Evaluation of Various Cooling Systems After Exercise-Induced Hyperthermia

• Published in: Journal of athletic training Vol. 52; no. 2; pp. 108 - 116
• Main Authors: Tan, Pearl M S, Teo, Eunice Y N, Ali, Noreffendy B, Ang, Bryan C H, Iskandar, Iswady, Law, Lydia Y L, Lee, Jason K W
• Format: Journal Article
• Language: English
• Published: United States National Athletic Trainers Association 01.02.2017
• Subjects: Alloys; Body Composition; Climate; Cold; Cross-Over Studies; Cryotherapy; Data collection; Esophagus; Exercise; Exercise - physiology; Exercise Test; Fever; Heart Rate - physiology; Heat; Heat Stroke - etiology; Heat Stroke - physiopathology; Heat Stroke - therapy; Heatstroke; Humans; Laboratories; Male; Original Research; Outcome Measures; Patients; Perception - physiology; Physical Exertion; Physical fitness; Scientific Concepts; Temperature; Thermosensing; Water; Young Adult; core temperature; exertional heat stroke; safety
• ISSN: 1062-6050; 1938-162X
• DOI: 10.4085/1062-6050-52.1.11

Rapid diagnosis and expeditious cooling of individuals with exertional heat stroke is paramount for survival. To evaluate the efficacy of various cooling systems after exercise-induced hyperthermia. Crossover study. Laboratory. Twenty-two men (age = 24 ± 2 years, height = 1.76 ± 0.07 m, mass = 70.7 ± 9.5 kg) participated. Each participant completed a treadmill walk until body core temperature reached 39.50°C. The treadmill walk was performed at 5.3 km/h on an 8.5% incline for 50 minutes and then at 5.0 km/h until the end of exercise. Each participant experienced 4 cooling phases in a randomized, repeated-crossover design: (1) no cooling (CON), (2) body-cooling unit (BCU), (3) EMCOOLS Flex.Pad (EC), and (4) ThermoSuit (TS). Cooling continued for 30 minutes or until body core temperature reached 38.00°C, whichever occurred earlier. Body core temperature (obtained via an ingestible telemetric temperature sensor) and heart rate were measured continuously during the exercise and cooling phases. Rating of perceived exertion was monitored every 5 minutes during the exercise phase and thermal sensation every minute during the cooling phase. The absolute cooling rate was greatest with TS (0.16°C/min ± 0.06°C/min) followed by EC (0.12°C/min ± 0.04°C/min), BCU (0.09°C/min ± 0.06°C/min), and CON (0.06°C/min ± 0.02°C/min; P < .001). The TS offered a greater cooling rate than all other cooling modalities in this study, whereas EC offered a greater cooling rate than both CON and BCU (P < .0083 for all). Effect-size calculations, however, showed that EC and BCU were not clinically different. These findings provide objective evidence for selecting the most effective cooling system of those we evaluated for cooling individuals with exercise-induced hyperthermia. Nevertheless, factors other than cooling efficacy need to be considered when selecting an appropriate cooling system.