title: Earlier and greater hand pre-shaping in the elderly: a study based on kinematic analysis of reaching movements to grasp objects.
abstract: BACKGROUND
  Elderly people are less able to manipulate objects skilfully than young adults. Although previous studies have examined age-related deterioration of hand movements with a focus on the phase after grasping objects, the changes in the reaching phase have not been studied thus far. We aimed to examine whether changes in hand shape patterns during the reaching phase of grasping movements differ between young adults and the elderly.
  
  
  METHODS
  Ten healthy elderly adults and 10 healthy young adults were examined using the Simple Test for Evaluating Hand Functions and kinetic analysis of hand pre-shaping reach-to-grasp tasks. The results were then compared between the two groups. For kinetic analysis, we measured the time of peak tangential velocity of the wrist and the inter-fingertip distance (the distance between the tips of the thumb and index finger) at different time points.
  
  
  RESULTS
  The results showed that the elderly group's performance on the Simple Test for Evaluating Hand Functions was significantly lower than that of the young adult group, irrespective of whether the dominant or non-dominant hand was used, indicating deterioration of hand movement in the elderly. The peak tangential velocity of the wrist in either hand appeared significantly earlier in the elderly group than in the young adult group. The elderly group also showed larger inter-fingertip distances with arch-like fingertip trajectories compared to the young adult group for all object sizes.
  
  
  CONCLUSIONS
  To perform accurate prehension, elderly people have an earlier peak tangential velocity point than young adults. This allows for a longer adjustment time for reaching and grasping movements and for reducing errors in object prehension by opening the hand and fingers wider. Elderly individuals gradually modify their strategy based on previous successes and failures during daily living to compensate for their decline in dexterity and operational capabilities.
authors.affiliation: Faculty of Rehabilitation, Shijonawate Gakuen University, Osaka, Japan.|Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Tamaru
authors.affiliation: Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Naito
authors.affiliation: Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishikawa
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000502:physiology*; D016022:Case-Control Studies; D005260:Female; D005385:Fingers / Q000502:physiology*; D006225:Hand / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D009048:Motor Skills / Q000502:physiology*; D009068:Movement; D011597:Psychomotor Performance; D014953:Wrist / Q000502:physiology*
keywords: STEF; grasping movement; inter-fingertip distance; pre-shaping; reaching movement