Carbohydrate-Electrolyte Feedings Improve 1 h Time Trial Cycling Performance

Abstract

Carbohydrate-electrolyte (CE) feedings have been shown to improve endurance performance at moderate intemsities (60 - 75 % VO₂max) and of more than 2 h duration. The effects of CE feedings during high intensity exercise (i.e. ≥ 80 % VO₂max) of shorter duration (~ 1 h) are less clear. Therefore the purpose of the present study was to investigate the effect of the ingestion of a 7.6 % CE solution during exercise on time trial cycling performance of approximately 1 h. This type of performance testing has been shown to be more reproducible (coefficient of variation 3.35 %) than the traditional exercise test to exhaustion. On two occasions and in random order nineteen endurance trained cyclists completed an exercise test requiring the accomplishment of a set amount of work as fast as possible (time trial) under strictly standardized conditions. At the start and during the trials they drank in total 14 ml/kg of either a 7.6 % CE solution or artificially flavored and colored water (placebo). Time to complete the set amount of work was significantly reduced and thus performance was significantly increased (p < 0.001) with the CE drink by 2.3 %. Time to complete the set amount of work was 58.74 ± 0.52 min with CE and 60.15 ± 0.65 min with placebo (p < 0.001). 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 CE and at 74.8 % Wmax with placebo (p < 0.001). It was concluded that also in relative short term (1 h) high intensity (75 % Wmax) cycling exercise ingestion of a carbohydrate-electrolyte solution compared to placebo improves performance.