Resumen de Metabolic Responses to Exercise after Carbohydrate Loads in Healthy Men and Women
Ian A. Macdonald, Kostas Tsintzas, Naruemon Leelayuwat, Kishor Patel
Purpose: This study aimed to investigate gender differences in i) pancreatic insulin secretory ([beta]-cell sensitivity) and whole body insulin sensitivity responses to an intravenous carbohydrate (CHO) load, and (ii) metabolic responses to exercise after both intravenous and oral CHO loads.
Methods: Seven untrained healthy men and seven age-, body mass-, and [latin capital V with dot above]O2max-matched women performed two trials. In one trial they cycled for 60 min at 50% [latin capital V with dot above]O2max, starting 60 min after ingestion of a carbohydrate-rich meal (ME trial). In the other trial, subjects were infused with 20% dextrose solution to maintain blood glucose concentration at approximately 8 mmol[middle dot]L-1 for 60 min (INF trial), then the infusion rate was maintained constant during the following 60 min while exercising at 50% [latin capital V with dot above]O2max.
Results: There was no gender effect on [beta]-cell sensitivity (serum insulin: 161 +/- 37 and 159 +/- 28 pmol[middle dot]L-1 for men and women, respectively) and whole body insulin sensitivity (155 +/- 24 and 135 +/- 29 mg[middle dot]KgFFM-1[middle dot]min-1 per pmol[middle dot]L-1 x 100 for men and women, respectively). This may explain the similarity in glycemic, substrate oxidation and other metabolic responses to exercise after both intravenous and oral CHO loads in men and women.
Conclusion: These results suggest that moderate exercise performed in the postprandial state presents a similar challenge to the ability of healthy, untrained men and women to perform exercise without a substantial decline in plasma glucose concentration below fasting values.
