Imposed Cold-water Ingestion during Open Water Swimming in Internationally Ranked Swimmers

The authors explored the effects of open water swimming in a tropical environment on both core temperature (T c) and thermal perceptions of high-level swimmers during an official international 10-km race and two 5-km swimming tests. The swimmers drank neutral water (i. e., 28.0±3.0°C) ad libitum every 2,000 m during Competition, whereas the ingested volume was imposed in the 5-km tests: every 1,000 m, they drank 190 mL of cold water (CW, 1.1±0.7°C) or neutral water (NW, 28.0±3.0°C). They also self-rated their thermal comfort and sensation (TC and TS), and their T c was recorded. The study demonstrated that adequate fluid intake significantly decreased T c in swimmers swimming at race pace in hot water (i. e., 37.5±0.3°C vs. 38.3±0.4°C, in NW vs. Competition, respectively). This effect was more pronounced with cold water (i. e., 36.7±1.1°C, in CW). No significant changes were noted in mean heart rate (i. e., 145±5, 143±4 and 141±5 bpm for NW, CW and Competition, respectively). Further studies are needed to explore the effect of this cooling method on the performances of international swimmers during tropical swimming events.