Long-term strength training reverses the effects of aging on skeletal muscle of health elderly men.

Abstract: Introduction:  Aging is related to a gradual decline in skeletal muscle mass, which is associated with morphological modifications such as reduced muscle fiber cross-sectional area and satellite cell content. Data also suggest that a short-term strength training period can be an effective instrument to rejuvenate these morphological parameters and to restore muscle mass. Therefore, the aim of this study is to investigate the effects of one year progressive strength training on fiber type-specific morphological parameters (fiber type composition, fiber area, satellite cell content, myonuclear number and domain) in skeletal muscle of elderly men.   Methods: Thirteen healthy elderly men (age range, 66-77 years) were randomly assigned into training (T) (n=7) and control (C) (n=6) groups. 52 weeks of progressive strength training was performed. Before and after the training, muscles biopsies were collected from the middle part of the vastus lateralis by percutaneous needle biopsy technique. Muscle biopsies were examined for muscle fiber type composition, fiber type-specific hypertrophy and alterations in satellite cell content, myonuclear content and domain using immuno-histochemistry.   Results: At baseline, myonuclear content and mean fiber area was larger in type I fibers compared to type II fibers (p<0.05). No statistically significant differences were found in fiber type composition, mean fiber area, satellite cell content and myonuclear domain between T and C groups at baseline. By the end of the training period, fiber area was increased by 59% (p<0.05) in type I and 71% (p<0.05) in type II. Satellite cell content, myonuclear content and myonuclear domain were increased after training in type I by 58% (p<0.05), 33% (p<0.05), and 20% (p<0.05), respectively. Similar increases in satellite cell content (+65%; p <0.05), myonuclear content (+36%; p <0.05) and myonuclear domain (+25%; p<0.05) were seen in type II fibers. Conclusion: The current study reported that long-term strength training is an excellent tool to prevent sarcopenia. It is demonstrated that skeletal muscle in elderly is capable to enhance satellite cell and myonuclear content, which contributed to muscle hypertrophy.