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consumed immediately prior to exercise is considered similar to carbohydrate consumed during the session.
Thus, during moderate-intensity exercise in a thermoneutral environment, it appears that solid and liquid forms of carbohydrate are equally useful as a source of additional fuel, provided that fluid needs are also met. It is likely, however, that the intake of solid carbohydrate foods during exercise of higher intensity, particularly during running, incurs a higher risk of gastrointestinal problems. Some athletes may be at an increased risk of such problems and the presence of significant amounts of fat, protein or fibre in some carbohydrate-rich foods may exacerbate these problems. However, the range and boundaries of characteristics of carbohydrate sources that are suitable for various activities have not been systematically investigated. It is likely that considerable differences exist between individuals.
Apart from the gastrointestinal preferences of at least some athletes, the use of liquid forms of carbohydrate during exercise offers the advantage of simultaneous replacement of fluid losses. Dehydration has a major effect on performance and the perception of effort during exercise. The enhancement of exercise performance resulting from fluid replacement has been shown to be independent of and additive to the beneficial effects of carbohydrate intake (36). Commercial sports drinks (carbohydrateelectrolyte beverages of 48% carbohydrate concentration) have been tailor-made to promote efficient delivery of fluid and carbohydrate needs during exercise. At a typical concentration of ~6% carbohydrate, an intake of ~760 ml/hour will allow most athletes to achieve adequate fuel intake during prolonged exercise; this ratio of fluid and carbohydrate delivery can be altered according to the individual needs of the athlete and their exercise situation by changing the concentration of the drink (42). Given the widespread popularity of these drinks and the simplicity with which they allow nutrition guidelines to be achieved, it is not surprising that their use is supported, if not directly promoted, by the major groups involved in sports nutrition education (50).
Nevertheless, a range of other carbohydrate-rich drinks and foods, including chocolate bars, may be consumed successfully by athletes during exercise and may be chosen on the basis of practical issues such as taste, cost and availability. Solid foods such as chocolate bars are a portable carbohydrate supply for athletes who need to transport their own provisions (e.g. road cyclists, cross-country skiers and hikers). They may also offer some taste variety and satiety for athletes undertaking ultra-endurance events. Whether an athlete 'on the move' such as a runner has the opportunity to unwrap and consume a bar might be taken into consideration, as must the 'keeping' characteristics of chocolate bars in hot conditions.
Rapid recovery of fuel stores is important when the athlete has to train or compete within 824 hours. This is a common issue in the training schedules of élite athletes,
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