Effects of unilateral, bilateral in-phase and anti-phase modes of a functional task on non-paretic arm kinematics in acute stroke

Introduction: Arm dysfunction is not confined to the contralesional arm.Understanding intralimb kinematics of the non-paretic arm in stroke individualsprovides insight to mechanisms of action underlying bilateral upper limbtraining (BT). This study aimed to compare the effects of unilateral, bilateralin-phase and anti-phase modes of a functional task on dominant/non-paretic armkinematics in healthy and acute stroke individuals respectively.

Methods: 7 healthy and 13 acute stroke individualsunderwent 3D motion capture of unilateral, bilateral in-phase and anti-phasemodes of a functional grasp task. Intralimb kinematics was assessed throughmovement time, peak velocity, movement smoothness and movement directness.

Results: In healthy individuals, dominant arm movementdisplayed no significant difference in any of the intralimb kinematic measuresbetween unilateral, bilateral in-phase and bilateral anti-phase grasp task. Inacute stroke individuals, non-paretic arm movement became significantly slower(Z=-3.180,p=0.001), jerkier (Z=-3.184, p=0.001) and with lower peak velocity (Z=-3.110,p=0.002) during bilateral in-phase grasp task compared to unilateral task mode.Furthermore, in acute stroke individuals, non-paretic arm movement becamesignificantly slower (Z=-3.181, p=0.001) and jerkier (Z=-3.181, p=0.001) duringbilateral anti-phase grasp task compared to unilateral task mode.

Conclusion: Bilateral in-phase and anti-phase taskmodes altered non-paretic arm kinematics instroke individuals, but not dominantarm kinematics in healthy individuals. Specifically, non-paretic arm kinematicsin stroke individuals became slower and jerkier during bilateral in-phase andanti-phase grasp task compared to unilateral task modes. Kinematic responses tobilateral task modes is affected by stroke. Therapists should note detrimentalperformance effects of bilateral training modes on the non-paretic arm.