title: Effect of endurance and/or strength training on muscle fiber size, oxidative capacity, and capillarity in hemodialysis patients.
abstract: We previously reported reduced limb muscle fiber succinate dehydrogenase (SDH) activity and capillarity density and increased cross-sectional areas (CSAs) of all fiber types in maintenance hemodialysis (MHD) patients compared with matched controls that may contribute to their effort intolerance and muscle weakness. This study evaluated whether endurance training (ET), strength training (ST), or their combination (EST) alters these metabolic and morphometric aberrations as a mechanism for functional improvement. Five groups were evaluated: 1) controls; 2) MHD/no training; 3) MHD/ET; 4) MHD/ST; and 5) MHD/EST. Training duration was 21.5 ± 0.7 wk. Vastus lateralis muscle biopsies were obtained after HD at baseline and at study end. Muscle fibers were classified immunohistochemically, and fiber CSAs were computed. Individual fiber SDH activity was determined by a microdensitometric assay. Capillaries were identified using antibodies against endothelial cells. Type I and IIA fiber CSAs decreased significantly (10%) with EST. In the ET group, SDH activity increased 16.3% in type IIA and 19.6% in type IIX fibers. Capillary density increased significantly by 28% in the EST group and 14.3% with ET. The number of capillaries surrounding individual fiber type increased significantly in EST and ET groups. Capillary-to-fiber ratio increased significantly by 11 and 9.6% in EST and ET groups, respectively. We conclude that increments in capillarity and possibly SDH activity in part underlie improvements in endurance of MHD patients posttraining. We speculate that improved specific force and/or neural adaptations to exercise underlie improvements in limb muscle strength of MHD patients.
authors.affiliation: Division of Pulmonary/Critical Care Medicine, The Burns & Allen Research Institute, Cedars-Sinai Medical Center, Los Angeles, California; michael.lewis@cshs.org.
authors.forename: Michael I
authors.initials: MI
authors.lastname: Lewis
authors.affiliation: Division of Pulmonary/Critical Care Medicine, The Burns & Allen Research Institute, Cedars-Sinai Medical Center, Los Angeles, California;
authors.forename: Mario
authors.initials: M
authors.lastname: Fournier
authors.affiliation: Los Angeles Biomedical Research, Institute at Harbor-UCLA Medical Center, Torrance, California;
authors.forename: Huiyuan
authors.initials: H
authors.lastname: Wang
authors.affiliation: El Camino College, Torrance, California; and.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Storer
authors.affiliation: Los Angeles Biomedical Research, Institute at Harbor-UCLA Medical Center, Torrance, California; David Geffen School of Medicine at UCLA, Los Angeles, California; and.
authors.forename: Richard
authors.initials: R
authors.lastname: Casaburi
authors.affiliation: Los Angeles Biomedical Research, Institute at Harbor-UCLA Medical Center, Torrance, California; David Geffen School of Medicine at UCLA, Los Angeles, California; and The UCLA Fielding School of Public Health, Los Angeles, California.
authors.forename: Joel D
authors.initials: JD
authors.lastname: Kopple
mesh_terms: D000328:Adult; D002196:Capillaries / Q000502:physiology*; D002197:Capillary Action; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism / Q000502:physiology*; D010084:Oxidation-Reduction; D010807:Physical Endurance / Q000502:physiology*; D006435:Renal Dialysis; D055070:Resistance Training
keywords: chronic renal failure; exercise training; muscle capillaries; muscle fiber oxidative capacity; muscle fiber size