1 Wen CP

Wai JP

Tsai MK

et al. Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. Chi Pang Wen and colleaguesclaim that exercising for 15 min per day results in a 14% reduced risk of all-cause mortality (0·86, 95% CI 0·81–0·91). Further, they claim that every additional 15 min of daily exercise beyond the minimum daily amount of 15 min reduces all-cause mortality by an additional 4% (2·5–7·0).

This cannot be true, however, since the risk of mortality is an absolute. The risk can be postponed, but it cannot be reduced, as Wen and colleagues claim, and nor can it be eliminated. In other words you can run faster, but you arrive later.

We are aware of just two reported exceptions to this otherwise invariable rule and they are Elijah, who while still alive went up by a whirlwind into heaven (Kings 2:11), and Enoch, who was translated that he should not see death (Genesis 5:24). The details of Enoch's final end are veiled in mystery but Elijah's heavenward passage in a fiery chariot was witnessed by his servant Elisha, who picked up Elijah's mantle as it fell to the ground and thereafter assumed his master's role as prophet. In any event, neither episode occurred in the context of a randomised controlled trial.

We contend, therefore, that the risk of mortality for everyone—prophets included—is 1·0 (1·0–1·0).

We declare that we have no conflicts of interest.