Carbohydrate loading is a strategy involving changes to training and nutrition that can maximise muscle glycogen (carbohydrate) stores prior to endurance competition.
Sports such as cycling, marathon running, longer distance triathlon, cross-country skiing and endurance swimming benefit from carbohydrate loading.
The technique was originally developed in the late 1960’s and typically involved a 3-4 day ‘depletion phase’ involving 3-4 days of hard training plus a low carbohydrate diet. This depletion phase was thought to be necessary to stimulate the enzyme glycogen synthase. This was then followed immediately by a 3-4 day ‘loading phase’ involving rest combined with a high carbohydrate diet. The combination of the two phases was shown to boost muscle carbohydrate stores beyond their usual resting levels.
Muscle glycogen levels are normally in the range of 100-120 mmol/kg ww (wet weight). Carbohydrate loading enables muscle glycogen levels to be increased to around 150-200 mmol/kg ww. This extra supply of carbohydrate has been demonstrated to improve endurance exercise by allowing athletes to exercise at their optimal pace for a longer time. It is estimated that carbohydrate loading can improve performance over a set distance by 2-3%.
The following diet is suitable for a 70kg athlete aiming to carbohydrate load:
This sample plan provides ~ 14,800 KJ, 630g carbohydrate, 125g protein and 60g fat.
Dr. Manish Pardeshi