Automated approach for quantifying the repeated sit-to-stand using one body fixed sensor in young and older adults

Much is known about the sit-to-stand (STS) and its biomechanics. Currently, however, there is little opportunity for instrumented quantification of the STS as part of screening or diagnosis in clinical practice. The objectives of the present study were to describe the feasibility of using an automated approach for quantifying the STS using one sensor location and to start testing the discriminative validity of this approach by comparing older and younger adults. 15 older subjects recruited from a residential care home and 16 young adults performed 5 repeated sit-to-stand and stand-to-sit movements. They were instrumented with a small and lightweight measurement system (DynaPort®) containing 1 triaxial seismic accelerometer and 3 uniaxial gyroscopes fixed in a belt around the waist. Durations of the (sub-)phases of the STS were analyzed and maximum angular velocities were determined. All successful STS cycles were automatically detected without any errors. The STS duration in the older adults was significantly longer and more variable in all phases (i.e., sit-to-stand, standing, stand-to-sit and sitting) compared to the young adults. Older adults also exhibited lower trunk flexion angular velocity. The results of this first fully automated analysis of instrumented repeated STS movements demonstrate that several STS parameters can be identified that provide a basis for a more precise, quantitative study of STS performance in clinical practice.