The world population is ageing rapidly. This is creating challenges for global healthcare systems, which must make new provisions for older adults.

The ageing process contributes to the decline in physical capacity that leads to loss of independence in performing life activities. Immobility and instability are the most significant predictors and indicators of physical disability and dependence. As a result, a variety of assistive devices exist to address immobility and instability in older adults, including walkers, canes, crutches, wheelchairs and hand rails.

Falls are the main consequence of instability and threaten both quality of life and independence. Unintentional falls are the leading cause of injury-related deaths in people aged 65 and above, and most falls happen when performing transitions. Sit-to-stand (STS) transitions are the most common transitions among the daily mobility activities. The ability to perform STS transitions successfully is therefore one of the most important activities to focus attention on.

As a result of physical deterioration, older adults will sooner or later be faced with their own physical limitations, and in particular, will not be able to provide enough torque at critical body joints to make the STS transition.

This research first aims to develop a tool to find the best handle location for older adults based on the physical limits they are most likely to face.

In line with the physics of the STS transition, the “seat-off point”, when subjects lose their seat support, was chosen as the most challenging point of the task. This was coupled with the “nose over toes” posture recommended by occupational therapists to older adults. The tool was run for the seat-off point and the nose-over-toes posture, to provide a map of joint torques and hand forces required for all potential handle locations at this challenging point.

An additional case study was undertaken of the untutored behaviour of older adults engaging in the STS transition. This experimental set-up measured the kinematics and kinetics of body motion during the STS transition using different handle locations in the sagittal plane. The results were compared with the predictions of the tool. These experiments showed that the older adults followed a wide variety of centre of mass trajectories and achieved different levels of hand assistance through the handles.

This research contributes to a better understanding of older adults’ behaviour while utilising hand assistance during the STS transition, highlighting a range of individual strategies and limitations, and it provides a rationale for optimal handle locations in the sagittal plane for the symmetrical two-hand assistance case.