Journal
JOURNALS OF GERONTOLOGY SERIES A-BIOLOGICAL SCIENCES AND MEDICAL SCIENCES
Volume 71, Issue 10, Pages 1289-1294Publisher
OXFORD UNIV PRESS INC
DOI: 10.1093/gerona/glv231
Keywords
Cyclooxygenase; Prostaglandin; Fiber-type specific; Sarcopenia
Categories
Funding
- National Institutes of Health [R01 AG020532, R01 AG038576]
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Common cyclooxygenase (COX)-inhibiting drugs enhance resistance exercise induced muscle mass and strength gains in older individuals. The purpose of this investigation was to determine whether the underlying mechanism regulating this effect was specific to Type I or Type II muscle fibers, which have different contractile and metabolic profiles. Muscle biopsies (vastus lateralis) were obtained before and after 12 weeks of knee-extensor resistance exercise (3 days/week) from healthy older men who consumed either a placebo (n = 8; 64 +/- 2 years) or COX inhibitor (acetaminophen, 4 gram/day; n = 7; 64 +/- 1 years) in double-blind fashion. Muscle samples were examined for Type I and II fiber cross-sectional area, capillarization, and metabolic enzyme activities (glycogen phosphorylase, citrate synthase, beta-hydroxyacyl-CoA-dehydrogenase). Type I fiber size did not change with training in the placebo group (304 +/- 590 mu m(2)) but increased 28% in the COX inhibitor group (1,388 +/- 760 mu m(2), p < .1). Type II fiber size increased 26% in the placebo group (1,432 +/- 499 mu m(2), p < .05) and 37% in the COX inhibitor group (1,825 +/- 400 mu m(2), p < .05). Muscle capillarization and enzyme activity were generally maintained in the placebo group. However, capillary to fiber ratio increased 24% (p < .1) and citrate synthase activity increased 18% (p < .05) in the COX inhibitor group. COX inhibitor consumption during resistance exercise in older individuals enhances myocellular growth, and this effect is more pronounced in Type I muscle fibers.
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