what does your vo2 max score tell you about your fitness?
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some of the highest vo2 max scores belong to elite endurance athletes who can tolerate high levels of intense aerobic exercise for extended periods of time. cross-country skiers and cyclists typically own some of the most impressive scores, with an 18-year-old cyclist from norway posting an all-time high vo2 max of 97.5.
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it used to be only elite athletes knew their vo2 max. considered an objective measure of aerobic fitness, vo2 max testing was typically performed in labs by trained personnel, making it inaccessible to most exercise enthusiasts. but all that changed when smart watches (apple, garmin, etc.) started offering a user-friendly alternative to lab-based testing.
vo2 max measures the capacity of the body’s circulatory and respiratory systems to supply oxygen to the working muscles. more simply put, it’s the maximum (max) volume (v) of oxygen (o2) your body can transport in a single minute. typically expressed by the number of kilograms of oxygen transported per kilogram of body weight per minute, the average vo2 max for a middle-age male 36-55 years of age is 32-38ml/kg/min. for middle-age women, an average vo2 max is 28-33ml/kg/min. the greater the amount of oxygen your body can circulate during a bout of exercise the longer you can sustain the energy needed to fuel your workout.
during lab-based tests, the exerciser runs on a treadmill (or pedals a stationary bike) wearing a heart rate monitor and mask while lab personnel measure how much oxygen is consumed and how much carbon dioxide is expelled. speed/resistance is gradually increased until exhaustion sets in, which is when vo2 max is reached.
some of the highest vo2 max scores belong to elite endurance athletes who can tolerate high levels of intense aerobic exercise for extended periods of time. cross-country skiers and cyclists typically own some of the most impressive scores, with an 18-year-old cyclist from norway posting an all-time high vo2 max of 97.5.
age, body weight/height and sex all affect vo2 max. men, because of their greater quantity of muscle mass, post higher vo2 max scores than women. age, on the other hand, is generally associated with a lower vo2 max, because of a slowing down of the body’s metabolic systems. weight also affects your score as larger bodies work harder to deliver oxygen to the working muscles.
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but vo2 max isn’t only a measure of fitness, it’s also linked to cardiovascular health, making it an important indicator of health and longevity. the higher your vo2 max, the lower the risk of heart disease.
how do smart watches determine vo2 max? sensors built into the watch capture the user’s heart rate and motion (speed, distance, elevation) that combined with their self-reported sex, age, height and weight are used to estimate vo2 max. if you’ve been monitoring the vo2 max score displayed on your smart watch, you’ve probably noticed it’s a dynamic number. that’s because it fluctuates based on your workout habits. if you’re exercising less often or less strenuously than previous weeks, your score can decrease. but if you’ve increased the volume and intensity of your workouts, you’ll likely notice a jump in vo2 max.
before you go around bragging about your impressive vo2 max, keep in mind smart watch-based calculations are an estimate only. and since most brands don’t share the algorithm used to calculate vo2 max, it’s hard to assess how the score is calculated.
only a couple of studies have attempted to validate vo2 max estimates generated by a smartwatch (apple watch series 7, series 9 and ultra 2) with tests done in a certified lab. both reached similar conclusions it underestimated vo2 max in individuals with high levels of fitness and overestimated the score in those with low levels of fitness.
the other issue with vo2 max scores generated by a smartwatch is the algorithm used is often changed, which breaks the link between your historical and current score. this is often the reason for a sudden drop or rise in vo2 max without a change in health or fitness regimen.
sleep and recovery are also important when it comes to maintaining or improving vo2 max. elite athletes may notice a decrease in their vo2 despite increasing their training intensity largely because of fatigue. in fact, coaches and athletes often monitor vo2 max to determine whether more rest, not more exercise, is needed.
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also worth understanding is a high vo2 max doesn’t guarantee superior performance. athletes with the highest vo2 max aren’t always the ones standing on top of the podium. several other physiological, biomechanical and psychological factors contribute to athletic performance. that said, almost all of the world’s best endurance athletes have an impressive vo2 max, some of which can be attributed to genetics, which is one of the reasons they’re among the best of the best.
for the recreational athlete monitoring their own vo2 max, it isn’t only about tracking your fitness. since it’s also associated with a reduced risk of all-cause mortality, consider it an assessment of your health as well. most smartwatches rate vo2 max as high, above average, below average or low, so work toward achieving an average to above average rating.
to boost your vo2 max, include more high intensity exercise into your workout regimen, even if it’s only in short bouts. long, slow distances (running, walking, cycling, swimming) are great at building endurance, but pushing your body into that uncomfortable zone is what increases aerobic fitness.
no longer a tool used solely by elite athletes, tracking vo2 max is just one more feature smart watches have to offer. it’s also one more tool to monitor your health and fitness.
this article was originally published in the montreal gazette on november 16, 2025.
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