title: The influence of caffeine ingestion on strength and power performance in female team-sport players.
abstract: BACKGROUND
  The aim of this study was to examine the influence of caffeine supplementation on knee flexor and knee extensor strength before, during and after intermittent running exercise in female team-sport players taking oral contraceptive steroids (OCS).
  
  
  METHODS
  Ten healthy females (24 ± 4 years; 59.7 ± 3.5 kg; undertaking 2-6 training sessions per week) taking low-dose monophasic oral contraceptives of the same hormonal composition took part in a randomised, double-blind, placebo-controlled crossover-design trial. Sixty minutes following the ingestion of a capsule containing 6 mg∙kg-1body mass anhydrous caffeine or artificial sweetener (placebo), participants completed a 90-min intermittent treadmill-running protocol. Isometric strength performance and eccentric and concentric strength and power of the knee flexors and knee extensors (using isokinetic dynamometer), as well as countermovement jump (CMJ), was measured before, during and after the exercise protocol, as well as ~12 h post-exercise. Blood samples were taken before, during and post-exercise to measure glucose, insulin and free fatty acids (FFA).
  
  
  RESULTS
  Caffeine supplementation significantly increased eccentric strength of the knee flexors (P< 0.05) and eccentric power of both the knee flexors (P< 0.05) and extensors (P< 0.05). However, there was no effect on isometric or concentric parameters, or CMJ performance. FFA was elevated with caffeine supplementation over time (P< 0.05) while levels of glucose and insulin were not affected by caffeine intake.
  
  
  CONCLUSIONS
  Caffeine supplementation increased eccentric strength and power in female team-sport players taking OCS both during an intermittent running protocol and the following morning.
authors.affiliation: School of Sport and Exercise, Massey University, Auckland, New Zealand.
authors.forename: Ajmol
authors.identifier: 0000-0002-6093-1435
authors.initials: A
authors.lastname: Ali
authors.affiliation: School of Sport and Exercise, Massey University, Auckland, New Zealand.
authors.forename: Jemma
authors.initials: J
authors.lastname: O'Donnell
authors.affiliation: School of Sport and Exercise, Massey University, Auckland, New Zealand.
authors.forename: Andrew
authors.initials: A
authors.lastname: Foskett
authors.affiliation: School of Food and Nutrition, Massey University, Auckland, New Zealand.
authors.forename: Kay
authors.initials: K
authors.lastname: Rutherfurd-Markwick
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D002110:Caffeine / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise; D005260:Female; D006801:Humans; D007717:Knee; D053580:Muscle Strength / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D010919:Placebos; D012420:Running; D013177:Sports; D055815:Young Adult
chemical_list: D010919:Placebos; D002110:Caffeine
keywords: Knee extensors; Knee flexors; Muscle function; Pharmacological ergogenic aid; Supplementation