Sex differences in naturally occurring leg muscle pain and exertion during maximal cycle ergometry

This investigation examined the role of sex in perceptions of leg muscle pain during exercise. Males (N = 26; age = 23.2 +/- 3.9) and females (N = 26; age = 21.9 +/- 3.5) matched on weekly energy expenditure completed a ramped maximal cycle ergometry test. Leg muscle pain thresholds were determined and pain intensity ratings as well as ratings of perceived exertion were obtained during and after exercise. The power output at pain threshold was lower in females (129.9 +/- 46.5 watts) compared to males (148.2 +/- 56.6 watts). Peak power output and peak pain intensity ratings were lower (P < 0.001) in females (211.3 +/- 39.1 watts; 5.5 +/- 2.9) compared to males (303.6 +/- 27.5 watts; 8.5 +/- 2.3). A Sex X Relative Intensity (i.e., % peak power output) ANOVA revealed that females reported lower pain ratings at each relative intensity examined (F = 17.7; df = 1.50; p < 0.001). The primary conclusion of this investigation is that females rate naturally occurring leg muscle pain as less intense than males when data are relativized to peak power output.