Pre-exercise carbohydrate meals: application of glycemic index

Abstract

These results suggest a pre-exercise LGI may positively affect maximal performance following sustained exercise. The LGI maintained higher plasma glucose levels at the end of 2 h of strenuous exercise than the HGI, which may have better supported subsequent maximal effort.

The effects of low and high glycemic index foods on exercise performance and beta-endorphin responses

“…In our study an initial increase of glucose was observed and then plateaued whereas insulin continued to increase up to 30 minutes following the ingestion of foods. The same glucose and insulin response prior to exercise was seen in De Marco et al study when the same amount of carbohydrates was ingested [17]. This response of glucose and insulin is common since the initial increase in glucose constitutes the main stimulus for the delayed insulin increase.…”

“…On the other hand, there are several studies that examined the effects of different GI foods, at different times prior to exercise, on exercise performance and substrate metabolism that suggest an improvement of exercise performance following LGI food consumption prior to exercise [17,36-40]. Thomas et al [36] were amongst the first ones that expressed interest in the role of GI in sports nutrition.…”

“…A significant 20 min prolonged workout was performed after consumption of the LGI foods that was accompanied by more stable glucose levels and higher free fatty acid concentration during exercise. De Marco et al [17] also showed a 59% increase in time to exhaustion after a 2-h submaximal bout in a LGI trial compared with a HGI trial accompanied by a relative hyperglycemia and lower RPE and RQ [17]. Moore et al [38] administered low and high GI foods 45 min prior to a 40 km cycling trial and found a significantly improved performance following the LGI trial.…”

“…There are several studies that examined the effects of foods of various GI values prior to exercise with inconsistent results being reported in regards to performance [17-20] and carbohydrate utilization during exercise [17,19]. Exercise performance has been positively affected by low glycemic index (LGI) food [17] and remained unaffected by high glycemic index (HGI) food [18,19].…”

“…There are several studies that examined the effects of foods of various GI values prior to exercise with inconsistent results being reported in regards to performance [17-20] and carbohydrate utilization during exercise [17,19]. Exercise performance has been positively affected by low glycemic index (LGI) food [17] and remained unaffected by high glycemic index (HGI) food [18,19]. Even though there is inconsistency regarding the benefits of the ingestion of foods of varying GI on exercise performance, several findings indicate that ingestion of LGI foods may be more suitable over HGI consumption prior to prolonged exercise because they enhance carbohydrate availability during exercise [21,22].…”