Love studies like this, in which people were actually tested for an objective measure of fitness and then followed over time to see who died first. The upshot? Fitness lowers the risk of mortality. The higher level of METs you can produce in an exercise test, the less likely you are to die compared to someone who was less fit. Women with lower METs lived as long as men who had outperformed them on the test.

Results. There were 29,470 men (51.4%) and 27,814 women (48.6%) with mean ages of 53 and 54 years, respectively. Overall, men achieved 1.7 METs higher than women (P<.001). During median follow-up of 10 years, there were 6402 deaths. The mortality rate for men in each MET group was similar to that for women, who achieved an average of 2.6 METs lower (P=.004). Fitness was inversely associated with mortality in both men (hazard ratio [HR], 0.84 per 1 MET; 95% CI, 0.83-0.85) and women (HR, 0.83 per 1 MET; 95% CI, 0.81-0.84). This relationship did not plateau at high or low MET values.

Conclusion. Although men demonstrated 1.7 METs higher than women, their survival was equivalent to that of women demonstrating 2.6 METs lower. Furthermore, higher MET values were associated with lower mortality for both men and women across the range of MET values. These findings are useful for tailoring prognostic information and lifestyle guidance to men and women undergoing stress testing.

Source: Sex Differences in Cardiorespiratory Fitness and All-Cause Mortality – Mayo Clinic Proceedings