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.ObjectivesTo 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.DesignDescriptive study using a force platform and a 3-dimensional (3D) motion capture system.SettingMotion analysis laboratory in a college setting.ParticipantsElderly volunteers (N=41; 15 men, 26 women; 71.8±5.2y).InterventionsNot applicable.Main Outcome Measures3D coordinate data and the movement of the center of pressure.ResultsThe 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 (β=.319, .470) in multivariate regression analysis, but trunk rotation was not (β=.162, .095). When the reach distance was measured using the heel as a reference, the correlation was stronger.ConclusionsTo evaluate dynamic balance, a 1-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.