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An important dietary energy need is for adequate carbohydrate (CHO) to meet the fuel requirements of the training programme. The energy requirements for exercise are met largely by oxidation of fat and carbohydrate. Whereas body fat stores are adequate to supply the energy cost of exercise for may days, CHO stores are vulnerable. With prolonged training each day the body may turn over in excess of its total body CHO stores. Furthermore, there is an obligatory need for CHO oxidation when the intensity of exercise is high (e.g. >70% V02 max). Therefore, daily replacement and supplementation of CHO intake may be needed to provide the fuel needs for a strenuous training programme, particularly to maintain the intensity of training sessions. Inadequate CHO intake will gradually lead to a depletion of muscle glycogen stores and may reduce the ability of the athlete to complete their desired training load.

The guidelines for healthy eating in most countries recommended an increase in CHO intake, particularly from nutrient-dense CHO-rich foods such as cereal and grain foods, fruit, starchy vegetables and legumes. It is generally recommended that CHO intake should provide at least 50-55% of total energy intake. Although the exact CHO needs of athletes vary according to their muscle mass and training load, this general guideline is likely to meet the fuel requirements of most athletes. For some athletes, it is important to maximize daily glycogen storage. This may be to support the fuel needs of a prolonged and high intensity training programme, or to ‘fuel up’ in anticipation of a prolonged competition bout. In such a case, an intake of approximately 7-10 g of CHO per kg body mass (BM) per 24 hours in needed.

This may represent 50-70% of total energy intake of the athlete, and requires both planning and good knowledge of nutrition to achieve. Practical challenges which limit the intake of CHO include the bulkiness of many high-fibre CHO-rich foods, and the reduced opportunities for eating in a busy day. A pattern of ‘grazing’ (frequent meals and snacks), together with reliance on portable and compact CHO-rich choices is recommended (see Table 1). Eating a CHO rich snack or meal providing at least 1g CHO per kg BM straight after a training session is considered good practice for enhanced recovery. It appears that the depleted muscle is most responsive to CHO supplied immediately after exercise. More importantly, it allows the athlete to optimize the refuelling time before the next training session; a factor which may be important for athletes who undertake more than one training sessions each day.