Reliability of maximum isometric hip and knee torque measurements in children with cerebral palsy using a paediatric exoskeleton – Lokomat

Background The Lokomat (by L-Force tool) allows the measurement of the maximum voluntary isometric torque (MVIT) at the knee and hip joints in a standing position, as close as possible to the posture adopted during walking. However, the reliability of this measurement in children with cerebral palsy (CP) remains unknown. The main goal of this study was to evaluate inter and intra-tester reliability of a novel tool (L-Force) in CP population. Procedure L-Force reliability was determined in 17 children with CP by two experienced therapists. We collected MVITs in hip and knee flexors and extensors. Relative and absolute reliability of maximum joint torques were estimated using the intra-class correlation coefficient (ICC) and standard error of measurement (SEM), respectively. The correlation between L-Force and hand-held dynamometer (HHD) was also reported. Findings ICCs were good to excellent for intra and inter-tester reliability (all P ≤ 0.001). The SEM ranged from 2.0 to 4.1 Nm (12.1 to 21.7%) within-tester and from 2.1 to 3.5 Nm (11.9 to 22.5%) between testers. The correlation was fair to good between L-Force and HHD measures (r = [0.50–0.75]; all P ˂ 0.01) with higher values for flexors than extensors. Conclusion The L-Force is a reliable tool for quantifying the hip and knee flexors and extensors torques in children with cerebral palsy with an important timesaving and in a more functional posture than traditional HHD

Effects of dance therapy on balance, gait and neuro-psychological performances in patients with Parkinson's disease and postural instability

Postural Instability (PI) is a core feature of Parkinson’s Disease (PD) and a major cause of falls and disabilities. Impairment of executive functions has been called as an aggravating factor on motor performances. Dance therapy has been shown effective for improving gait and has been suggested as an alternative rehabilitative method. To evaluate gait performance, spatial-temporal (S-T) gait parameters and cognitive performances in a cohort of patients with PD and PI modifications in balance after a cycle of dance therapy

Concept of an exoskeleton for industrial applications with modulated impedance based on Electromyographic signal recorded from the operator

The introduction of an active exoskeleton that enhances the operator power in the manufacturing field was demonstrated in literature to lead to beneficial effects in terms of reducing fatiguing and the occurrence of musculo-skeletal diseases. However, a large number of manufacturing operations would not benefit from power increases because it rather requires the modulation of the operator stiffness. However, in literature, considerably less attention was given to those robotic devices that regulate their stiffness based on the operator stiffness, even if their introduction in the line would aid the operator during different manipulations respect with the exoskeletons with variable power. In this thesis the description of the command logic of an exoskeleton for manufacturing applications, whose stiffness is modulated based on the operator stiffness, is described. Since the operator stiffness cannot be mechanically measured without deflecting the limb, an estimation based on the superficial Electromyographic signal is required. A model composed of 1 joint and 2 antagonist muscles was developed to approximate the elbow and the wrist joints. Each muscle was approximated as the Hill model and the analysis of the joint stiffness, at different joint angle and muscle activations, was performed. The same Hill muscle model was then implemented in a 2 joint and 6 muscles (2J6M) model which approximated the elbow-shoulder system. Since the estimation of the exerted stiffness with a 2J6M model would be quite onerous in terms of processing time, the estimation of the operator end-point stiffness in realtime would therefore be questionable. Then, a linear relation between the end-point stiffness and the component of muscle activation that does not generate any end-point force, is proposed. Once the stiffness the operator exerts was estimated, three command logics that identifies the stiffness the exoskeleton is required to exert are proposed. These proposed command logics are: Proportional, Integral 1 s, and Integral 2 s. The stiffening exerted by a device in which a Proportional logic is implemented is proportional, sample by sample, to the estimated stiffness exerted by the operator. The stiffening exerted by the exoskeleton in which an Integral logic is implemented is proportional to the stiffness exerted by the operator, averaged along the previous 1 second (Integral 1 s) or 2 seconds (Integral 2 s). The most effective command logic, among the proposed ones, was identified with empirical tests conducted on subjects using a wrist haptic device (the Hi5, developed by the Bioengineering group of the Imperial College of London). The experimental protocol consisted in a wrist flexion/extension tracking task with an external perturbation, alternated with isometric force exertion for the estimation of the occurrence of the fatigue. The fatigue perceived by the subject, the tracking error, defined as the RMS of the difference between wrist and target angles, and the energy consumption, defined as the sum of the squared signals recorded from two antagonist muscles, indicated the Integral 1 s logic to be the most effective for controlling the exoskeleton. A logistic relation between the stiffness exerted by the subject and the stiffness exerted by the robotic devices was selected, because it assured a smooth transition between the maximum and the minimum stiffness the device is required to exert. However, the logistic relation parameters are subject-specific, therefore an experimental estimation is required. An example was provided. Finally, the literature about variable stiffness actuators was analyzed to identify the most suitable device for exoskeleton stiffness modulation. This actuator is intended to be integrated on an existing exoskeleton that already enhances the operator power based on the operator Electromyographic signal. The identified variable stiffness actuator is the DLR FSJ, which controls its stiffness modulating the preload of a single spring

The Effects Of Various Warm-Up Devices on Bat Velocity and Trajectory in Collegiate Baseball Players

Purpose: The purpose of this study was to examine the effects of various weighted warm-up devices on standard baseball bat velocity and trajectory in collegiate baseball players. Methods: Three, right-handed hitters (mean age= 19.3yrs ±1.5yrs; height= 1.74m±.13m; mass=81kg ±20.4kg; baseball experience=14.2 ±1.3) volunteered for this study. Maximal bat velocity was obtained by swinging the 30oz standard bat for the control condition. Participants were then instructed to perform a general and specific warm-up with each of the weighted bats (standard bat with 16oz donut ring (46oz total) and standard bat with 24oz power sleeve (54oz total)) on separate days. Following the warm-up procedures, participants were instructed to swing 3 times with the 30oz standard bat for maximal velocity while impacting the ball resting on the tee located belt-high and in the middle of home plate.Results: No significant differences were revealed by Shewart Chart method for baseball bat velocity or trajectory. Also, it was observed that all participants swung the bat at its lowest point in its trajectory for all conditions. Conclusion: Based upon no changes in the dependent variables in the population tested, Division II collegiate athletes can choose any of the warm-up devices investigated because no deleterious effects were observed

The Effects Of Various Warm-Up Devices on Bat Velocity and Trajectory in Collegiate Baseball Players

Purpose: The purpose of this study was to examine the effects of various weighted warm-up devices on standard baseball bat velocity and trajectory in collegiate baseball players. Methods: Three, right-handed hitters (mean age= 19.3yrs ±1.5yrs; height= 1.74m±.13m; mass=81kg ±20.4kg; baseball experience=14.2 ±1.3) volunteered for this study. Maximal bat velocity was obtained by swinging the 30oz standard bat for the control condition. Participants were then instructed to perform a general and specific warm-up with each of the weighted bats (standard bat with 16oz donut ring (46oz total) and standard bat with 24oz power sleeve (54oz total)) on separate days. Following the warm-up procedures, participants were instructed to swing 3 times with the 30oz standard bat for maximal velocity while impacting the ball resting on the tee located belt-high and in the middle of home plate.Results: No significant differences were revealed by Shewart Chart method for baseball bat velocity or trajectory. Also, it was observed that all participants swung the bat at its lowest point in its trajectory for all conditions. Conclusion: Based upon no changes in the dependent variables in the population tested, Division II collegiate athletes can choose any of the warm-up devices investigated because no deleterious effects were observed

Physiotherapy management of contractures after acquired brain injury

The first part of the thesis investigates treatments for contracture management. The hypothesis is that passive stretch is effective when a high intensity is used and when it is combined with treatments that target the underlying causes of contractures. To support this hypothesis, a case report was presented which described a resolution of severe knee contractures following an intensive program of passive stretch administered in conjunction with motor control training. Two randomised controlled trials were conducted to assess if electrical stimulation was an effective adjunct treatment to address spasticity and muscle weakness, factors believed to contribute to contractures. The findings of both studies demonstrate that electrical stimulation administered in conjunction with passive stretch is not more useful than passive stretch alone for people with severe motor and cognitive impairments. This result highlights a need to consider other treatment options in future research. The second part of the thesis investigates the impact of ankle contractures on the knee joint. An observational study establishes the link between ankle contractures and increased knee extension, and identifies the two gait patterns that are associated with simulated ankle contractures. This information contributes to the understanding of gait deviations that are secondary to ankle contractures