Effects of laughter on pain tolerance and muscle soreness induced by eccentric exercise

Chronic pain affects 116 million people, a number larger than the total affected by cardiovascular disease, cancer, and diabetes combined. Currently there is not a singular treatment known to provide relief from chronic pain, and the treatments that do exist are not effective for all. Novel ways to effectively treat chronic pain are needed. Laughter has been known to provide a multitude of health benefits, however it is not universally accepted as a treatment for pain. The purpose of this study was to investigate if laughter provided by comic relief can influence pain tolerance and muscle soreness compared to an uninteresting documentary. Forty, young and healthy participants were recruited from the University of Texas at Austin and underwent a randomized cross-over experiment. Each participant was exposed to a comedy video eliciting laughter as well as a documentary after inducing delayed onset muscle soreness in one leg at a time. Pain tolerance was tested on each participants’ leg before and after the videos. An interaction of time and treatment was found to be significant in a mixed model: after watching the documentary video participants’ pain tolerance was decreased by 13.3 N compared to the comedy. Pain tolerance in the sore leg was decreased by 17.3± 5.0 N after viewing the documentary video, but did not change after watching the comedy. Similar results were seen in the control leg (p<.05) (20.6±5.0 N vs. 1.5±3.4 N). There was no interaction of leg and treatment, and no dose response was elucidated. We speculate that thirty-minutes of watching a comedy eliciting laughter provides psychological changes through the gate control theory and physiological changes through released endorphins that significantly influence pain tolerance. It is possible that thirty minutes of a comedy provoking laughter can provide pain relief that can restore the quality of life of individuals suffering from chronic pain.