The ability to rise from a chair to reach a standing position is impaired after stroke. This paper aims to review for the first time the factors that impact the ability to rise from a chair and identify recommendations for post-stroke rehabilitation. In order to analyse relevant scientific publications (French and English), the search terms "stroke", "rehabilitation" and "sit-to-stand" (STS and its variations) were used. The initial literature search identified 122 titles and abstracts for full review and 46 were retained because both the junior and senior researchers agreed that they were aligned with the objectives of this review. During STS, most individuals with hemiparesis able to stand independently presented several changes such as lateral deviation of the trunk towards the unaffected side (ipsilesional side), asymmetrical weight bearing (WB) and asymmetry of knee moment forces. Interestingly, the WB asymmetry was observed even before seat-off, when subjects with hemiparesis still had their thighs in contact with the chair suggesting a planned strategy. Among other interesting results, the time to execute the STS was longer than in controls and influenced by the sensorimotor deficits. A greater risk of falling was observed with a need for more time to stabilize the body during STS and especially during the extension phase. Some rehabilitation interventions may be effective in improving STS duration, WB symmetry and the ability to stand independently with repeated practice (mentally or physically) of STS tasks. However, more research is essential to further investigate effects of specific training protocols and pursue better understanding of this complex and demanding task, particularly for stroke patients who need assistance during this transfer.

Manual assembly operations are sensitive to human errors that can diminish the quality of final products. The paper shows an application of human reliability analysis in a realistic manufacturing context to identify where and why manual assembly errors occur. The techniques SHERPA and HEART were used to perform the analysis of human reliability. Three critical tasks were selected for analysis based on quality records: (1) installation of three types of brackets using fasteners, (2) fixation of a data cable to the assembly structure using cushioned loop clamps and (3) installation of cap covers to protect inlets. The identified error modes with SHERPA were: 36 action errors, nine selection errors, eight information retrieval errors and six checking errors. According to HEART, the highest human error probabilities were associated with assembly parts sensitive to geometry-related errors (brackets and cushioned loop clamps). The study showed that perceptually engaging assembly instructions seem to offer the highest potential for error reduction and performance improvement. Other identified areas of action were the improvement of the inspection process and workers’ provision with better tracking and better feedback. Implementation of assembly guidance systems could potentially benefit worker’s performance and decrease assembly errors.

Background. In hemiparetic individuals, sit-to-stand (STS) transfer is characterized by asymmetric weight-bearing and altered trunk kinematics that can be improved by positioning the affected foot behind the nonaffected one. Objective. To examine the influence of frontal trunk kinematics on medio-lateral displacements of the center of pressure (CP) during STS performed with the feet placed in 2 different positions, as well as relationships between these parameters, medio-lateral stability, and clinical scores of the participants. Methods. Eighteen patients with chronic stroke and 15 control individuals were evaluated during sit-to-stand transfers either in spontaneous foot position or with their affected or dominant foot placed behind, respectively. Medio-lateral CP, pelvis, and shoulder displacement were analyzed using 3D kinematic and kinetic data recordings of the whole task. Motor and sensory impairment, spasticity, muscle strength, and equilibrium were evaluated by standard scales. The possible time during which a participant could prevent a fall (minimal time-to-contact) was used as a stability index. Results. Spontaneously, the deviation of the CP of stroke participants paralleled the tilt of the trunk toward the nonaffected side, as early as the first third of the task. With the affected foot placed behind, trunk position did not differ from those of control participants who executed the transfer spontaneously. Hemiparetic participants were less stable than control participants. Placement of the feet had no significant effect on the stability of either group. Stability was strongly associated with better motor scores on the Chedoke-McMaster Stroke Assessment. Conclusions. In hemiparetic individuals, improving STS symmetry by positioning the affected foot behind the nonaffected one did not decrease medio-lateral stability, which was associated with the level of stroke-related motor impairments.