Chemically Activated Cooling Vest’s Effect on Cooling Rate Following Exercise-Induced Hyperthermia: A Randomized Counter-Balanced Crossover Study

Abstract

Background and objectives: Exertional heat stroke (EHS) is a potentially lethal, hyperthermic condition that warrants immediate cooling to optimize the patient outcome. The study aimed to examine if a portable cooling vest meets the established cooling criteria (0.15 °C·min−1 or greater) for EHS treatment. It was hypothesized that a cooling vest will not meet the established cooling criteria for EHS treatment. Materials and Methods: Fourteen recreationally active participants (mean ± SD; male, n = 8; age, 25 ± 4 years; body mass, 86.7 ± 10.5 kg; body fat, 16.5 ± 5.2%; body surface area, 2.06 ± 0.15 m2. female, n = 6; 22 ± 2 years; 61.3 ± 6.7 kg; 22.8 ± 4.4%; 1.66 ± 0.11 m2) exercised on a motorized treadmill in a hot climatic chamber (ambient temperature 39.8 ± 1.9 °C, relative humidity 37.4 ± 6.9%) until they reached rectal temperature (TRE) >39 °C (mean TRE, 39.59 ± 0.38 °C). Following exercise, participants were cooled using either a cooling vest (VEST) or passive rest (PASS) in the climatic chamber until TRE reached 38.25 °C. Trials were assigned using randomized, counter-balanced crossover design. Results: There was a main effect of cooling modality type on cooling rates (F[1, 24] = 10.46, p < 0.01, η2p = 0.30), with a greater cooling rate observed in VEST (0.06 ± 0.02 °C·min−1) than PASS (0.04 ± 0.01 °C·min−1) (MD = 0.02, 95% CI = [0.01, 0.03]). There were also main effects of sex (F[1, 24] = 5.97, p = 0.02, η2p = 0.20) and cooling modality type (F[1, 24] = 4.38, p = 0.047, η2p = 0.15) on cooling duration, with a faster cooling time in female (26.9 min) than male participants (42.2 min) (MD = 15.3 min, 95% CI = [2.4, 28.2]) and faster cooling duration in VEST than PASS (MD = 13.1 min, 95% CI = [0.2, 26.0]). An increased body mass was associated with a decreased cooling rate in PASS (r = −0.580, p = 0.03); however, this association was not significant in vest (r = −0.252, p = 0.39). Conclusions: Although VEST exhibited a greater cooling capacity than PASS, VEST was far below an acceptable cooling rate for EHS treatment. VEST should not replace immediate whole-body cold-water immersion when EHS is suspected.

Recovery with a fan-cooling jacket after exposure to high solar radiation during exercise in hot outdoor environments

“…The decrease rate in Tre during post-exercise recovery in the FAN trial was 0.021 ± 0.002°C/min and did not significantly differ from that in the CON trial. This value is lower than the cooling rate recommended in the treatment of exertional heat stroke (0.15°C/min) as well as the rate obtained using a cooling vest (0.06 ± 0.02°C/min) ( 25 ). Differences observed in the above recommended values or the results of previous studies might be due to various factors related to the relationship between Ta and Tsk, skin surface area of the cooling and heat transfer occurring during recovery.…”

“…The decrease rate in Tre during post-exercise recovery in the FAN trial was 0.021 ± 0.002°C/min and did not significantly differ from that in the CON trial. This value is lower than the cooling rate recommended in the treatment of exertional heat stroke (0.15°C/min) as well as the rate obtained using a cooling vest (0.06 ± 0.02°C/min) (25). Differences The rectal (A), tympanic (B) and mean skin temperatures (C) under the CON and FAN trials.…”

A Systematic Review of Post-Work Core Temperature Cooling Rates Conferred by Passive Rest

“…A single dataset was extracted from 38 of the included studies [19,, with the remaining six studies yielding two datasets each [63][64][65][66][67][68]. These 50 datasets from 44 included studies reported findings from a total of 562 participants (461 male, 84 female, 17 sex not reported) who undertook passive cooling.…”