Impact of creatine on muscle performance and phosphagen stores after immobilization
European Journal of Applied Physiology
This study investigated the effect of creatine (CR) supplementation during cast-immobilization to preserve skeletal muscle total work, power and intramuscular phosphocreatine (PCr) kinetics during dynamic exercise.
Twenty-five active individuals (24 ± 4 years,) performed wrist flexion exercise within a 1.9 Tesla superconducting magnet before and after 1 week of cast-immobilization. An incremental protocol to fatigue and two constant load (CL1 and CL2) exercise bouts were performed. While casted, participants consumed either 20 g day−1 of CR or a placebo (PLA). 31P magnetic resonance spectroscopy was used to quantify in vivo intramuscular PCr levels.
No significant group × time interaction effects were found for work or power throughout all exercise bouts. Total work was significantly reduced over time in both groups (p = 0.049) during the incremental exercise bout. Work production in CL1 tended (p = 0.073) to attenuate in the CR group, compared to PLA. No changes were observed in CL2. Baseline PCr significantly decreased with casting in PLA (PRE: 26.6 ± 6.3 vs. POST: 22.5 ± 5.6 mM kg−1 wet muscle, p = 0.003). No change (p = 0.31) was observed in the CR group. Changes in work production were significantly correlated with changes in resting PCr in CR (r = −0.63, p = 0.021) but not PLA (r = −0.36, p = 0.26) group.
Results suggest decreases in short-term endurance may be due to alternations of PCr status and/or metabolism. More research is needed to fully determine the efficacy of CR supplementation during short-term immobilization.
Fransen, Jeremy C.; Zuhl, Micah; Kerksick, Chad M.; Cole, Nathan; Altobelli, Steve; Kuethe, Dean O.; and Schneider, Suzanne, "Impact of creatine on muscle performance and phosphagen stores after immobilization" (2015). Faculty Scholarship. 140.