The impact of a phase-change cooling vest on heat strain and the effect of different cooling pack melting temperatures

Abstract

Cooling vests (CV) are often used to reduce heat strain. CVs have traditionally used ice as the coolant, although other phase-change materials (PCM) that melt at warmer temperatures have been used in an attempt to enhance cooling by avoiding vasoconstriction, which supposedly occurs when ice CVs are used. This study assessed the effectiveness of four CVs that melted at 0, 10, 20 and 30 °C (CV₀, CV₁₀, CV₂₀, and CV₃₀) when worn by 10 male volunteers exercising and then recovering in 40 °C air whilst wearing fire-fighting clothing. When compared with a non-cooling control condition (CON), only the CV₀ and CV₁₀ vests provided cooling during exercise (40 and 29 W, respectively), whereas all CVs provided cooling during resting recovery (CV₀ 69 W, CV₁₀ 66 W, CV₂₀ 55 W and CV₃₀ 29 W) (P < 0.05). In all conditions, skin blood flow increased when exercising and reduced during recovery, but was lower in the CV₀ and CV₁₀ conditions compared with control during exercise (observed power 0.709) (P < 0.05), but not during resting recovery (observed power only 0.55). The participants preferred the CV₁₀ to the CV₀, which caused temporary erythema to underlying skin, although this resolved overnight after each occurrence. Consequently, a cooling vest melting at 10 °C would seem to be the most appropriate choice for cooling during combined work and rest periods, although possibly an ice-vest (CV₀) may also be appropriate if more insulation was worn between the cooling packs and the skin than used in this study.

Effect of a Cooling Vest on Core Temperature in Athletes With and Without Spinal Cord Injury

“…RPCM vests (a specific gel vest, as used in this study) have the ability to remain solid at higher temperatures (>10°C) than ice vests and thus are less likely to cause local vasoconstriction or skin breakdown. 27 The cooling vest showed no significant effect on T c in any group (TP, HP, LP, AB) or condition. There was a significant difference (P < .001) in mean baseline temperatures between persons with (namely the TP and LP groups) and without SCI.…”

Mild evaporative cooling applied to the torso provides thermoregulatory benefits during running in the heat

“…Cooling methods, such as air‐ and water‐cooled systems (Stephenson et al., ), garments made of phase‐change materials (House et al., ), as well as the use of menthol (Gillis et al., ), have been developed and shown to be potentially effective in preserving performance in the heat due to their effects on T sk and thermal sensation (Hasegawa et al., ). The beneficial effects of these cooling strategies have been shown to vary largely according to the environmental conditions (i.e., the higher the heat load, the more beneficial the cooling), the duration of cooling (i.e., the longer the more beneficial), and most importantly, to the type and duration of exercise performed (i.e., cooling is more beneficial for endurance exercise performed for up to 60 min as opposed to single sprint exercise) (Wegmann et al., ).…”

Evaluation of two cooling systems under a firefighter coverall

“…Therefore it can be speculated that there has been a slight cooling effect that outweighed the extra physiological strain caused by carrying the cooling system. The lack of a reduction in heart rate and core temperature has been shown before in studies using ice vests and PCM vests with melting points above 10 C (Banta and Braun, 1992;Gao et al, 2011;House et al, 2013), indicating that affecting core temperature requires substantial cooling power. Further, total body circulating liquid cooling has been reported to be more effective than torso only (Cadarette et al, 2002), as applied in this study.…”

“…However, only a few studies investigated direct active cooling during work (e.g. House et al, 2013), which may be the most effective way of reducing heat strain. For firemen this implies the use of a portable cooling system worn under the personal protective clothing.…”