title: Effects of creatine monohydrate supplementation on simulated soccer performance.
abstract: OBJECTIVE
  To determine the effects of acute short-term creatine (Cr) supplementation on physical performance during a 90-min soccer-specific performance test.
  
  
  METHODS
  A double-blind, placebo-controlled experimental design was adopted during which 16 male amateur soccer players were required to consume 20 g/d Cr for 7 d or a placebo. A Ball-Sport Endurance and Speed Test (BEAST) comprising measures of aerobic (circuit time), speed (12- and 20-m sprint), and explosive-power (vertical jump) abilities performed over 90 min was performed presupplementation and postsupplementation.
  
  
  RESULTS
  Performance measures during the BEAST deteriorated during the second half relative to the first for both Cr (1.2-2.3%) and placebo (1.0-2.2%) groups, indicating a fatigue effect associated with the BEAST. However, no significant differences existed between groups, suggesting that Cr had no performance-enhancing effect or ability to offset fatigue. When effect sizes were considered, some measures (12-m sprint, -0.53 ± 0.69; 20-m sprint, -0.39 ± 0.59) showed a negative tendency, indicating chances of harm were greater than chances of benefit.
  
  
  CONCLUSIONS
  Acute short-term Cr supplementation has no beneficial effect on physical measures obtained during a 90-min soccer-simulation test, thus bringing into question its potential as an effective ergogenic aid for soccer players.
authors.affiliation: AUT University, Sports Performance Research Inst New Zealand, Auckland, New Zealand.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Williams
authors.forename: Grant
authors.initials: G
authors.lastname: Abt
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Kilding
mesh_terms: D000054:Acceleration; D000328:Adult; D003401:Creatine / Q000008:administration & dosage* / Q000009:adverse effects; D019587:Dietary Supplements; D004311:Double-Blind Method; D005080:Exercise Test; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000187:drug effects; D058573:Performance-Enhancing Substances / Q000008:administration & dosage* / Q000009:adverse effects; D010807:Physical Endurance / Q000187:drug effects*; D012420:Running; D012916:Soccer; D013647:Task Performance and Analysis; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D058573:Performance-Enhancing Substances; D003401:Creatine