La créatine module les filières énergétiques durant un effort d'endurance
Effect of Creatine Loading on Oxygen Uptake during a 1-km Cycling Time Trial
Medicine & Science in Sports & Exercise: December 2015 - Volume 47 - Issue 12 - p 2660–2668 DE ANDRADE NEMEZIO
Purpose: For the first time, we investigated the effects of altering cellular metabolic capacitance, via a 5-d creatine (Cr) loading protocol (20 g·d−1), on oxygen uptake (V˙O2), accumulated oxygen deficit, muscle recruitment, and performance during a 1-km cycling time trial.
Methods: In a double-blind, randomized, placebo-controlled design, 19 amateur cyclists were allocated to a Cr (n = 10, V˙O2peak = 56.0 ± 7.8 mL·kg−1·min−1) or placebo (n = 9, V˙O2peak = 56.0 ± 8.4 mL·kg−1·min−1) group, and performed a 1-km cycling time trial before and after the supplementation period.
Results: Body mass was significantly increased in the Cr group (P < 0.05), but not in the placebo group. Participants adopted an “all-out” pacing strategy in both groups. However, Cr loading reduced V˙O2 immediately after the beginning (12th to 23th seconds), and this was accompanied by a reduced aerobic and increased anaerobic contribution. The V˙O2 mean response time was slower (pre: 17.2 ± 5.6 s vs post: 19.9 ± 4.6 s), the total O2 uptake was reduced (pre: 4.64 ± 0.59 L vs post: 4.47 ± 0.53 L), and the oxygen deficit was increased (pre: 0.82 ± 0.27 L vs post: 0.98 ± 0.25 L) after Cr loading. No differences were observed in the placebo group for these variables. Plasma lactate and integrated electromyography were not altered in either group, nor was the time to complete the trial (Cr group: pre: 89.1 ± 6.7 s vs post 89.1 ± 6.2 s and placebo group: pre 85.9 ± 4.9 s vs post 87.0 ± 5.4 s).
Conclusion: Cr loading slows the V˙O2 response and increases the anaerobic contribution during a 1-km cycling time trial.
