Football is played worldwide and takes place in a variety of environmental conditions. Competitions are often held in environments which differ from the conditions that players typically experience. The aim of this study was to investigate hydration and sweating responses of players during a match played in hot weather conditions. Methods Twenty-two males completed a FIFA-regulation football match in 34.3±0.6oC, 64±2% relative humidity. On arrival at the stadium, ~45min prior to the match start, players emptied their bladder and the specific gravity of the urine (Usg) was determined by refractometry. Then from 30-15min prior to the match start all players were weighed to the nearest 20g on an electronic balance when wearing only underwear. Immediately after being weighed players were prepared for sweat sample collection (Maughan et al 2007). Sweat collection patches were removed at half-time and samples were analysed for sodium and potassium concentration by flame photometry. On match completion players were reweighed wearing only underwear within 15min of the match end. During the match players had access to drinking water via individually numbered bottles. Drinking was neither encouraged nor discouraged during the match and players were left to behave as they wished with regards to drinking. All drink bottles were weighed on electric scales measuring to the nearest 1g, prior to and at the end of the match to determine the volume consumed by each player. Data are presented as mean±SD. Results Pre-match Usg (1.011±0.006) indicated that players started the match in a euhydrated state. Players lost 1.51±0.64kg over the duration of the match ranging from a gain of 0.12kg to a loss of 2.92kg. This is equivalent to a body mass loss of 2.2±1.0%. Players drank 1653±487ml, so their estimated sweat volume was 3.1±0.6l. Sweat sodium concentration was 45±9mmol/l and potassium concentration 3.5±0.4mmol/l. This translated into losses of 139±39mmol of sodium or ~8.1±2.3g of salt. Discussion Although Usg indicated that most players started the match in a euhydrated state (<1.020; Sawka et al, 2007), individual data indicated that two players presented with pre-match USg greater than 1.020 which may be indicative of hypohydrateion. It is clear that some players developed significant hypohydration over the course of the match, and it would be predicted that their performance would be reduced. None-the-less, because of the high sweat rates in some players (in the order of 2.5l/h) these individual are unlikely to be able to prevent the development of hypohydration with the current match format. References Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. (2007) Med Sci Sports Exerc, 39, 377-390. Maughan RJ, Watson P, Evans GH, Broad N, Shirreffs SM. (2007) Int J Sports Nutr Exerc Metab, 17, 583-594.
© Copyright 2009 14th annual Congress of the European College of Sport Science, Oslo/Norway, June 24-27, 2009, Book of Abstracts. Published by The Norwegian School of Sport Sciences. All rights reserved.