Introduction: The aim of this study was to investigate the effectiveness of a caffeinated energy drink to enhance physical performance in elite junior tennis players. Methods: A double-blind, placebo controlled and randomized experimental design was used in this experiment. In two different sessions separated by one week, 14 young (16 ± 1 years) elite level tennis players ingested 3 mg of caffeine per kg of body mass in the form of an energy drink or the same drink without caffeine (placebo). After 60-min for caffeine absorption, participants performed a maximal handgrip strength test, a maximal velocity serving test, an 8×15 m sprint test and then played a simulated singles match (best of 3 sets) against an equally ranked opponent. Body mass was measured before and after the matches and the instantaneous running speed was assessed using global positioning system (GPS) devices. Due to the differences in matches` duration, data on running distance were calculated per hour of play. Heart rate was individually recorded and the matches were video-taped and notated afterwards. Results: In comparison to the placebo, the ingestion of the caffeinated energy drink increased handgrip force by ~4.2 ± 7.2% (P = 0.03), the running pace over 18 km/h (46.7 ± 28.5 vs 63.3 ± 27.7 m/h; P = 0.02) and the number of sprints (12.1 ± 1.7 vs 13.2 ± 1.7 bouts/h; P = 0.05) during the simulated match. Besides, the caffeinated energy drink slightly increased the sweat rate (0.5 ± 0.3 vs 0.7 ± 0.3 L/h; P=0.04) during the match although it minimally affected the dehydration level attained (0.1 ± 0.5 vs 0.2 ± 0.4%; P=0.04). There was a tendency for increased maximal velocity during the 8×15m sprint test (22.3 ± 2.0 vs 22.9 ± 2.1 km/h; P = 0.07) and higher percentage of points won on service with the caffeinated energy drink (49.7 ± 9.8 vs 56.4 ± 10.0%; P = 0.07). The energy drink neither improved ball velocity during the serving test (42.6 ± 4.8 vs 42.7 ± 5.0 m/s; P = 0.49) nor affected mean heart rate (143 ± 3 vs 144 ± 4 bmp; P = 0.35) or maximal heart rate (181 ± 3 vs 178 ± 4 bmp; P = 0.44) during the match. Discussion: The present investigation offers new information about the ergogenicity of caffeinated energy drinks. A dose equivalent to 3 mg of caffeine/kg,in a form of an energy drink was effective to enhance the physical performance of elite junior tennis players by increasing handgrip force, high-intensity running and tending to increase the percentage of points won on service during a simulated tennis match
© Copyright 2014 19th Annual Congress of the European College of Sport Science (ECSS), Amsterdam, 2. - 5. July 2014. Veröffentlicht von VU University Amsterdam. Alle Rechte vorbehalten.