http://www.ncbi.nlm.nih.gov/pubmed/23090317

J Strength Cond Res. 2012 Oct 19. [Epub ahead of print]

Post-Menopausal Effects of Resistance Training on Muscle Damage and Mitochondria.

Manfredi TG, Monteiro M, Lamont LS, Fiatarone Singh M, Foldvari M, White S, Cosmas A, Urso ML.

Source

1Energy Metabolism Laboratory, Kinesiology Department, University of Rhode Island, Kingston, Rhode Island, 02881-0810 2Nutrition, Exercise Physiology, and SarcopeniaLaboratory, Jean Mayer US Department of Agriculture Human Research Center on Aging, Tufts University, Boston, 02111 3School of Exercise and Sport Science, University of Sydney, Lidcombe, New South Whales 1825, Australia 4Select Medical Sports Medicine and Outpatient Rehabilitation, West Hartford, CT. 06107 5Military Performance Division, US Army Research Institute of Environmental Medicine (USARIEM), Natick, MA 01760.

Abstract

The purpose of this study was to measure the effects of a 12 month, progressive resistance training intervention on muscle morphology and strength gains in postmenopausal women. Skeletal muscle biopsies were obtained from the vastus lateralis of five (N=5) independent community dwelling women, (mean age: 75.6 ± 4.28 yrs; mean height: 163 ± 5.34 cm; mean weight: 72 ± 17.5 kg) before, six months and 12 months after progressive resistance training. Muscle strength (1-RM) was measured at the same time points. After six months of training morphological analysis revealed evidence of increased proteolysis and tissue repair, and rudimentary fiber development. The percent of Z bands with mild Z band disruption increased from 43.9% at baseline to 66.7% after six months of training (p < 0.01). Mitochondrial volume also increased (% of mitochondria = 0.86% at baseline, 1.19% at six months and 1.04% at 12 months, p<0.05) and there was a shift to larger sized mitochondria. The training did not result in statistically significant increases in muscle leg strength (p<0.18). It appears that mild Z band disruption acts as a precursor for increased protein synthesis and stimulates an increase in mitochondrial mass. Therefore, while a progressive resistance training program in this population did not increase muscle strength, it did demonstrate clinical applications that lend support to the importance of resistance training in older adults.