Sex Differences In Muscle Pain

Abstract

Women report clinical musculoskeletal pain more frequently than men (Rollman, 2001 and Unruh, 1996). In addition, after a disabling musculoskeletal injury, women return to work and retain work at a lower rate than men (McGeary et al., 2003). However, the literature concerning sex differences in exercise-induced muscle pain, in particular, currently suggests that no sex differences exist. PURPOSE This investigation adds to the literature on exercise-induced muscle pain by assessing not only pain ratings, but also pain during activities and self-care behaviors for pain. METHODS Forty-four university students (59.5% women) called into a telephone data collection system at 24, 48, and 72 hours after eccentric contractions. The participants rated the levels of muscle pain, the frequency and effects of pain during activities, and the performance of self-care behaviors. RESULTS Muscle pain intensity (F3,129 = 43.94, p <.01, ± 2 = .51) and unpleasantness (F3,129 = 40.32, p <.01, η2 = .48) increased from baseline so the protocol successfully induced muscle pain. No sex differences in pain ratings were observed when total work during the eccentric contractions was controlled. The perception of pain during daily activities and the performance of self-care behaviors did not differ between the sexes. However, a significant sex by time interaction indicated greater interference in activities from the muscle pain at 72 hours for women than men (F1,41 = 6.20, p = .02, η2 = .13). CONCLUSION No sex differences were detected in pain ratings, pain during daily activities, or self-care behaviors. However, women reported more interference from pain with activities, which may be related to greater strength deficits and decreases in range of motion as described by other investigations. When compared to the previous literature, these findings provide additional evidence that sex differences depend upon the type of muscle pain and the pain measurement method. Thus, caution in generalizing the research findings in this area is warranted. Furthermore, this investigation of clinically relevant delayedonset muscle pain indicates that multiple methods of pain measurement should be incorporated into patient assessment. Supported by University of Missouri-Columbia School of Health Professions Undergraduate Research Mentorship Program Fall 2003 and Undergraduate Research Scholars Program 2005 to Victoria L. Gormley and a NIAMS Postdoctoral Fellowship Grant (AR08623-01) to Dr. Erin A Dannecker.