The Year in Fitness: Exercise, Add Intensity, Live to See Another Year

The overarching message of this year’s exercise-related science was that physical activity, in almost any form and amount, changes the arc of our lives.

But much of this research also hinted that there may be something unique about pushing yourself at least a little extra that alters and ramps up the benefits of exercise, beginning deep within our cells.

Oh, and several studies also helpfully told us that hot baths are a fine idea for those of us who work out, even if the weather is warm.

But intensity was the theme of 2017. One of the first studies I wrote about this year detailed the career and physiology of Robert Marchand, a diminutive French centenarian who took up competitive cycling as a retiree and began setting age-group records.

But after a physiologist revamped his once-leisurely training, adding some strenuous pedaling, Mr. Marchand decisively bettered his own records and, at the age of 103, set a new world mark for the most miles pedaled in an hour by a centenarian.