Vascular and Temperature Changes During and After Applications of Superficial Heat Therapy

Abstract

Although superficial heat treatments—such as moist heat pack (MHP) and warm whirlpool (WLP)—are common for musculoskeletal injuries, treatment effects of MHP and WLP in terms of vascular and temperature responses are not clear. PURPOSE: To assess changes vascular (volume, diameter, and velocity of blood flow) and temperature (skin and inner tissue—2.5 cm deep) reaction on ankle joint during and after applications of MHP and WLP. METHODS: Nineteen healthy adults underwent one of three treatment sessions (45 °C of MHP or WLP, or control: no treatment for 20-min). Vascular reactions were measured using a Doppler ultrasound (4 MHz) at the posterior tibial artery (10 cm above the medial malleolus). Temperature probes (60 Hz) were attached on the skin of lateral foot (1 cm below from the lateral malleolus for skin and inner tissue—insulated by neoprene fabric. After baseline measurements, each treatment was randomly applied to the area just blow from the right lateral malleolus. Each measurement was recorded at baseline and every 3-min thereafter until the end of the protocol (total time: 42-min). To test treatment effects over time, 3×16 mixed model ANOVAs and Tukey-Kramer post-hoc tests were performed (p<0.05). RESULTS: From the baseline values, WLP immediately increased volume (50%, p<0.0001) and velocity (46%, p<0.0001) of blood flow, and increased values were maintained during treatment (F30,846=3.6, p<0.0001). After the removal of WLP, increased values were maintained for 13-min as compared to baseline (p=0.02). MHP did not produce any change in vascular reaction. Both MHP (2 °C, p<0.0001) and WLP (6 °C, p<0.0001) immediately increased skin temperature, and increased temperatures were maintained until the removal of both treatments (F30,846=47.6, p<0.0001). Both MHP (4 °C, p<0.0001) and WLP (6 °C, p<0.0001) took 3-min to increase temperature in the inner tissue (F30,846=52.9, p<0.0001). An increased temperature (2 °C from baseline) was maintained for 10-min (MHP) and 12-min (WLP) after the removal of each treatment. CONCLUSIONS: When treating tissues, especially located in 2.5 cm deep (e.g. ankle sprain), WLP may produce a similar effect as deep thermotherapy since it increases vascular response and inner tissue temperature. Application of MHP should be reconsidered as it does not affect vascular reaction at all.