In 122,007 treadmill-tested patients, the fittest had one fifth the risk of death of the least fit

Retrospective cohort at the Cleveland Clinic: consecutive adults referred for treadmill testing, 1991–2014. Median follow-up 8.4 years, 13,637 deaths. Mean age 53.4. Fitness groups by age- and sex-specific percentile of peak estimated METs, from low (under the 25th) to elite (97.7th and above).

For comparison in the same model: diabetes 1.40 (1.34–1.46), coronary artery disease 1.29 (1.24–1.35). Elite still beat high fitness (HR 0.77, 0.63–0.95), including in people aged 70 and over (HR 0.71, 0.52–0.98).

Elite thresholds in METs (1 MET = 3.5 mL/kg/min): men 40–49 at least 14.7, 50–59 14.0, 60–69 13.0, 70–79 11.5, 80+ 10.0; women 40–49 13.3, 50–59 13.0, 60–69 11.1, 70–79 10.0, 80+ 8.4.

Observational, in a referred clinical population. METs were estimated from treadmill speed and grade, not measured by gas exchange. "No upper limit" means no observed harm at the top; it does not prove that more fitness keeps adding benefit.

VO₂max is in the battery for this reason. We report it as a percentile against norms and never as a mortality multiplier for you.