Aerobic Upper-Limb Exercise-Induced Hypoalgesia: Does It Work?

Background: Aerobic exercise reduces pain sensitivity, a phenomenon known as exercise-induced hypoalgesia (EIH); however, little is known about EIH when the upper limbs are aerobically exercised. This study aimed to test the acute effect of a single aerobic upper-limb exercise on pain threshold and pain intensity in healthy participants, with two different protocols for controlling intensity. Methods: 31 participants performed two 20 min exercise sessions a week apart. In each session, the intensity was controlled by a target heart rate (THR) of 60% of heart rate reserve or by a rate of perceived exertion (RPE) of 7/10 on the Borg scale. Pain threshold for pressure (PPT) heat (HPT) and pain intensity in response to Tonic Heat Pain (THP) were measured pre- and post-exercise. To examine the effect of exercise in each protocol on pain sensitivity, rmANOVA was conducted. Results: Pain sensitivity remained unchanged following arm exercise in both protocols (PPT, p = 0.67; HPT, p = 0.56; and THP p = 0.39). Higher HR in the THR protocol was demonstrated with a significant protocol X time, interaction effect (F-(3) = 11.194 p < 0.004). Conclusions: Moderate-high-intensity upper-limb aerobic exercise did not affect pain sensitivity in healthy individuals. Exercise intensity when controlled by THR showed a higher mean heart rate compared to exercise intensity based on RPE.