DISCUSSION
EIH, muscle soreness, hypoalgesia, pain
HEAT, SECONDARY, CONTRACTION
We investigated the changes in pain perception following running exercises in healthy individuals. Our results revealed that the changes in PPT and PPTol increased with running time. The PPT and CPM responses to moderate‐ and low‐intensity running were significantly higher than those to high‐intensity exercise during the running sessions and follow‐ups. Furthermore, improvements in PPTol after moderate‐intensity running were significantly greater than those after high‐intensity running. These results indicate that the modulation of the effects of EIH may involve distinct central mechanisms influenced by the context of exercise.Previous studies have examined similar changes in PPT of exercised and non‐exercised limbs following exercise with different intensities. For instance, Hoffman et al. (The effects of EIH following exercises of various intensities may be introduced by the interaction between muscle contraction and C‐fiber inputs during treadmill running. Muscle contraction can activate C fibers during exercise (Adreani et al., Potential mechanisms of EIH induced via running with different intensities. CPM, conditioned pain modulation; DOMS, delayed onset muscle soreness; EIH, exercise‐induced hypoalgesia.The role of CPM responses on the effects has also been investigated by Lemley et al. (Additionally, low‐ or moderate‐intensity exercise can improve pain tolerance. Vaegter et al. (The changes in pain tolerance observed during exercise may also be attributed to the improvements in cognitive process (Holmes et al., This study has several limitations. First, the indicators of the pain tests were limited. For instance, adding heat pain detection and tolerance thresholds might provide a more complete description of changes in pain perception. Second, the individuals' pain tolerance thresholds might have been influenced by previous pain experiences and subjective emotional perceptions, leading to a diverse range of responses. Thus, we set strict exclusion criteria to minimize possible bias. Finally, all the participants in this study were female. Considering the potential sex differences in EIH and CPM responses following running exercises, future studies should consider including both male and female participants to provide a comprehensive understanding of these effects.Thus, aerobic exercise of low to moderate intensity could be an ideal and implementable strategy for preventing and managing various pain conditions, considering the secondary changes in pain perception. However, high‐intensity running revealed no significant advantage in terms of primary or secondary analgesic effects.