Physical Activity Levels Predict Exercise-induced Hypoalgesia in Older Adults

Prior research indicates that older adults exhibit a deficient capacity to activate multiple pain inhibitory mechanisms, including pain inhibition after acute exercise termed exercise-induced hypoalgesia (EIH). The influence of physical activity levels and psychological processes on EIH in older adults remains unclear. Purpose This study examined potential psychological and physical activity predictors of the magnitude of EIH after submaximal isometric exercise in healthy older adult men and women. Methods Fifty-two healthy older adults completed a test of EIH, the Pain Catastrophizing Scale, the Tampa Scale of Kinesiophobia, and wore an accelerometer on the hip for 1 wk to assess physical activity levels. For the test of EIH, participants complete a 3-min isometric handgrip at 25% of maximum voluntary contraction. Pressure pain thresholds (PPT) and a 30-s continuous heat pain test were completed before and immediately after the exercise. Results Mixed-model ANOVA revealed that older adults demonstrated significantly decreased PPT after isometric exercise (P = 0.030), and no changes on the heat pain trials from pretest to posttest (P > 0.05). A multiple regression revealed that accumulated moderate to vigorous physical activity (MVPA) per week significantly predicted the change in PPT after exercise ( = 0.35, P = 0.012). Participants who averaged greater MVPA experienced a greater increase in PPT after exercise. No relationships were found with EIH and the psychological variables. Conclusions Older adults did not exhibit EIH after submaximal isometric exercise. However, those who did more MVPA per week experienced a greater magnitude of pain inhibition after acute exercise.