A shirt containing multistage phase change material and active cooling components was associated with increased exercise capacity in a hot, humid environment

Abstract

Recent advances in clothing design include the incorporation of phase change materials (PCM) and other active cooling components (ACC) to provide better body heat dissipation. The purpose of this study was to determine the effect of wearing a shirt containing multistage PCM/ACC on exercise capacity at low (5.0), moderate-high (7.5) and extreme (9.0) levels of the physiological strain index (PSI). Fourteen individuals tested two shirts (control vs. cooling) during 45-min of interval running in a hot, humid (35 ± 1 °C; 55 ± 6% RH) environment. The cooling shirt resulted in an 8% improvement in exercise capacity at a PSI of 7.5 (p < 0.05). The observed increase in exercise capacity would likely translate to a significant improvement in exercise performance. More research is needed to determine a best practice approach for the use of cooling clothing as a counter to exercise-induced heat exposure. Practitioner Summary: In this report, we demonstrate that when forced to exercise in a hot, humid environment, an individual's exercise capacity may increase by as much as 8% when wearing a shirt composed of multistage phase change material and active cooling components.

A novel vest with dual functions for firefighters: combined effects of body cooling and cold fluid ingestion on the alleviation of heat strain

“…The present study found that wearing the cooling vest lowered the rise of T re during recovery more rather than during exercise, and the beneficial influence became greater when adding cold fluid ingestion. A considerable number of investigations reported the beneficial effect of wearing cooling garments on core body temperature during exercise or recovery [44][45][46][47] , which lead to reduced PSI 48) and increased exercise tolerance time 49) , but another considerable number of research found no core body temperature benefit from wearing cooling garments [50][51][52] .…”

Heat Safety in the Workplace: Modified Delphi Consensus to Establish Strategies and Resources to Protect the US Workers

“…Such finishes and films, especially when worn in combination with other layers, block both convective and evaporative heat transfer from the body to the external environment, increasing risk of heat‐related illness. On the material level, ways to improve physiological comfort have been explored including incorporating phase change materials (PCMs) (Butts et al., 2017 ; McFarlin et al., 2016 ), wicking and moisture management treatments, and infrared heat reflective finishes. The majority of these textile finishes, however, have proven to be ineffective for occupational applications due to the excessive amounts of treatment needed, which negates the benefits due to added material weight, as well as the relatively short period of time for which they are effective.…”

Advanced Functional Materials for Intelligent Thermoregulation in Personal Protective Equipment

“…It has also been reported that mixing phase change materials with active cooling components such as metals and/or highly conductive ceramics and encapsulated soluble alcohols such as xylitol that cool in contact with water vapor could allow a PCM to repeatedly lose heat and thus create an effect similar to a recharging of the cooling effect of the PCM during exposure to heat. A study has shown that depositing a mixture of PCM/highly conductive metals on the surface of a sweater could allow the development of a textile layer creating a multistage cooling effect [313]. Nafion ® , being a selectively and highly water-permeable, sulfonated tetra fluoro ethylene-based fluoro-polymer copolymer, has been the subject of recent work to develop a reversible moisture sensitive garment to support personal thermoregulation in warm environments.…”