A Study on Exercise Levels and Mortality Showing that More is Not Necessarily Better
Past epidemiological studies have found little or very mixed evidence that more or different types of exercise are better. There is clearly a big difference between no exercise and regular moderate exercise, but adding more exercise on top of that doesn't seem to have any reliably greater association with long-term health and lower mortality rates. On the other hand there are studies to show that elite athletes live significantly longer than the general population, but there it may be the case that a successful career in athletics selects for those who are more robust and more likely to live longer anyway. Here is a study demonstrating an interesting pattern of association between levels of exercise and mortality:
People who are physically active have at least a 30% lower risk of death during follow-up compared with those who are inactive. However, the ideal dose of exercise for improving longevity is uncertain. The aim of this study was to investigate the association between jogging and long-term, all-cause mortality by focusing specifically on the effects of pace, quantity, and frequency of jogging. As part of the Copenhagen City Heart Study, 1,098 healthy joggers and 3,950 healthy nonjoggers have been prospectively followed up since 2001. Cox proportional hazards regression analysis was performed with age as the underlying time scale and delayed entry.Compared with sedentary nonjoggers, 1 to 2.4 hours of jogging per week was associated with the lowest mortality (multivariable hazard ratio [HR]: 0.29). The optimal frequency of jogging was 2 to 3 times per week (HR: 0.32) or ≤1 time per week (HR: 0.29). The optimal pace was slow (HR: 0.51) or average (HR: 0.38). The joggers were divided into light, moderate, and strenuous joggers. The lowest HR for mortality was found in light joggers (HR: 0.22), followed by moderate joggers (HR: 0.66) and strenuous joggers (HR: 1.97). The findings suggest a U-shaped association between all-cause mortality and dose of jogging as calibrated by pace, quantity, and frequency of jogging. Light and moderate joggers have lower mortality than sedentary nonjoggers, whereas strenuous joggers have a mortality rate not statistically different from that of the sedentary group.