The glycaemic index and sports nutrition

Carbohydrate (CHO) is the main fuel for exercising muscles, therefore the amount, timing and type of CHO food ingested is an important part of an athlete's daily dietary intake. The amount and timing of CHO ingestion has been investigated extensively. It has been suggested that the glycaemic index (GI) of CHO foods influences CHO availability during exercise and the rate of glycogen synthesis post-exercise. Although low-GI (LGI) CHO foods are mostly recommended for the pre-exercise meal, ingesting high-GI (HGI) CHO foods pre-exercise mostly does not result in hypoglycaemia in healthy individuals during exercise. HGI and LGI CHO foods yield similar results in terms of exercise performance and perceived rate of exertion. HGI and moderate GI (MGI) CHO foods are recommended during exercise. However, fructose in high concentrations is not recommended owing to increased risk of gastrointestinal distress. LGI CHO foods are not recommended during a short recovery period (< 6 hours) because of their slow rate of absorption and indigestible CHO, which seems to be a poor substrate for glycogen synthesis.