Assessment of Hand Vasodilation and Clothing Thermal Comfort

Abstract

The purpose of this mini-review was to look at the impact of clothes covering different skin locations between the extremities and the torso on variations in body core temperature during exercise. How much does hand vasodilation help with heat loss from the extremities and garment thermal comfort while exercising?In experiment 1, seven subjects exercised on a bicycle ergometer at a Ta of 30⁰C. Subjects wore two different types of clothing: A, designed to expose upper extremities and B, designed to expose the torso, covered identically 71% skin of body surface area. T_re increased to 37.88 ⁰C in clothing A and to 38.14⁰C in clothing B at the end of  exercise, respectively. The findings clearly demonstrated that the upper extremities are more efficient in dissipating heat from the body than the torso. In experiment 2, seven subjects exercised for 25 minutes and then rested for 20 minutes at a Ta of 20.0⁰C. In OCCL, both wrists were occluded with a cuff for 30 minutes to stop hand blood flow. In CONT, the wrists were not occluded, finger T_sk increased from 20.5⁰C to 34.0⁰C, and forearm T_sk increased concomitantly from 25.4⁰C to 27.7⁰C during and after exercise. In OCCL, however, T_sks in the finger and forearm did not increase at all during wrist occlusion. Despite of a compensatory increase in thermo-physiological responses, T_es was significantly higher in OCCL than in CONT. We found that hand vasodilation is critical for increasing heat dissipation from the upper extremities, inhibiting body core temperature rise and improving clothing thermal comfort under heat load.