The three-second workout could also be useful as a stopgap to help maintain or even add to our arm strength for those of us who are buried under work or family commitments and are unable to get to the gym.

1. Just find a dumbbell that feels heavy — you might start with a 10-pound version, for instance, if you are new to weight training.
2. Lift it with both hands, to start a biceps curl, then lower it with one hand through a count of three seconds to complete a short, sharp and draining eccentric contraction.

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 tota...