title: Adaptations in capillarization and citrate synthase activity in response to endurance training in older and young men.
abstract: The time-course of adaptation in cardiorespiratory fitness, measures of capillarization, and citrate synthase (CS) activity were examined in seven older (O; 69 ± 7 years) and seven young (Y; 22 ± 1 years) men pre-, mid-, and posttraining during a 12-week endurance training program. Training was performed on a cycle ergometer three times per week for 45 minutes at ~70% of maximal VO(2) (VO(2max)). VO(2max) and maximal cardiac output increased similarly from pre- to posttraining in O and Y (p < .05), and maximal a-vO(2diff) was greater (p < .05) posttraining in O and Y. CS was elevated at mid- and posttraining compared with pretraining in both O and Y (p < .05). Indices of capillarization increased 30%-40% in O and 20%-30% in Y and were elevated at posttraining compared with pre- and midtraining in both groups (p < .05). This study showed that both O and Y undertaking similar endurance training displayed capillary angiogenesis and improved mitochondrial respiratory capacity.
authors.affiliation: School of Kinesiology, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Murias
authors.forename: John M
authors.initials: JM
authors.lastname: Kowalchuk
authors.forename: Darmyn
authors.initials: D
authors.lastname: Ritchie
authors.forename: Russell T
authors.initials: RT
authors.lastname: Hepple
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Doherty
authors.forename: Donald H
authors.initials: DH
authors.lastname: Paterson
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000367:Age Factors; D000368:Aged; D002196:Capillaries / Q000502:physiology*; D002950:Citrate (si)-Synthase / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply*; D018919:Neovascularization, Physiologic; D010101:Oxygen Consumption; D010807:Physical Endurance
chemical_list: D002950:Citrate (si)-Synthase