Characteristics of Muscle Fiber Type Are Predictive of Skeletal Muscle Mass and Strength in Elderly Men

Authors

  • Lex B. Verdijk PhD,

    1. From the *Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
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  • Tim Snijders MSc,

    1. From the *Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
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  • Milou Beelen MD,

    1. From the *Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
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  • Hans H.C.M. Savelberg PhD,

    1. From the *Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
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  • Kenneth Meijer PhD,

    1. From the *Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
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  • Harm Kuipers Prof,

    1. From the *Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
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  • Luc J.C. van Loon PhD

    1. From the *Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
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Address correspondence to Lex Verdijk, Department of Human Movement Sciences, Faculty of Health, Medicine and Life Sciences, Maastricht University Medical Centre+, P.O. Box 616, 6200 MD Maastricht, the Netherlands. E-mail: Lex.Verdijk@bw.unimaas.nl

Abstract

OBJECTIVES: To investigate the relationship between skeletal muscle fiber type-specific characteristics, circulating hormone concentrations, and skeletal muscle mass and strength in older men.

DESIGN: Cross-sectional analyses.

SETTING: University research center.

PARTICIPANTS: Forty-one community dwelling elderly men (≥65).

MEASUREMENTS: Leg strength (1-repetition maximum, 1RM) and whole-body and limb muscle mass were determined, and muscle fiber type composition, cross-sectional area (CSA), myonuclear content, and satellite cell (SC) content were assessed in skeletal muscle biopsy samples. In addition, blood samples were collected to determine serum testosterone, sex hormone–binding globulin, insulinlike growth factor (IGF)-1, and IGF binding protein-3 concentrations.

RESULTS: Muscle mass correlated with muscle strength (0.41 ≤ correlation coefficient (r)≤0.72; P<.01). Muscle fiber CSA, myonuclear content, and SC content were significantly lower in type II than in type I muscle fibers. Myonuclear and SC content were positively correlated with muscle fiber CSA. Furthermore, greater muscle fiber CSA (type I and II) was associated with greater thigh muscle area and muscle strength (0.30 ≤ r ≤ 0.45; P<.05). Testosterone concentration was positively correlated with muscle mass and muscle fiber CSA. Regression analysis showed that SC content, myonuclear content, and testosterone concentration are predictive of muscle fiber CSA. Furthermore, muscle mass and type II muscle fiber CSA are predictive of muscle strength.

CONCLUSION: Skeletal muscle mass and strength in elderly men are positively correlated with muscle fiber type–specific CSA, myonuclear content, and SC content. These findings support the assumption that a decline in SC content plays an important role in age-related decline in muscle mass and strength.

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