Motion sensors offer the possibility to obtain spatiotemporal measures of mobility-related activities such as sit-stand and stand-sit transitions. However, the application of new sensor-based methods for assessing sit-stand-sit performance requires the detection of crucial events such as seat on/off in the sensor-based data. Therefore, the aim of this study was to evaluate the agreement of detecting sit-stand and stand-sit events based on a novel body-fixed-sensor method with a force-plate based analysis.

Objective: To investigate the correlation between objective and subjective evaluation of patients with total hip replacement.Design: Prospective preliminary trial comparing the Western Ontario and McMaster University questionnaire (WOMAC) and gait analysis preoperatively and three months postoperatively.Setting: A German academic orthopaedic centre specializing in total hip replacement surgery.Subjects: Seventeen patients (median age 70 years) with hip osteoarthritis.Intervention: All patients had had a primary unilateral total hip replacement.Main measures: WOMAC questionnaire to assess self-perceived health status and gait analysis to determine objective gait parameters.Results: Performance of walking as well as subjective judgement of health status improved following surgery (gait speed P = 0.0222; stride length P = 0.038; stance phase ratio P = 0.0466; WOMAC P < 0.0001). However, the correlation between gait parameters and WOMAC was poor ( r = -0.27 or less). Correlation between changes of walking parameters and WOMAC was bad to good ( r = 0.01 to r = -0.72).Conclusion: The WOMAC questionnaire might not reflect walking performance. The addition of gait analysis is recommended to gain objective information about the quality of gait.

Background. Changes in performance of standing up from a chair have been related to measures of strength or power. However, the sit-to-stand (STS) transfer requires that the individual exerts forces with appropriate magnitude and timing. These coordinative aspects have received less attention. This study aims to analyze differences in STS performance in older people based on measures that are derived from ground reaction forces (GRFs) during STS transfer. Methods. One hundred thirty-five participants (84.5% women; mean age 82.5 years) stood up from a chair as fast as possible. Time of stabilization after reaching an upright position, power, maximum vertical GRF, increase of vertical GRF, overshoot of vertical GRF over body weight, and left–right difference of GRF were measured by a force plate under each foot. To explain variance of total time to stand up, these variables were used as independent variables in a linear regression model. Results. Eighty-one percent of variance of total time to stand up was explained by the independent variables. The strongest predictor of total time was time of stabilization (F = 459.4). Another model of linear regression explained 37% of variance of time to reach an upright position, with increase of GRF as the strongest predictor (F = 38.3). Influence of maximum vertical GRF was weak in both models. Conclusions. Variables related to coordination of strength, measured during STS transfer, were able to explain a high proportion of variance of time to rise from a chair. Stabilization after reaching an upright position seems to be a parameter worth further investigation.