Efficiency of unimanual and bimanual reach in persons with and without stroke.

Background: Deficiencies in motor control are one of the largest challenges faced by stroke survivors in regaining their independence after stroke.

Objective: This study investigated movement efficiency in people with and without stroke during both unimanual and bimanual upper extremity reaching tasks.

Method: Twenty-five participants (12 with stroke and 13 age-matched controls) between the ages of 36-69 years randomly experienced testing conditions involving reaching forward unimanually and bimanually at a preferred speed in a single session. Kinematic and kinetic outcomes included movement time, movement units, peak velocity, and percentage of movement time to peak velocity.

Results: In stroke participants, the unimpaired limb accommodated its movements to that of the less efficient paretic limb during bimanual conditions indicating yoked movement efficiency because its performance was more efficient (P < 0.05) in unilateral trials, whereas the impaired limb's performance did not differ between the unimanual and bimanual conditions (P>0.05). Control subjects elicited greater movement efficiency than participants with stroke.

Conclusion: Motor efficiency of the unimpaired upper extremity may be adversely influenced when yoked with the impaired limb during symmetrical simple movements in persons with stroke. As such, motor efficiency is not exclusively limited to the impaired side, the effects of which may be task dependent.