Two isothermal challenges yield comparable physiological and subjective responses
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ORIGINAL ARTICLE
Two isothermal challenges yield comparable physiological and subjective responses L. Klous1 · A. Psikuta3 · K. Gijsbertse2 · D. Mol2 · M. van Schaik2 · H. A. M. Daanen1 · B. R. M. Kingma2,4,5 Received: 18 July 2019 / Accepted: 3 September 2020 © The Author(s) 2020
Abstract Purpose Ventilated vests are developed to reduce thermal stress by enhancing convective and evaporative cooling from skin tissue underneath the vest. The purpose of this study is to investigate whether thermal stress is equal when a ventilated vest is worn compared to a no-vest situation with similar dry thermal resistance. Methods Nine healthy males walked on a treadmill (7 km h−1) for 45 min in a desert climate (34 °C, 20% relative humidity) with and without ventilated vest. Gastrointestinal temperature (Tgi), heart rate (HR), and skin temperature (Tsk) were continuously monitored. Local sweat rate (LSR) was assessed two times on six skin locations. Subjective ratings were assessed every 10 min. Results Final Tgi (37.6 ± 0.1 °C for vest and 37.6 ± 0.1 °C for no-vest), HR (133 ± 7 bpm and 133 ± 9 bpm) and mean Tsk (34.8 ± 0.7 °C and 34.9 ± 0.6 °C) were not different between conditions (p ≥ 0.163). Scapula skin temperature (Tscapula) under the vest tended to be lower (baseline to final: ΔTscapula = 0.35 ± 0.37 °C) than without vest (ΔTscapula = 0.74 ± 0.62 °C, p = 0.096). LSR at locations outside the vest did not differ with and without vest (p ≥ 0.271). Likewise, subjective responses did not differ between conditions (χ2 ≥ 0.143). Conclusions We conclude that two systems with similar dry thermal resistance and, therefore, similar required evaporation, resulted in similar thermal stress during paced walking in a hot-dry environment. Local ventilation did not alter the sweating response on locations outside the vest. Keywords Ventilated vest · Thermal resistance · Thermal stress · Local sweat rate Abbreviations Ax (m2) Surface area of x ANOVA Analysis of variance Communicated by Narihiko Kondo. * B. R. M. Kingma [email protected] 1
Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
2
TNO, Netherlands Organization for Applied Scientific Research, Defense, Safety & Security, Soesterberg, Kampweg 55, 3769 DE Soesterberg, The Netherlands
3
Empa, Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland
4
Department of Nutrition, Exercise and Sports, Section for Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
5
Department of Energy Technology, Eindhoven University of Technology, Eindhoven, The Netherlands
ArmL Left arm ArmR Right arm BDU Battle dress uniform Emax (W) Maximum evaporative heat loss Ereq (W) Required evaporation for heat balance fcl,x Local clothing area factor of x HR (bpm) Heart rate Ix (m2KW−1) Thermal insulation of x Ix,r (m2 KW−1) Resultant thermal insulation of x LCPB Ballistic and load-bearing vest LegL Left leg LegR Right leg LSR (gm−2 h−1) Local swea
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