More Muscle with Longer Rest Periods

More Muscle with Longer Rest Periods

by: Robbie Durand

Just by reading this title of the article, many lifters will be confused because taking short rest periods has been the foundation for many bodybuilding protocols. In the early 70 and 80s, all bodybuilders trained with rest periods less than 60 seconds because this was thought to promote muscle growth. It is known that resistance training increases in testosterone levels may be related to reduced plasma volume, acute blood lactate augmentation, and adrenergic stimulation. Free testosterone is a portion of testosterone not bound to the sex hormone binding globulin (SHBG) protein and is considerably biologically active, able to interact with androgen receptors and its expression has been shown to hold some relation to total testosterone values.

In the early 90’s, world renowned researchers William Kraemer found that 60 second rest periods resulted in greater testosterone responses than 3-minute rest periods. Another study examining hormones responses to varying rest periods. Researchers had subject’s rest 60, 90, and 120 seconds over four sets at 85% of 1RM squat and bench press to failure on circulating growth hormone, and total testosterone concentrations. The authors found that resting 60 seconds between sets, resulted in higher GH immediately post-workout compared to resting 120 seconds; but in contrast, resting 90 or 120 seconds between sets, resulted in higher total testosterone concentrations immediately post-workout compared to resting 60 seconds. So this made researchers question, what is the optimal rest period between sets to increase muscle mass?

Researchers examine the influence of rest period duration (1 vs. 3- minute between sets) on acute hormone responses to a high intensity and equal volume bench press workout. Ten resistance trained men performed 2 bench press workouts separated by 1 week. Each workout consisted of 5 sets of 3 repetitions performed at 85% of 1-repetition maximum, with either 1-or 3-minute rest between sets. Circulating concentrations of total testosterone, free testosterone, cortisol, testosterone/cortisol ratio, and growth hormone were measured at pre-workout, and immediately post, 15 minutes and 30 minutes’ post-workout.

At the end of the study, although both short and long rest periods enhanced acute testosterone values, the longer rest promoted a longer lasting elevation for both total and free testosterone. Since the the cortisol values did not change throughout any post-exercise verification for either rests, the total testosterone/cortisol ratio was significantly elevated for both rests in all post-exercise moments compared to pre-exercise. The growth hormone values did not change for both rest lengths. Traditionally, professionals prescribe longer rests between sets (e.g. 3 to 5- minute) for strength developing purposes. This experiment is on parallel to this practice once we have found that although both rest protocols (1 and 3-minute) enhanced testosterone values, the longer rest (3-minute) provided a longer lasting elevation for both testosterone and free testosterone.

Key Points of the Study:

-3 minute rest periods resulted in greater free and total testosterone responses compared to 1 minute rest periods.

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