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Electrical stimulation (ES) is a modality used to increase skin blood flow (SBF) and to aid in wound healing. A greater SBF in non wounded skin is induced if ES is used in a warm environment compared to a thermoneutral environment, where ES is usually applied. Therefore, in this paper, a method to investigate the effect of local heating and ES on the SBF is developed. A total of 33 males (18–40 years) were divided into group G ( n = 15) who received the ES during a global heating protocol and group L ( n = 18) who received ES during a local heating protocol. In the global heating protocol, ES (30 Hz, 250 μs) was applied for 15 min on the subject's thigh in thermoneutral (25 ± 0.5°C) and warm (35 ± 0.5°C) environments. In the local heating protocol, ES was applied for 15 minutes at 25°C, 35°C and 40°C local skin temperatures. A laser Doppler imager measured the SBF in both protocols pre, during, and post ES. The results of the experiment showed the significant differences in the SBFs were found at pre, during, and post ES in a thermoneutral environment or when the skin was locally cooled to 25°C. The SBFs were significantly increased during and post ES after global heating or during local heating at 35°C and 40°C. There were no significant differences in SBFs between the warm environment and at 35°C of local heating. However, the SBF response to ES was the highest at 40°C of local heating. Thus, ES during local heating of the skin, as well as during global heating is an effective method to increase SBF. [ABSTRACT FROM AUTHOR]

The purpose of this study was to quantify the thermal transfer characteristics of the skin in relation to body composition as assessed by the ability of water immersion and hot and cold packs with different thicknesses of towels layers to heat or cool deep tissue. Two sets of experiments were conducted to determine the interrelationships between body fat content and muscle temperature after immersion of the limb in water or the application of hot and cold packs. In the first series of experiments, subjects immersed their lower body in water at 42, 37, 34, 27, 24 and 0°C for 20 minutes. Muscle temperature was measured in the skin above and in the belly of the quadriceps and medial gastrocnemius muscles by a thermistor on the skin and one implanted with a 20-gauge needle 25 mm below and perpendicular to the skin. To see the effect of circulation, a series was conducted with the circulation occluded. In the second series, hot or cold packs were used with different thicknesses of towel layers. The muscle temperature after immersion in water approached that of the packs within approximately 20 minutes. In contrast, when hot and cold packs were used with various thickness of towels ranging from 2 to 10 mm in thickness, the change in muscle temperature was much less and it was still changing at the end of a 20 minute period. Subjects with high body fat changed their deep tissue temperatures much more slowly with a time constant nearly double that of the thin subjects with all modalities. Even after water immersion, if the body fat exceeded 25% of the subject's weight, 20 min of immersion was not enough to either warm the muscle or cool it down substantially. Cold packs and hot packs were very ineffective in changing muscle temperature under these same conditions. Body fat plays a major role, as did limb blood flow in controlling the movement of heat across the limb. [ABSTRACT FROM AUTHOR]