title: Sarcopenia is related to physical functioning and leg strength in middle-aged women.
abstract: BACKGROUND
  In the aging process, loss of muscle is relatively continuous, but the initiation, timing, and amount of muscle loss that relate to functional compromise are poorly described. Also poorly understood is whether strength and functioning in aging are related to the amount of lean mass and its change as well as to the amount of fat mass and its change.
  
  
  METHODS
  The purpose of the study was to ascertain whether 3-year lean and fat mass change predicted functional status in 712 African American and Caucasian women, aged 34-58 years. Fat and lean mass were assessed with bioelectrical impedance. Lower leg strength (torque) was measured with a portable isometric chair, and two indices of physical functioning, walking velocity and double support (both feet touching the surface while walking), were measured with an instrumented gait mat.
  
  
  RESULTS
  Almost 9% of middle-aged women had at least a 6% loss (>2.5 kg) of lean mass over the 3-year observation period. Women who lost at least 2.5 kg of lean mass had slower walking velocity and less leg strength, although women who simultaneously gained more than 2.5 kg of fat mass (at least 7.5%) did not have less leg strength. Age was significantly associated with less velocity, less leg strength, and more time in double support.
  
  
  CONCLUSIONS
  Even in middle-aged women, there is loss of lean mass among almost 1 woman in 10, and this loss of lean mass (sarcopenia) is associated with greater compromise in physical functioning.
authors.affiliation: School of Public Health, University of Michigan, Ann Arbor, MI 48104-2205, USA. mfsowers@umich.edu
authors.forename: MaryFran R
authors.initials: MR
authors.lastname: Sowers
authors.forename: Mary
authors.initials: M
authors.lastname: Crutchfield
authors.forename: Kerry
authors.initials: K
authors.lastname: Richards
authors.forename: Margaret K
authors.initials: MK
authors.lastname: Wilkin
authors.forename: Anna
authors.initials: A
authors.lastname: Furniss
authors.forename: Mary
authors.initials: M
authors.lastname: Jannausch
authors.forename: Daowen
authors.initials: D
authors.lastname: Zhang
authors.forename: Melissa
authors.initials: M
authors.lastname: Gross
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000328:Adult; D001741:Black or African American; D000375:Aging / Q000473:pathology / Q000502:physiology*; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D017097:Electric Impedance; D005260:Female; D005500:Follow-Up Studies; D005684:Gait / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008137:Longitudinal Studies; D035002:Lower Extremity / Q000502:physiology*; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology*; D009133:Muscular Atrophy / Q000473:pathology / Q000503:physiopathology*; D016138:Walking / Q000502:physiology; D044465:White People