[Differences in biomechanical parameters during sit to stand transfer between elderly with and without history of frequent falls]

Safer chairs for elderly patients: design evaluation using electromyography and force measurement

A vast majority of patient fall events in hospitals involve the elderly. In inpatient care settings, despite the risk of fall, patients are encouraged to leave their bed, move around their room, and sit on their chair to progress in their healing. Despite the vital role of patient chair design in improving recovery, few studies have examined the ergonomic requirements of safe patient chairs. This study examined the impact of manipulating horizontal and vertical positions of armrests in a test chair on required physical effort during Stand-to-Sit-to-Stand (St-Si-St) transitions among 15 elderly women. Physical effort was measured using: (1) surface electromyography (sEMG); (2) force measurement by load cells; (3) video recording. Findings showed non-linear patterns of change in required physical effort due to changes in armrests' height and distance. It was also found that minimum effort is associated with armrests higher and farther apart than those in typical patient chairs. Practitioner Summary: Safe chairs are essential for inpatient recovery, yet their ergonomic features are not investigated. Impact of changes in chair armrests on required physical effort was examined using electromyography, force measurement and video recording. Armrests higher and farther apart than those in typical patient chairs may be safer for elderly patients.

Reliability and validity of a smartphone-based application for the quantification of the sit-to-stand movement in healthy seniors

INTRODUCTION

Recently, it has been demonstrated that biomechanical parameters measured with accelerometers during everyday activities might provide early information about mobility in seniors. The use of smartphones has been suggested for this purpose. The aim of this study was to develop and validate a smartphone-based application for the quantification of the sit-to-stand movement (STS) in healthy seniors.

METHODS

Sixteen healthy seniors performed the STS with a smartphone first attached to the lower back and then to the sternum. The subjects' vertical ground reaction forces (VGRF) and vertical acceleration (VAcc) were recorded simultaneously using two force plates (reference standard) and the smartphone, respectively. VAcc data were converted to force; power was then calculated based on both force-time curves. Subsequently, the total movement duration (Ttotal), peak force (Fmax), rate of force development (RFD) and peak power (Pmax) were determined. Relative (intraclass correlation coefficient [ICC]) and absolute (standard error of measurement [SEM]) reliability were also calculated. For the variables showing strong reliability (ICC≥0.75), Pearson correlation coefficients (r) between VGRF- and VAcc-derived data and one-sample T-tests for the mean differences were carried out.

RESULTS

In the sternal configuration, all variables showed strong reliability (range: 0.86-0.93), except the smartphone-derived parameter RFD (ICC=0.43). Fmax and Ttotal were found to be highly valid (r=0.86 and 0.98, respectively).

CONCLUSION

The results showed that the smartphone-based application can be used as a reliable and valid tool for the quantification of the STS in healthy seniors if the proposed protocol is followed.