Daily dietary carbohydrate intake requirements vary depending on the training intensities and durations. For daily light-to-moderate-intensity exercise sessions that last no more than 1 h, 3-5 g of carbohydrate per kg body weight should be sufficient, while higher-intensity exercise training accumulating between 1 and 5 h of exercise per day may require carbohydrate intakes of 6-12 g/kg/day (24-26). On the day of competition, for races lasting longer than 1 h, carbohydrate intake of 1-4 g/kg within 1-4 h prior to the start of the race is suggested. For races lasting less than 1 h, no carbohydrate intake is necessary in the few hours prior to the race. For endurance races lasting between 1 and 1.5 h, suggested carbohydrate intake is 30-60 g/h, and this may be increased to 90 g/h for events lasting several hours (24-25). Intake recommendations during the race are not based on body weight because the carbohydrate oxidation rate of exogenously supplied carbohydrate is not correlated with body weight (26).
-Glen Gaesser, PhD