CARBOHYDRATE FEEDINGS IMPROVE 1 H TIME TRIAL CYCLING PERFORMANCE* 221

Abstract

Carbohydrate (CHO) feedings have been shown to improve endurance performance at moderate intensities (60-75% VO2max) and of more than 2 h duration. The effects of carbohydrate feedings during high intensity exercise (i.e. ≥ 80% VO2max) of shorter duration (-1 h) are less clear. The purpose of the present study therefore was to investigate the effect of a ingestion of a 7.6% CHO solution during exercise on time trial performance of approximately 1 h. On two occasions nineteen endurance trained cyclists completed an exercise test requiring the accomplishment a set amount of work as fast as possible under strictly standardized conditions. This test has been shown to be highly reproducible (coefficient of variation 3.35%, Jeukendrup et al. MSSE 27 in press 1995). At the start and during the trials they drank either a 7.6% CHO solution or artificially flavored and colored water (placebo). The rate of CHO ingestion was about 1 g/min in the carbohydrate trial. Time to complete the set amount of work was significantly reduced and thus performance was significantly increased (P<0.001) with the CHO drink by 2.3%. Time to complete the set amount of work was 58.74 ± 0.52 min with CHO and 60.15 ± 0.65 min with placebo. Average workload during the time trials was 297.5 ± 1.4 W and 291.0 ± 10.3 W respectively. Subjects exercised at 76.4 ± 0.7% of their maximal work rate (Wmax) with CHO and at 74.8% Wmax with placebo. It was concluded that carbohydrate feedings ingested at a rate of ≈ 1 g/min during exercise improve time trial cycling performance of about 1 h duration.