title: Dose response effects of a caffeine-containing energy drink on muscle performance: a repeated measures design.
abstract: BACKGROUND
  Energy drinks have become the most used caffeine-containing beverages in the sport setting. The aim of this study was to determine the effects of two doses of a caffeine-containing energy drink on muscle performance during upper- and lower-body power-load tests.
  
  
  METHODS
  In a randomized order, twelve active participants ingested 1 and 3 mg of caffeine per kg of body weight using a commercially available energy drink (Fure®, ProEnergetics) or the same drink without caffeine (placebo; 0 mg/kg). After sixty minutes, resting metabolic rate, heart rate and blood pressure were determined. Then, half-squat and bench-press power production with loads from 10 to 100% of 1 repetition maximum was determined using a rotator encoder.
  
  
  RESULTS
  In comparison to the placebo, the ingestion of the caffeinated drink increased mean arterial pressure (82 ± 7 < 88 ± 8 ≈ 90 ± 6 mmHg for 0 mg/kg, 1 mg/kg, 3 mg/kg of caffeine, respectively; P < 0.05) and heart rate (57 ± 7 < 59 ± 8 < 62 ± 8 beats/min, respectively; P < 0.05) at rest in a dose response manner, though it did not affect resting metabolic rate. While the ingestion of 1 mg/kg of caffeine did not affect maximal power during the power-load tests with respect to the placebo, 3 mg/kg increased maximal power in the half-squat (2554 ± 167 ≈ 2549 ± 161 < 2726 ± 167 W, respectively; P < 0.05) and bench-press actions (349 ± 34 ≈ 358 ± 35 < 375 ± 33 W, respectively; P < 0.05).
  
  
  CONCLUSIONS
  A caffeine dose of at least 3 mg/kg in the form of an energy drink is necessary to significantly improve half-squat and bench-press maximal muscle power.
authors.affiliation: Exercise Physiology Laboratory, Camilo José Cela University, C/ Castillo de Alarcon, 49, Villafranca del Castillo, 28692, Spain. jdelcoso@ucjc.edu.
authors.forename: Juan
authors.initials: J
authors.lastname: Del Coso
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Salinero
authors.forename: Cristina
authors.initials: C
authors.lastname: González-Millán
authors.forename: Javier
authors.initials: J
authors.lastname: Abián-Vicén
authors.forename: Benito
authors.initials: B
authors.lastname: Pérez-González