eLife Assessment
Nold et al. examined exercise-induced pain modulation in a pharmacological within-subject fMRI study using the opioid-antagonist naloxone and different levels of aerobic exercise and pain. This study provides valuable findings showing that the intensity of exercise does not seem to impact the hypoalgesic effect; however, the evidence is incomplete for the claims relating to the overall effect of exercise on pain, since they cannot be tested with the proposed experimental design.