(7) RELATIONSHIP BETWEEN REPETITIONS COMPLETED AND RATING OF PERCEIVED EXERTION IN RESISTANCE EXERCISE SETS TO FAILURE: EFFECT OF GENDER AND EXERCISE

Purpose:  To determine the relationship between repetitions completed and the reported rating of perceived exertion (RPE) during a resistance exercise set to failure. Furthermore, this study will investigate the influence of gender and exercise on this relationship.

Methods: Data from 10 subjects were included in this analysis. All subjects initially had their 1-repetition maximum (1RM) estimated using the Brzycki equation on the back squat, bench press, deadlift and bent over row exercise. Back squat and deadlift were classified as lower body exercises (LOWER), while bench press and bent over rows were classified as upper body exercise (UPPER). Subjects then completed three sets to failure of each exercise at 75% of their estimated 1RM during a resistance exercise workout with 2 minutes between sets. Each workout was completed on two separate occasions; except for one subject who withdrew after 1 workout due to time constraints. All sets were completed until failure and then were assessed for RPE using the OMNI scale. A total of 228 sets were recorded; however, 7 sets were excluded from the analysis due to an insufficient RPE (< 5). Spearman rho correlations were conducted to assess the relationship between repetitions completed and RPE. One-way ANOVA was completed to compare the repetitions completed per set between each reported RPE (5-10). Two-way (gender×exercise) ANOVAs were conducted on repetitions completed and RPE. All significant main effects and interactions were followed with post hoc pairwise comparisons. Alpha level was set to p< 0.05. All data are presented as mean±standard deviation.

Results: Spearman’s rho correlation revealed a significant negative correlation between repetitions completed and RPE (ρ=-0.235, p< 0.001). ANOVA revealed a significant difference (p=0.050) in repetitions completed between sets with different RPE. Sets with a reported RPE of 6 (10.76±4.22 repetitions) resulted in significantly (p=0.045) more repetitions than sets with an RPE of 10 (7.39±4.95 repetitions). Two-way ANOVA revealed a main effect of gender for RPE (p=0.027), but no significant main effect of exercise (p=0.674) or interaction (p=0.075). Post hoc tests revealed a significantly greater RPE for females (8.37±1.25 AU) when compared to males (7.98±1.26 AU). For repetitions completed, two-way ANOVA revealed a significant gender×exercise interaction (p=0.036). Post hoc tests revealed no difference between males (7.41±3.57 repetitions) and females (7.71±3.23 repetitions) for upper body exercise (p=0.961); however, females (11.93±5.71 repetitions) completed significantly more repetitions per set than males (9.17±3.40 repetitions) for lower body exercises (p=0.004).

Conclusions: During sets to failure, RPE negatively correlates to the number of repetitions completed, indicating that RPE may be more indicative of an individual’s fatigue rather than the amount of work they are completing. However, females seem to complete more repetitions and report a lower RPE during sets to failure than males, particularly during lower body exercises. Practical Application: Practitioners should be aware of how individuals interpret RPE scales when using them to gauge exercise intensity. This is especially true when working with both males and females as they appear to perform and interpret sets to failure differently.

Acknowledgements: None