Stroke is the leading cause of long term disability with improved walking being an important goal following stroke. Understanding deficits that result in reduced walking performance by hemiparetic subjects is important for the design of effective rehabilitation strategies. The goal of this research was to investigate muscle coordination and mechanical work in hemiparetic walking and mechanisms of acceleration and deceleration in nondisabled walking as a framework for investigating non-steady state walking in hemiparetic subjects. Musculoskeletal modeling and simulation analyses were used to compare individual muscle contributions to important walking subtasks and muscle mechanical work by representative hemiparetic subjects (limited community and community walkers) during pre-swing with a representative speed and age-matched control. Simulation analyses identified decreased paretic soleus and gastrocnemius contributions to forward propulsion and power generation as the primary impairment in the limited community walker compared to the control. Comparison of mechanical work showed that total paretic and non-paretic fiber work was increased in the limited community walker, which was primarily related to decreased fiber and tendon work by paretic soleus and gastrocnemius. The decreased output by the ankle plantar flexors required compensatory work by other muscles. Also, the experimental analyses of accelerated and decelerated walking showed that the ankle plantar flexor moment was positively related to braking and propulsive impulses, which increased with speed. Thus, deficits of the paretic plantar flexors limit forward propulsion and increase mechanical work during pre-swing, and would limit the ability of hemiparetic walkers to accelerate and decelerate, which are essential tasks in daily living activities. For the community walker, simulation analyses showed that deficits in paretic swing initiation are a primary impairment. Specifically, the paretic gastrocnemius and hip flexors contributed less to swing initiation in the community walker compared to the control subject. Total paretic and non-paretic fiber work was increased in the community walker, primarily due to increased work by the hip abductors and adductors. Because step length and step frequency were positively related to walking speed in accelerated and decelerated walking, impaired paretic swing initiation would likely limit the community walker’s ability to accelerate and decelerate. / text

To get the maximal output of your exercise in gym machines, there are different factors to be considered. For example the strength of the muscle varies dependent on the position of the muscles. To get the best results of the exercise the load has to reduce and increase at specific positions. This study was made in cooperation with Caretaker Scandinavia AB, a company for sales, marketing and development in health care. They are general agent for Nordic Gym who works with manufacturing of equipment and machines for gym and fitness. The aim of this study was to generate a method of measurement to evaluate and control the biomechanics of Nordic Gym´s workout equipment. A protocol for an ergonomic analysis on the equipment has also been elaborated. One of the methods to measure the biomechanics was to measure the torque through the whole movement. The other method was electromyography (EMG). The EMGequipment registers electric signals that are generated in a working muscle, and makes it possible to see when the maximum muscle activity achieves. The results of those measurements will be compared to the muscles strengthprofile which describes how the muscle generates power in different positions throughout the movement. To measure the ergonomics an ergonomic protocol where produced, which was based on ergonomics aspect, adapted to gym machines. The method of measurement where tested on Nordic Gym´s training machine 101SE leg extension and Free Motion´s machine Leg Extension GZF18013 and this machines where controlled and evaluated. Two test persons tried out the machines and the machines where analysed in an ergonomic and a biomechanical perspective. The result shows that the biomechanics of Nordic Gym´s machine where a bit better than the biomechanics of FreeMotion´s machine. But in the both case the difference between the values of torque is marginal, to improve the biomechanics insistence a bigger different should be necessary to use. The ergonomic analyse of the machines showed that the ergonomics where good and well planed. Both machines had some small ergonomic lacks, which can be improved.

Upper-limb hemiparesis caused by stroke can severely limit a survivor's ability to perform activities of daily living. Treatment involves intensive, repetitive therapy that can strain limited resources. Rehabilitation devices have been developed to help reduce therapist burden and increase access to therapy. However, adoption is complicated due to their expense and use of complex actuators. A rehabilitation tool without actuators was developed to perform reaching under varying resistance in the transverse plane and measure the reaction force at the handle. Force measurements from the device were validated through comparison with a standard force plate. A new method to calculate the center of applied pressure on a spherical handle mounted on a load cell was developed and validated using 3D modeling. Finally, a study conducted on healthy subjects demonstrated directional effects on the trajectory length and straightness, while resistance effects were seen for the maximum force, time-to-peak velocity and time-to-peak force.

No description available.

Upper-limb hemiparesis caused by stroke can severely limit a survivor's ability to perform activities of daily living. Treatment involves intensive, repetitive therapy that can strain limited resources. Rehabilitation devices have been developed to help reduce therapist burden and increase access to therapy. However, adoption is complicated due to their expense and use of complex actuators. A rehabilitation tool without actuators was developed to perform reaching under varying resistance in the transverse plane and measure the reaction force at the handle. Force measurements from the device were validated through comparison with a standard force plate. A new method to calculate the center of applied pressure on a spherical handle mounted on a load cell was developed and validated using 3D modeling. Finally, a study conducted on healthy subjects demonstrated directional effects on the trajectory length and straightness, while resistance effects were seen for the maximum force, time-to-peak velocity and time-to-peak force.

The purpose of this study was to assess the effectiveness and user-acceptability of three Mark 3 water pump carriage systems for the Aviation and Forest Fire Management division of the Ontario Ministry of Natural Resources (OMNR). Twenty Ontario Fire Rangers were recruited to wear three different designs of the Mark 3 carriage system (Original, Modified, and OMNR Prototype) through a circuit of tasks that simulated a Fire Ranger’s working environment. Subjective ratings were determined for difficulty of loading/unloading, discomfort, system stability and overall performance after each pump condition with a final ranking questionnaire on the same variables after circuit completion. Two tri-axial accelerometers mounted on each pump and the sternum of each participant provided data for calculation of relative pump-carrier accelerations. Measures were determined for the mean relative accelerations, 50th and 90th percentile acceleration amplitude distributions, and median acceleration frequencies. One-way repeated measures ANOVA with post-hoc comparisons were conducted on the objective and subjective rating data followed by ranking each score to attain a total score. Overall, the OMNR Prototype was ranked as the best system. It received a first place ranking for all subjective variables and a first place ranking in 10/18 objective variables with a second place ranking on 6/18 scores. It was concluded that the OMNR Prototype will be recommended for implementation as the OMNR fire suppression system. However, prior to full implementation, additional in-field evaluations should be conducted. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2010-05-21 15:44:33.548

Background Obesity is associated with an increased risk of back pain, attributed to elevated mechanical load. Back injury risk is also determined by movement patterns (kinematics) and physiological factors (exertion, muscle activation). Lifting, particularly repetitive, is the most frequently cited injurious activity. However, in spite of the obvious relation, a paucity of information exists quantifying the interaction of obesity and repetition during lifting. Purpose To determine the effects of obesity and repetition on mechanical, kinematic and physiological lifting outcomes. Methods: An individual-specific, biomechanical model (based upon 3D photogrammetry) was developed to estimate the effect of obesity on back load during lifting (study 1). Lifting strategy and physiological outcomes related to obesity were examined in a fixed-pace, repetitive lifting task (study 2). The effect of task constraints on lifting strategy of high and normal BMI individuals were determined (study 3), followed by an evaluation of muscle activation responses during a repetitive trunk motion similar to that encountered during lifting (study 4). Results: Obesity-specific alterations of important determinants of back load (inertia, CMloc) were revealed. Obesity was related to a substantial increase in back load (M=+197.3, SE=16.8 Nm about L5/S1), however the effect differed across lifting tasks. The lifting strategy of high-BMI individuals was characterized by an increased distance to the external mass (M=+4.7, SE=1.8 cm) and shorter lift duration (M=230, SE=130 msec), with increased cardiovascular effort (M=+7.4, SE=3.4% HRmax) but no change in perceived exertion. Lifting frequency was not a major determinant of lifting strategy, however strategy was influenced by the presence and type of external pacing. A phase-specific, rapid alteration in muscle activation response was evident in the MMG signal during the initial repetitions of a repetitive trunk motion. Conclusion: The effect of obesity during lifting is task-dependent, and cannot be attributable solely to mechanical factors. Future studies should consider tasks that are unconstrained, and examine the initial familiarization period of repetitive tasks, specifically the lowering phase of motions. These findings have relevance to back injury mechanisms related to obesity and the design of injury prevention programs for individuals with a high BMI.

The main purpose of this study was to measure the differences in ground reaction forces (GRFs) produced from an anteroposterior versus a mediolateral style hockey skating arm swing. Twenty four elite level female hockey players performed each technique while standing on a ground mounted force platform, all trials were filmed using two video cameras. Force data was assessed for peak scaled GRFs in the frontal and sagittal planes, and resultant GRF magnitude and direction. Upper limb kinematics were assessed from the video using Dartfish video analysis software, confirming that the subjects successfully performed two significantly distinct arm swing techniques. The mediolateral arm swing used a mean of 18.38° of glenohumeral flexion/extension and 183.68° of glenohumeral abduction/adduction while the anteroposterior technique used 214.17° and 28.97° respectively. The mediolateral arm swing produced 37% greater frontal plane and 33% lesser sagittal plane GRFs than the anteroposterior arm swing. The magnitudes of the resultant GRFs were not significantly different between the two techniques however the mediolateral technique produced a resultant GRF with a significantly larger angle from the direction of travel (44.44°) as compared to the anteroposterior technique (31.60°). The results of this study suggest that the direction of GRFs produced by the mediolateral arm swing more consistent with the direction of lower limb propulsion, perhaps resulting in a greater contribution to high velocity skating. Based on the findings from the present study ice hockey skaters should perform the mediolateral arm swing to maximize the effective GRFs produced with each stride.

<p> We address outflow boundary conditions for blood flow modeling. In particular, we consider a variety of fundamental issues in the structured tree boundary condition. We provide a theoretical analysis of the numerical implementation of the structured tree, showing that it is sensible but must be performed with great care. We also perform analytical and numerical studies on the sensitivity of model output on the structured tree's defining geometrical parameters. The most important component of this dissertation is the derivation of the new, generalized structured tree boundary condition. Unlike the original structured tree condition, the generalized structured tree does not contain a temporal periodicity assumption and is thus applicable to a much broader class of blood flow simulations. We describe a numerical implementation of this new boundary condition and show that the original structured tree is in fact a rough approximation of the new, generalized condition.</p><p> We also investigate parameter selection for outflow boundary conditions, and attempt to determine a set of structured tree parameters that gives reasonable simulation results without requiring any calibration. We are successful in doing so for a simulation of the systemic arterial tree, but the same parameter set yields physiologically unreasonable results in simulations of the Circle of Willis. Finally, we investigate the extension of recently introduced PDF methods to smooth solutions of systems of hyperbolic balance laws subject to uncertain inputs. These methods, currently available only for scalar equations, would provide a powerful tool for quantifying uncertainty in predictions of blood flow and other phenomena governed by first order hyperbolic systems. </p>

Walking is the most common form of mobility in humans. For lower limb mobility impairments, a common treatment is to prescribe an ankle-foot orthosis (AFO) or brace, which is a passive device designed to resist undesired ankle-foot motion. Recent advances in actuator technology have led to the development of active AFOs (AAFOs). However, these devices are generally too bulky for everyday use and are limited to applications such as gait training for rehabilitation. The aim of this research was to investigate the feasibility of developing a novel Active Ankle-Foot Stabilizer (AAFS). The design criteria were mainly based on the strengths and limitations of existing AFOs. The sagittal plane functional requirements were determined using simulated gait data for elderly individuals and drop foot patients; however, it is intended that the device would be suitable for a wider range of disabilities including ankle sprains. A model of the foot was introduced to modify the moment of a deficient ankle where young healthy adult kinematics and kinetics were assumed. A moment deficit analysis was performed for different gait periods resulting in an AAFS model with two components: a linear rotational spring to modify the ankle joint rotational stiffness, and a torque source. The frontal plane functional requirements for the AAFS were modeled as a linear rotational spring which responded to particular gait events. A novel Variable Rotational Stiffness Actuator (VSRA) AFO was also investigated. It consisted of an actuated spring medial and lateral to the ankle to control sagittal plane ankle stiffness and a passive leafspring posterior to the ankle to control frontal plane ankle stiffness. Due to high forces and profile limitations, a spring and rotation actuator that satisfied the design criteria could not be developed, resulting in an infeasible design. Considering the high forces and moments required by the AAFS, a pneumatic approach was adopted. A novel Airbeam AFO, which consisted of a shank cuff and a foot plate to which airbeams were attached proximally and distally to the ankle, was examined. The joint rotational stiffness of the ankle would be controlled by the inflation of these individual cylindrical airbeams. To satisfy the functional requirements, the airbeam diameters and pressures were too large to meet the design criteria and were unrealistic for a portable device. Finally, a Pneumatic Sock AFO, which proved to best satisfy the functional requirements within the design criteria, was examined. The design consisted of an inner sock worn on the ankle, surrounded by anterior, posterior, medial, and lateral bladders which inflate against outer fabric shells. Although promising, the Pneumatic Sock AFO requires further investigation in regards to manufacturing and behaviour characterization before a functional prototype can be developed. Mechanical test methods to characterize the behaviour of the Pneumatic Sock AFO in the sagittal and frontal planes were developed including the control components required, the configuration of a test rig, and test procedures.