A comparison of moist heat, dry heat, chemical dry heat and icy hot for deep tissue heating and changes in tissue blood flow.

Abstract

Background: Intermittent bouts of heavy activity at greater than normal exercise intensity can cause delayed onset muscle soreness (DOMS). Several products are commercially available, all alleging to reduce DOMS. In the present investigation, 40 subjects (average age 27.0+/-4.4 years, average BMI 26.8) were assessed to determine the effect of 4 of these products on skin and muscle temperature and blood flow during 2 hours of application. These included ThermaCare Dry Heat Wraps, ThermaCare Moist Heat Wraps, Icy Hot Patches, and hydrocollator heat packs. Methods; Blood flow was measured (by laser doppler flow meter) over and in the quadriceps muscle and tissue temperature was measured (by thermistors and thermocouples) in these same areas. Results: The results of the study indicated that only ThermaCare Dry and Moist Heat Wraps both heated the muscle and increased muscle blood flow. The menthol and methyl salicylate compounds in Icy Hot cooled muscle. Skin blood flow increased 300% after the moist heat was applied after 45 minutes, low level continuous dry heat almost 256% but it took 105 minutes to reach this flow, hydrocollator heat wraps increased by 201% but only for only first 45 minutes and then back to baseline, a slight reduction in skin blood flow was seen with Icy Hot gel applied to the skin. Moist heat caused muscle temperature to increase by an average of 3.1 Deg C. Dry heat caused muscle temperature to increase by 2.2 Deg C, while hydrocollator packs increased temperature by 0.4 Deg C. Icy hot had no effect on muscle temperature. Conclusion: Continuous low level heat products had better penetration into muscle and increased blood flow the best compared to hydrocollator heat packs and Icy Hot patches.