Comparison of rolling resistance, propulsion technique and physiological demands between a rigid, folding and hybrid manual wheelchair frame.

BACKGROUND: When selecting a manual wheelchair frame, the choice between rigid and folding frames carries significant implications. Traditional folding frames are expected to have more rolling resistance and power dissipation caused by frame deformation, while they are more convenient for transportation, such as in a car. A new hybrid frame, designed to be more rigid, aims to minimize power dissipation while still retaining foldability. AIM: This study aimed to assess rolling resistance, power output, propulsion technique and physiological demands of handrim wheelchair propulsion across three different frames: a rigid frame, a hybrid frame and a conventional folding frame. MATERIALS AND METHODS: Forty-eight able-bodied participants performed coast-down tests using inertial measurement units to determine rolling resistance. Subsequently, four-minute submaximal exercise block under steady-state conditions at 1.11 m/s were performed on a wheelchair ergometer (n = 24) or treadmill (n = 24) to determine power output, propulsion technique and physiological demands. RESULTS: Repeated measures ANOVA revealed that the hybrid frame exhibited the lowest rolling resistance (7.0 ± 1.5N, p ≤ 0.001) and required less power output (8.3 ± 1.0W, p ≤ 0.001) at a given speed, compared to both the folding (9.3 ± 2.2N, 10.8 ± 1.4W) and rigid frame (8.0 ± 1.9N, 9.4 ± 1.6W). Subsequently, this resulted in significantly lower applied forces and push frequency for the hybrid frame. The folding frame had the highest energy expenditure (hybrid: 223 ± 44 W, rigid: 234 ± 51 W, folding: 240 ± 46 W, p ≤ 0.001). CONCLUSION: The hybrid frame demonstrated to be a biomechanically and physiologically beneficial solution compared to the folding frame, exhibiting lower rolling resistance, reduced power output, and consequently minimizing force application and push frequency, all while retaining its folding mechanism.

A hybrid frame, developed as an intermediary solution between a folding and rigid frame, presents reduced biomechanical and physiological demands compared to a folding frame. This is attributed to its decreased need for propulsive forces and energy expenditure, resulting from lower rolling resistanceDespite the hybrid frame offering lower rolling resistance and thus requiring less propulsive force as the rigid frame, it experiences internal power losses due to movement between its interconnected pieces. Consequently, the net mechanical efficiency of the hybrid frame is inferior to that of the rigid frame, resulting in a similar energy expenditure between the hybrid and rigid frames.The hybrid frame emerges as a potentially more advantageous option than a conventional folding frame, as it diminishes biomechanical and physiological strain while retaining a folding mechanism, to ensure easy transportation.

Handrim Wheelchair Propulsion Technique in Individuals With Spinal Cord Injury With and Without Shoulder Pain: A Cross-sectional Comparison.

OBJECTIVE: The aim of this study was to compare handrim wheelchair propulsion technique between individuals with spinal cord injury with and without shoulder pain. DESIGN: A cross-sectional study including 38 experienced handrim wheelchair users with spinal cord injury was conducted. Participants were divided into the "shoulder pain" ( n = 15) and "no-shoulder pain" ( n = 23) groups using the Local Musculoskeletal Discomfort scale. Kinetic and spatiotemporal aspects of handrim wheelchair propulsion during submaximal exercise on a motor-driven treadmill were analyzed. Data were collected using a measurement wheel instrumented with three-dimensional force sensors. RESULTS: After correction for confounders (time since injury and body height), linear regression analyses showed that the pain group had a 0.30-sec (95% confidence interval, -0.5 to -0.1) shorter cycle time, 0.22-sec (95% confidence interval, -0.4 to -0.1) shorter recovery time, 15.6 degrees (95% confidence interval, -27.4 to -3.8) smaller contact angle, and 8% (95% confidence interval, -15 to 0) lower variability in work per push compared with the no-pain group. Other parameters did not differ between groups. CONCLUSIONS: This study indicates that individuals with spinal cord injury who experience shoulder pain propel their handrim wheelchair kinematically differently from individuals with spinal cord injury without shoulder pain. This difference in propulsion technique might be a pain-avoiding mechanism aimed at decreasing shoulder range of motion.

Parametric Bayesian filters for nonlinear stochastic dynamical systems: a survey.

Nonlinear stochastic dynamical systems are commonly used to model physical processes. For linear and Gaussian systems, the Kalman filter is optimal in minimum mean squared error sense. However, for nonlinear or non-Gaussian systems, the estimation of states or parameters is a challenging problem. Furthermore, it is often required to process data online. Therefore, apart from being accurate, the feasible estimation algorithm also needs to be fast. In this paper, we review Bayesian filters that possess the aforementioned properties. Each filter is presented in an easy way to implement algorithmic form. We focus on parametric methods, among which we distinguish three types of filters: filters based on analytical approximations (extended Kalman filter, iterated extended Kalman filter), filters based on statistical approximations (unscented Kalman filter, central difference filter, Gauss-Hermite filter), and filters based on the Gaussian sum approximation (Gaussian sum filter). We discuss each of these filters, and compare them with illustrative examples.