title: Experimental chronic low-frequency resistance training produces skeletal muscle hypertrophy in the absence of muscle damage and metabolic stress markers.
abstract: Volitional animal resistance training constitutes an important approach to modeling human resistance training. However, the lack of standardization protocol poses a frequent impediment to the production of skeletal muscle hypertrophy and the study of related physiological variables (i.e., cellular damage/inflammation or metabolic stress). Therefore, the purposes of the present study were: (1) to test whether a long-term and low frequency experimental resistance training program is capable of producing absolute increases in muscle mass; (2) to examine whether cellular damage/inflammation or metabolic stress is involved in the process of hypertrophy. In order to test this hypothesis, animals were assigned to a sedentary control (C, n = 8) or a resistance trained group (RT, n = 7). Trained rats performed 2 exercise sessions per week (16 repetitions per day) during 12 weeks. Our results demonstrated that the resistance training strategy employed was capable of producing absolute mass gain in both soleus and plantaris muscles (12%, p < 0.05). Furthermore, muscle tumor necrosis factor (TNF-alpha) protein expression (soleus muscle) was reduced by 24% (p < 0.01) in trained group when compared to sedentary one. Finally, serum creatine kinase (CK) activity and serum lactate concentrations were not affected in either group. Such information may have practical applications if reproduced in situations where skeletal muscle hypertrophy is desired but high mechanical stimuli of skeletal muscle and inflammation are not.
authors.affiliation: Laboratory of Applied Nutrition and Metabolism, Physical Education and Sport School, University of Sao Paulo, Sao Paulo, Brazil. neloz@usp.br
authors.forename: Nelo Eidy
authors.initials: NE
authors.lastname: Zanchi
authors.forename: Fabio Santos
authors.initials: FS
authors.lastname: Lira
authors.forename: Marilia
authors.initials: M
authors.lastname: Seelaender
authors.forename: Antonio Herbert
authors.initials: AH
authors.lastname: Lancha
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D003402:Creatine Kinase / Q000097:blood; D005260:Female; D006801:Humans; D006984:Hypertrophy / Q000378:metabolism* / Q000473:pathology; D019344:Lactic Acid / Q000097:blood; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000473:pathology / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D055070:Resistance Training; D013312:Stress, Physiological; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D015415:Biomarkers; D014409:Tumor Necrosis Factor-alpha; D019344:Lactic Acid; D003402:Creatine Kinase