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Skeletal muscle mass and contractile properties in elderly humans: a longitudinal study
Author(s) -
Fielding Roger A.,
Reid Kieran F.,
Phillips Edward M.,
Krivickas Lisa S.,
Hughes Virginia A.,
Roubenoff Ronenn,
Frontera Walter R.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.lb116-d
Subject(s) - muscle hypertrophy , skeletal muscle , muscle mass , sarcopenia , medicine , anatomy , muscle fibre , muscle contraction , isometric exercise , endocrinology , chemistry
The purpose of this study was to examine longitudinal changes in skeletal muscle in 12 older men and women (T1 = 1997–1998; T2 = 2005–2006). Peak torque, muscle cross sectional area of the knee extensor and flexors, and contractile properties of permeabilized single muscle fibers were evaluated. Subject mean age was 71.1 ± 5.4 and 80.0 ± 5.3 yrs at T1 and T2 respectively (average length of follow‐up 8.9 yrs). Peak torque of the knee extensors declined at both low and high angular velocities (60°/s: 2.6 ± 1.1 %/yr (P < 0.001); 240°/s: 4.2 ± 1.2 %/yr (P < 0.001)). Muscle cross sectional area of the knee extensors declined (−5.7 ± 4.5%, P < 0.004), whereas muscle cross sectional area of the knee flexors remained unchanged (−3.2 ± 9.0%, P = 0.25). Peak force (Po) increased in both Type I (22.7%) and Type IIa (12.2%) fibers along with an increase in specific force (SF) of type I fibers (28.4%) but not type IIa fibers. These data suggest that the age‐related loss in skeletal muscle mass may result in compensatory hypertrophy and increased Po in surviving muscle fibers. This adaptive mechanism may be an attempt to preserve whole muscle strength in response to age‐associated atrophy.