When it comes to strength training, there's nothing magical about three sets. In fact, a single set of 12 repetitions can generally build muscle just as efficiently as can multiple sets of the same exercise. So if you're short on time, try this approach: Work your major muscle groups two or three times a week. Do a single set of each exercise, using a weight or resistance level heavy enough to tire your muscles after about 12 repetitions.
Sep. 10, 2011