title: Postmenopausal effects of resistance training on muscle damage and mitochondria.
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 5 independent community-dwelling women (mean age: 75.6 ± 4.28 years; mean height: 163 ± 5.34 cm; mean weight: 72 ± 17.5 kg) before 6 months and 12 months after progressive resistance training. Muscle strength (1 repetition maximum) was measured at the same time points. After 6 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 6 months of training (p < 0.01). Mitochondrial volume also increased (percent of mitochondria = 0.86% at baseline, 1.19% at 6 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, although 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.
authors.affiliation: Energy Metabolism Laboratory and Kinesiology Department, University of Rhode Island, Kingston, Rhode Island, USA.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Manfredi
authors.forename: Michael A
authors.initials: MA
authors.lastname: Monteiro
authors.forename: Linda S
authors.initials: LS
authors.lastname: Lamont
authors.forename: Maria F
authors.initials: MF
authors.lastname: Singh
authors.forename: Mona
authors.initials: M
authors.lastname: Foldvari
authors.forename: Sebrina
authors.initials: S
authors.lastname: White
authors.forename: Arthur C
authors.initials: AC
authors.lastname: Cosmas
authors.forename: Maria L
authors.initials: ML
authors.lastname: Urso
mesh_terms: D000222:Adaptation, Physiological; D000368:Aged; D001706:Biopsy; D005260:Female; D006801:Humans; D008928:Mitochondria / Q000502:physiology / Q000648:ultrastructure*; D053580:Muscle Strength; D017698:Postmenopause / Q000502:physiology*; D059748:Proteolysis; D052097:Quadriceps Muscle / Q000473:pathology* / Q000502:physiology* / Q000648:ultrastructure; D055070:Resistance Training