title: The effect of walking speed on lower-extremity joint powers among elderly adults who exhibit low physical performance.
abstract: OBJECTIVE
  To compare peak joint powers and joint angles between comfortable and fast walking speeds among a group of elderly adults who exhibit low physical performance, and to test the primary hypothesis that peak ankle powers would not change when walking speed was increased, but that peak hip power output would increase significantly with speed.
  
  
  METHODS
  Three-dimensional analysis of joint kinematics and kinetics during comfortable and fast walking by both healthy and low-performing elderly adults (age, >70y).
  
  
  METHODS
  Gait laboratory.
  
  
  METHODS
  Twenty-four healthy elderly adults and 27 elders who exhibited low performance on a standard battery of walking, standing balance, and chair-rise tasks that places them at risk of mobility-related disability.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Peak lower-extremity joint powers and joint angles.
  
  
  RESULTS
  Low-performing elders increased both ankle and hip power outputs to increase walking speed. However, peak ankle power remained significantly below that of the healthy elderly adults even when the low-performing elders walked at a faster gait speed. Joint-power changes in the low-performing elderly were accompanied by a reduction in hip extension and ankle dorsiflexion, and an increase in transverse pelvic rotation.
  
  
  CONCLUSIONS
  Compared with healthy elderly, the low-performing elderly adults showed speed-independent differences in ankle and hip mechanics that may reflect underlying neuromuscular impairments. In particular, an understanding of the interdependent contributions of hip flexibility and ankle power limitations seem important to inform interventions to maintain gait into advanced age.
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Graf
authors.forename: James O
authors.initials: JO
authors.lastname: Judge
authors.forename: Sylvia
authors.initials: S
authors.lastname: Ounpuu
authors.forename: Darryl G
authors.initials: DG
authors.lastname: Thelen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D005684:Gait / Q000502:physiology; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D010809:Physical Fitness / Q000502:physiology*; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*