From time immemorial—or at least since the 1950s—the mantra for people looking to boost muscular size and strength has been to lift heavy weights (usually defined as those that can be lifted only from three to 10 times with proper form).
However, a study published in the Journal of Applied Physiology says that half-century of research is, well, heavy-handed (Mitchell et al., 2012).
Researchers at McMaster University in Canada recruited 18 healthy men to participate in the study, all of whom were in their early 20s and recreationally active, but who hadn’t lifted weights before. Over a period of 10 weeks, subjects were assigned a combination of three different programs that required them to complete as many repetitions as possible on the leg extension machine, depending upon their assigned programs—eight to 12 reps for the heaviest weights and 25 to 30 reps for the lightest. The three programs used in the combinations were: