Comparison of the one-arm and two-arm functional reach test in young adults

Abstract

[Purpose] We investigated which functional reach test was more highly correlated with center of pressure excursion, a one-arm reach or a two-arm reach, and explored the relationship between reach distance and trunk rotation in the case of one-arm reach. [Subjects] The subjects were 25 healthy young adults (14 males, 11 females; average age 21.2 years, range 19-30 years). [Methods] Three-dimensional coordinate data (of both acromions and the right index finger) and the movement of the center of pressure were recorded. [Results] In a comparison of measurements of one-arm reach and a two-arm reach, the correlation between the reach distance and the center of pressure excursion was significantly higher for the one-arm reach. In one-arm reach, there was no noticeable correlation between the reach distance and trunk rotation. With multiple regression analysis, trunk rotation was not a significant factor affecting reach distance. When using the heel as a reference, the correlation between reach distance and center of pressure excursion was the strongest. [Conclusion] To evaluate dynamic balance, the one-arm reach is more suitable for young adults. It is useful to measure the reach distance from a fixed point (e.g. heel), or to develop an adjustment technique that can reproduce the starting position.