Sex Differences in Ratings of Perceived Exertion and Muscle Pain During Eccentric Contractions

Abstract

1515 Few studies have examined sex differences in ratings of perceived exertion (RPE) and muscle pain during eccentric exercise. This is problematic due to the importance of eccentric contractions to functional activities and reports of lower RPE and muscle pain during eccentric contractions compared to concentric contractions. PURPOSE: To examine sex differences in RPE and muscle pain intensity and unpleasantness during eccentric isokinetic contractions. METHODS: Men (n = 34) and women (n = 40) aged about 20 years (SD = 2.20) completed eccentric strength testing with the elbow flexors of their dominant arms to determine their 5 repetition maximum (5RM). Then they completed 3 sets of 12 eccentric repetitions at 90°/s with a preload of 16% of 5RM and 60 s rest periods in between each set. Differentiated RPE (CR-10 scale) and pain (0–100 numerical scales) were assessed immediately after strength testing and each set. RESULTS: Two-way (Sex × Set) ANOVAs indicated that RPE, F2,144 = 30.92, pp < .01, η2 = .30, pain intensity, F2,144 = 31.98, pp < .01, η2 = .31, and pain unpleasantness, F2,144 = 22.23, pp < .01, η2 = .24, increased across the sets. A main effect for Sex was observed for RPE, F1,72 = 4.29, pp = .04, η2 = .06, but this effect was absent when total work across the three sets was a covariate, F1,71 = 0.34, pp = .58, η2 < .01. No other main effects or Sex by Set interactions were observed. In addition, comparisons of the women and men with RPEs between 9 and 10 for the first, second, or third sets (ns = 28–31) did not show a significant sex difference in average percentage of peak torque produced. CONCLUSION: Lower RPE for women than men during eccentric contractions has been reported, but we did not detect such a difference. In addition, we did not observe sex differences in muscle pain during eccentric contractions, which contradicts a previous report of lower muscle pain in women than men. However, such sex-related comparisons may be affected by the method of controlling for sex differences in strength and the parameters of the eccentric contractions preformed (e.g., velocity). This investigation was supported by a NIAMS postdoctoral research fellowship (F32 AR08623-02) to Erin A. Dannecker, Ph.D.