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Updated: May 3, 2026

The Impact of Motor Task Conditions on Goal-Directed Arm Reaching Kinematics and Trunk Compensation in Chronic Stroke Survivors
Published on: May 2, 2021
Arm and trunk movement kinematics during seated reaching within and beyond arm's length in people with stroke: a
Ching-Yi Wu1, Rong-Jiuan Liing2, Hsieh-Ching Chen3
1C. Wu, ScD, OTR/L, Department of Occupational Therapy and Graduate Institute of Behavioral Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan, and Healthy Ageing Research Center, Chang Gung University, Taoyuan, Taiwan.
Background:
Kinematic analysis is commonly used to objectively measure upper extremity movement performance after stroke. However, the concurrent validity and predictive validity of arm-trunk kinematics during reaching within and beyond arm's length have not been studied.
Objective:
The aim of this study was to estimate the concurrent validity of kinematic measures before and after treatment and the predictive validity for reaching within and beyond arm's length after stroke.
Design:
This was a secondary analysis study.
Methods:
Ninety-seven participants with stroke (mean age=55.9 years [SD=10.9]) received intensive treatment every weekday for 3 to 4 weeks. Kinematic reaching tasks and the Wolf Motor Function Test (WMFT) were used before and after treatment. The validity of the kinematic measures was estimated in relation to WMFT scores.
Results:
Of the 8 kinematic variables that were measured, index movement time before treatment (R2=.227-.362) and trunk movement time and trunk displacement after treatment (R2=.095-.346) had the strongest association with the WMFT at both reaching distances. Trunk movement time and trunk displacement before treatment explained 6.9% to 14.9% of the variance in the WMFT after treatment. Kinematic variables explained 6.9% to 49.3% and 9.4% to 38.7% of the variance in the WMFT during a task within arm's length and beyond arm's length, respectively.
Limitations:
The study has limited generalizability.
Conclusions:
Different kinematic variables may partially reflect motor function before and after treatment to a limited degree. Although the predictive validity was modest, trunk movement may be considered a prognostic determinant of motor function after treatment. A reaching task within arm's length may be a more suitable measure of kinematic performance for describing motor function than a reaching task beyond arm's length.
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