Study shows fitness metric may influence longevity - but does VO2 max tell us the whole story?

VO2 max – your body’s ability to transport and use oxygen during intense exercise – is more than just a measure of athletic performance. Long regarded as the gold standard for cardiovascular fitness, this key metric, measured in millilitres of oxygen per kilogram of body weight per minute (ml/kg/min), is now linked to something even more important: longevity. New research reveals that those with a higher VO2 max not only perform better in endurance sports but also have a signifi cantly lower risk of cardiovascular disease, hypertension, type-2 diabetes, and even premature death. In short, boosting your VO2 max could be one of the most powerful ways to extend your life.

Health and human performance specialist Dr David Lipman explains why VO2 max is such a reliable indicator of cardiovascular fitness: “It encompasses many body systems. It shows how much you can breathe in and get from your lungs to your blood and from your blood to the muscles.” The higher an athlete’s VO2 max, the more fuel they can burn at their top end. “There is a large genetic component,” adds Lipman, “but it is also trainable.”

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Improving your VO2 max in a bid to increase longevity is attracting more and more mainstream interest. The question of whether a higher VO2 max equates to a longer life is, of course, compelling. However, Lipman cautions that, in this instance, correlation is not causation. “I think VO2 max is just a measure of the type of lifestyle that will allow you to live longer,” he says. “If you have a good, healthy diet, good body composition, a balance of volume and intensity, and some strength training, it is likely that you will have a high VO2 max.”

One study investigating midlife cardiorespiratory fitness and the longterm risk of mortality, published in the Journal of the American College of Cardiology in 2018, explored the role played by physical fitness in longevity. The study tracked the relationship between VO2 max and mortality among 5,000 middle-aged men over 46 years. The results showed that each unit increase in VO2 max was associated with a 45-day increase in lifespan. Those with the highest fitness levels lived almost five years longer on average than their less fit counterparts. The study’s long duration and large sample size make it a persuasive piece of evidence that VO2 max isn’t just a measure of performance but a powerful predictor of longevity too.

Even so, establishing a causative link is challenging. High VO2 max is often related to consistent physical activity and a generally healthier lifestyle. A much more recent study, published last year in the Journal of Clinical Endocrinology and Metabolism, sought to unravel the complex relationships between VO2 max and factors including body composition, physical activity and longevity. The study highlighted the importance of other lifestyle and genetic factors such as lean muscle mass and physical activity, and concluded that, despite being a strong predictor of mortality, VO2 max is not causally associated with longevity.

“VO2 max is measurable and quantifiable,” explains Lipman. “It is an output measure, making it a good indicator that the whole system is in good order.” Maximal oxygen update is an appealing figure to track for anyone focusing on improving their cardiovascular health, but longevity is determined by a complex interplay of many factors. “There are other surprising predictors of longevity such as grip strength and leg strength,” adds Lipman. Just like VO2 max, these benchmarks likely correlate to longer life because strength is one part of the longevity jigsaw puzzle.

VO2 max naturally declines with age, typically at a rate of about 1% per year after age 30. This decline is largely due to physiological changes that occur as part of the ageing process, such as decreased cardiac output (the amount of blood pumped per beat), reduced muscle mass and lower pulmonary function. However, it can be hard to distinguish between the effects of biological ageing and the effects of reduced physical activity. “It is a case of use it or lose it,” says Lipman, explaining that VO2 max declines more slowly in those who continue to train.

A study published in the Journal of the American Society for Preventative Cardiology in 2007 revealed how controlled endurance exercise impacts aerobic fitness among older adults. This meta-analysis of 41 clinical trials involving 2,102 participants aged 60 and above explored the effects of aerobic exercise on VO2 max. The results indicated a moderate but meaningful increase in VO2 max, translating to a net improvement of 16.3%. The biggest gains accrued to those whose exercise programme extended beyond 20 weeks and who trained at an intensity of 60- 70% of VO2 max.

Lipman urges caution: “Much of the research on older people uses sedentary individuals. Training status is super relevant in such studies.” In other words, untrained people find it easier to make significant improvements. “Most people can increase their VO2 max from the lower end of the range if they are untrained. However, if you are already highly trained, there is less room for improvement.” The good news is that, whether you are new to exercise or an experienced athlete, you can improve or maintain your VO2 max through training.

“There are two types of training you can use to boost your VO2 max,” explains Paul Vousden, owner of endurance sports gym Strength2Speed. “In the absolute simplest terms, you need low-intensity activity where you are a little bit out of breath for a long time, or short but very hard efforts.” In Vousden’s view, while younger riders might focus on boosting their aerobic fitness with long Zone 2 rides, a better route for veterans is shorter, sharper intervals. “Older riders who have been training for many years already have an endurance base, so the focus on short, hard VO2 intervals allows them more time for recovery than if they were doing long, steady base mileage.”

Does Lipman agree with this shorter, more intense approach? “From a performance standpoint, you need high and low intensity,” he says. He points out that, at a population level, most of us need to be moving around more – be it walking, cycling or jogging – at a low intensity. “It could be that short doses of high intensity are more important for certain people – if you only have very limited time, high intensity is the way to go.”

While maintaining a high VO2 max can contribute significantly to healthier, more resilient ageing, longevity does not revolve around this one factor. It is true that having a higher VO2 max is associated with better health outcomes, but genetic factors, lifestyle choices, environmental influences and access to healthcare all play a part in life expectancy. To live as healthily as possible for as long as possible, we need to take a holistic approach that encompasses strength training, eating well, maintaining good body composition and looking after our mental health. Still, it’s good to know as we’re smashing out those hard reps on the turbo that maintaining a high VO2 max can undoubtedly contribute to a healthier, longer life.

The research suggests that, yes, this is indeed a risk. While regular cardio is strongly linked to longer life, a higher incidence of heart problems such as atrial fibrillation and scarring has been recorded among athletes who have undertaken very high-volume, high-intensity exercise over many years. Some experts also have concerns relating to the oxidative stress that may result from prolonged high intensity work. While moderate exercise is anti-inflammatory, excessive endurance training may suppress immune function and increase inflammation.

A 2015 study published in the Journal of the American College of Cardiology supported the theory of a ‘U-shaped curve’ whereby the lowest mortality risk corresponds to moderate levels of exercise but increases towards the very high end of the volume axis. Light to moderate joggers were found to have the lowest mortality risk, whereas extreme runners had similar mortality rates to sedentary people.

Changes to VO2 max take time, so there is little point in testing frequently. “Knowing your VO2 max is not relevant in terms of setting your training zones,” says coach Paul Vousden. If you are following a power-based training schedule, it makes more sense to do a simple FTP test [a test of your Functional Threshold Power, the power you can produce over an hour] every few weeks. Even so, VO2 max is a nice-to-know figure to have measured occasionally.

The most accurate method of testing your VO2 max is with a graded exercise test in a lab setting, with a trained technician capturing and measuring expired respiratory gases. Many fitness trackers and smartwatches offer VO2 max estimates based on heart rate data and activity levels, but the accuracy is low. Wearable devices can be useful for tracking trends in fitness over time but treat their VO2 max estimates with caution.

Mindful that it had been at least a decade since I last had my VO2 max test, this feature provided the perfect incentive for a re-test. Having not followed a serious training for a similar length of time, I was curious to find out how much damage had been done. I visited Mapdec Cycle Works in Kendal, where owner Vousden put me through my paces with 18 minutes of masked-up torture. “There is no point waiting until you are fit to get tested,” he reassured me. “You need to know where you are starting from.”

Looking at my numbers, I cringed at my peak power, a wattage I used to warm up at, but I was delighted to find that my VO2 max had remained good, at 53ml/kg/min – a figure classed as excellent for my age. My brief moment of smugness was soon brushed away as Vousden reminded me that VO2 max alone does not equate to race-winning performance. “Using VO2 max as a measure of general well-being is more important than your lactate threshold or your power output,” he began diplomatically, “but if you want to be competitive, we need to see some improvement in power output.”