Reduced Ribosomal Protein S6 Phosphorylation following Progressive Resistance Exercise in Growing Adolescent Rats

• Published in: Journal of strength and conditioning research 2012-06, Vol.26 (6), p.1657-1666
• Main Authors: Hellyer, Nathan J., Nokleby, Jessica J., Thicke, Bethany M., Zhan, Wen-Zhi, Sieck, Gary C., Mantilla, Carlos B.
• Format: Article
• Language: English
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/JSC.0b013e318231abc9

The purpose of the present study was to investigate moderate intensity progressive resistance exercise (PRE) in growing adolescent rats and its effect on muscle hypertrophy (defined as an increase in fiber cross-sectional area). We hypothesized that in adolescent animals moderate intensity PRE would increase: 1) fiber cross-sectional area (CSA); 2) myosin heavy chain (MyHC) content; and 3) expression and phosphorylation of cell signaling molecules involved in translational regulation, compared to age-matched sedentary controls (SED). In the PRE group, three-week old male rats were trained to climb a vertical ladder as a mode of PRE training such that by 10 weeks, all animals in the PRE group had progressed to carry an additional 80% of body weight per climb. In agreement with our hypotheses, we observed that 10 weeks of moderate PRE in adolescent animals was sufficient to increase CSA of muscle fibers and increase MyHC content. Average muscle fiber CSA increased by greater than 10% and total MyHC content increased by 35% (p