TOPICAL HEAT PROVIDES PAIN RELIEF OF DELAYED ONSET MUSCLE SORENESS OF THE DISTAL QUADRICEPS MUSCLES:

213 The objective of this randomized, multi-site, single (investigator) blind, parallel study was to determine the effect of a wearable, heat-generating knee wrap treatment on delayed onset muscle soreness (DOMS) of the distal third of the thigh musculature. Healthy adult volunteer subjects participated in an open-chain dynamic leg press exercise consisting of 8 sets of 8 repetitions of an eccentric contraction of the quadriceps muscles of each leg using 150-200% of body weight. Two days after exercise, subjects with moderate or greater pain intensity in the distal third of the quadriceps muscles were randomly assigned a knee wrap treatment (wrap temperature 40°C, 38°C, 36°C, or a non-heated placebo) for 8 consecutive hours of wear on one knee while wearing a non-heated placebo wrap on the contralateral knee. Subjective pain relief (PR) over the 8 hour treatment period was measured using a 6 point categorical scale in which 0=no relief and 5=complete relief. PR scores (mean±SEM) in subjects treated with 40°C (2.50±0.13) and 38°C (2.36±0.13) heat wraps were higher (p≤0.021) than those treated with two non-heated placebo wraps (1.65±0.23). There was no significant difference in PR scores between the groups treated with 36°C (1.75±0.13) and two non-heated placebo wraps. Topical heat treatment for 8 hours provided significant PR for DOMS of the distal quadriceps musculature. Topical heat treatment provides pain relief by inhibiting nociception in the dorsal horn of the spinal cord ("gate control") and increasing skeletal muscle relaxation and tissue blood flow.