Validity and reliability of two protocols for measuring Reachable Workspace Volume in able-bodied and stroke subjects

Abstract

BACKGROUND:

Researchers are measuring Reachable Workspace Volume(RWV) to assess the effects of various interventions on impaired upper extremity function. These measurement protocols have not been validated.

OBJECTIVE:

Assess the validity and reliability of two RWV protocols.

METHODS:

Fifteen able-bodied subjects and eight stroke subjects participated. Two RWV protocols (POLES and PLANES) were completed and compared with hemi-spheric volume estimations using the average reach in the Modified Functional Reach Test (MFRT). RWV, based on the movement of a single hand marker, was calculated using a 3D motion analysis system (Vicon, Centennial, CO, USA). Intraclass correlation coefficients (ICC) represented reliability, Pearson's linear correlation coefficient (r) between RWVs and MFRT represented validity, and p < 0.05 represented significant differences between the volumes.

RESULTS:

For the able-bodied subjects, the POLES protocol had excellent validity and excellent reliability, the PLANES protocol had good validity and excellent reliability, and both RWVs were significantly larger than estimated MFRT volume. In the stroke subjects, both protocols had good validity, excellent reliability, and RWVs which were significantly smaller than the estimated MFRT volume.

CONCLUSIONS:

Both measurement protocols provided valid and reliable measures of RWV. MFRT may underestimate RWV in able-bodied subjects, and overestimate RWV in stroke subjects.