Skin Temperature Feedback Increases Thermoregulatory Efficiency and Decreases Required Microclimate Cooling Power
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA THERMAL AND MOUNTAIN MEDICINE DIVISION
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Personal protective equipment PPE markedly increases heat strain, reduces work performance, and increases the incidence of heat casualties. Microclimate cooling MCC technologies have been successfully used to alleviate this heat strain in mounted soldiers, but cooling limitations, power and weight restrictions do not currently make this technology applicable to dismounted soldiers. This composite of studies investigated the potential for intermittent-regional cooling and skin temperature feedback approaches to better enable MCC systems for the dismounted soldier. PURPOSE The purposes of this study were to 1 determine, using a variety of intermittent cooling paradigms, the optimal skin temperature for maximizing thermoregulatory efficiency, and 2 examine the potential power savings associated with using biofeedback to maintain optimal skin temperature. METHODS Two studies were conducted using the same facilities and test equipment. In study one, 5 male soldiers exercised moderately 500W in a warm environment 30 deg C, 30rh while wearing PPE clo 2.1 imclo .32 over a water-perfused 21 deg C liquid MCC garment covering the head, chest, back, and legs 72 of body surface area, BSA. All four body regions were independently controlled. A matrix of six randomized trials was conducted in which conventional MCC constant perfusion, CP, no MCC NC, or 4 trials of intermittent and regional IR1-4 MCC was provided. IR1-4 was time-activated and onoff cooling ratios and the BSA cooled were systematically varied. In study two, 8 male soldiers were subjected to the same conditions as study one, but only three trials were performed to include CP, IR2 2 min on 2 min off, 72 BSA, and skin temperature feedback STF, 72 BSA using a skin temperature range of 33-35 deg C. Heart rate HR, body core Tc and skin temperatures Tsk were measured at regular intervals in both studies.
- Stress Physiology
- Biomedical Instrumentation and Bioengineering