The effect of self-selecting the number of repetitions on motor performance and psychological outcomes

Abstract

In resistance-training, the number of repetitions can be either fixed and predetermined (e.g., 3 sets of 10 repetitions), or selected by the trainee during ongoing sets (e.g., 3 sets of 8-12 repetitions). The first approach is more goal-focused while the latter is more autonomy-focused. Here we compared these two approaches in motor performance and psychological outcomes. Nineteen resistance-trained participants (10-males) first completed one repetition-maximum (RM) tests in the barbell-squat and bench-press, and were familiarized with the isometric mid-thigh pull (IMTP). In the next two counterbalanced sessions, participants completed two sets of the squat and bench-press using 70%1RM, and two sets of the IMTP. In the predetermined session, participants completed 10 repetitions in all sets, and in the self-selected session, participants chose how many repetitions to complete out of an 8-12 range. Bar-velocity was measured in the squat and bench-press, and force production in the IMTP. Enjoyment, perceived-autonomy, and approach-preferences were collected post-sessions. We observed comparable bar-velocity, force production, and enjoyment in both conditions (all BF01 > 2.1), and an even approach-preferences split. However, in the self-selected condition, participants demonstrated considerable variability in the number of repetitions and reported greater perceived-autonomy. Given the similarities between approaches, both can be used with this cohort based on their personal-preference.

Conflict of interest statement

The authors declare that they have no competing interests.

© 2020. Springer-Verlag GmbH Germany, part of Springer Nature.

Figures

Fig. 1

Distribution of bar-velocity and force over the set in each exercise and condition. The gray lines represent the values of individual participants, fitted using the locally estimated scatterplot smoothing (LOESS) method, and the fitted regression model in a black line. a–d depict bar-velocity in the bench press and squat in each condition, respectively. e, f depict force-output in the IMTP in each condition

Fig. 2

Distribution of the self-determined repetitions. a–c depict the percent of sets in which each number of repetition was performed from 8–12, in the bench press, squat and IMTP, respectively

Fig. 3

Extent of preference ratings of each participant for either the fixed approach (negative values; e.g., −100) or the self-determined approach (positive values; e.g., 100). Note that participants 8 and 9 rated 0 which indicates they had no preference