title: Maximal voluntary and functional performance levels needed for independence in adults aged 65 to 97 years.
abstract: OBJECTIVE
  Age-related loss of muscle mass and cardiovascular endurance can lead to impairments in muscle force production and cardiac function that, in turn, limit performance in activities essential to everyday living. The purposes of this study were: (1) to identify the "breakpoint" or threshold of maximal voluntary performance and performance in ordinary daily function and (2) to evaluate the predictive validity of the threshold to identify the ability to live independently without self-reported functional limitation.
  
  
  METHODS
  Men and women (N=192; mean age=76 years, SD=7, range=65-97) were recruited from single-family community dwellings or retirement communities with multiple levels of care. Physical function was measured with the Continuous-Scale Physical Functional Performance Test (CS-PFP). Maximal voluntary performance measures included peak oxygen consumption (VO(2peak)) and isokinetic knee extensor torque (KET). Segmented linear regression models of the CS-PFP on the physical performance measures were used to determine the threshold values and their confidence intervals. A logistic regression model was used to evaluate the ability of the CS-PFP scores to identify those living independently and to further illustrate the concepts of threshold and physical reserve.
  
  
  RESULTS
  Threshold values identified for VO(2peak) (20 mL x kg(-1) x min(-1)) and KET (2.5 N x m/[kg x m(-1)]) were associated with an average of CS-PFP score of 57 units. The threshold accurately predicted individuals reporting functional limitations.
  
  
  CONCLUSIONS
  The thresholds provide a mechanism for easily estimating an individual's physical reserve, predicting dependency in living status, and providing unbiased guidance for intervention in late-life independence.
authors.affiliation: Department of Exercise Science, University of Georgia, 300 River Rd, Athens, GA 30602-6554, USA. mecress@coe.uga.edu
authors.forename: M Elaine
authors.initials: ME
authors.lastname: Cress
authors.forename: Mary
authors.initials: M
authors.lastname: Meyer
mesh_terms: D000203:Activities of Daily Living; D000368:Aged / Q000502:physiology*; D000369:Aged, 80 and over; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D010101:Oxygen Consumption; D010807:Physical Endurance; D015203:Reproducibility of Results; D019415:Torque