Liquid IceTM fails to cool the skin surface as effectively as crushed ice in a wet towel

Abstract

One sought to compare surface cooling produced by two cryotherapy modalities (crushed ice in a room temperature wet towel and Liquid IceTM). Twenty-five university students (10 female and 15 male) between 19 and 29 years of age (mean±SD: 21.36±2.33) participated in this study. Skin surface temperature was measured prior to, immediately after 20-minute application, and 20-minute postapplication of the cryotherapy modality using an infrared camera. Both cryotherapy modalities decreased the baseline skin surface temperature (crushed ice: 28.6±1.3 to 6.8±1.8°C; Liquid IceTM: 28.6±1.6 to 25.2±1.56°C; p<0.001). Similarly, at 20 minutes postapplication of both cryotherapy modalities the skin surface temperature remained significantly inferior to baseline (crushed ice: 21.8±1.0°C; Liquid IceTM: 27.4±1.6°C; p<0.001). The magnitude of the decrease was greater after the application of crushed ice in a room temperature wet towel than Liquid IceTM, both immediately after application (temperature fall: 21.8±1.6°C versus 3.4±0.7°C; p<0.001) and 20 minutes postapplication (temperature fall: 6.8±0.8°C versus 1.2±0.6°C; p<0.001). Assuming that greater cooling seems to be better, the present results suggest that: 1) a 20-minute application of crushed ice in a room temperature wet towel is more effective at cooling skin temperature than evaporative cooling menthol-based products and 2) Liquid IceTM is not a clinically useful modality.