Objective approach to a design of a whole body, water cooled suit

In an attempt to design an efficient whole body, water cooled suit, a comparison was made of the effects of cooling 10 different body regions by circulating water: neck, face, upper arms, lower arms, hands, chest, back, thighs, lower legs, and feet. Three subjects performed moderate work at 21.3°C, and in heat (49.3°C DB, 31.4°C WB), without cooling and while cooling each of the above body regions. The difference between responses to the 2 no cooling conditions was considered as the amount of heat strain to be reduced to cause 100% alleviation. According to this, cooling of either the back, chest, or thighs resulted in 66.67% reduction in body heat storage (S); cooling of either the upper arms, lower arms or hands decreased S by 30%; lower legs and feet cooling decreased S by 60% and 50% respectively, while face and neck cooling decreased S by 19% and 53% respectively. Minor sweat rate changes occurred as a result of cooling as compared with no cooling. The results served as a basis for an efficient design of a whole body cooling suit in which the head and upper extremities would receive 15% of the tubing each, while the torso and lower extremities would receive 38% and 32% of tubing respectively.