Effects of Creatine Supplementation During Resistance Training on Myosin Heavy Chain (MHC) Expression in Rat Skeletal Muscle Fibers

• Published in: Journal of strength and conditioning research Vol. 24; no. 1; pp. 88 - 96
• Main Authors: Aguiar, Andreo F, Aguiar, Danilo H, Felisberto, Alan DS, Carani, Fernanda R, Milanezi, Rachel C, Padovani, Carlos R, Dal-Pai-Silva, Maeli
• Format: Journal Article
• Language: English
• Published: United States National Strength and Conditioning Association 01.01.2010; Lippincott Williams & Wilkins Ovid Technologies
• Subjects: Animals; Body Weight - drug effects; Creatine - pharmacology; Eating - drug effects; Eating - physiology; Electrophoresis, Polyacrylamide Gel; Fibers; Gene expression; Genotype & phenotype; Human subjects; Influence; Male; Muscle, Skeletal - chemistry; Muscle, Skeletal - drug effects; Muscle, Skeletal - physiology; Muscular system; Myosin Heavy Chains - analysis; Myosin Heavy Chains - drug effects; Proteins; Rats; Rats, Wistar; Resistance Training; Rodents; Studies; Water - metabolism
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/JSC.0b013e3181aeb103

Aguiar, AF, Aguiar, DH, Felisberto, ADS, Carani, FR, Milanezi, RC, Padovani, CR, and Dal-Pai-Silva, M. Effects of creatine supplementation during resistance training on mysoin heavy chain (MHC) expression in rat skeletal muscle fibers. J Strength Cond Res 24(1)88-96, 2010-The purpose of this study was to utilize a rodent model to test the hypothesis that creatine (Cr) supplementation during resistance training would influence the pattern of slow-twitch muscle myosin heavy chain (MHC) isoforms expression. Male Wistar rats (2-3 months old, 250-300 g) were divided into 4 groupsNontrained without creatine supplementation (CO), nontrained with creatine supplementation (CR), trained without creatine supplementation (TR), and trained with creatine supplementation (TRCR). TR and TRCR groups were submitted to a resistance training program for 5 weeks (5 days/week) for morphological and biochemical analysis of the soleus muscle. Weightlifting exercise involved jump sessions into water, carrying progressive overload equivalent to percentage of body weight. CR and TRCR groups were given creatine at 0.5 g/kg/d. Both Cr supplementation and resistance training alone or associated did not result in significant alterations (p > 0.05) in body weight gain, food intake, and muscle weight in the CR, TR and TRCR groups compared to the CO group. Also compared to the CO group, the CR group showed a significant (p < 0.02) increase in MHCI content and a reduction in MHCII; inversely, the TR group increased the MHCII content and reduced MHCI (p < 0.02). When combined, both creatine and resistance training did not promote significant (p > 0.05) changes in MHC content of the TRCR group compared to the CO group. The data show that Cr supplementation provides a potential action to abolish the exercise-induced MHC isoform transitions from slow to fast in slow-twitch muscle. Thus, Cr supplementation might be a suitable strategy to maintaining a slow phenotype in slow muscle during resistance training, which may be favorable to maintenance of muscle oxidative capacity of endurance athletes.