Different Exercises Generate Similar Musculoskeletal Adaptations—the Difference Is in the Total Work: Response

Author’s Response

We appreciate the letter referring to our recently published work in this journal, as in addition to demonstrating that the article received attention from our peers, it gives us the opportunity to discuss the topic.

The letter deals with the contribution of volume (sets × repetitions × load) in resistance exercise to muscle adaptations based on an elegant study by Figueiredo et al. ² However, it should be noted that muscle adaptations are not a single thing or a set of features that behave in exactly the same way. As the aforementioned article explains, “In this article we review the effects of volume on hypertrophy and health, but not strength, because exercise intensity seems to be the predominant variable modulating muscle strength, in comparison to other variables.” ² Therefore, volume is not as important for strength as it is for hypertrophy, because for strength, intensity is more important. Another elegant study cited in the letter from our colleagues also demonstrates this difference between strength and hypertrophy. ³ In that study, the authors observed that groups that submitted to 3 resistance exercise programs with different volumes and/or intensities presented the same hypertrophic gain, but only the groups that trained at a higher intensity showed an increase in strength. ³

That said, we must remember that, as highlighted in Table 1 of our study, ⁴ muscle strength was our primary outcome. Also, as mentioned in the Methods section, “Patients in the intervention group underwent an 8-week program of unilateral resistance exercises (only for the donor limb).” Finally, Figures 1 and 2 of our study demonstrate that the intervention group performed the lunge, leg press, terminal extension, leg extension machine, and straight leg raise unilaterally, while the control group performed the squat, leg press, and leg extension machine bilaterally and the terminal extension and straight leg raise unilaterally. It is also explained in the same section that both groups performed 3 sets of 12 repetitions, with 2 seconds for the concentric phase, 2 seconds for the eccentric phase, and a 1-minute rest between sets. ⁴

Therefore, even if we consider the issue of the bilateral deficit, ¹ it is notable that in our study, the control group mobilized heavier weights than the intervention group, in addition to performing more sets (as this group performed unilateral exercises in both legs). While this could logically result in greater energy expenditure and greater volume (sets × repetitions × load), we did not perform this analysis because it was not directly related to our primary outcome.

To conclude, as the primary outcome of our study was muscle strength and we standardized the intensity (weight to perform 12 repetitions) duly adjusted for the 2 study conditions (uniform or bilateral execution), we understand that our research question was satisfactorily answered.

Marcio de Paula e Oliveira, PT, PhD Brasılia, Federal District, Brazil