Ventilated Vest and Tolerance for Intermittent Exercise in Hot, Dry Conditions With Military Clothing

Introduction: Recent research has focused on developing air-ventilated garments to improve evaporative cooling in military settings. This study assessed a ventilated vest (Vest) in hot (45 degrees C), dry ( 10%) RH) ambient conditions over 6 h of rest and exercise. It was hypothesized that the Vest would lower the thermal strain and increase the amount of exercise done by subjects. Methods: Eight healthy heat-acclimated men, wearing combat clothing, body armor, and a 19-kg load in webbing walked on a treadmill at 5 km . h(-1) at a 2% incline until rectal temperature (T-rec) reached 38.5 degrees C. They then rested until T-rec reached 38 degrees C, at which point they recommenced walking. Or) one occasion the subjects wore a Vest, blowing ambient air around the torso. On the second occasion Subjects did not wear the vest (NoVest). Exercise/rest ratio, T-rec, skin temperature (T-sk), sweat responses, rating of perceived exertion (RPE), and thermal comfort (TC) were measured. Results: Subjects wearing the Vest exercised for significantly longer (18%; 11 min/h) as a percentage of total exposure time, stopped exercise significantly less often [Mean (SD); NoVest: 3 (2) slops; Vest: 1 (2) stops], and maintained significantly lower skin temperature under the body armor [T-chest: NoVest 37.55.(0.51)degrees C; Vest: 35.33 (1.00)degrees C; T-back: NoVest: 36.85 (0.83)degrees C; Vest: 35.84 (0.88)degrees C]. The Vest provided 28 W of cooling during exercise and 73 W when at rest as estimated by thermometry. Conclusion: A ventilated vest can provide cooling, and thereby reduce thermal strain and increase exercise clone in dry environmental temperatures up to 45 degrees C, without causing skin irritation and discomfort.