The effect of water intake on body temperature during rugby matches

The effect of drinking up to 1 litre of fluid on water deficit, sweat loss and rectal temperature was determined during three separate rugby matches played in thermoneutral environments. Each player was allotted a litre of fluid and encouraged to drink 500 ml before the start of the game and a further 500 ml at half-time. The players were weighed and rectal temperatures determined before and after the matches. Rectal temperatures were markedly elevated after all three matches and reached levels which may have been high enough to have impaired performance towards the end of the game. The volume of fluid ingested by the players had no influence on final rectal temperatures. The majority of the players had sweat rate/rectal temperature relationships similar to those of heat-acclimatized subjects. It is concluded that, in a thermoneutral environment, the ingestion of volumes of fluid up to 1 litre has no significant beneficial effect on thermoregulation during rugby games, and that the role of the clothing worn may have a greater influence on thermoregulation than was hitherto envisaged.