Introduction: In several previous studies, the effects of caffeine ingestion on exercise performance, blood metabolites and physiological responses were equivocal, possibly due to different experimental protocols and caffeine dosage employed. However, no studies have examined the influence of caffeine on physiological and metabolic responses and on performance in exercise simulating a soccer game in a well-controlled laboratory environment. Therefore, the aim of the present study was to examine the effects of caffeine ingestion on metabolic and physiological responses and on exercise performance during a protocol simulating a soccer game on treadmill in welltrained soccer players. Methods: Twenty well-trained male soccer-players (age, 22 ± 4; weight, 74.2 ± 7.7 kg; height, 1.80 ± 0.05 m, body fat, 11.5 ±3.7 %, VO2max, 60.8 ± 4.3 ml/min/kg) underwent two experimental trials after ingestion of either 6 mg/kg caffeine or placebo, in a controlled laboratory environment, using a simulated soccer game protocol on treadmill. Plasma glucose, lactate, free fatty acids (FFA), glycerol and epinephrine concentrations, heart rate (HR), countermovement jumps (CMJ), reaction time, rating of perceived exertion (RPE), arterial blood pressure (BP) and soccer-specific time to fatigue were evaluated. Results: Plasma glucose, lactate, FFA, glycerol and epinephrine concentrations, HR, CMJ, BP and time to fatigue were significantly higher, while RPE was significantly lower with caffeine compared with placebo (p<0.05). Reaction time did not differ between the trials (p>0.05). Discussion: Caffeine was found to enhance CMJ and soccer-specific time to fatigue; increase the concentration of blood metabolites, HR and BP; and reduce RPE during a simulated soccer-specific treadmill protocol. These results may suggest that there is a direct stimulant action of caffeine on metabolic and physiological responses and/or on central and peripheral (e.g., neuromuscular junction) nervous system contributing to improving high-intensity endurance performance and muscle explosiveness, respectively.
© Copyright 2016 21st Annual Congress of the European College of Sport Science (ECSS), Vienna, 6. -9. July 2016. Published by University of Vienna. All rights reserved.