Smoothness evaluation indices during sit-to-stand-to-sit motions in healthy older females and after hip fracture using an accelerometer

Abstract

Abstract Background: Studies that quantify the quality of sit-to-stand-to-sit (STS) motions, particularly in smoothness, are limited. This study aims to investigate the possibility and usefulness of qualitative evaluation during STS. Methods: This study included 36 females aged over 60 years, including 18 participants in each of the healthy and hip fracture groups. Measurements were performed at two different speeds: five STS as fast as possible (STSF) and 2 s for each motion (STS2s). Indices of smoothness, including the harmonic ratio (HR) and power spectrum entropy (PSE), were calculated from the measured data in each of the three axial directions and were compared. Results: HR in the vertical direction was significantly higher in the healthy group than in the hip fracture group for STSF and STS2s. Furthermore, PSE for all directions and triaxial composites was significantly lower for STS2s. Conclusion: This study suggests the usefulness of HR and PSE as qualitative evaluations for STS.