Thermal comfort and sensation in men wearing a cooling system controlled by skin temperature

Objective: The study was done to determine whether thermal comfort (TC), thermal sensation (TS), and subjective factors gauging environmental stress were negatively affected with different cooling methods in men exercising in chemical protective clothing. Background: Previous studies have reported that intermittent regional cooling improved the efficacy of cooling as compared with constant cooling (CC), but no studies have addressed whether there is any improvement in thermal comfort. Methods: Eight male volunteers exercised at moderate work intensity (425 W) in three microclimate cooling tests. The circulating fluid in the cooling garment was provided during exercise to the head (6% body surface area [BSA]), torso (22% BSA), and thighs (44% BSA) and manipulated under three methods: (a) CC, (b) pulsed cooling (PC), and (c) PC activated by mean skin temperature ((T) over bar (sk)) control (PCskin). TC and TS ratings were recorded every 20 min during the 80-min test. Results: TC and TS ratings were not different for PCskin and CC; thus the participants perceived PCskin as being similar to CC. TS was significantly warmer with PC than with PCskin and CC (p <.001). In PCskin, <(T)over bar>(sk) was significantly higher than in PC and CC (p <.001), and PCskin was rated as being not as warm as PC according to TS. Conclusion: This indicates that the PCskin method was perceived as being as cool as CC and cooler than PC. Application: These findings indicate that the PCskin cooling method is an acceptable alternative to CC and PC based on human perceptions.