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

Abstract

This study investigated the separate and combined effects of skin cooling and cold fluid ingestion on the alleviation of heat strain when wearing protective firefighting clothing at an air temperature of 30°C with 50%RH. A vest with the dual functions of cooling and providing sports drink supply (1.2% body mass) was developed. Eight males participated in the following four conditions: control [CON], drinking only [DO], cooling only [CO], and both cooling and drinking [CD]. The results showed that rectal (T re), mean skin temperature (T sk) and heart rate (HR) during recovery were lower for CD than for CON (p<0.05), while no significant differences between the four conditions were found during exercise. CO significantly reduced mean T sk and HR and improved thermal sensation, whereas DO was effective for relieving thirst and lowering HR in recovery. In summary, the combined effect of skin cooling and fluid ingestion was synergistically manifested in T re , T sk and thermal sensation in recovery.Practitioner Summary: The present results provide data on a novel vest that contributes to alleviating firefighters' heat strain. Because a cooling vest after melting may be a burden for firefighters, this study indicates a practical way to reduce the additional weight load of the vest by drinking the melted fluid of the cooling packs.

Cooling Between Exercise Bouts and Post-exercise With the Fan Cooling Jacket on Thermal Strain in Hot-Humid Environments

“…During the post-exercise recovery, there were faster rates of fall in lower-body as well as upper-body skin temperatures in FCJ trial in comparison to CON trial ( Table 1 ). These findings are consistent with previous studies that used upper-body cooling with an ice-vest ( Kim et al, 2020 ) or whole-body fanning ( Carter et al, 1999 ). These studies have reported lower-body as well as upper-body skin temperatures during the post-exercise recovery in compensable (30°C) ( Kim et al, 2020 ), or uncompensable (40°C) ( Carter et al, 1999 ) heat stresses.…”

“…These findings are consistent with previous studies that used upper-body cooling with an ice-vest ( Kim et al, 2020 ) or whole-body fanning ( Carter et al, 1999 ). These studies have reported lower-body as well as upper-body skin temperatures during the post-exercise recovery in compensable (30°C) ( Kim et al, 2020 ), or uncompensable (40°C) ( Carter et al, 1999 ) heat stresses. These observations may indicate that the fan cooling jacket use reduces whole-body skin temperature quickly while promoting falls in upper-body skin temperature within less than 5 min and lower-body skin temperature at more than 5 min but less than 10 min during recovery following exercise under our experimental settings.…”

“…In line with many previous studies using cooling between exercise bouts ( Duffield et al, 2003 ; Cleary et al, 2014 ; Schranner et al, 2017 ; Lynch et al, 2018 ; Naito et al, 2018 ; Chaen et al, 2019 ; Chalmers et al, 2019 ) and post-exercise ( Kim et al, 2020 ), lower TS and/or TC were apparent during and following exercise in with (FCJ) than without (CON) cooling trial in this study ( Figures 5A,B ). This indicates that cooling between exercise bouts and post-exercise with the fan cooling jacket would be an effective method to lower thermal perceptual and discomfort during and following exercise in compensable hot-humid environments.…”

COVID-19 and thermoregulation-related problems: Practical recommendations

“…Precooling is an effective way to reduce heat strain. The combination of external precooling such as the use of a cool-vest [31] and internal precooling, such as ingesting cold drinks [32] or ice-slurry [33] lowers the body heat content, thus providing a heat sink [34]. Ice slurry ingestion studies have not addressed patterns of consumption in habitual users of this strategy but typically assessed it as an intervention amongst athletes/ workers that are accustomed to drinking cold water but less accustomed to large volumes of ice slurry.…”