Dose-response of 1, 3, and 5 Sets of Resistance Exercise on Strength, Local Muscular Endurance, and Hypertrophy

To the Editor: We read with interest a recent article by Radaelli et al. (3) titled “Dose-response of 1, 3, and 5 sets of resistance exercise on strength, local muscular endurance, and hypertrophy” and would like to congratulate the authors for conducting this complex and interesting study. However, we noted a number of issues that are worthy of clarification. Concerning the methods, an apparent terminology mistake arises when authors state that all groups performed sets to concentric failure and then state that “the training resistance was increased by 5–10% for the next session when subjects were able to perform more than 12 repetitions in all sets of an exercise. ” It has been previously reported that if young men perform 12 repetitions to concentric failure in the bench press and rest for 3 minutes, they will be able to perform around 8 repetitions at the same load in the next set (4). This suggests that participants were likely not training to concentric failure. Table 1 shows values of volume load more than 3 times greater for the 3 sets group and more than 5 times greater for the 5 sets group, in comparison with the 1 set group. This suggests that repetitions were kept constant without load reductions between sets, reinforcing that sets may be not have been performed to concentric failure (4–7). Knowing if the participants were really performing repetitions to concentric failure is important for interpreting the results, as previous study reported significant differences between performing 1 set to “self-determined” repetition maximum and “real” concentric failure in well-trained participants (1). Moreover, clarification is also important to allow the correct replication of the study by other researchers and its application by coaches and athletes who wants to follow the authors’ recommendations. We might also consider the statistical analyses performed. In viewing Table 1, it seems evident that the preintervention values were very different between groups, with the 1 set group generally showing lower values than the other groups. For example, the 5 sets group had a preintervention value almost 40% higher than the 1 set group in the bench press, which causes us to question the use of analysis of variance (ANOVA) (in fact, authors cannot make statements about “strength gains” based on ANOVA results, as the test does not indicate this). When calculating the percent increases, results were similar among groups performing 1, 3, or 5 sets: bench press—13.49, 17.30, and 11.16%; lat pull-down—18.65, 12.00, 16.58%; shoulder press—22.47, 23.68, 35.18%; leg press—15.71, 15.48, and 12.89%. So we have strong reasons to question the statistical method used and to suppose that the differences reported would not exist if the comparison were performed with a procedure that take in account the initial values, such as analysis of covariance. This supposition is reinforced by the fact ANOVA resulted in no difference in the leg press, which is the only exercise where the initial values were not so discrepant between groups. It is important to note that this little (or even null) difference occurs at the expense of 200–400% increases in training volume and duration! Therefore, since lack of time is the most common cited barrier for exercise adoption and that increasing the number of sets from 1 to 3 has been shown to promote a large drop-out rate (2), one should be cautious before recommending a minimum of 3 sets per exercise as it can interfere with adherence without bringing justifiable results. We thank the authors and editorial board for their efforts with this publication but we believe that it is important to consider these clarifications with regard to terminology and methods as which might affect outcomes and interfere with the reproduction of the study protocol. PAULO GENTIL JAMES FISHER JAMES STEELE ANTONIO ARRUDA College of Physical Education and Dance, Federal University of Goiania, GO, Brazil Center for Health Exercise and Sport Science, Southampton Solent University, East Park Terrace, Southampton, United Kingdom Human Performance Laboratory, University of Petrolina, Petrolina, PE, Brazil