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 performed a study that literally changed the world of bodybuilding overnight. In this landmark study, he reported that heavy resistance training protocols with shortened rest periods (< 1 minute) between sets elicits greater growth hormone (GH) and testosterone responses than resistance training protocols with longer rest periods (> 3 minutes). 1 Since then, bodybuilders have kept rest duration under 1 minute. 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?
A new study in the Journal of Strength and Conditioning Research found that performing short rest periods led to a decrease in the number of repetitions performed in the workout. In the study, resistance-trained men performed an upper body workout that consisted of two experimental training sessions. Both sessions consisted of 3 sets of 8 repetitions with an 8-repetition maximum resistance of six upper body exercises (wide-grip lat pulldown, close-grip pulldown, machine seated row, barbell row lying on a bench, dumbbell seated arm curl and machine seated arm curl). The two experimental sessions differed only in the length of the rest period between sets and exercises; one session was performed with a 1-minute rest period and the other with a 3-minute rest period. It should be of no surprise that the group that rested 3 minutes between sets was able to perform a greater number of repetitions compared to the 1-minute rest session. Think about a few extra repetitions performed each workout over a six-month period…how much added strength and size would that add up to? So should you use short rest periods year-round at the expense of using less repetitions and a lighter weight?

Increasing rest duration between sets will allow you to train with more repetitions using a heavier weight. To increase muscle mass, you must train with heavier weights and more tension must be applied to the muscle. The late Arthur Jones, in his book, noted that, “Adding muscular size will ALWAYS make you stronger and increasing your strength will ALWAYS increase your muscular size. To increase the strength of a muscle, you must increase its size. Increasing the size of a muscle will increase its strength. There is a definite relationship between muscular strength and muscular size.” Clearly, the biggest bodybuilders are stronger and train with heavier weights. Tom Platz, who many consider had the best legs in bodybuilding, could squat 705 pounds for 8 reps. Ronnie Coleman and Branch Warren are big poundage lifters, and look at their size.   

Longer Rest Periods Are Needed For Strength Gains
Volume is most easily defined as the number of sets of an exercise multiplied by the number of repetitions (sets x reps). If size is the name of the game, taking slightly longer rest periods and using a heavier weight is going to allow you to use a heavier weight, which will allow more muscle growth. The two most important aspects relating to volume are the mechanical stress (i.e., tension) applied to muscle tissue and the amount of time this stress is applied. If you want to get stronger, you have to take longer rest periods between sets. The recommended rest interval increases when programs are designed for strength or power (e.g., 2–5 minutes).6 Resting a little longer between sets is going to allow you to use a heavier weight and crank out more repetitions. For example, one study compared squat strength increases in three groups assigned to either a 3-minute, 90-second or 30-second rest interval between sets. Subjects in each group performed 5 sets of 10 repetitions two times per week for five weeks. At the conclusion of the study, subjects in the 3-minute group demonstrated greater strength increases vs. the other two groups.7 Another study demonstrated comparable results when rest period length was examined on muscular power and bench press exercise. Subjects performed 10 sets of six maximal effort repetitions at 70 percent of their 1 RM and with a 1-, 3-, or 5-minute rest interval betweens sets. The results demonstrated that from set 1 to set 10, the power did not decrease for the 3- or 5-minute rest conditions (4.8 percent and 2 percent, respectively), but did decreased by a whopping 27 percent in the 1-minute rest condition.12 Additionally, Division III football players with at least two years of lifting experience could perform more repetitions with a 3-minute rest period compared to a 1-minute rest period using 3 sets with 10 RM resistance in the bench press and leg press. It was concluded that a 1-minute interval between sets was not enough to complete successive sets of 10 repetitions with 10 RM resistance. However, with 3-minute rest periods, it was possible to complete successive sets of 10 repetitions with a 10 RM weight.