title: Histochemical and enzymatic characteristics of skeletal muscle in master athletes.
abstract: Many older athletes are capable of endurance performances equal to those of young runners who have higher maximal O2 uptakes (VO2max). To determine whether this is a result of differences in skeletal muscle characteristics, gastrocnemius muscle biopsy samples were obtained from eight master athletes [aged 63 +/- 6 (SD) yr] and eight young (aged 26 +/- 3 yr) runners. The young runners were matched with the master athletes for 10-km running performance and for their volume, pace, and type of training. Despite similar 10-km run times, VO2max was 11% lower (P less than 0.05) in the master athletes. Fiber type distribution did not differ between groups, with both groups having 60% type I and very few type IIb fibers. Succinate dehydrogenase and beta-hydroxyacyl-CoA dehydrogenase activities, however, were 31 and 24% higher in the master athletes compared with the matched young runners, whereas lactate dehydrogenase activity was 46% lower (all P less than 0.05). The capillary-to-fiber ratio was also greater in the master athletes; however, capillary density was similar in the two groups, because of the master athletes' 34% larger (P less than 0.05) type I fibers. These differences in skeletal muscle characteristics may explain the master athletes' ability to perform as well as some young runners despite having a lower VO2max.
authors.affiliation: Section of Applied Physiology, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: A R
authors.initials: AR
authors.lastname: Coggan
authors.forename: R J
authors.initials: RJ
authors.lastname: Spina
authors.forename: M A
authors.initials: MA
authors.lastname: Rogers
authors.forename: D S
authors.initials: DS
authors.lastname: King
authors.forename: M
authors.initials: M
authors.lastname: Brown
authors.forename: P M
authors.initials: PM
authors.lastname: Nemeth
authors.forename: J O
authors.initials: JO
authors.lastname: Holloszy
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism; D004798:Enzymes / Q000378:metabolism; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000033:anatomy & histology / Q000098:blood supply / Q000378:metabolism*; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology*; D012420:Running
chemical_list: D004798:Enzymes