A New Experimental Model Of Muscle Pain In Humans Based On Short-Wave Diathermy

Experimental models of pain in humans are crucial for understanding pain mechanisms. The most often used muscle pain models involve the injection of algesic substances, such as hypertonic saline solution or nerve growth factor, or exercise-induced delayed onset muscle soreness (DOMS). However, these models are either invasive or take substantial time to develop, and the elicited level of pain/soreness is difficult to control. To overcome these shortcomings, we propose to elicit muscle pain by a localized application of short-wave diathermy (SWD). In this crossover study, SWD was administered to eighteen healthy volunteers to the wrist extensor muscle group, with a constant stimulation intensity and up to 4 minutes. We measured pressure pain threshold (PPT) and pinprick sensitivity (PPS) and performed a psychophysical evaluation of muscle soreness at baseline and at 0, 30 and 60 minutes. SWD evoked localized muscle pain/soreness in the wrist extensor muscle group and a decrease of PPT in the treated arm compared with the control arm that lasted for at least 60 minutes, reflecting ongoing hyperalgesia after SWD application. PPS was not significantly altered 30 to 60 min following SWD, suggesting a minimal contribution from skin tissue to sustained hyperalgesia.