Does this mean that everyone (except those with heart failure) can or should throw away their pills and begin aerobics? The answer is far from established by this paper. First, the kinds of exercise done by the patients and the medications they took varied enormously; the statistical analysis, though elaborate, was in essence crude, and it might have been that there were subgroups whose results differed from those of larger groups in which they were included. Many of the patients in the trials of exercise were also taking medicine; if they had not been, the results might well have been very different. For example, the medicine might have increased their exercise tolerance and therefore been an essential precondition of the beneficial effects of exercise.
The authors also warn that very little is known of the ill effects, if any, of exercise. It is here that Sir Winston might have been able to defend his anti-exercise stance.
Suppose the necessary exercise takes half an hour each day: that means that it occupies 11 or 12 full days of waking time per year. Over ten years, that is equivalent to four months of waking time. If the exercise does not prolong life on average by more than 4 months per ten years it is not worth doing – unless it is enjoyed for its own sake. And since this paper gives us only the relative and not the absolute risks of death, we cannot say whether taking exercise is worth the time expended on it.
So Sir Winston might have been right after all – though personally I doubt it.