Date of Graduation

5-2024

Document Type

Thesis

Degree Name

Master of Athletic Training (MAT)

Degree Level

Graduate

Department

Health, Human Performance and Recreation

Advisor/Mentor

Brendon P. McDermott

Committee Member

Luzita Vela

Second Committee Member

Elizabeth Parke

Keywords

Exertional heat stroke; Emergency management; Whole-body cooling; Cooling rate; Heat illness

Abstract

Context: Research suggests that ATs lack compliance with EHS management and do not adopt gold-standard recommendations for EHS. Body bags filled with ice and water may offer an alternative method of cold-water immersion (CWI) that is more portable and accessible than rigid cold tubs. Anecdotally, this treatment has been used successfully in ambulances and at mass participation events for exertional heat illness treatment. The purpose of this study was to determine whole-body cooling rates when using body bags (BB) to facilitate partial CWI to treat exertional hyperthermia. Methods: Nine (8 male) participants (24 ± 4y, 175 ± 7cm, 83.6 ± 21.6kg) completed two randomized, crossover trials one week apart. Trials were completed on outdoor recreational turf fields and included a self-paced 400-m warm-up, 1609-m run, and 100-m sprints until core temperature reached 38.9°C or volitional exhaustion. Following exercise, participants were cooled for a maximum of 30-min lying supine in the shade (control; CON) or in BB filled with 20 gallons of ice-water and oscillated continuously. Following cooling, patients sat upright for a 15-minute recovery. Rectal temperature (Trec) and heart rate (HR) were taken throughout exercise, every minute of cooling, and every 5 minutes of recovery. Thermal and thirst sensation were assessed after every set of sprints and at the first and last minute of cooling and recovery. Rating of perceived exertion (RPE) was assessed after each set of sprints. Data were analyzed using repeated measures ANOVA or paired t-tests where appropriate with alpha set at p<.05. Results: WBGT between trials was not significantly different (day 1: 28.70 ± 1.23°C; day 2: 28.17 ± 0.83°C, p= 0.726). There was no difference in maximum Trec (BB: 39.19 ± 0.47°C; CON: 39.11 ± 0.43°C; p= 0.448), HR (BB: 183 ± 13bpm; CON: 190 ± 9bpm; p= .213), RPE (BB: 18 ± 2; CON: 18 ± 2; p >.999), Thirst (p=.617), or thermal sensation (p=0.729) during exercise. Fluid consumed (p=.404), body mass changes (p = .898), 400-m run times (p = .186) and 1609-m run times (p = .174) were no different between trials. Whole-body cooling rate for BB was 0.110 ± .04°C/min, whereas CON cooling produced a cooling rate of 0.040 ± .02°C/min (p = .002). Total cooling time was significantly faster with BB (13.2 ± 5.8min) compared to CON (27.6 ± 4.2min; p = .002). Thermal sensation was significantly lower throughout cooling in BB versus CON (p <.001). Conclusion: BB cooling provides acceptable cooling rates for lowering Trec. In settings where full body CWI is not feasible, partial CWI via BB offers an effective alternative. Key words: Exertional heat stroke, Emergency management, Whole-body cooling, Cooling rate, Heat illness

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