Welsch, E. A., Sedlock, D. A., Flynn, M. G., Glenn, J., & Park, K.-S. (2006). Carbohydrate supplementation during prolonged intermittent exercise in women. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 1400.

"Intermittent activity is characteristic of some team sports and/or training regimens. The preferred strategy by many athletes for minimizing fatigue and increasing carbohydrate (CHO) availability throughout these events is to consume CHO-containing beverages during the rest periods. Research suggests that men experience performance improvements following CHO ingestion, but it is unclear whether women respond as favorably to CHO supplementation". This study determined how women respond to CHO supplementation during prolonged intermittent exercise. Endurance-trained female runners (N = 10) completed two intermittent treadmill runs separated by one month (i.e., during the follicular phase of the menstrual cycle). Trials were double-blind and counterbalanced, and consisted of four 20-minute steady state (SS) running bouts at 70% VO2max, each followed by a 5-minute rest period. A 5k self-paced time trial performance run (TT) immediately followed the last rest period. Subjects ingested test beverages [6% CHO solution or an artificially sweetened placebo (P)] during the rest periods. Each dose was 0.6 g CHO/kgBW/h (~250mL). Perceived exertion ratings (RPE) and fingertip blood samples were taken during the last two minutes of each steady-state exercise bout and immediately after the time trial.

Time trial performance significantly improved with carbohydrate compared to placebo, although ratings of perceived exertion were similar between trials. Lactate and CHO oxidation tended to be higher with CHO. Steady-state data showed significantly higher blood glucose with CHO, but glycerol and lactate were similar between trials.

Implication. Carbohydrate supplementation in endurance-trained women improved running performance while maintaining the same perception of effort.

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