WHAT DOES A SET MEAN IN EXERCISE?
Sets are a complete round of repetitions. Once you have completed the recommended amount of repetitions for each exercise, you will have completed a set. For example, twelve repetitions of a chest-press motion equal one set.
Sets refer to how many times you will repeat that exercise for the set number of repetitions. For example, you do 12 squats and rest. Then you do another 12 squats, rest, and then another 12. You have now completed three sets of 12 reps. If you do three sets of 15 reps of biceps curls, you will perform 15 repetitions, rest, 15 repetitions, rest, and finish with 15 repetitions. Sometimes the word reps are left out, and trainers will just tell you to complete three sets of 15.
HOW MANY SETS?
So if for hypertrophy, the intensity of each set (as a measure of how close to failure that set was, rather than load) is more important, how many sets should we do?
There is a collection of evidence which suggest that in the first 6-12 weeks of a training program there is no difference between one and multiple sets (both trained and untrained participants), and there is a collection of evidence which suggests that three sets is the minimum for any training effect (both trained and untrained participants) and some in between .
The evidence which suggests that there isn’t any difference may be running into a few key issues (as a casual, non-systematic analysis):
The shorter time frame may have meant that the majority of change is neurological, reducing the size of effect for A lot of studies compared 1 vs multiple sets of multiple exercises many of which had lots of cross-over in which muscles were actually trained, such that multiple sets were performed per muscle group in single set groups.
Studies may be experiencing a maximum hypertrophy response, such that any further sets couldn’t increase the size of the response. This coupled with the above point could mean that studies may have missed a difference between 1 and 3 sets, but noticed no difference between 3 and 9 sets (assuming 3 exercises per muscle group).
In the very few longer term studies available, the evidence is stronger towards more sets creating a larger effect size. This could be explained by familiarity with exercises (in terms of technique and neuromuscular factors) being key in more volume having a larger effect. It could be related to resistance to further change as the participant’s base level of strength and muscular size increases, and the need for volume to overcome that resistance. Many advanced strength athletes have noted that an increase in number of sets was key to continued strength and muscle development.
REST INTERVAL BETWEEN SETS IN STRENGTH TRAINING:
Strength training has become one of the most popular physical activities for increasing characteristics such as absolute muscular strength, endurance, hypertrophy and muscular power. For efficient, safe and effective training, it is of utmost importance to understand the interaction among training variables, which might include the intensity, number of sets, and rest interval between sets, exercise modality and velocity of muscle action. Research has indicated that the rest interval between sets is an important variable that affects both acute responses and chronic adaptations to resistance exercise programmes. The purpose of this review is to analyze and discuss the rest interval between sets for targeting specific training outcomes (e.g. absolute muscular strength, endurance, hypertrophy and muscular power). The Scielo, Science Citation Index, National Library of Medicine, MEDLINE, Scopus, Sport Discus and CINAHL databases were used to locate previous original scientific investigations. The 35 studies reviewed examined both acute responses and chronic adaptations, with rest interval length as the experimental variable. In terms of acute responses, a key finding was that when training with loads between 50% and 90% of one repetition maximum, 3-5 minutes’ rest between sets allowed for greater repetitions over multiple sets. Furthermore, in terms of chronic adaptations, resting 3-5 minutes between sets produced greater increases in absolute strength, due to higher intensities and volumes of training. Similarly, higher levels of muscular power were demonstrated over multiple sets with 3 or 5 minutes versus 1 minute of rest between sets. Conversely, some experiments have demonstrated that when testing maximal strength, 1-minute rest intervals might be sufficient between repeated attempts; however, from a psychological and physiological standpoint, the inclusion of 3- to 5-minute rest intervals might be safer and more reliable. When the training goal is muscular hypertrophy, the combination of moderate-intensity sets with short rest intervals of 30-60 seconds might be most effective due to greater acute levels of growth hormone during such workouts. Finally, the research on rest interval length in relation to chronic muscular endurance adaptations is less clear. Training with short rest intervals (e.g. 20 seconds to 1 minute) resulted in higher repetition velocities during repeated submaximal muscle actions and also greater total torque during a high-intensity cycle test. Both of these findings indirectly demonstrated the benefits of utilizing short rest intervals for gains in muscular endurance. In summary, the rest interval between sets is an important variable that should receive more attention in resistance exercise prescription. When prescribed appropriately with other important prescriptive variables (i.e. volume and intensity), the amount of rest between sets can influence the efficiency, safety and ultimate effectiveness of a strength training programme.
FACTORS AFFECTING THE LENGTH OF THE REST INTERVAL BETWEEN RESISTANCE EXERCISE SETS:
Research has indicated that multiple sets are superior to single sets for maximal strength development. However, whether maximal strength gains are achieved may depend on the ability to sustain a consistent number of repetitions over consecutive sets. A key factor that determines the ability to sustain repetitions is the length of rest interval between sets. The length of the rest interval is commonly prescribed based on the training goal, but may vary based on several other factors. The purpose of this review was to discuss these factors in the context of different training goals. When training for muscular strength, the magnitude of the load lifted is a key determinant of the rest interval prescribed between sets. For loads less than 90% of 1 repetition maximum, 3-5 minutes rest between sets allows for greater strength increases through the maintenance of training intensity. However, when testing for maximal strength, 1-2 minutes rest between sets might be sufficient between repeated attempts. When training for muscular power, a minimum of 3 minutes rest should be prescribed between sets of repeated maximal effort movements (e.g., plyometric jumps). When training for muscular hypertrophy, consecutive sets should be performed prior to when full recovery has taken place. Shorter rest intervals of 30-60 seconds between sets have been associated with higher acute increases in growth hormone, which may contribute to the hypertrophic effect. When training for muscular endurance, an ideal strategy might be to perform resistance exercises in a circuit, with shorter rest intervals (e.g., 30 seconds) between exercises that involve dissimilar muscle groups, and longer rest intervals (e.g., 3 minutes) between exercises that involve similar muscle groups. In summary, the length of the rest interval between sets is only 1 component of a resistance exercise program directed toward different training goals. Prescribing the appropriate rest interval does not ensure a desired outcome if other components such as intensity and volume are not prescribed appropriately.