By. Dr. Sean Delanghe BSc (Hons), DC

If you run, cycle, swim, or do pretty much any type of endurance exercise, you’ve probably heard of VO₂max. It’s often described as one of the best measures of cardiovascular fitness, and you’ll now find it reported on many Garmin, Apple and other fitness watches. But does having a higher VO₂max actually have anything to do with how long we live?

A recent systematic review and meta-analysis provides some pretty compelling evidence that it does.

First, what exactly is VO₂max?

VO₂max is essentially a measure of how much oxygen your body can use when you’re exercising as hard as you can. It reflects the combined ability of your lungs to bring in oxygen, your heart and blood vessels to deliver it, and your muscles to use it. It is usually expressed as millilitres of oxygen per kilogram of body weight per minute (mL/kg/min).

A true VO₂max is traditionally measured in a laboratory while exercising to exhaustion, usually running or cycling. However, fitness can also be estimated using exercise tests and mathematical equations. This distinction becomes important in the study.

What did the researchers actually do?

The researchers performed a systematic review and meta-analysis, meaning they combined the results of many previous studies rather than looking at one group of people. They found 42 studies representing 35 different cohorts and more than 3.8 million observations, including more than 362,000 deaths from any cause and 56,000 cardiovascular deaths.

The studies measured fitness in several different ways. Some directly measured VO₂max in a laboratory, while others estimated fitness using maximal or submaximal exercise tests, or even equations that did not require an exercise test. The researchers wanted to determine whether these different measures of cardiorespiratory fitness were associated with mortality in a similar way.

What did they find?

The results were remarkably consistent. For every 1 MET higher level of fitness, which is approximately 3.5 mL/kg/min of VO₂max, there was an association with approximately a 14% lower risk of death from any cause and a 16% lower risk of death from cardiovascular disease.

Put another way, people with higher cardiorespiratory fitness tended to live longer. And this wasn’t a small study — we’retalking about millions of observations across dozens of studies. The relationship was also broadly similar whether fitness was directly measured or estimated.

That doesn’t mean, however, that increasing your VO₂max by 1 MET will automatically reduce your personal risk of death by exactly 14%. This is an important distinction when interpreting health research.

Does higher VO₂max actually cause people to live longer?

Ready for the most obvious statement of the day? Correlation does not equal causation! We don’t know for certain if this relationship is CAUSAL.

Most of the evidence in this review came from observational studies. These can tell us that two things are strongly associated, but they cannot completely prove that one causes the other. People with higher fitness may also exercise more, smoke less, eat differently, have healthier body weights or have fewer underlying health problems.

The researchers adjusted for many potential confounding factors, but statistical adjustment can never eliminate every possible influence. So the safest interpretation is that higher fitness is strongly and consistently associated with lower mortality risk. That’s different from saying that deliberately increasing your VO₂max by a specific amount will produce a predictable reduction in your risk of death.

What about people who aren’t endurance athletes?

This may actually be one of the most useful parts of the research. You don’t need to be a marathon runner to benefit from being fit.

Previous research suggests that some of the largest health differences occur when people move from very low fitness to moderate fitness. In other words, going from very unfit to reasonably fit may be considerably more important for health than taking an already-fit person and making them extremely fit.

So while a VO₂max of 55 might be impressive, someone increasing their fitness from 25 to 35 may be making a much more meaningful change to their health than an already-fit person going from 50 to 55. The goal isn’t necessarily to become an elite endurance athlete. Getting out of the very-low-fitness category appears to be particularly important.

Do you need a laboratory VO₂max test?

Long story short- NO! The researchers found broadly similar associations between mortality and both directly measured and estimated cardiorespiratory fitness.

That doesn’t mean every smartwatch gives you an accurate VO₂max. Wearable devices use algorithms and estimates, and their accuracy can vary. What the research suggests is that estimated fitness can still contain useful information about health at a population level, even when it isn’t measured in a laboratory.

What does this mean for you?

The practical takeaway is pretty simple: you don’t need to obsess over your VO₂max number. Instead, think about cardiorespiratory fitness as something you can develop and maintain throughout your life.

If you’re currently inactive, you don’t need to start training like an Olympian. Walking regularly, cycling, swimming, jogging or other activities that challenge your cardiovascular system can improve fitness. If you’re already active, adding some higher-intensity exercise can help push your fitness further. And if you’re an endurance athlete, VO₂max can be an interesting performance metric, but it certainly isn’t the only measure that matters.

The bigger picture is that cardiorespiratory fitness appears to be one of the strongest measurable markers we have for long-term health.

And the beauty is you don’t need an elite VO₂max to be healthy, and you don’t need a laboratory test to start improving your fitness. The important thing is to keep moving, challenge your cardiovascular system consistently, and strive to find FUN ways maintain your fitness throughout your life.

If you have any questions about improving your overall health, feel free to reach out to our Waterloo based chiropratros, physiotherapists and registred massage therapists HERE.