Abstract des Autors

This study compared the physiological responses and performance following the ingestion of a waxy starch (WS), resistant starch (RS), glucose (GL) and an artificially-sweetened placebo (PL) ingested prior to exercise. Ten college-age, male competitive cyclists completed four experimental protocols consisting of a 30 min isokinetic, self-paced performance ride preceded by 90 min of constant load cycling at 66% VO2max. Thirty min prior to exercise, they ingested 1 g/kg body weight of GL, WS, RS, or PL. At rest, GL elicited greater serum glucose and insulin responses than all other trials. During exercise, however, serum glucose, insulin, blood C-peptide and glucagon responses were similar among trials. The mean total carbohydrate oxidation rates (CHOox) were higher during the GL, WS, and RS trials (2.59+/-0.13, 2.49+/-0.10, and 2.71+/-0.15 g/min, respectively) compared to PL (2.35+/-0.12 g/min). Subjects were able to complete more work during the performance ride when they ingested GL (434+/-25.2 kJ) or WS (428+/-22.5 kJ) compared to PL (403+/-35.1 kJ). They also tended to produce more work with RS ingestion (418+/-31.4 kJ), although this did not reach statistical significance. These results indicate that preexercise CHO ingestion in the form of starch or glucose maintained higher rates of total carbohydrate oxidation during exercise and provided an ergogenic benefit during self-paced cycling. Verf.-Referat