EFFECTS OF A NEWLY DESIGNED MILITARY SHIRT ON PHYSIOLOGICAL RESPONSES UNDER HEAT STRESS
Keywords:
Battle dress uniform / heat exchange / thermoregulation / physiological strainAbstract
The operations of military forces require wearing battle dress uniform and a protective ballistic vest which may increase physiological strain and impair physical performance in hot and humid environment. Objective: to investigate and compare the effects of two military shirts; a newly designed long-sleeved military shirt (NMS) and a traditional military shirt (CON) on physiological responses, time to exhaustion (TTE), and subjective perception during exercise in hot and humid condition (NMS; 35.3 ± 0.1๐C, 50.6 ± 1.2%, CON; 35.1 ± 0.2๐C, 50.7 ± 0.8%). Method: Twelve healthy and physically active males (Age: 20.8 ± 0.4 years; BW: 66.6 ± 1.7 kg; Height: 173.6 ± 1.6 cm) volunteered to participate in this study. Subjects completed two experimental trials wearing NMS or CON covered by the standard military protective vest in a randomized order. Subjects walked on a motorized treadmill (3.5 km/h, 0% grade), wear a combat helmet and carry mission load including rifle and back pack over 120 minutes or until exhaustion. Core temperatures (TGI), Skin temperatures, stroke volume (SV), cardiac output (CO), oxygen consumption rate (VO2), rating of perceived exertion (RPE), and thermal responses were measured at rest and every 5 minutes during exercise. Two-way repeated measurement ANOVA was used to test the main effects of shirts and times, and interaction effect. Paired t-test and Wilcoxon signed rank test were applied for sweat loss, time to exhaustion and thermal subjective responses, respectively. Results: no main effect of shirts and interaction effects of shirts and time on core temperature and skin temperature, HR, VO2, SV, and RPE were observed. Moreover, TTE and thermal responses of NMS and CON trials were not significantly different. However, CO at the end of exercise of CON (18.0 ± 0.5 L.min-1) and NMS (16.6 ± 0.45 L.min-1) was significantly different.Conclusion: Wearing NMS beneath a protective vest during exercise in hot, humid environment did not exert any different effects on time to exhaustion, physiological responses, and subjective perception when compared to CON. It is possible that a protective vest that covered the military shirt may impede the effectiveness of NMS on heat transfer.
(Journal of Sports Science and Technology 2017; 17(2): 97-108)
Keywords: Battle dress uniform / heat exchange / thermoregulation / physiological strain
*Corresponding author: Metta PINTHONG
College of Sports Science Technology, Mahidol University,
NakhonPathom, Thailand 73170
E-mail: [email protected]
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