I suppose I’m willing to invest 3 seconds a day. Gretchen Reynolds reports in the NY Times (gift link = no paywall):

Could three seconds a day of resistance exercise really increase muscular strength?

That question was at the heart of a small-scale new study of almost comically brief weight training. In the study, men and women who contracted their arm muscles as hard as possible for a total of three seconds a day increased their biceps strength by as much as 12 percent after a month.

The findings add to mounting evidence that even tiny amounts of exercise — provided they are intense enough — can aid health. I have written about the unique ways in which our muscles, hearts, lungs and other body parts respond to four seconds of strenuous biking, for instance, or 10 seconds of all-out sprinting, and how such super-short workouts can trigger…