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Phosphocreatine resynthesis is not affected by creatine loading.
K Vandenberghe1, P Van Hecke, M Van Leemputte
1Faculty of Physical Education and Physiotherapy, Department of Kinesiology and Faculty of Medicine, Katholieke Universiteit Leuven, Belgium.
Medicine and Science in Sports and Exercise
|March 4, 1999
Summary
Creatine supplementation increases muscle phosphocreatine (PCr) levels, enhancing power output during intense intermittent exercise. However, it does not speed up PCr resynthesis during isometric contractions.
Area of Science:
- Exercise Physiology
- Sports Nutrition
- Biochemistry
Background:
- Oral creatine supplementation is known to enhance power output during high-intensity intermittent muscle contractions.
- Elevated intracellular phosphocreatine (PCr) concentration, facilitating PCr resynthesis, is a potential mechanism for this ergogenic effect.
Purpose of the Study:
- To investigate the effect of creatine loading on muscle PCr breakdown and resynthesis.
- To assess the impact of creatine loading on muscle performance during high-intensity intermittent muscle contractions.
Main Methods:
- A double-blind, randomized, cross-over study involving 9 healthy young male volunteers.
- 31P-NMR spectroscopy of the gastrocnemius muscle and isokinetic dynamometry for knee-extension torque.
- Measurements were taken before and after 2 and 5 days of either placebo or creatine administration.
Main Results:
- Creatine loading (2 and 5 days) significantly increased resting muscle PCr concentration by 11% and 16%, respectively.
- Torque production during maximal intermittent knee extensions increased by 5-13% after 2 or 5 days of creatine supplementation.
- Creatine loading did not significantly affect the rate of PCr breakdown or resynthesis during intermittent isometric calf contractions.
Conclusions:
- Creatine loading effectively increases muscle PCr concentration.
- Performance during rapid, dynamic intermittent muscle contractions is improved with creatine loading.
- Creatine loading does not enhance muscle PCr resynthesis during intermittent isometric contractions.