Purpose: To examine the effect on short-duration, high-intensity cycling time-trial (TT) performance when a semisolid breakfast containing carbohydrate (CHO) or a taste- and texture-matched placebo is ingested 90 min preexercise compared with a water (WAT) control.
Methods: A total of 13 well-trained cyclists (mean [SD]: age = 25 [8] y, body mass = 71.1 [5.9] kg, height = 1.76 [0.04] m, maximum power output = 383 [46] W, and peak oxygen uptake = 4.42 [0.53] L·min-1) performed 3 experimental trials examining breakfast ingestion 90 min before a 10-min steady-state cycle (60% maximum power output) and an ∼20-min TT (to complete a workload target of 376 [36] kJ). Subjects consumed either WAT, a semisolid CHO breakfast (2 g carbohydrate CHO·kg-1 body mass), or a taste- and texture-matched placebo (PLA). Blood lactate and glucose concentrations were measured periodically throughout the rest and exercise periods.
Results: The TT was completed more quickly in CHO (1120 [69] s; P = .006) and PLA (1112 [50] s; P = .030) compared with WAT (1146 [74] s). Ingestion of CHO caused an increase in blood glucose concentration throughout the rest period in CHO (peak at 30-min rest = 7.37 [1.10] mmol·L-1; P < .0001) before dropping below baseline levels after the steady-state cycling.
Conclusion: A short-duration cycling TT was completed more quickly when subjects perceived that they had consumed breakfast (PLA or CHO) 90 min prior to the start of the exercise. The improvement in performance is likely attributable to a psychological rather than physiological effect.
Keywords: carbohydrate; exercise; fasted; placebo; time trial.