VO2max and longevity: what the research says about fitness and living longer

Few numbers in medicine predict how long you will live as strongly as your cardiorespiratory fitness. Here is the evidence, study by study, and how to read it without over-reading it.

The big studies

Blair et al., 1989 — the Aerobics Center Longitudinal Study

Researchers at the Cooper Institute followed more than 13,000 men and women who had completed a maximal treadmill test. Over about eight years, the least fit groups had far higher death rates than the moderately and highly fit, even after accounting for age, smoking, cholesterol, blood pressure and other factors. The largest drop in risk came between the lowest fitness group and the next one up.

Kodama et al., 2009 — meta-analysis in JAMA

Pooling 33 studies with about 100,000 participants, this analysis found that each 1-MET higher fitness (1 MET = 3.5 ml/kg/min of VO2max) was associated with about 13% lower risk of death from any cause and about 15% lower risk of cardiovascular events.

Mandsager et al., 2018 — 122,007 treadmill tests at Cleveland Clinic

Patients who had a treadmill test between 1991 and 2014 were grouped by performance for their age and sex. Over a median of 8.4 years:

• Risk of death fell steadily from the lowest to the highest fitness group.
• The lowest group had roughly five times the adjusted risk of the "elite" group (top 2.5%).
• In the same cohort, the risk linked to low fitness was as large as, or larger than, the risk linked to smoking, diabetes or coronary artery disease.
• There was no upper limit: elite fitness was associated with lower risk than high fitness, including in older people.

The American Heart Association, 2016

In a scientific statement, the AHA argued that cardiorespiratory fitness should be assessed routinely in clinical practice as a "clinical vital sign", alongside blood pressure, cholesterol and smoking.

What these studies do not prove

• They are observational. Fit people differ in many ways (genes, income, diet, existing disease). Researchers adjust for what they can measure, but not for everything.
• Some low fitness reflects illness that hasn't been diagnosed yet.
• Fitness was mostly measured once. Studies that measured it twice, though, found that people who became fitter had lower risk than those who stayed unfit — a hint that improving helps.

Together with trials showing that training improves blood pressure, insulin sensitivity and heart function, the overall picture is strong: being fitter is very likely to make you live longer and better.

How big a change is worth it?

1 MET is 3.5 ml/kg/min. For an unfit adult, gaining 3–7 ml/kg/min with a few months of regular training is common. The research suggests the biggest health gain comes from leaving the bottom group — going from unfit to moderately fit.

What to do

1. Find your baseline: a watch estimate, a field test or a lab test. Compare it with the norms for your age.
2. Build easy aerobic volume most days — walking counts if you're starting out. See 80/20 training.
3. Add one interval session per week once you're comfortable, such as the Norwegian 4×4.
4. Keep it up: fitness fades within weeks of stopping. See how fast you lose VO2max.

Sources

• Blair SN, et al. Physical fitness and all-cause mortality: a prospective study of healthy men and women. JAMA, 1989.
• Kodama S, et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis. JAMA, 2009.
• Mandsager K, et al. Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Netw Open, 2018.
• Ross R, et al. Importance of assessing cardiorespiratory fitness in clinical practice: a case for fitness as a clinical vital sign. Circulation, 2016.