One of the purposes of endurance exercise is to build up your cardiorespiratory fitness (CRF), which is the ability of your body to supply oxygen to your muscles during physical activity. Research suggests that CRF is an important predictor of age-related diseases like high blood pressure, obesity, diabetes, and heart disease; low CRF is also correlated with a 4-fold increase in all-cause mortality.
When it comes to measuring your CRF, fitness trackers have become a popular staple because they allow for heart rate tracking, timing your runs/walks, calories burned, and steps taken. One metric of CRF that your fitness tracker can’t provide you with is your maximal oxygen consumption or VO2Max—a little known fitness marker that not only gives you information about your physical fitness, but is also linked with mitochondrial health and longevity.
What Is VO2Max?
In exercise physiology, VO2Max is the maximum amount of oxygen that your body can use during exercise and is often used as a more direct measure of CRF than heart rate. Oxygen is a necessary component of ATP production in the mitochondria, so increasing the amount of oxygen available to your cells can increase mitochondrial density and thus improve ATP production at the cell level.
Source: Oxygen consumption at rest. Jackson, A., et. al. (2004). Physical Activity for Health and Fitness—Updated Edition. Champaign, Il: Human Kinetics.
O2 consumption rises when we begin to exercise then hits a steady state during which it remains stable until you reach the point of exhaustion and stop. Fluid loss, electrolyte depletion, and glycogen depletion limit our capacity for exercise, so achieving a steady state quickly is important for exercise performance and overall fitness. Your ability to achieve a steady state varies based on your activity level and health status. On the low end of the spectrum are sedentary individuals who rarely perform exercise and heart patients who are limited in their ability to perform exercise because of a weakened heart muscle. On the opposite end of the spectrum we have high-performance athletes who exercise every day for 3 or more hours and have a high capacity for endurance training. Individuals who regularly engage in exercise are more adept at taking in, delivering, and using oxygen (and subsequently making ATP at the cell level) than individuals who rarely exercise because they hit the steady state more rapidly. Consequently, fit individuals tend to have a higher VO2Max than their unfit age and gender-matched peers.
How Is It Measured?
We can measure VO2Max in a variety of ways. The most accurate way is through direct measure, but this method requires access to a physiology or sports medicine lab and isn’t feasible for the majority of people. That’s where submaximal measures come into the picture. These proxy methods provide accurate estimates of VO2Max for little to no cost and can serve as guidelines to help track VO2Max over time. Submaximal measures include:
- Walking/Running Tests—requires the subject to run or walk 1-1.5 miles to calculate VO2Max based on your heart rate in the last ¼ mile of the test or immediately after stopping.
- Heart Rate—uses your exercise or post-exercise heart rate to calculate VO2Max. Exercises may include running, walking, cycling, or any endurance exercise that elevates the heart rate.
- Step Test—requires subjects to perform a stepping sequence (up-up-down-down) over a period of 3 mins to calculate VO2Max based on recovery heart rate (HR measured for 15 seconds at the end of the test).
- Nonexercise Data—requires subjects to fill out questionnaires (i.e., PA-R, demographic data, BMI) and uses nonexercise data to give a composite score as a proxy for VO2Max. This test is used for large groups rather than individuals.
Is VO2Max Really a Good Metric to Track for Longevity?
Based on what we read, VO2Max is an excellent metric for gauging CRF which is important for chronic disease risk reduction, and as it turns out, improving your VO2Max is also a great way to max out your mitochondrial health and improve your lifespan.
As a quick refresher, mitochondrial dysfunction is a hallmark of aging and as our mitochondria lose their ability to repair damage and make energy, we begin to age at the cellular level. According to sources we found, VO2Max peaks around age 30 and steadily declines with each successive decade by 10%; however, recent research shows that increasing VO2Max improves oxygen delivery and use inside the cells and can help you maintain your health over the course of your lifespan. Furthermore, regular endurance training (3-5x per week) at any age can help improve VO2Max by 15-20%.
We also found that VO2Max is linked with all-cause mortality. In this prospective cohort study of 792 men with an average follow-up of 45 years, participants were divided into tertile groups based on their predicted VO2Max ranging from low to high. Following statistical analysis, researchers found that a low VO2 max level increased the risk of death by 21%, an association that held even after adjusting for established cardiovascular risk factors like smoking, blood pressure, and total cholesterol.
To get into the nitty gritty, we love this episode of Peter Attia’s podcast featuring Dr. Iñigo San Millán, Assistant Professor at the University of Colorado School of Medicine. Admittedly, the episode is on the long side (approx. 3 hours), but you can skip to the good stuff starting at the 1 hour mark where Dr. Millán talks about his research on mitochondrial health in elite athletes and those of lower fitness levels (aka poor VO2Max). Our three key takeaways were:
- Fat burning and lactate production are good proxy measures of mitochondrial function—if you don’t use fat stores or if you produce a lot of lactic acid when you exercise, your mitochondrial health suffers.
- Elite athletes and very fit individuals have on average 3-4x the amount of mitochondria compared to normal individuals making them more efficient at delivering and using oxygen to make energy. The size of mitochondria in fit individuals is also larger than that of unfit individuals.
- To improve mitochondrial function and efficiency, Dr. Millán recommends what he calls “Zone 2 training” in which you engage in low intensity exercise (working at 50–70 percent of your max heart rate for 10-60 mins) to maximize fat oxidation and stimulate mitochondrial biogenesis.
In reading and listening to all of this, we came to the conclusion that it’s not about whether you become an elite athlete, but rather how, and if, you choose to engage in physical activity and use VO2Max as your fitness guide. Endurance training is undoubtedly good for your heart and lungs, but knowing that it can help give your mitochondria a boost and turn back the clock is a bit of extra motivation. The best part is that even as we increase in years, the effects of endurance training hold regardless of our health status.
How Can I Calculate My VO2Max and Apply It?
We don’t have access to a physiology lab and it’s likely that you don’t either. That’s why we suggest a submaximal test to calculate VO2Max if you’re ready to start tracking your CRF. Among our staff, the consensus was that the walk and/or run test are the easiest methods to get an estimate, but you can use any method that you feel comfortable doing. We recommend the 1-mile walk for anyone who isn’t used to regular exercise, has exercise-related injuries, or has been told by their doctor not to engage in strenuous physical activity; the 1.5-mile run is appropriate for those who get regular exercise and don’t have any injuries or conditions that prevent them from running. There’s also no need to memorize equations or break out your calculator app; we found this awesome calculator online that allows you to input your test data and get your VO2Max estimate immediately.
It’s important to remember that your VO2Max is affected by several factors including age, gender, fitness level, and elevation. It’s a malleable metric that can get better or worse depending on your lifestyle behaviors. If you’ve calculated your VO2Max and are curious to see where you fall on the spectrum, check out the tables below to gauge your CRF.
The next obvious step is figuring out what to do once you know where you fall on the fitness spectrum. One of the reasons we love using VO2Max as a metric is that it’s something you can readily improve just by getting your heart pumping. Two research-backed methods we found are:
- HIIT—Research suggests that interval training is one of the best ways to improve VO2Max because it helps your body’s oxygen-dependent and independent processes become more efficient. Check out this article to get started with HIIT in just 11 minutes per day.
- Continuous Endurance Training—
- For the experienced athlete/fitness enthusiast: run, walk, bike, or row at 90-95% of your max heart rate (calculated as 220 - age) to increase the amount of blood your heart can pump per minute.
- For those new to exercise: run, walk, bike, or row at 50-70% of your max heart rate. Click here for a table that shows you target heart rates by age.
Don’t worry if you end up starting on the very poor end of the spectrum. As you continue to engage in endurance exercise, you’ll see your VO2Max improve over time. If you’re already at a good starting point, challenging yourself during your training sessions will help push your VO2Max from good to superior. Regardless of where you’re starting and what your ultimate goal is, the most important thing is to use exercise as a tool to improve your longevity and overall health. Your mitochondria will thank you!
Share your experiences with VO2Max with us or anything we may have left out: firstname.lastname@example.org
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