Risk Factors and Predictors of Hypothermia and Dropouts During Open-Water Swimming Competitions

To measure core temperature (Tcore) in open-water (OW) swimmers during a 25-km competition and identify the predictors of Tcore drop and hypothermia-related dropouts. Twenty-four national- and international-level OW swimmers participated in the study. Participants completed a personal questionnaire...

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Bibliographic Details
Published in:	International journal of sports physiology and performance Vol. 16; no. 11; p. 1692
Main Authors:	Drigny, Joffrey, Rolland, Marine, Pla, Robin, Chesneau, Christophe, Lebreton, Tess, Marais, Benjamin, Outin, Pierre, Moussay, Sébastien, Racinais, Sébastien, Mauvieux, Benoit
Format:	Journal Article
Language:	English
Published:	United States 01-11-2021
Subjects:	Body Temperature - physiology Humans Hypothermia - etiology Risk Factors Swimming - physiology Water thermosensing body composition water sports body temperature regulation
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Summary:	To measure core temperature (Tcore) in open-water (OW) swimmers during a 25-km competition and identify the predictors of Tcore drop and hypothermia-related dropouts. Twenty-four national- and international-level OW swimmers participated in the study. Participants completed a personal questionnaire and a body fat/muscle mass assessment before the race. The average speed was calculated on each lap over a 2500-m course. Tcore was continuously recorded via an ingestible temperature sensor (e-Celsius, BodyCap). Hypothermia-related dropouts (H group) were compared with finishers (nH group). Average prerace Tcore was 37.5°C (0.3°C) (N = 21). 7 participants dropped out due to hypothermia (H, n = 7) with a mean Tcore at dropout of 35.3°C (1.5°C). Multiple logistic regression analysis found that body fat percentage and initial Tcore were associated with hypothermia (G2 = 17.26, P < .001). Early Tcore drop ≤37.1°C at 2500 m was associated with a greater rate of hypothermia-related dropouts (71.4% vs 14.3%, P = .017). Multiple linear regression found that body fat percentage and previous participation were associated with Tcore drop (F = 4.95, P = .019). There was a positive correlation between the decrease in speed and Tcore drop (r = .462, P < .001). During an OW 25-km competition at 20°C to 21°C, lower initial Tcore and lower body fat, as well as premature Tcore drop, were associated with an increased risk of hypothermia-related dropout. Lower body fat and no previous participation, as well as decrease in swimming speed, were associated with Tcore drop.
ISSN:	1555-0273
DOI:	10.1123/ijspp.2020-0875