Muscle soreness after exercise is common, and can reduce the ability to perform in the days following. While cold is the most commonly recommended modality after exercise, both heat and cold have been prescribed. This study assessed the effect of sustained heat treatment on both objective and subjective measures of delayed-onset muscle soreness (DOMS).

The 20 subjects were randomized to one of three groups, including heat wraps applied immediately after exercise (group 1), heat wraps applied 24 hours after exercise (group 2) or a control. To provoke DOMS, subjects were engaged in squatting exercises for 15 minutes. Patients were assessed for muscle

soreness with a visual analogue (VAS) scale, for strength and range of motion, and for changes in plasma biomarker measurements at baseline and 48 hours after exercise. Heat therapy was applied by placing a ThermaCare heat wrap on each leg over the quadriceps for eight hours.

At 24 hours post-exercise, the control group demonstrated a 23.8% loss of muscle strength as compared with baseline, with group 2 demonstrating similar results. In group 1, no significant reduction in strength was noted on any post-exercise day. An increase in pain was found after exercise for all three groups, peaking by post-exercise day two. Significantly less pain was noted by group 1 on the first and second days after exercise (P<0.001), but not day three. Greater pain-free passive range of motion was noted in group 1 than in the other two groups.

This study found that, after intense exercise, immediate, low level heat wraps applied for eight hours can reduce delayed-onset muscle soreness and post-exercise strength reductions.