title: Sarcopenic indices in community-dwelling older adults.
abstract: BACKGROUND
  Sarcopenic (SP) indices are used to estimate loss of skeletal lean mass and function and to determine the prevalence of SP in older adults. It is believed that older women and men with lower skeletal lean mass will be weaker and have more functional limitations.
  
  
  OBJECTIVE
  (1) To classify community-dwelling older adults using 2 common SP indices: appendicular lean mass/height² (ALM/ht²) and skeletal muscle index (SMI), and (2) to determine each indices value as indicators of lower extremity strength and physical function.
  
  
  METHODS
  The sample consisted of 154 community-dwelling older adults (111 women and 43 men; mean age = 82.4, SD = 3.6 years; mean body mass index = 25.8, SD = 4.4 kg/m). Each underwent whole-body dual-energy x-ray absorptiometry to assess lean mass. The 9-item modified Physical Performance Test and self-selected walking speed were used to evaluate function. Lower extremity strength was measured bilaterally using isokinetic dynamometry.
  
  
  RESULTS
  The ALM/ht² index classified 75 participants (49%) as SP and 79 (51%) as nonsarcopenic (NSP). The SMI classified 129 participants (84%) as SP and 25 (16%) as NSP. There were no differences in functional measures between groups by gender using either index after classification. The ALM/ht index was more strongly correlated with peak torque of all lower extremity muscle groups (r = 0.276-0.487) compared with the SMI (r = 0.103-0.344). There was no relationship between SP index and physical function.
  
  
  CONCLUSIONS
  There were marked differences in how 2 SP indices classified community-dwelling older adults. Lower extremity strength was lower in older women classified as SP than NSP using the ALM/ht index, but LE strength was not different in older men. However, no lower extremity strength differences were observed between SP and NSP men or women using the SMI classification. None of the SP index uniformly identified community-dwelling older adults with functional or strength deficits.
  
  
  CONCLUSIONS
  Detection of strength deficits using SP indices alone may be gender-specific and may not reflect strength or functional decline in community-dwelling men aged 80 years or older. Given associations between lower extremity strength and physical function, strength measures remain a better predictor of physical performance than SP indices for community-dwelling older men and women.
authors.affiliation: Applied Kinesiology Laboratory, Program in Physical Therapy, Washington University School of Medicine, St Louis, Missouri, MO 63108, USA. emerriwether@wustl.edu
authors.forename: Ericka N
authors.initials: EN
authors.lastname: Merriwether
authors.forename: Helen H
authors.initials: HH
authors.lastname: Host
authors.forename: David R
authors.initials: DR
authors.lastname: Sinacore
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D005260:Female; D015577:Geriatric Assessment / Q000379:methods*; D006801:Humans; D057187:Independent Living; D008297:Male; D053580:Muscle Strength; D026741:Physical Therapy Modalities; D055948:Sarcopenia / Q000175:diagnosis* / Q000453:epidemiology