How Vigorous Exercise Builds VO2 Max and Heart Flexibility

Dr. Rhonda Patrick: I've spent a lot of time thinking about this question: What type of exercise is best for improving quality of life, extending lifespan, and reaching your maximum genetic potential? From everything I've examined, vigorous-intensity exercise seems to be one of the most important types of exercise for longevity. By vigorous, I mean getting your heart rate to at least 80 percent of your maximum heart rate.

I've reached that conclusion by looking at several kinds of data, starting with VO2 max, or cardiorespiratory fitness. It is one of the best indicators of longevity that we have. VO2 max is the maximum amount of oxygen you can take in during maximal exercise, and it is a biomarker for cardiorespiratory fitness. I sometimes use those terms interchangeably.

Studies of people in different age groups show that the biggest benefit from improving VO2 max occurs when people go from low to low-normal fitness. That change is associated with about a 2.1-year increase in life expectancy. Simply getting out of the low zone is one of the best things you can do. Going from low to high-normal is associated with almost a three-year increase in life expectancy, and going from low to high is associated with almost a five-year increase. On average, each one-unit change in VO2 max was associated with a 45-day increase in life expectancy.

Another huge study, published in JAMA in 2018, examined fitness, with cardiorespiratory fitness as part of the equation. People with the most elite fitness and highest VO2 max had an 80 percent reduction in all-cause mortality compared with people with the lowest fitness. If I remember correctly, the discussion said there was no upper limit to the life-expectancy benefits of high VO2 max or cardiorespiratory fitness, within the limits of normal human potential.

That raises the question of how to improve VO2 max. If I am not an elite endurance athlete training 20 to 30 hours per week, but I am a committed exerciser working out about five days per week, how do I reach a high VO2 max? A lot of the literature suggests that high-intensity, vigorous exercise is one of the most important ways to get there.

Martin Gibala, whom I had on the podcast not long ago, brought a large study to my attention. It examined people doing moderate-intensity exercise, more like zone 2 training. They were doing endurance or aerobic exercise at an intensity where they could still have a somewhat breathy conversation. Although they met the standard guideline of about two and a half hours per week, 40 percent of the study population did not improve their VO2 max. The researchers called them nonresponders.

I was surprised that people doing two and a half hours of aerobic exercise did not all improve their VO2 max. When they started doing vigorous-intensity exercise, however, they were able to improve it. You can improve VO2 max with lower- or moderate-intensity exercise, especially if you put in many hours, as elite athletes do. Elite athletes may train 20 to 30 hours per week, and they also do a lot of vigorous-intensity exercise.

For the average committed exerciser, or even the casual exerciser who works out two or three days per week, I think vigorous-intensity exercise should make up most of the workout time. VO2 max is one part of the evidence, but one study from Benjamin Levine's group at UT Southwestern was a turning point for me.

The researchers studied healthy but sedentary 50-year-olds. They did not have hypertension, type 2 diabetes, or other measured diseases, but they were not physically active. I would describe them as not unhealthy rather than healthy. The researchers put them on a two-year exercise program. Dr. Levine studies structural changes in the heart. As we age, the heart gets smaller and stiffer, so the question was whether an exercise program could reverse that part of heart aging.

The exercise program was progressive. It began at a more moderate intensity, but participants quickly progressed to vigorous-intensity exercise. They reached about 75 to 80 percent of their maximum heart rate and exercised five days per week, usually for 20 to 30 minutes. That is an intensity most people can maintain for 20 to 30 minutes. Above 80 percent of maximum heart rate, maintaining the effort for that long becomes difficult for most people.

On one of those days, participants did the Norwegian 4x4 protocol, a form of high-intensity interval training with longer intervals. Longer intervals appear to be especially important for improving VO2 max. They combine intensity, which stresses the cardiovascular system and forces it to become more efficient at delivering oxygen to tissues, with duration.

Each interval involves four minutes of the most intense exercise you can sustain for four minutes, followed by three minutes of recovery at about zone 1. You need that recovery because you are about to repeat the four-minute effort. You repeat the sequence four times.

Participants did the Norwegian 4x4 once per week. After two years, these 50-year-olds had reversed the structural aging pattern of their hearts by the equivalent of about 20 years. Their hearts looked more like 30-year-old hearts than 50-year-old hearts.

Thomas DeLauer: How many times a week?

Dr. Rhonda Patrick: They worked out five days per week for two years.

Thomas DeLauer: Jeez.

Dr. Rhonda Patrick: This was not low- or moderate-intensity training or zone 2. The sham control group did the same amount of exercise, but they did stretching, bodyweight resistance training, yoga, and similar activities. Those are beneficial, and muscle mass is very important, but the control group experienced none of the same changes in the heart. They probably had beneficial metabolic, muscle-mass, and strength changes, but we are talking about the heart.

Vigorous exercise was important for reversing the heart's structural aging changes, including stiffness and reduced size, along with other technical measures. Those changes reversed after only two years of vigorous exercise in these 50-year-olds. That blew my mind and made me think there was something important here.

With that said, any type of exercise, including any form of aerobic or cardiovascular exercise, is very beneficial. Building a habit and exercising consistently are important. I think vigorous exercise is key, and there are many other reasons I would like to discuss. But if you will never do intense exercise and will consistently go out for a zone 2 run several times per week, then that is the right exercise for you.

Any exercise can produce benefits, including metabolic changes. Health has many different endpoints. But if you are trying to optimize what you do for your heart, brain, mental health, and lungs, I am convinced that vigorous-intensity exercise is the...