title: Coupling between skeletal muscle fiber size and capillarization is maintained during healthy aging.
abstract: BACKGROUND
  As muscle capillarization is related to the oxidative capacity of the muscle and the size of muscle fibres, capillary rarefaction may contribute to sarcopenia and functional impairment in older adults. Therefore, it is important to assess how ageing affects muscle capillarization and the interrelationship between fibre capillary supply with the oxidative capacity and size of the fibres.
  
  
  METHODS
  Muscle biopsies from healthy recreationally active young (22 years; 14 men and 5 women) and older (74 years; 22 men and 6 women) people were assessed for muscle capillarization and the distribution of capillaries with the method of capillary domains. Oxidative capacity of muscle fibres was assessed with quantitative histochemistry for succinate dehydrogenase (SDH) activity.
  
  
  RESULTS
  There was no significant age-related reduction in muscle fibre oxidative capacity. Despite 18% type II fibre atrophy (P = 0.019) and 23% fewer capillaries per fibre (P < 0.002) in the old people, there was no significant difference in capillary distribution between young and old people, irrespective of sex. The capillary supply to a fibre was primarily determined by fibre size and only to a small extent by oxidative capacity, irrespective of age and sex. Based on SDH, the maximal oxygen consumption supported by a capillary did not differ significantly between young and old people.
  
  
  CONCLUSIONS
  The similar quantitative and qualitative distribution of capillaries within muscle from healthy recreationally active older people and young adults indicates that the age-related capillary rarefaction, which does occur, nevertheless maintains the coupling between skeletal muscle fibre size and capillarization during healthy ageing.
authors.affiliation: School of Healthcare Science, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Barnouin
authors.affiliation: School of Healthcare Science, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK.
authors.forename: Jamie S
authors.initials: JS
authors.lastname: McPhee
authors.affiliation: Institut de Myologie, UPMC UM 76, INSERM U 974, CNRS UMR 7215, Pitle-Salpetriere Hospital, 47-83 Boulevard de l'Hopital 75013, Paris, France.
authors.forename: Gillian
authors.initials: G
authors.lastname: Butler-Browne
authors.affiliation: School of Healthcare Science, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK.|Istituto di Anatomia Patologica, Dipartimento di Scienze Mediche, Chirurgiche e della Salute, University of Trieste, Cattinara Hospital, Strada di Fiume 447, 34149, Trieste, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Bosutti
authors.affiliation: Physiotherapy & Sports Science, Health Sciences Centre, School of Public Health, Belfield, Dublin 4, D04 V1W8, Ireland.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: De Vito
authors.affiliation: School of Healthcare Science, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Jones
authors.affiliation: Division of Medical Sciences & Graduate Entry Medicine, School of Medicine, Faculty of Medicine & Health Sciences, MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, Derby Royal Hospital, University of Nottingham, Uttoxeter Road, Derby, DE22 3DT, UK.
authors.forename: Marco
authors.initials: M
authors.lastname: Narici
authors.affiliation: AP-HP-Centre de Référence de Pathologies Neuromusculaire Paris Est-Institut de Myologie, Paris, France.
authors.forename: Anthony
authors.initials: A
authors.lastname: Behin
authors.affiliation: Institut de Myologie, UPMC UM 76, INSERM U 974, CNRS UMR 7215, Pitle-Salpetriere Hospital, 47-83 Boulevard de l'Hopital 75013, Paris, France.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Hogrel
authors.affiliation: School of Healthcare Science, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK.|Lithuanian Sports University, 6 Sporto St, LT-44221, Kaunas, Lithuania.
authors.forename: Hans
authors.initials: H
authors.lastname: Degens
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D001706:Biopsy; D002196:Capillaries / Q000166:cytology* / Q000473:pathology; D048429:Cell Size; D005260:Female; D000073656:Healthy Aging / Q000473:pathology / Q000502:physiology*; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000473:pathology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000473:pathology; D010101:Oxygen Consumption / Q000502:physiology; D055815:Young Adult
keywords: Ageing; Capillary; Muscle fibre; Oxidative capacity; Succinate dehydrogenase