As winter sets in and as the season of gluttony arrives, three studies in November issues of scientific journals appropriately focus on the benefits of exercise. It’s none too soon for me since I haven’t hit the trail for two weeks.

I’ve been literally laid low with a respiratory infection. I know that some people say that they keep on exercising when they are sick.

But one of my doctors, David Tanner, was out sick at the same time as I have been down with a bug. He is professionally a...