General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Our aim was to examine the effect of a synthetic material undergarment on heat stress during exercise in a hot environment. Ten active males completed two trials of intermittent (50min walking, 10min sitting) treadmill walking over 3h in 35°C and 30% relative humidity. Subjects wore wildland firefighter flame-resistant meta-aramid blend pants and shirt with either a 100% cotton (C) or flame-retardant modacrylic undergarment (S), while carrying a 16-kg pack, helmet and leather gloves. Exercise was followed by a 30-min rest period without pack, helmet, gloves, and outerwear shirt. Rectal temperature and physiological strain were greater in S than C (P=0.04). No significant differences were found for heart rate, rating of perceived exertion, energy expenditure or skin temperature between C and S. Skin blood flow increased significantly in S following the second hour of exercise, resulting in a time×trial interaction (P=0.001). No significant differences for skin blood flow were found post exercise. Sweat rate and percent dehydration were not different between C and S. These data indicate that, of the two undergarments investigated, the synthetic undergarment negatively affected physiological factors that have been shown to indicate an increased risk of heat-related injuries.
Protective clothing worn by wildland firefighters (WLFF) may increase physiological strain and heat stress factors due to increased insulation and decreased ventilation. PURPOSE: To examine the effects of a flame resistant synthetic material base layer on heat stress factors. METHODS: Ten recreationally active males (25 ± 6.1 yrs, 80.9 ± 8.4 kg, 11.1 ± 5.3% fat, 4.4 ± 0.6 L•min-1 VO 2 max) completed two trials of intermittent (50 min walking, 10 min sitting) treadmill walking (4km/hr, 4% grade) over 3 hours in a hot, dry environment (35⁰C, 30% rh). Participants wore standard WLFF Nomex green pants, Nomex yellow shirt with either a 100% cotton (C) or flame resistant synthetic material base layer (S), while carrying a 16kg pack, hard hat, and gloves. Exercise was followed by a 30 minute rest period without the pack, hard hat, gloves, and Nomex yellow shirt. Core (T c) and skin (T sk) temperatures were measured continuously throughout the trial. Physiological strain index (PSI) was calculated using heart rate and T c. Skin blood flow (SBF) was recorded for two minutes prior to walking, for five minutes during each break, and for three, five minute periods during the 30 minutes following exercise. Water was scripted at 8 ml/kg/hr. RESULTS: No significant differences were found for T c (p=0.077) and T sk (p=0.086) between C and S. Significant main effects for time were found for T c (p<0.001) and T sk (p=0.003). Significant main effects for time (p<0.001) and trial (p=0.04) were found for PSI. SBF increased significantly in S following the second hour of exercise, resulting in a time*trial interaction (p=0.001). No significant differences for SBF were found between C and S post-exercise (p=0.089). CONCLUSION: These data indicate that a flame resistant synthetic material base layer negatively affects physiological factors that have been shown to indicate an increased risk of heat-related injuries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.