Skeletal muscle hypertrophy following resistance training is accompanied by a fiber type-specific increase in satellite cell content in elderly men.
We determined muscle fiber type-specific hypertrophy and changes in satellite cell (SC) content following a 12-week resistance training program in 13 healthy, elderly men (72 +/- 2 years). Leg strength and body composition (dual-energy X-ray absorptiometry and computed tomography) were assessed, and muscle biopsy samples were collected. Leg strength increased 25%-30% after training (p < .001). Leg lean mass and quadriceps cross-sectional area increased 6%-9% (p < .001). At baseline, mean fiber area and SC content were smaller in the Type II versus Type I muscle fibers (p < .01). Following training, Type II muscle fiber area increased from 5,438 +/- 319 to 6,982 +/- 503 microm(2) (p < .01). Type II muscle fiber SC content increased from 0.048 +/- 0.003 to 0.084 +/- 0.008 SCs per fiber (p < .001). No changes were observed in the Type I muscle fibers. In older adults, skeletal muscle tissue is still capable of inducing SC proliferation and differentiation, resulting in Type II muscle fiber hypertrophy.
Verdijk
Lex B
LB
Department of Human Movement Sciences, Faculty of Health, Medicine and Life Sciences, Maastricht University, P.O. Box 616, 6200 MD Maastricht, the Netherlands. lex.verdijk@bw.unimaas.nl
Gleeson
Benjamin G
BG
Jonkers
Richard A M
RA
Meijer
Kenneth
K
Savelberg
Hans H C M
HH
Dendale
Paul
P
van Loon
Luc J C
LJ
D015502:Absorptiometry, Photon; D000368:Aged; D000375:Aging / Q000378:metabolism / Q000502:physiology*; D000704:Analysis of Variance; D000886:Anthropometry; D001707:Biopsy, Needle; D001823:Body Composition; D015930:Diet Records; D006801:Humans; D006984:Hypertrophy; D007150:Immunohistochemistry; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000473:pathology; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*; D011336:Probability; D012016:Reference Values; D055070:Resistance Training; D012494:Sampling Studies; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism / Q000473:pathology*; D014057:Tomography, X-Ray Computed