title: Delayed postural control during self-generated perturbations in the frail older adults.
abstract: OBJECTIVE
  The aim of this study was to investigate the coordination between posture and movement in pathological aging (frailty) in comparison with normal aging, with the hypothesis that in pathological aging, postural control evolves towards a more reactive mode for which the perturbation induced by the movement is not anticipated and leads to delayed and late postural adjustments.
  
  
  METHODS
  Elderly subjects performed rapid focal arm-raising movements towards a target, from an upright standing position in two stimuli conditions: simple reaction time and choice reaction time (CRT). Hand and center of pressure (CoP) kinematics were compared between a control group and a frail group of the same age.
  
  
  RESULTS
  In frail individuals, the entire movement was impaired and slowed down. In addition, postural adjustments that classically precede and accompany the focal arm movement were delayed and reduced, especially in the CRT condition in which the motor prediction is more limited. Finally, a correlation between the time to CoP maximal velocity and the timed up- and-go score was observed.
  
  
  CONCLUSIONS
  In these patients, it was concluded that the control of the CoP displacement evolved from a proactive mode in which the perturbation associated with the arm movement is anticipated toward a more reactive mode in which the perturbation is compensated by late and delayed adjustments.
authors.affiliation: UFR STAPS, Université de Bourgogne, Dijon, France. alexandre.kubicki@u-bourgogne.fr
authors.forename: Alexandre
authors.initials: A
authors.lastname: Kubicki
authors.forename: François
authors.initials: F
authors.lastname: Bonnetblanc
authors.forename: Geoffroy
authors.initials: G
authors.lastname: Petrement
authors.forename: Yves
authors.initials: Y
authors.lastname: Ballay
authors.forename: France
authors.initials: F
authors.lastname: Mourey
mesh_terms: D000222:Adaptation, Physiological; D000368:Aged; D000369:Aged, 80 and over; D001132:Arm; D001288:Attention; D003071:Cognition; D005260:Female; D016330:Frail Elderly; D006801:Humans; D008297:Male; D009069:Movement Disorders / Q000175:diagnosis*; D004856:Postural Balance; D011187:Posture; D011597:Psychomotor Performance; D011930:Reaction Time; D013647:Task Performance and Analysis