To determine the effects of acute short-term creatine (Cr) supplementation on physical performance during a 90-min soccer-specific performance test.
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.
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.
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.
Williams and Kilding are with AUT University, Sports Performance Research Inst New Zealand, Auckland, New Zealand. Abt is with the Dept of Sport, Health and Exercise Science, The University of Hull, Kingston upon Hull, UK. Correspondence concerning this article should be addressed to Andrew Kilding. E-mail: firstname.lastname@example.org