately afterward, and 24, 48 and 72-hours post-exercise.

    Both groups had elevated creatine kinase and soreness immediately after performing the exercise. Those who took curcumin reported less soreness 48 and 72 hours after the exercise, even though there was no difference in creatine kinase levels between the two groups. The participants' erythrocyte sedimentation rate was elevated immediately after the exercise, but the levels were within normal limits with little difference between the two groups. Those who took curcumin performed better on the vertical jump over time, but the placebo group saw decrements in the performance of this test.

    These findings suggest that curcumin reduces soreness and helps maintain muscular power following plyometric exercise.

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  • Different forms of vitamin D have distinct impacts on muscle mass and strength. www.medicalnewstoday.com
    Vitamin D Muscle

    The loss of muscle mass and strength, known as sarcopenia, is a significant problem in aging, affecting both healthspan and quality of life. Findings from a recent study suggest that vitamin D affects muscle function through diverse metabolic pathways.

    Clinicians determine a person’s vitamin D status by measuring 25-hydroxyvitamin D3, or 25(OH)D3 — the inactive circulating form of vitamin D. However, a new technique, high-throughput liquid chromatography-tandem mass spectrometry (LC-MS/MS), allows researchers to quantify additional vitamin D metabolites. While these other metabolites, part of what is termed the vitamin D metabolome, are present in low concentrations in the blood, they can perform critical functions in tissues, such as muscles.

    Previous research has examined the relationship between vitamin D and muscle function yielding inconsistent results; however, these studies have mainly focused on 25(OH)D3. The current study investigated whether other vitamin D metabolites are associated with muscle function.

    The cross-sectional study involved 116 healthy adults who performed handgrip and lower limb strength tests, while a subset of 85 participants consented to thigh muscle biopsies. The authors assessed the participants' vitamin D status using LC-MS/MS, steroid metabolites from urine samples, and the expression of 92 genes from the muscle biopsies. The authors also measured lean body mass and body fat percentages.

    Only 14 percent of participants had normal vitamin D levels, while 28 percent had insufficient levels, and 58 percent were found to be deficient. Subjects with a higher percent body fat had lower vitamin D levels. Participants with higher muscle mass had higher active vitamin D levels. Those with higher active, but not inactive vitamin D levels scored better on the muscle strength tests. The authors observed that the expression of 24 skeletal muscle genes correlate with levels of serum 25(OH)D3.

    These findings highlight the complex relationship between vitamin D, gene expression, and muscle function. They suggest that the maintenance of muscle mass and strength is complicated, and it may be more appropriate to measure other vitamin D forms rather than just 25(OH)D3.

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  • Exercise can reset the circadian clock in the muscles of mice. www.sciencedaily.com
    Exercise Circadian Rhythm Muscle

    The circadian rhythm is the body’s 24-hour cycle of biological, hormonal, and behavioral patterns that, when disrupted, has profound implications for human healthspan. Findings from a recent study suggest that a single bout of exercise can reset the circadian clock in the skeletal muscles of mice.

    The circadian clock coordinates gene expression in nearly all cells in a time-dependent manner. Cues from the environment, known as zeitgebers, can alter the circadian clock in a process known as entrainment. Light acts as the primary zeitgeber, but activity, stress, and eating also affect circadian timing. Exercise affects body temperature, heart rate, and many other metabolic parameters and might also entrain the circadian clock.

    The current study investigated whether exercise would act as a zeitgeber for the circadian clock in the skeletal muscles of mice. Transgenic mice completed a sixty-minute bout of moderate‐intensity exercise at different times during their rest or active periods. The authors of the study observed that mice exercised during their typical rest period exhibited a shift in the muscle circadian clock. However, mice exercised during their active phase showed no effects on the circadian rhythm.

    To factor out the hormonal and temperature effects of exercise, the authors developed an in vitro model system using time‐synchronized rodent muscle cells. They subjected these cells to an electrical current, to simulate muscle contractions, and measured the expression of known molecular clock‐related genes. The authors found that electrical stimulation altered the expression of clock genes, and shifted the circadian clock in a pattern similar to that observed in the mouse model system.

    Taken together these findings suggest that a single bout of exercise can alter the circadian clock — making it a true zeitgeber. The specific effect of exercise on the circadian clock depends on the time when it is performed. While further studies are needed to determine if these findings translate to humans, the authors propose that shift workers might benefit from timed exercise to offset some of the negative effects of circadian disruption.

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  • Whole-body heat exposure alters skeletal muscle signaling and mitochondrial biogenesis in humans. www.frontiersin.org
    Muscle Sauna

    Muscle loss can occur as part of a disease process, trauma, or aging. Although exercise can prevent muscle loss, some medical conditions or physical limitations can make exercise difficult or even impossible. Findings from a new study indicate that hyperthermia may preserve or increase muscle mass and increase mitochondrial biogenesis.

    Hyperthermia is a state of elevated core body temperature that activates molecular mechanisms that mitigate protein damage and drive the body’s in-house repair systems. Mitochondrial biogenesis is the process by which new mitochondria are made inside cells. Many factors can activate mitochondrial biogenesis including exercise, hyperthermia, and others.

    The study involved nine healthy young men (average age, 35 years) who underwent two 60-minute sessions of passive heat treatment, separated by one week. One session was a whole-body treatment at 44˚C to 50˚C (111˚F to 122˚F) and 50 percent humidity. The other session was a single-leg treatment using a water-perfused suit at approximately 50˚C (122˚F). The authors of the study monitored core, skin and quadriceps muscle temperatures throughout the sessions and took muscle biopsies before, 30 minutes after, and three hours after the heat treatments.

    The whole-body heat treatment switched on the activity of molecules involved in the Akt/mTOR biological pathway, a critical regulator in maintaining skeletal muscle mass. It also increased the expression of heat shock proteins and Nrf2. Nrf2 is a cellular protein that regulates the expression of antioxidant and stress response proteins. Its activity is an indicator of mitochondrial biogenesis. These changes were not evident when the participants received single-leg heat treatment, suggesting that whole-body hyperthermia elicits systemic improvements involved in muscle maintenance and mitochondrial health.

    Interestingly, whole-body heat inhibited the activity of some FOXO proteins and switched on the activity of some genes involved in atrophy. Further study is needed to determine the full effects of whole-body hyperthermia on muscle atrophy.

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  • Keeping lower back pain at bay: Exercises designed by Lithuanians are 3 times more efficient www.eurekalert.org
    Exercise Muscle

    From the article:

    “According to Dr. Kliziene, the stability of lumbar segments is an essential element of body biomechanics. Previous research evidence shows that in order to avoid the lower back pain it is crucial to strengthen the deep muscles, which are stabilising the lumbar area of the spine.

    […]

    The static positions are to be held from 6 to 20 seconds; each exercise to be repeated 8 to 16 times.

    […]

    As soon as 4 weeks in lumbar stabilisation programme, it was observed that the cross-section area of the multifidus muscle of the subjects of the stabilisation group has increased; after completing the programme, this increase was statistically significant. This change was not observed in the strengthening group. Moreover, although both sets of exercises were efficient in eliminating lower back pain and strengthening the muscles of the lower back area, the effect of stabilisation exercises lasted 3 times longer - 12 weeks after the completion of the stabilisation programme against 4 weeks after the completion of the muscle strengthening programme."

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  • More abdominal fat drives loss of fluid intelligence whereas more muscle mass protects against loss. www.sciencedaily.com
    Brain Fat Muscle Protein Intelligence Weight Loss

    Fluid intelligence – the ability to creatively solve problems without prior knowledge or learning – declines with age, often as early as the third decade of life. Evidence from a new study suggests that body composition influences declines in fluid intelligence, and these declines may be related to immune system activation.

    Body composition describes an individual’s body fat and lean mass. Excess body fat promotes systemic inflammation (which can promote neuroinflammation) and drives immune-related inflammatory processes. Lean muscle mass, however, may be protective against inflammation.

    The study involved more than 4,400 middle-aged and older men and women living in the United Kingdom. The participants' body composition, cognitive function, blood leukocytes (white blood cells), and variables such as age, education level, and socioeconomic status were measured every other year for a period of six years.

    The authors of the study found that higher levels of body fat, especially abdominal fat, were associated with greater losses of fluid intelligence. The losses appeared to be related to sex-specific increases in blood leukocyte counts and inflammation, as evidenced by higher levels of C-reactive protein.

    These findings point to the importance of maintaining a healthy body weight throughout life as a strategy to reduce or prevent cognitive decline.

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  • Post-workout ice baths may hinder muscle protein synthesis www.sciencedaily.com
    Muscle Cold Stress Protein

    Post-workout ice baths and increased dietary protein intake have long been used by athletes as strategies to build muscle. Findings from a new study suggest that ice baths may hinder muscle protein synthesis by interfering with dietary protein uptake into muscles.

    The study participants included 12 healthy young men who engaged in a single resistance‐type exercise session and then immersed both their legs in water for 20 minutes. One leg was immersed in cold water (8°C, 46°F) while the other leg was immersed in water that was slightly warmer than room temperature (30°C, 86°F). Afterward, the participants consumed an amino acid-rich beverage.

    The authors of the study monitored the uptake of the amino acids and subsequent muscle protein synthesis for two weeks. Analyses of blood, saliva, and muscle tissue revealed that cold water immersion after resistance‐type exercise reduces muscle protein synthesis, which could impair muscle conditioning.

    Interestingly, an older study found that cold water immersion reduced the risk of cancer and enhanced longevity in mice. The contradictory findings of these two studies suggest that cold exposure may be harmful in certain contexts, but beneficial in others, and that timing of the exposure is critical.

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  • Metformin supplementation prevented gains in lean muscle mass in healthy people 65 years and older who engaged in resistance training. onlinelibrary.wiley.com
    Exercise Aging Muscle Insulin Dairy Metformin

    Age-related skeletal muscle mass and strength is a leading cause of the functional decline and loss of independence in older adults. Resistance training exercise is a highly effective strategy for maintaining or building muscle mass. A new study suggests that metformin, a drug commonly used to treat type 2 diabetes, blunts the effects of resistance training.

    Metformin is in a class of drugs called biguanides, which act by decreasing liver gluconeogenesis (the production of glucose in the liver), decreasing glucose uptake in the gut, and increasing overall glucose utilization by improving insulin sensitivity in skeletal muscle and fat tissue. Scientific evidence suggests that metformin modulates aging processes to improve healthspan and extend lifespan in multiple organisms.

    The present study involved 94 healthy men and women aged 65 years and older who were randomized to take either a 1,700-milligram dose of metformin daily (a typical dose prescribed for diabetes and prediabetes) or a placebo for 14 weeks. The participants also performed supervised resistance training for the duration of the study. At the end of the study, participants who took the placebo exhibited greater gains in lean body mass and thigh muscle mass than those who took metformin.

    Although metformin is a safe and effective treatment for type 2 diabetes, these findings underscore concerns about the possible negative effects of metformin use in healthy older adults.

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  • Daily heat treatments, applied during 10 days of immobilization, prevented the loss of mitochondrial function and prevented muscle atrophy. www.physiology.org
    Heat Stress Muscle Sauna Protein Dairy

    A new study found that daily heat treatments applied locally to muscle during 10 days of immobilization prevented the loss of mitochondrial function, increased heat shock protein levels, and attenuated skeletal muscle atrophy by 37% compared to sham control in a small trial in humans.

    I am really glad to see this replicated now in humans. There’s were two similar studies that I covered in past videos, which showed that whole body heat treatment (similar to a sauna) prevented muscle atrophy and increased muscle regrowth after immobilization, however, these were done in mice. The difference is that this shows a pretty similar phenomenon in humans! This isn’t too surprising. The main reason for that is because the mechanism in animal research was already all worked out. The prevention of muscle atrophy and muscle regrowth in mice was shown to be dependent on the robust activation of heat shock proteins. These proteins are highly conserved in humans in function, playing an extremely apparent similar molecular role. More importantly, we already knew from prior research that heat shock proteins increase by ~50% after 30 minutes in a 163 ºF (73 ºC).

    The results of this new study have important implications. While exercise interventions remain the most effective strategy to maintain or increase muscle mass and respiratory capacity, during periods of immobilization due to injury or for other reasons exercise can become more challenging. Heat therapy through modalities such as a sauna or even local heating (as is the case in this study) may ultimately serve as a very useful alternative or adjunct therapy to maintain skeletal muscle metabolic function and preserve muscle mass!

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  • A new study shows the "obesity paradox,” the idea that obese people live longer than those of normal weight, may be explained by muscle mass. journals.plos.org
    Obesity Aging Muscle Weight Loss

    A new study shows the “obesity paradox,” the idea that obese people live longer than those of normal weight, may be explained by muscle mass.

    After accounting for muscle mass, high BMI no longer associates with greater survival. Some have hypothesized that excess fat stores are beneficial for counteracting episodes of catabolic stress. However, the risk of death increased with low muscle mass and greater body fat.

    This study also found that skeletal muscle mass was an independent risk factor for mortality in the general population, and this was more pronounced among younger adults…which is interesting because most studies on muscle mass and mortality focus on a geriatric population.

    Skeletal muscle mass could directly influence survival and could protect against loss of functional status due to aging or the onset of chronic disease. However, since this is an observational nature study, a causal relationship cannot be determined. There is always the possibility that there may be other confounding health-related factors that were not accounted for.

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  • Packing on the muscle via inhibition of cancer-related protein and myostatin increases cancer survival in mice. www.sciencedaily.com
    Cancer Muscle Protein

    FTA:

    There was evidence to suggest that tumors secrete activin, such that circulating levels of the protein rise in those with cancer. Activin is closely related to another protein, called myostatin, which is known to be important in muscle […]

    Animals lacking myostatin or taking treatments that block it grow bigger muscles. There was some evidence to suggest that activin blockers might have a similar effect.

    Based on that hunch, the researchers treated mice with cancer and associated cachexia with a recombinant and soluble version of the ActRIIB receptor (sActRIIB), a kind of molecular “decoy” that potently inhibited both activin and myostatin activity. That treatment reversed the animals' muscle loss and prolonged their survival by several weeks on average.

    “In tumor-bearing mice with profound cachexia, blocking this pathway not only prevents muscle wasting but completely reverses the loss of muscle, strength and anorexia,” Han said. (Anorexia is another symptom of cachexia, but appetite stimulants and nutritional supplements don’t help much.)

    note: cachexia = muscle wasting

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