The premenstrual syndrome: psychophysiologic concomitants of perceived stress and low back pain

The effects of experimentally induced and personally relevant stressors on low back EMG activity during 3 phases of the menstrual cycle in women with the premenstrual syndrome (PMS) and premenstrual low back pain were examined. Thirty-nine women reporting either PMS and premenstrual severe low back pain (group 1), PMS with premenstrual moderate low back pain (group 2), or those reporting neither condition (group 3) participated. During each of 3 menstrual phase-specific assessment sessions, participants were exposed to a neutral stimulus, an experimentally induced stressor, and 2 personally relevant stressors in a randomized order. Concomitant monitoring of low back EMG activity and heart interbeat interval was undertaken. Results indicated that participants in group 1 evidenced greater EMG changes in response to personal stressors compared to the neutral stimulus and experimentally induced stress during the premenstrual phase. EMG activity in response to personal stress was also significantly higher during the premenstrual phase than during the menstrual and intermenstrual phases for group 1, and higher than EMG changes evidenced by groups 2 and 3 during the same phase. Group 2, while not reporting as severe premenstrual back pain as did group 1, reported moderate levels of back pain and evidenced greater physiological reactivity to a personal stressor than did group 3. The findings highlight the link between personally relevant stressors and concomitant physiologic responsivity and the role that this arousal may play in the maintenance and exacerbation of premenstrual low back pain.