Muscle tension and time under tension are critical for promoting muscle hypertrophy (growth). Weight training programs manipulate load, repetitions and sets, and rest intervals. Very few
studies have examined the ideal structure of a weight-training program. Research from New Zealand found that athletes could complete more reps in the bench press when allowed frequent, short rest
periods than when they took longer rest periods. Subjects trained with a weight they could bench press six times (6 RM). They did one of three workouts (WO) on separate days: four sets of six
repetitions with 5 minutes of rest between sets (WOl); eight sets of three repetitions with 130 seconds rest between sets (W02); or eight sets, alternating between one set of three repetitions and
one set to failure with 130 seconds between sets (W03).
Athletes completed 25 percent more reps and achieved higher blood lactate levels during W03. Increasing the frequency of rest intervals allowed the athletes to do more repetitions and caused greater metabolic disturbance, both of which may promote muscle hypertrophy.