Motor-Equivalent Intersegmental Coordination Is Impaired in Chronic Stroke

Area of Science:

• Neurorehabilitation
• Biomechanics
• Motor Control

Background:

• Kinematic abundance allows varied movement strategies for task execution.
• Post-stroke individuals may use trunk displacement to compensate for upper limb (UL) deficits.
• Movement adaptation in tasks needing specific inter-segment coordination can be limited post-stroke.

Purpose of the Study:

• To test movement adaptation in individuals with chronic stroke and controls.
• To assess adaptation in both arms of stroke survivors and the non-dominant arm of controls.
• To evaluate the influence of trunk movement on adaptive arm positioning and reaching.

Main Methods:

• Two no-vision reaching tasks involving trunk movement were used: Stationary Hand Task (SHT) and Reaching Hand Task (RHT).
• Trunk movement was unexpectedly blocked in 40% of trials to assess adaptive responses.
• Outcome measures included gain (compensation for trunk displacement) and endpoint deviation.

Main Results:

• Individuals post-stroke exhibited lower gains and greater endpoint deviation in the more-affected UL compared to the less-affected UL and controls.
• Higher gains and smaller deviations were associated with less sensorimotor impairment, higher activity levels, and better sitting balance.
• Lower gains correlated with diminished UL adaptability.

Conclusions:

• Upper limb (UL) adaptability in individuals post-stroke is limited, especially in tasks requiring specific inter-joint coordination.
• Condition-specific adaptability tests can quantify UL adaptability.
• These tests may track changes in adaptability during rehabilitation.