title: Caffeinated energy drinks improve volleyball performance in elite female players.
abstract: OBJECTIVE
  The objective of this study is to determine the effects of a caffeine-containing energy drink on female volleyball players' performance.
  
  
  METHODS
  Thirteen elite female volleyball players ingested 3 mg·kg of caffeine with an energy drink or the same drink without caffeine (placebo drink) in a double-blind and randomized study. Then, participants performed the following: standing spike, jumping spike, spike jump, blocking jump, squat jump, countermovement jump, manual dynamometry, and the agility t-test. A simulated volleyball game was played, videotaped, and notated afterward.
  
  
  RESULTS
  In comparison to the placebo drink, the ingestion of the caffeinated energy drink increased the ball velocity in the standing spike (19.2 ± 2.1 vs 19.7 ± 1.9 m·s, P = 0.023) and in the jumping spike (17.9 ± 2.2 vs 18.8 ± 2.2 m·s, P = 0.038) and the jump height in the squat jump (28.1 ± 3.2 vs 29.4 ± 3.6 cm, P = 0.028), countermovement jump (32.0 ± 4.6 vs 33.1 ± 4.5 cm, P = 0.018), spike jump (43.3 ± 4.7 vs 44.4 ± 5.0 cm, P = 0.025), and block jump (35.2 ± 5.1 vs 36.1 ± 5.1 cm, P = 0.044). Furthermore, the caffeinated energy drink decreased the time needed to complete the agility t-test (11.1 ± 0.5 vs 10.9 ± 0.3 s, P = 0.036). During the game, the volleyball actions categorized as successful were more frequent with the caffeinated energy drink (34% ± 9% vs 45% ± 9%, P < 0.001), whereas imprecise actions decreased (28% ± 7% vs 14% ± 9%, P < 0.001) when compared with the placebo drink.
  
  
  CONCLUSIONS
  Commercially available energy drinks can significantly improve physical performance in female volleyball players. Increased physical performance led to improved accuracy during an actual volleyball match.
authors: 1Department of Physical Education, School of Medicine and Health Science, University of Alcalá, Madrid, SPAIN; 2Sport Science Institute, Exercise Physiology Laboratory, Camilo José Cela University, Madrid, SPAIN; and 3Department of Physical Education, National Institute of Physical Education (INEF), Polytechnic University of Madrid, Madrid, SPAIN.
authors: Alberto
authors: A
authors: Pérez-López
authors: Juan José
authors: JJ
authors: Salinero
authors: Javier
authors: J
authors: Abian-Vicen
authors: David
authors: D
authors: Valadés
authors: Beatriz
authors: B
authors: Lara
authors: Cesar
authors: C
authors: Hernandez
authors: Francisco
authors: F
authors: Areces
authors: Cristina
authors: C
authors: González
authors: Juan
authors: J
authors: Del Coso
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D002110:Caffeine / Q000008:administration & dosage*; D004311:Double-Blind Method; D061215:Energy Drinks; D005260:Female; D006801:Humans; D009048:Motor Skills / Q000502:physiology; D054798:Volleyball / Q000502:physiology*; D055815:Young Adult
chemical_list: D002110:Caffeine