title: Age-related structural changes in upper extremity muscle tissue in a nonhuman primate model.
abstract: BACKGROUND
  Longitudinal studies of upper extremity aging in humans include logistical concerns that animal models can overcome. The vervet is a promising species with which to study aging-related processes. However, age-related changes in upper extremity muscle structure have not been quantified in this species. This study measured age-related changes to muscle structure, examined relationships between muscle structure and measures of physical performance, and evaluated the presence of rotator cuff tears.
  
  
  METHODS
  Muscle structure (volume, optimal fiber length, and physiologic cross-sectional area (PCSA)) of 10 upper extremity muscles was quantified from the right upper limb of 5 middle-aged and 6 older adult female vervets.
  
  
  RESULTS
  Total measured PCSA was smaller (P = .001) in the older adult vervets than in the middle-aged vervets. Muscle volume reduction predominate the age-related reductions in PCSA. Total measured PCSA was not correlated to any measures of physical performance. No rotator cuff tears were observed. Supraspinatus volume was relatively larger and deltoid volume relatively smaller in the vervet compared with a human.
  
  
  CONCLUSIONS
  The vervet is an appropriate translational model for age-related upper extremity muscle volume loss. Functional measures were not correlated to PCSA, suggesting the vervets may have enough strength for normal function despite loss of muscle tissue. Reduced relative demand on the supraspinatus may be responsible for the lack of naturally occurring rotator cuff tears.
authors.affiliation: Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Winston-Salem, NC, USA; Department of Biomedical Engineering, Wake Forest School of Medicine, Winston-Salem, NC, USA; Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA.
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Santago
authors.affiliation: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Johannes F
authors.initials: JF
authors.lastname: Plate
authors.affiliation: Department of Pathology (Comparative Medicine) and the Wake Forest Primate Center, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Shively
authors.affiliation: Department of Pathology (Comparative Medicine) and the Wake Forest Primate Center, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Register
authors.affiliation: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Smith
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA. Electronic address: ksaul@ncsu.edu.
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Saul
mesh_terms: D000375:Aging; D000818:Animals; D002522:Chlorocebus aethiops; D057645:Deltoid Muscle / Q000033:anatomy & histology / Q000502:physiology; D005260:Female; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology; D017006:Rotator Cuff / Q000033:anatomy & histology* / Q000502:physiology; D000070636:Rotator Cuff Injuries; D034941:Upper Extremity / Q000033:anatomy & histology* / Q000502:physiology
keywords: Aging; function; muscle; primate; volume loss