Co-ingestion of caffeine and carbohydrate after meal does not improve performance at high-intensity intermittent sprints with short recovery times.

Abstract

To determine the effects of co-ingesting caffeine (CAF) and carbohydrate (CHO) on high-intensity intermittent sprints (HIS) performance and physiological responses. Twelve active males underwent 4 interventions at least 7days apart in a randomized, double-blind, placebo-controlled, balanced trial. A meal contained 65% CHO was provided 2h before the HIS test. Participants ingested the placebo (PLA) or CAF (6mgkg(-1) BW) 1h before taking an HIS test, and ingested a PLA or CHO solution (0.8gkg(-1)BW) before undergoing the testing protocol. The HIS protocol comprised ten sets of 5×4-s sprints on a cycle ergometer with a 2-min recovery between each set. There was no significant difference between peak power output and mean power output between trials (p>0.05). Compared with PLA, CAF+CHO resulted in a 5.2% reduction in total work, corresponding to a 24.7-25.7% increase in fatigue at the end stage of the HIS. The administration of CAF+CHO supplementation also resulted in an 11.1% increase in blood lactate, and elevated blood glucose concentrations throughout HIS testing compared with PLA (p<0.05). Cortisol concentrations also increased with CAF+CHO intake compared with PLA; however, there was no significant effect of CAF+CHO supplementation on testosterone concentrations. Co-ingestion of CAF and CHO did not improve high-intensity sprint cycling performance or reduce fatigue in active males. Moreover, combined CAF and CHO supplementation might facilitate catabolism during prolonged high-intensity intermittent exercise.