Fen Lasseel, Bakala Academy – Athletic Performance Center, KU Leuven
Resistance training is a key-ingredient in the training program of most athletes. Resistance training as a rule involves multiple sets of muscle contractions. Often attention is primarily focused on the training volume (number of repetitions/sets per exercise), rather than on the duration of the rest period interspersing the sets. However, the main objective of strength training differs between athletes and sports disciplines. For instance, high jumpers are seeking for improvement in muscle strength in the absence of body weight increase due to muscle mass accretion (~muscle ‘hypertrophy’). Similarly, many cyclists aim at boosting muscle strength while avoiding excess muscle hypertrophy. Otherwise power output per kg body weight (Watt/kg) could be reduced, which is detrimental to performance in uphill racing. Conversely, body builders prefer a training strategy that causes maximal stimulation of muscle mass.
Whether resistance training is most explicit to either increasing muscle volume or to enhance muscle strength a.o. depends on the rest intervals between sets. Available research clearly indicates that varying rest intervals between sets produces differential training responses in both neuromuscular and endocrine systems.
Resistance training aiming to primarily enhance muscle strength, while limiting muscle hypertrophy?
A rest interval of 2-4 min between sets is needed to sustain the prescribed number of repetitions per set, without great reductions in training weight. In general, the more repetitions are included per set, the more rest is required between sets, with a maximum of 4 min though.
Resistance training aiming to primarily increase muscle mass, say ‘body-building’?
A rest interval of 30-40 sec between sets is needed to create maximal exhaustion in combination with a high volume. The training weight across sets remains constant, and thus the number of repetitions shall often (slightly) decrease over consecutive sets. Still, even the final set must contain a minimum of 6 repetitions. In case the number of repetitions is less than 6, the resistance for that specific set must be reduced.
In conclusion, athletes who are targeting muscle strength should manage a rest interval of 2-4 min, while athletes primarily aiming at increasing muscle mass should rest for only 30-45 sec between sets.
De Salles BF, Simao R, Miranda F, Da Silva Novaes J, Lemos A, M. Willardson J. (2009) Rest Interval between Sets in Strength Training. Sports Med 39 (9): 765-777