Exercise-induced analgesia and the role of reactivity in pain sensitivity

The present study was designed to evaluate whether pain perception and pain tolerance are altered by submaximal aerobic exercise. Sixty male volunteers were randomly assigned to one of two control or experimental groups in the first of two sessions. In session 1, baseline measures of pain tolerance and pain perception were obtained for half of the subjects in each of the experimental and control groups, respectively. In addition, all subjects completed the Reactivity Scale, followed by estimation of their maximum aerobic power (V)over dot O-2 max) using the Canadian Home Fitness Test. In session 2, the subjects in the two experimental groups exercised for 12 min by climbing a double step to pre- recorded musical cadences, working on average at 63% (V)over dot O-2 max, whereas the subjects in the two control groups spent approximately 12 min completing two short unrelated questionnaires. Measures of pain tolerance and pain perception were obtained from all subjects after exercising or completing questionnaires. Pain tolerance was assessed by the amount of time (up to 10 min) that subjects could voluntarily endure a 2300 g pressure to the index finger of their dominant hand. Pain perception was defined by participants' intensity ratings on an 11- point scale, made at 30 and 60 s. The results showed that reactivity and exercise were significant predictors of pain tolerance, together accounting for approximately 22% of the variance. The finding that submaximal workloads produce analgesia supports the potential usefulness of exercise in therapeutic intervention.