Short-term creatine supplementation does not improve muscle activation or sprint performance in humans.
The purpose of this study was to examine the influence of short-term creatine (Cr) supplementation on exercise-induced transverse relaxation time (T2) and sprint performance during maximum intermittent cycling exercise using the muscle functional magnetic resonance imaging (mfMRI) technique. Twelve men were divided into a Cr supplementation group [the Cr group, taking 4 x (5 g Cr monohydrate + 2.5 g maltodextrin)/day], or a placebo supplementation group (the P group, taking 4 x 7.5 g maltodextrin/day). The allocation to the groups was based on cycling tests and the subject's physical characteristics, and thus was not randomized. A double-blind research design was employed for a 5-day supplementation period. mfMR images of the right thigh were collected at rest and immediately after two, five, and ten 6-s sprint bouts of maximum intermittent cycling exercise with a 30-s recovery interval between sets. Before and after supplementation, blood was taken to calculate lactate accumulation, and the muscle volume of the thigh was determined by MRI. Following supplementation, there was significant body mass gain in the Cr group ( P<0.05), whereas the P group did not change. The exercise-induced T2, blood lactate levels and sprint performance were not affected by Cr supplementation in any sprint bouts. These results suggest that short-term Cr supplementation does not influence short duration repetitive sprint performance and muscle activation and/or metabolic state during sprint cycling evaluated by mfMRI of the skeletal muscle in humans.
Graduate School of Health and Sport Science, Nippon Sport Science University, 7-1-1 Fukasawa, Setagaya, 158-8508, Tokyo, Japan. kinugasa@nittai.ac.jp
Ryuta
R
Kinugasa
Hiroshi
H
Akima
Akemi
A
Ota
Atsutane
A
Ohta
Katsumi
K
Sugiura
Shin-Ya
SY
Kuno
D000284:Administration, Oral; D000328:Adult; D019412:Anatomy, Cross-Sectional / Q000379:methods; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D003401:Creatine / Q000008:administration & dosage*; D019587:Dietary Supplements; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000187:drug effects / Q000502:physiology*; D012420:Running / Q000502:physiology*
D019344:Lactic Acid; D003401:Creatine