title: Knee strength and lower- and higher-intensity functional performance in older adults.
abstract: OBJECTIVE
  This study characterizes the linear relations among knee strength, work capacity, and lower- and higher-intensity measures of functional performance in ambulatory, high-functioning older adults.
  
  
  METHODS
  Sixty-two seniors (average age = 73.4 +/- 7.3 yr) participated in the study. Isokinetic measures included the peak flexion/extension torque produced during five continuous repetitions and the total flexion/extension work performed during 20 repetitions (60 degrees x s(-1)). Functional measures included lower-intensity tests (timed 8-foot and 50-foot walking tests at the participants' "normal" pace, and a standing reach task) and higher-intensity tests (a timed 50-foot "brisk" walk, timed chair stands, and a timed stair climb).
  
  
  RESULTS
  Isokinetic strength and work capacity measures explained between 41% and 54% of the variance in the higher-intensity functional models and only between 31% and 33% of the variance in the lower-intensity models. The strength of the associations, approximated by the beta coefficients of the strength and work terms, was also greater for the higher-intensity functional tasks.
  
  
  CONCLUSIONS
  Further research is warranted to determine whether exercises that increase knee strength and work capacity, improve brisk walking, stair climbing, and chair standing capabilities in older adults.
authors.affiliation: Department of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles 90033, USA. gsalem@hsc.usc.edu
authors.forename: G J
authors.initials: GJ
authors.lastname: Salem
authors.forename: M Y
authors.initials: MY
authors.lastname: Wang
authors.forename: J T
authors.initials: JT
authors.lastname: Young
authors.forename: M
authors.initials: M
authors.lastname: Marion
authors.forename: G A
authors.initials: GA
authors.lastname: Greendale
mesh_terms: D000368:Aged; D015444:Exercise; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology*; D015141:Los Angeles; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011795:Surveys and Questionnaires; D019415:Torque; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing