Guidelines for daily carbohydrate intake: do athletes achieve them?
ABSTRACT Official dietary guidelines for athletes are unanimous in their recommendation of high carbohydrate (CHO) intakes in routine or training diets. These guidelines have been criticised on the basis of a lack of scientific support for superior training adaptations and performance, and the apparent failure of successful athletes to achieve such dietary practices. Part of the problem rests with the expression of CHO intake guidelines in terms of percentage of dietary energy. It is preferable to provide recommendations for routine CHO intake in grams (relative to the body mass of the athlete) and allow flexibility for the athlete to meet these targets within the context of their energy needs and other dietary goals. CHO intake ranges of 5 to 7 g/kg/day for general training needs and 7 to 10 g/kg/day for the increased needs of endurance athletes are suggested. The limitations of dietary survey techniques should be recognised when assessing the adequacy of the dietary practices of athletes. In particular, the errors caused by under-reporting or undereating during the period of the dietary survey must be taken into account. A review of the current dietary survey literature of athletes shows that a typical male athlete achieves CHO intake within the recommended range (on a g/kg basis). Individual athletes may need nutritional education or dietary counselling to fine-tune their eating habits to meet specific CHO intake targets. Female athletes, particularly endurance athletes, are less likely to achieve these CHO intake guidelines. This is due to chronic or periodic restriction of total energy intake in order to achieve or maintain low levels of body fat. With professional counselling, female athletes may be helped to find a balance between bodyweight control issues and fuel intake goals. Although we look to the top athletes as role models, it is understandable that many do not achieve optimal nutrition practices. The real or apparent failure of these athletes to achieve the daily CHO intakes recommended by sports nutritionists does not necessarily invalidate the benefits of meeting such guidelines. Further longitudinal studies of training adaptation and performance are needed to determine differences in the outcomes of high versus moderate CHO intakes. In the meantime, the recommendations of sports nutritionists are based on plentiful evidence that increased CHO availability enhances endurance and performance during single exercise sessions.
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ABSTRACT: To assess the effect of a period of increasing training on dietary quantity and quality, a men's collegiate swim team (n = 24) was divided into two groups of equal skill at the start of a 25-week season of training and competition. After a 4-week conditioning period, the "Long" group underwent a 6-week period during which they swam up to 44,000 m.wk-1, while the "Short" group maintained their swimming at 22,000 m.wk-1. For the remainder of the season, the two groups swam together, performing the same volume and intensity of training. Two-day food intake records were obtained during the early season, during the period of increased training, and during the late season. Swimmers' diets during the early season averaged 15.3 MJ, with 55% from carbohydrate (500 g), and exceeded RDAs for all nutrients assessed. During the increased training period, energy and carbohydrate intakes of the Long group increased significantly (p less than 0.05) to 17.7 MJ and 600 g respectively, but the percentage of energy derived from carbohydrate, protein and fat was stable. Intakes of the Short group did not change over the season. Energy intake did not fully compensate for expenditure, as both groups maintained weight but lost subcutaneous fat. An increase in training volume appears to result in an increased consumption of the athletes' usual diets.International Journal of Sports Medicine 02/1992; 13(1):47-51. · 2.27 Impact Factor
- International Journal of Sports Medicine 03/1988; 9(1):1-18. · 2.27 Impact Factor
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ABSTRACT: Food consumption of 11 male, intercollegiate football athletes (19.6±0.4 yr old (mean±S.E.), 108.1±2.9 kg BW, 191±1 cm HT) was studied over 3 consecutive weekdays to characterize nutritional intakes relative to food choice behavior. Subjects took all meals from a training table, and they trained 2.0 hr/d. The investigators observed and recorded the kinds and amounts of foods eaten by subjects. Food items from the trayline were weighed. Mean energy intake was 3593±217 kcal/d distributed as 22% protein, 39% fat, and 39% carbohydrate. Total carbohydrate intake (329±12 g/d) and its contribution to energy was less than generally recommended for athletes (500 g/d or 60% kcal). Subjects emphasized meat consumption; meat provided 33% kcal, 63% protein, and 45% fat intake. The overall mean intake of 10 vitamins and minerals exceeded the RDAs, but the intake of magnesium, folacin, and pyridoxine were 70–100% RDA. There were individual instances of marginal intakes (<70% RDA).Nutrition Research. 01/1987;