The Advanced Design of a Liquid Cooling Garment Through Long-Term Research: Implications of the Test Results on Three Different Garments

The most recent goal of our research program was to identify the optimal features of each of three garments to maintain core temperature and comfort under intensive physical exertion. Four males and 2 females between the ages of 22 and 46 participated in this study. The garments evaluated were the MACS-Delphi, Russian Orlan, and NASA LCVG. Subjects were tested on different days in 2 different environmental chamber temperature/humidity conditions (24°C/H∼28%; 35°C/H∼20%). Each session consisted of stages of treadmill walking/running (250W to 700W at different stages) and rest. In general, the findings showed few consistent differences among the garments. The MACS-Delphi was better able to maintain subjects within a skin and core temperature comfort zone than was evident in the other garments as indicated by a lesser fluctuation in temperatures across physical exertion levels. The LCVG provided the greatest amount of cooling, in some conditions this resulted in body overcooling as noted in declines in skin temperature below a comfort level. Physiological findings comparing garments with and without the hood were inconclusive; however, subjects rated both the MACS-Delphi with hood and the Orlan with hood as higher in overall thermal comfort. The implication of these findings, including important features and guidelines for the new design/modifications of an advanced exploration LCG are discussed.