Soccer requires field players to exercise repetitively at high intensities for the duration of a game, which can result in marked muscle glycogen depletion and hypoglycemia. A soccer match places heavy demands on endogenous muscle and liver glycogen stores and fluid reserves, which must be rapidly replenished when players complete several matches within a brief period of time. Low concentrations of muscle glycogen have been reported in soccer players before a game, and daily carbohydrate (CHO) intakes are often insufficient to replenish muscle glycogen stores, CHO supplementation during soccer matches has been found to result in muscle glycogen sparing (39%), greater second-half running distances, and more goals being scored with less conceded, when compared to consumption of water. Thus, CHO supplementation has been recommended prior to, during, and after matches. In contrast, there is currently insufficient evidence to recommend without reservation the addition of electrolytes to a beverage for ingestion by players during a game resulting in sweat losses of < 4% of body weight.
The authors are with the Medical Research Council and the University of Cape-Town Bioenergetics of Exercise Research Unit Department of Physiology, University of Cape Town Medical School, Observatory, South Africa 7925.