Validation Study for a Model of Acute Muscle Pain

Abstract

Eccentric exercise causes delayed onset muscle soreness (DOMS) with pain peaking 24–48 h after exercise. An acute inflammatory reaction is considered one of the underlying mechanisms of DOMS. Most models to induce DOMS use equipment based exercise programs which are not necessarily reflective of muscle pain acquired in daily life. This study investigated pain induced by walking down stairs as an alternative DOMS model. This randomized, subject and observer blinded, placebo-controlled study investigated muscle pain induced by walking down stairs in 80 volunteers (40 per group). Eccentric exercise consisted of walking down stairs with a total altitude of 460–600 m depending on body weight. Due to the potential contribution of inflammatory processes, 200 mg Celecoxib bid (CE) given for 7 days was used as control. Pain scoring was performed separate for the calf and quadriceps using an 11 point numerical analog scale. Rating was performed at rest and during walking down 20 stairs (contraction) at 12, 24, 36, 48, 60, 72, 96, 120 and 144 h after exercise. In addition, surface temperature (infrared thermometer) at trigger points and leg volumetry was evaluated as clinical surrogate markers for an inflammatory response. Maximum pain was observed during contraction in the calf at 24, 36 and 48 h after exercise (4.2±1.9, 4.8±2.2, 4.2±2.5). Pain was reduced for the CE group (3.7±1.6, 4.4±2.0, 3.8±1.9) with maximum numerical reduction after 72 h (2.7±2.4 vs. 2.0±1.6). The sum pain score was reduced by about 15% for the CE group (26.7 vs. 23.2). In general, substantially less pain was observed for the thigh and during rest. Surface temperature and volumetry did not show model or treatment induced changes. Walking down stairs induces reproducible, moderate, acute pain in the calf. CE showed modest treatment effects.