Measuring Methods for Functional Reach Test: Comparison of 1-Arm Reach and 2-Arm Reach

Kage H, Okuda M, Nakamura I, Kunitsugu I, Sugiyama S, Hobara T. Measuring methods for functional reach test: comparison of 1-arm reach and 2-arm reach. Arch Phys Med Rehabil 2009;90:2103-7. Objectives: To investigate which functional reach test better reflects the center of pressure excursion, a 1-arm reach or a 2-arm reach, and to investigate the effect of trunk rotation on the reach distance in a 1-arm reach. In addition, we considered the influence of the individual variation at the starting position. Design: Descriptive study using a force platform and a 3-dimensional (3D) motion capture system. Setting: Motion analysis laboratory in a college setting. Participants: Elderly volunteers (N=41; 15 men, 26 women; 71.8 +/- 5.2y). Interventions: Not applicable. Main Outcome Measures: 3D coordinate data and the movement of the center of pressure. Results: The correlation between the reach distance and the center of pressure excursion was significantly higher (P<.05) for the 1-arm reach (r=.60, .72) compared with a 2-arm reach (r=.41, .55). In the case of the 1-arm reach, center of pressure excursion was a significant factor affecting reach distance (beta=.319, .470) in multivariate regression analysis, but trunk rotation was not (beta=.162, .095). When the reach distance was measured using the heel as a reference, the correlation was stronger. Conclusions: To evaluate dynamic balance, a I-arm reach, which better reflects center of pressure excursion, is more valid. It is meaningful to reduce the individual variation of the acromion at the starting position.