New research published this month in the Journal of Applied Physiology challenges what strength training pundits have taught for years: In order to grow bigger muscles, you need to lift heavy weights. A team of researchers led by Stuart Philips at McMaster University in Canada separated subjects into two groups: one group did “heavy” weights for fewer reps (8-12 reps) and the other group lifted a lighter weight and performed more reps (20-25 reps). Subjects in both groups were “trained” meaning they had a minimum of 2 years of strength training experience (studies with “trained” subjects are often viewed as more credible because applying any type of strength training intervention produces positive results with subjects who are new to strength training). The researchers required both groups to train to momentary muscle failure. The result? After 12 weeks, both groups experienced the same improvements in muscle strength and muscle size. The researchers concluded, “We provide novel evidence of lifting markedly different (lighter versus heavier) loads (mass per repetition) during whole body resistance training on the development of muscle strength and hypertrophy in previously trained persons. Using a large sample size (n=49), and contradicting dogma, we report that the relative load lifted per repetition does not determine skeletal muscle hypertrophy nor, for the most part, strength development.”
Take home message: Despite what the majority of the strength training world believes, the amount of weight you lift isn’t the key; reaching momentary muscle failure is the real stimulus.