Exercise Intensity as a Determinant of Exercise Induced Hypoalgesia

The purpose of this study was to examine pain perception during and following two separate 30-min bouts of exercise above and below the Lactate Threshold (LT). Pain Threshold (PT) and Pain Intensity (PI) were monitored during (15 and 30 min) and after exercise (15 and 30 min into recovery) using a Cold Pressor Test (CPT) and Visual Analog Scale (VAS) for pain of the non-dominant hand. Significant differences in PT scores were found both during and after exercise conditions. Post hoc analysis revealed significant differences in PT scores at 30 min of exercise (P=0.024, P=0.02) and 15 min of recovery (P=0.03, P=0.01) for exercise conditions above and below LT, respectively. No differences (P=0.05) in PT scores were found at any time point between exercise conditions. No differences were found in PI scores at any time point within each trial (P=0.05) as well as between exercise conditions (p=0.05). Based upon these data, the effects of moderate exercise on PT appear to be similar at exercise intensities just above and below LT. This may indicate that the requisite intensity needed to ellicit Exercise-Induced Hypoalgesia may be lower than previously reported. Because a hypoalgesic effect was not observed in either condition until 30 min of exercise had been completed, total exercise time may be an important factor in the augmentation of pain perception under these conditions.