Hormones such as human growth hormone (GH) and testosterone have been shown to play a role in muscle hypertrophy and strength gains. One of the core training principles for muscle hypertrophy in bodybuilding is short rest— less than 1 minute between sets. In 1988, anabolic hormone guru William Kraemer, PhD, performed a study that literally changed the world of bodybuilding overnight. In this landmark study, Kraemer reported that heavy resistance training protocols with shortened rest periods (less than 1 minute) between sets elicited greater GH and testosterone response than resistance training protocols with longer rest periods (more than 3 minutes).1 A previous study published in the Journal of Strength and Conditioning Research examined the effects of three different loading routines on testosterone and cortisol levels.2 Subjects were randomly assigned to a power workout (8 sets of 6 reps, 45 percent of 1-repetition maximum, 3 minutes rest), a hypertrophy workout (10 sets of 10 reps, 75 percent of 1-repetition maximum, 2 minutes rest) and a maximal strength workout (6 sets of 4 reps, 88 percent of 1-repetition maximum, 4 minutes rest). The hypertrophy scheme (10 sets of 10 reps) increased testosterone and cortisol, whereas the power and maximal strength schemes produced little to no endocrine change. In general, the post-exercise testosterone and cortisol response to the hypertrophy scheme was greater than the other two schemes, which themselves displayed largely similar profiles. There is no doubt that short rest periods are going to lead to enhanced fat oxidation and a greater metabolic effect, but should you train with short rest periods year-round?

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It’s time to plan the winter bulk. You’ve been showing off those abs all summer, but as it starts to get colder, you might begin to wonder what your arms, chest, back, and legs would look like with another inch or two of muscle on them. There’s only one way to find out – use this winter to add some muscle!

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