Endurance athletes often look for ways to increase cardiorespiratory fitness beyond what exercise alone can provide, yet many proven methods are expensive and require major logistical demands. In a new study, researchers tested whether hot baths offer a simpler approach to stimulate cardiovascular adaptations.

The study enrolled 10 well-trained endurance runners with an average maximal oxygen consumption (VO₂max, the highest rate of oxygen use during intense exercise) of about 64 milliliters per kilogram per minute. Each runner completed two five-week blocks: one with hot water immersion and one control block with the same regular training. During the immersion block they sat in at least 40°C/104℉ water for 45 minutes, five times per week, usually after training. To maintain a consistent thermal load, the temperature was adjusted based on participants' heat perception and reached an average of about 41.7°C/107.1℉ by week five. The researchers focused on three key features of circulation: haemoglobin mass (the total amount of oxygen-carrying protein in red blood cells), total blood volume (the combined liquid and cell volume of blood), and left-ventricular end-diastolic volume (LVEDV, how much blood fills the main pumping chamber of the heart just before it contracts).

The runners already had high cardiorespiratory fitness, yet heat immersion still changed their blood, heart, and performance in measurable ways:

• VO₂max rose by 2.7 milliliters per kilogram per minute, roughly a 4% increase, after the heat block, while it stayed essentially unchanged during the control block.
• Haemoglobin mass increased by about 4% (from about 857 to 891 grams) in the heat condition, whereas it slightly declined in the control period. This was accompanied by red blood cell volume rising by about 7% (from about 2.45 to 2.62 liters).
• Plasma volume, the liquid part of blood, expanded by roughly 8% (about 250 milliliters) in the first week of hot baths, then began to trend back toward baseline after the second week.
• LVEDV increased by about 6% (from 170 to 180 milliliters). Resting stroke volume, the amount of blood pumped with each heartbeat, rose by around 7% (from 94 to 101 milliliters), which resulted in the heart pumping about 13% more blood per minute (from 4.5 to 5.1 liters). Comparable shifts did not appear during the control phase.
• Across the five weeks, participants acclimated to the heat. They showed a smaller rise in body temperature and an increase in sweat rate of roughly 38% (from about 1.3 to 1.8 liters per hour), while their ratings of heat and discomfort remained similar.

The sequence of changes points to a typical heat acclimation pattern. Plasma volume expanded in the early weeks. This early expansion is a well-known response to repeated heat exposure and reflects fluid shifting into the bloodstream and adjustments that help the body conserve more fluid during heat stress. As plasma expansion diluted the blood, it likely signaled the need for additional red blood cell production. In the later weeks, red blood cell volume and haemoglobin mass rose, which increased the blood's oxygen-carrying capacity. The larger circulating volume also increased how much blood returned to the heart, allowing the left ventricle to fill more completely and pump more with each beat. Further analysis showed that haemoglobin mass and LVEDV accounted for most of the heat-related rise in VO₂max.

Because this trial involved only ten runners, lacked a control condition where participants sat in normal-temperature water, and scheduled most baths immediately after exercise, the findings point to a promising but still preliminary approach that needs to be further tested. In this clip, Dr. Martin Gibala explains VO₂max's role in health and how non-athletes can optimize workouts to boost their cardiorespiratory fitness.

Cognitive decline and dementia are major challenges in aging societies, and with no treatment that can cure these conditions, prevention plays a central role in public health. In a large Australian cohort study, researchers asked whether older people's patterns of listening to music or playing a musical instrument predicted later cognitive performance.

The study followed 10,893 cognitively healthy adults (who were at least 70 years old) for about nine years. About three years into the study, they completed a one-time questionnaire that asked how often they listened to radio or music and how often they played a musical instrument, including singing. Each activity was later grouped into frequency levels, and the researchers also created a combined measure that reflected how often participants engaged in both behaviors. These exposure groups were then used to examine later risk of dementia, cognitive impairment without dementia (CIND), and long-term changes in cognitive performance.

The study identified several links between music engagement and later cognitive measures:

• Older adults who reported listening to music on most days had a 39% lower risk of dementia and a 17% lower risk of CIND than those who listened rarely or never. They also showed slower decline in overall cognition and memory, but the study did not find similar differences for word-finding or speed-related tasks.
• Participants who often or most days played a musical instrument had about 35 percent lower dementia risk than those who rarely or never played, although instrument playing alone was not clearly associated with CIND or with changes in cognitive test performance.
• People who frequently listened to music and played an instrument had a 33 percent lower dementia risk and a 22 percent lower risk of CIND than those who rarely or never did either activity.

These findings fit with the idea that mentally and emotionally stimulating activities can support a more flexible and efficient brain. Music activates several interconnected systems in the brain, among them attention, memory, movement, auditory processing, and emotion, and repeated activation over many years may strengthen the brain's capacity to compensate when certain pathways become less reliable. This capacity, often described as cognitive reserve, helps people maintain everyday thinking skills even when there is some underlying deterioration.

Although the study cannot prove that music itself prevents dementia, the work highlights music engagement as a low-cost, widely accessible candidate for dementia risk reduction strategies in older adults. Future intervention trials and longer observational studies will be needed to test whether altering music habits can change cognitive trajectories. My Cognitive Enhancement Blueprint offers a variety of other lifestyle interventions and protocols that have strong potential to improve cognitive performance and slow brain aging.

As populations age, scientists are searching for lifestyle factors that might help people stay functionally younger for longer, and multilingual language use has emerged as a promising candidate. In a new study, researchers examined whether living in countries where speaking more than one language is common is linked to slower aging.

The investigators analyzed 86,149 adults aged 51 to 90 from 27 European countries, all without a reported dementia diagnosis. They trained a statistical model to predict age from a mix of positive and adverse health indicators, then defined each person's biobehavioral age gap as the difference between predicted and actual age. These age gaps were linked to national statistics describing language use, and compared four kinds of language environments: mostly monolingual countries, those where residents commonly spoke one additional language, two additional languages, or three or more.

The analysis linked language environment to distinctive patterns of biobehavioral aging:

• In cross-sectional data, living in strongly monolingual countries more than doubled the odds of being in the accelerated aging group. Living in multilingual environments was linked to roughly half the odds of accelerated aging.
• Longitudinal results showed the same trend. Monolingual environments raised the risk of faster aging by 43%, while multilingual environments lowered it by about 30%.
• The effect was graded: the more additional languages people spoke, the stronger the protection, a pattern that strengthens confidence in observational findings.
• Adjusting for factors like migration, inequality, air quality, and political conditions didn't change the overall pattern. But in some models, the benefit of speaking three or more languages disappeared in cross-sectional data, and the benefit of speaking one additional language disappeared in longitudinal data.

These findings fit with the idea of cognitive reserve, the brain's capacity to cope with age-related changes by relying on more efficient or flexible networks. Regularly managing more than one language repeatedly engages attention, executive function (the systems that manage goals and task switching), and memory, and this sustained mental effort may strengthen vulnerable circuits in the brain.

The work suggests that language policy could be considered alongside physical activity, cardiovascular health, and other modifiable factors in strategies for healthy aging. Future studies that track individual language histories and test whether multilingual experience also dampens age gaps in people with neurodegenerative diseases or in intervention trials will be essential to determine how best to translate these population-level findings into practical recommendations. In this clip, Dr. Andrew Huberman discusses the power of effort, dopamine's role in motivation, and the mindset needed for effective learning — principles that can also support learning new languages.