These findings suggest that exercise-induced pain modulation depends on fitness level but not on sex.
Key Findings
Results
In an all-female sample of high fitness level, high-intensity exercise produced greater heat pain relief than low-intensity exercise, with the effect depending on stimulus intensity.
Sample was N=21 females of high fitness levels, using a paradigm similar to Nold et al., 2025.
The abstract reports 'an interaction of exercise intensity and stimulus intensity in heat pain'.
Pain relief was greatest 'especially at the highest stimulus intensity'.
Heat and pressure pain ratings were compared after high-intensity versus low-intensity exercise.
Results
For pressure pain, the effect of exercise intensity did not reach significance, but a similar trend to heat pain was observed.
The abstract states 'Despite results for pressure pain not reaching significance, a similar trend was evident.'
Analysis was in the same all-female sample (N=21).
Results
Pooled analysis of the current and previous study indicated that fitness level, but not sex, moderates exercise-induced pain modulation in heat pain.
Data from the current all-female study and the previous heterogeneous-sample study (Nold et al., 2025) were combined.
The abstract reports 'evidence for fitness level but not sex to moderate exercise-induced pain modulation in heat pain'.
This addressed the earlier exploratory suggestion of a sex × fitness × drug interaction.
Background
The study was motivated by exploratory findings from the previous study suggesting sex-dependent, fitness-dependent, and naloxone-sensitive exercise-induced hypoalgesia in males but not females.
In the earlier study, males showed increasing hypoalgesia after high- versus low-intensity exercise with increasing fitness level.
This effect was diminished when naloxone was administered.
These effects were not evident in females in the earlier sample, prompting testing of highly fit females.
Conclusions
The authors conclude that females at a high fitness level show exercise-induced pain modulation similar to that previously seen in males, and that fitness rather than sex explains differences.
Results suggest highly fit females show modulation after high- compared to low-intensity exercise.
Pooled data supported fitness level, not sex, as the moderator.
What This Means
This study asked whether the pain-reducing effect of hard exercise depends on being male or female, or on how fit a person is. An earlier study by the same group hinted that fitter men felt less pain after intense exercise, while women did not show the same pattern. But that earlier group of women was not very fit, so it was unclear whether sex or fitness was responsible.
To test this, the researchers studied 21 highly fit women. After intense exercise, the women reported less heat pain than after light exercise, and the difference was clearest at the strongest heat levels. Pressure pain showed a similar trend but it was not statistically significant. When the researchers combined data from this and the earlier study, fitness level, not sex, was linked to how much exercise reduced heat pain.
This research suggests that differences in exercise-related pain relief between men and women may reflect differences in fitness rather than sex itself. The sample was small and all female, and the pooled analysis combined two studies, so the findings are best viewed as supportive evidence rather than a final answer.
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