364 Individual and combined effects of hydration status and ice water dousing on physiological and performance indices during intermittent exercise in the heat. (3rd March 2020)

• Record Type: Journal Article
• Authors: Benjamin, Courteney L; Sekiguchi, Yasuki; Morrissey, Margaret C; Butler, Cody R; Filep, Erica M; Stearns, Rebecca L; Casa, Douglas J
• Is Part Of: British journal of sports medicine. Volume 54(2020)Supplement 1
• Page Start: A149
• Page End: A149
• Publication Date: 2020-03-03
• Subjects: Sports medicine -- Periodicals; 617.1027
• DOI: 10.1136/bjsports-2020-IOCAbstracts.364
• Languages: English
• ISSNs: 0306-3674

Abstract

Abstract : Background: Athletes often experience performance and safety decrements during intense exercise in the heat. Practical, effective modalities to mitigate risks and acheive peak performance is needed. Objective: To assess the effects of hydration and ice-water dousing on physiological and performance parameters during exercise in the heat. We hypothesized that euhydrated athletes who doused would present optimal physiological and performance outcomes. Design: Prospective, randomized balanced crossover. Setting: College team sports. Participants : 13 athletes (M±SD; body mass, 70.2±9.0 kg; height, 173±8cm; VO2max, 53.5±7.1 ml×kg -1 ×min -1 ). Interventions : Participants completed exercise in four conditions: Euhydrated without dousing (EuND), Dehydrated without dousing (DeND), Euhydrated with dousing (EuD), and Dehydrated with dousing (DeD). Each trial involved an individualized sport-specific intermittent treadmill protocol and performance tests in the heat (ambient temperature=33°C; relative humidity=50%). Participants doused four times throughout each trial using a specialized bottle (REIGN™, CamelBak, California, USA). Main outcome measurements: Internal body temperature (Trec ), heart rate (HR), and repeat sprint test. Results: EuND resulted in lower average HR and Trec compared to DeND (MD[95%CI]; HR, -8.7[1.5, 15.9]bpm, p=0.02; Trec, -0.4[-0.6, -0.2]°C, p=0.001). EuND averages were not different than EuD (MD[95%CI]; HR, 1.4[-4.3, 7.0]bpm, p=0.61; Trec, 0.1[-0.1, 0.3]°C, p=0.23) and DeND averages were not different than DeD (MD[95%CI]; HR, 1.9[-5.2, 9.0]bpm, p=0.57; Trec, -0.1[-0.1, 0.3]°C, p=0.30), however, dousing had moderate and large effects on Trec at the end of exercise (EuD vs EuND, ES=0.3; DeD vs DeND, ES=0.5) and small and moderate effects on HR (EuD vs EuND, ES=0.2; DeD vs DeND, ES=0.3). When dehydrated, dousing improved sprint performance at the end of exercise (MD[95%CI] -3.7[-6.9, -0.4] repetitions, p=0.03). Conclusions: Hydration improved physiological measures and dousing resulted in an additional enhancement in physiological and performance outcomes at the end of exercise. These practical strategies may reduce the risk of heat illness and optimize performance in heat.