Higher VO2 max goes with a longer life

VO2 max (the most oxygen your body can use at full effort) tracks closely with how long people live. Each step up in fitness goes with a lower risk of early death, and the benefit holds even at the top end. In one study of 750,302 veterans, low fitness carried more risk than any heart risk factor the researchers checked. The level you need for good heart health drops with age and sits a little lower for women.

Why it works

A high VO2 max reflects a heart that pumps more blood with each beat, healthy blood vessels, and muscles that use oxygen well. These studies show a link rather than proof of cause, so fitness may also stand in for other healthy habits.

What it means in practice

Raising your VO2 max by 1 MET (3.5 ml/kg/min) goes with about 13% lower risk of early death, wherever you start.

The evidence

• Kodama, S., Saito, K., Tanaka, S. et al. (2009). Cardiorespiratory Fitness as a Quantitative Predictor of All-Cause Mortality and Cardiovascular Events in Healthy Men and Women: A Meta-analysis. JAMA.

  Each 1-MET higher aerobic capacity (about 1 km/h faster running speed) went with 13% lower all-cause mortality and 15% fewer heart disease events. People below 7.9 METs had 1.70 times the death risk of people at 10.9 METs or more. The minimal fitness linked to substantially lower event rates was about 9, 8, and 7 METs for men at ages 40, 50, and 60. For women it was 7, 6, and 5 METs.

  n=102980

• Kokkinos, P., Faselis, C., Samuel, I.B.H. et al. (2022). Cardiorespiratory Fitness and Mortality Risk Across the Spectra of Age, Race, and Sex. Journal of the American College of Cardiology.

  Higher fitness went with lower death risk in a stepwise pattern across age, sex, and race, including people in their 70s and 80s. Risk was lowest at about 14 METs for both men and women, with no sign of extra risk at extremely high fitness. The least fit fifth had about 4 times the death risk of the extremely fit. Being unfit carried more risk than any of the cardiac risk factors examined.

  n=750302

Why we call confidence high

A meta-analysis of 33 cohort studies (102,980 people) found each extra MET of fitness went with 13% lower death risk. It also estimated the minimum healthy level for each age and sex (Kodama 2009). A cohort of 750,302 veterans found the same stepwise pattern across age, sex, and race, with the lowest risk near 14 METs and no rise at extreme fitness (Kokkinos 2022). Both studies are observational, so they show a strong link rather than proven cause.

Where it applies

Healthy adults in observational studies. Kodama's minimums by age and sex cover ages 40 to 60. Kokkinos covers ages 30 to 95, mostly men, all U.S. veterans.