title: Association of adiposity and muscle quality with physical function differs in young and old women.
abstract: OBJECTIVE
  This study aims were to investigate whether age differentially impacts the relationships between adiposity, muscle quality (MQ), and lower-extremity physical function in young and older women.
  
  
  METHODS
  Women aged 20 to 30 years (YOUNG group; n = 37) and women aged 64 to 80 years (OLD group; n = 39) were assessed for body composition via dual-energy X-ray absorptiometry. Isokinetic strength at 60 deg/second was assessed on a dynamometer. MQ was calculated as Nm / mineral-free lean mass (kg). Lower-extremity physical function was determined by an up-and-go (UPGO) challenge.
  
  
  RESULTS
  YOUNG women had lower relative adiposity (%Fat), greater leg lean mass, greater MQ, and faster UPGO time compared with OLD women (all P < 0.01). On linear regression analyses, mineral-free upper leg lean mass was the strongest predictor of UPGO performance in YOUNG women and independently explained 36% of the variance; in OLD women, age and adiposity were the strongest predictors and explained 57% and 40% of the variance, respectively.
  
  
  CONCLUSIONS
  Predictors of lower-extremity physical function differ between young and old women. These findings suggest that body composition and muscle capacity factors associated with function might change across the age span.
authors.affiliation: From the 1Department of Health and Exercise Science, University of Oklahoma, Norman, OK; 2Department of Kinesiology and Physical Education, Northern Illinois University, DeKalb, IL; and 3Department of Kinesiology, University of Georgia, Athens, GA.
authors.forename: Rebecca D
authors.initials: RD
authors.lastname: Larson
authors.forename: Mark M
authors.initials: MM
authors.lastname: Misic
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Evans
mesh_terms: D015502:Absorptiometry, Photon; D050154:Adiposity / Q000502:physiology*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001823:Body Composition / Q000502:physiology; D005260:Female; D006801:Humans; D007866:Leg; D016014:Linear Models; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D055815:Young Adult