Pain Inhibitory Mechanisms Are Unchanged but Facilitatory Mechanisms Are Decreased in Aerobically Fit Individuals...

Regular aerobic physical activity is increasingly being recommended for chronic pain management. The underlying mechanisms are, however, not fully understood and data concerning endogenous pain modulation (EPM) and physical activity are ambiguous. This study aimed to investigate the impact of regular aerobic physical activity on EPM mechanisms in pain-free adults.

This controlled study included 50 healthy participants: 22 in the aerobic group (≥ 3 h of aerobic-type training per week) and 28 in the control group (no regular engagement in aerobic physical activity). Aerobic training was self-reported. We evaluated EPM-comprising conditioned pain modulation (CPM), temporal summation of pain (TSP), and referred sensations (RS) elicited by standardised muscle palpation-across both trigeminal and spinal test sites. Cardiovascular parameters were also assessed. A composite index of normalised pain measures quantified global pain sensitivity.

Both groups showed a low incidence of RS. TS was significantly lower in the aerobic group, suggesting reduced facilitatory pain mechanisms. However, no differences were found in CPM between groups. The aerobic group had a lower global pain sensitivity index compared to controls. There were no differences in EPM between trigeminal or spinal test site.

The findings highlight that aerobic physical activity positively influences facilitatory pain mechanisms but not inhibitory aspects. This research underscores the potential of facilitatory mechanisms (RS and TS) as biomarkers for monitoring the effectiveness of aerobic training in pain modulation. Further longitudinal studies are recommended to explore the relationships between aerobic physical activity and EPM mechanisms in greater depth.

This study demonstrates that regular aerobic exercise has a positive impact on endogenous pain modulation by reducing temporal summation, a key facilitatory pain mechanism, in healthy individuals. This contribution advances our understanding of non-pharmacological pain management and may lead to personalised exercise-based strategies for pain relief.