Effects of wetted inner clothing on heat strain while wearing ventilation garments in hot-dry and warm-humid environments

Abstract

The present study examined 1) the effect of wearing a water-soaked inner t-shirt with a ventilation garment on heat strain in undertaking moderate-intensity exercise (metabolic rate: 200 W/m2) in heat (37 °C, 50% RH, 2.8 kPa) in study 1, and 2) whether the cooling was effective in hot-dry (40 °C, 30% RH, 2.2 kPa) and warm-humid (32 °C, 80% RH, 3.8 kPa) environments in study 2. It was hypothesized that 1) wearing a water-soaked t-shirt in combination with a ventilation garment would attenuate heat and cardiovascular strain compared with a dry t-shirt/ventilation garment combination; and 2) mitigation of heat and cardiovascular strain would be greater in the warm-humid condition.In the study 1, while intermittent walking in the heat for 60 min, eight male subjects wore a dry inner t-shirt without fanning of a ventilation jacket as a control (CON). Meanwhile, under a fanned ventilation jacket, the subject wore a dry inner t-shirt (DRY) or an inner t-shirt soaked with 350 mL of tap water (WET). Increases in rectal temperature in the WET trial (0.7 ± 0.2 °C) were lower than in the CON (1.3 ± 0.3 °C) and DRY (1.1 ± 0.2 °C) (both p<0.05) trials. Heart rate and sweat loss were lowest in the WET, followed by DRY, and then CON (all p<0.05).In the study 2, the attenuation in elevation of rectal temperature, heart rate, and sweat loss in WET was observed in both hot-dry and warm-humid environments. There was no difference in the attenuation between the hot-dry and warm-humid conditions.These findings demonstrate that wearing a water-soaked inner t-shirt while using a ventilation garment is an effective and practical cooling strategy to mitigate heat strain during moderate-intensity exercise in hot occupations. Public (The project research of National Institute of Occupational Safety and Health, Japan) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.