title: Impact of body mass index on the relationship between muscle quality and physical function in older women.
abstract: OBJECTIVE
  To investigate the impact of body mass index (BMI) (normal weight, overweight, obese) on the relationship between muscle quality (MQ) and physical function in community-dwelling older women.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  Community-dwelling older women (n = 94, 73.6 ± 5.4 y) stratified by BMI (normal weight: 20.0-24.9 kg/m2; overweight: 25.0-29.9 kg/m2; obese: ≥ 30.0 kg/m2).
  
  
  METHODS
  Body mass index using height and weight, leg extension power via the Nottingham power rig, body composition using dual-energy X-ray absorptiometry, and physical function (6-minute walk, 8-foot up-and-go, 30-second chair stand). Muscle quality was defined as leg power (watts) normalized for lower-body mineral-free lean mass (kg).
  
  
  RESULTS
  Following adjustments for covariates, muscle quality was significantly higher in women of normal BMI compared to overweight (10.0 ± 0.4 vs. 8.7 ± 0.4 watts/kg, p = 0.03). Muscle quality was a significant predictor of performance on the 6-minute walk and 8-foot up-and-go in normal and overweight women (all p < 0.05) and performance on the 30-second chair stand in normal and obese women (both p < 0.05). Body mass index did not significantly impact the association between MQ and physical function (all p > 0.05).
  
  
  CONCLUSIONS
  Muscle quality varies by BMI, yet the relationship to physical function is not significantly different across BMI groups. The results imply that interventions that increase MQ in older women may improve physical function, regardless of BMI.
authors.affiliation: Anne O. Brady, PhD, University of Georgia, Department of Kinesiology, 330 River Road, Athens, GA 30602, USA, anneobrady@gmail.com, Phone: 678-938-8862.
authors.forename: A O
authors.initials: AO
authors.lastname: Brady
authors.forename: C R
authors.initials: CR
authors.lastname: Straight
authors.forename: M D
authors.initials: MD
authors.lastname: Schmidt
authors.forename: E M
authors.initials: EM
authors.lastname: Evans
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D001823:Body Composition / Q000502:physiology; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology*; D035002:Lower Extremity / Q000033:anatomy & histology / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D009765:Obesity / Q000503:physiopathology; D050177:Overweight / Q000503:physiopathology; D012111:Residence Characteristics; D016138:Walking / Q000502:physiology*