Co-ingestion of caffeine and carbohydrate after meal does not improve performance at high-intensity intermittent sprints with short recovery times
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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 7 days apart in a randomized, double-blind, placebo-controlled, balanced trial. A meal contained 65 % CHO was provided 2 h before the HIS test. Participants ingested the placebo (PLA) or CAF (6 mg kg−1 BW) 1 h before taking an HIS test, and ingested a PLA or CHO solution (0.8 g kg−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.
KeywordsAnaerobic Cortisol Fatigue Nutrition Testosterone
Coefficient of variation
High-intensity intermittent sprints
Intraclass correlation coefficients
Mean power output
Peak power output
Rating of perceived exertion
We thank all the participants and research assistants for their efforts in the study. We also thank Dr. Todd A. Astorino for his expert consultation on nutrition. This study was supported by a research grant from the Ministry of Science and Technology, Taiwan (NSC 101–2410-H-110–085). This work was also particularly supported by “Aim for the Top University Plan” of the National Sun Yat-sen University, National Taiwan Normal University, and Ministry of Education, Taiwan, R.O.C.
Conflict of interest
The authors declare that they have no conflict of interests.
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