Modulation of Heat Pain Processing with Physical Exercise: a task fMRI Study

Purpose: Various psycho-physiological effects are promoted by physical exercise, including modulation of pain perception. Assuming central opioidergic mechanisms, we expected physical exercise (two hours outdoor run) to affect the affective dimensions of pain processing, as compared to a control condition (two hours outdoor walk).

Materials and Methods: Thermal heat-pain fMRI was performed in 20 athletes (mean age 39 years, range 23–59 years) before and after both interventions. The paradigm consisted of 2×5 blocks of 30sec stimulation phases (5x heat pain, 46.5°C/5x non-painful heat, 43.0°C). Examinations were performed on a 3T-Philips Achieva scanner using an 8-channel SENSE head coil.

Results: The McGill Affective Pain Questionnaire showed a significant time x exercise interaction and the post hoc comparisons revealed a significant decrease in the pre vs. post run condition (p<0.05, one-sided t-Test). In the imaging data, the interaction term (pre-post)run > (pre-post)walk was significant for the perigenual ACC and the periaqueductal gray (p<0.001 and SVC (10 voxel sphere)).

Conclusion: Exercise in athletes modulates the affective dimensions of pain processing via descending antinociceptive pathways. The specific effect on the affective dimension of pain and elevated peripheral endorphin levels (run > walk) suggest an underlying opioidergic effect promoted by exercise.