Purpose: Physical exercise causes alterations in pain sensitivity. Many studies verified so-called exercise-induced analgesia caused by submaximal aerobic intensity. This study aimed to determine the effect of an endurance exercise to exhaustion on pain sensitivity of healthy young men.
Method: Pressure pain thresholds (PPTs) [in Newton, (N)] of 50 healthy males (mean age 26 ± 4 years) were applied to knee, ankle and elbow joints as well as to the sternum and forehead. This was followed by a bout of cycling ergometer exercise to exhaustion. The whole process was repeated after 20 and 60 min respectively.
Results: Endurance exercise to exhaustion decreased PPTs at sternum and forehead significantly, while thresholds at the joints were not affected. Pain thresholds at forehead and sternum declined 20 min after exercise with the forehead's threshold being more reduced. PPTs remain decreased until 60 min after exercise (forehead: from 43.6 ± 15.2 N to 36.6 ± 19.8 N to 37.2 ± 13.4 N; sternum: from 46.8 ± 21.0 N to 42.5 ± 17.1 N to 44.8 ± 18.2 N). Modulation of pain sensitivity showed large effect sizes over time for both landmarks (forehead w = 0.65; sternum w = 0.50).
Conclusion: Exhaustive endurance exercise is followed by a hyperalgetic condition at forehead and sternum. This may be due to either a reduction in pain inhibiting or an activation in pain stimulating pathways.
Keywords: Exercise; Exercise induced analgesia; Hyperalgesia; Motion; Pain; Pressure pain thresholds.