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This thesis examined post-stroke gait asymmetry: a prevalent issue and one that has a number of associated negative consequences (e.g. challenged balance control, gait inefficiencies, increased risk of musculoskeletal injury to the non-paretic limb and decreased overall activity levels). This thesis is comprised of three studies that focused on 1) how gait symmetry should be measured, 2) how gait asymmetry may change in the long term post-stroke and 3) whether gait asymmetry is responsive to a rehabilitation intervention. A comparison of the most common expressions of spatiotemporal gait symmetry revealed that the simple symmetry ratio calculation was most appropriate on the basis of ease of interpretation and clinical usefulness. Swing time, stance time and step length were found to be the most useful gait parameters to assess for symmetry. Although related, swing time, stance time and step length ratios exhibit variation in the discrimination of post-stroke individuals, in their inter-relationships and in their relationship velocity. When when used together, swing time, stance time and step length asymmetry ratios may provide a complementary picture of the gait pattern and the quality of gait control. It was also demonstrated that swing time and stance time asymmetry were worse in later stages post-stroke when assessed cross-sectionally. In contrast, gait velocity did not exhibit this pattern. These results indicate that the control of gait (symmetry) may decline over time post-stroke, independent from the capacity for gait which remains constant (velocity). This dissociation in characteristics supports the concept that these two variables (symmetry and velocity) may represent separate features of post-stroke gait. Finally, individuals with sub-acute stroke are capable of altering the temporal symmetry of their gait in response to visual biofeedback. Individuals with sub-acute stroke differ in terms of the strategy they employ in response to biofeedback and the observed improvements in gait symmetry were not always achieved in the desired manner: increased use of the paretic lower extremity. This thesis presents new information regarding the asymmetrical nature of post-stroke gait. Future work may extend these findings to develop a comprehensive approach to gait measurement as well as gait interventions that encourage increased paretic limb use instead of compensatory behaviour.

Parkinson's is a neurological condition in which parts of the brain responsible for movements becomes incapacitated over time due to the abnormal dopamine equilibrium. Freezing of Gait (FOG) is one of the main Parkinson's Disease (PD) symptoms that affects patients not only physically but also psychologically as it prevents them from fulfilling simple tasks such as standing up or walking. Different auditory and visual cues have been proven to be very effective in improving the mobility of People with Parkinson's (PwP). Nonetheless, many of the available methods require user intervention or devices to be worn, charged, etc. to activate the cues. This research suggests a system that can provide an unobtrusive facility to detect FOG and falling in PwP as well as monitoring and improving their mobility using laser-based visual cues casted by an automated laser system. It proposes a new indoor method for casting a set of two parallel laser lines as a dynamic visual cue in front of a subject's feet based on the subject's head direction and 3D location in a room. The proposed system controls the movement of a set of pan/tilt servo motors and laser pointers using a microcontroller based on the real-time skeletal information acquired from a Kinect v2 sensor. A Graphical User Interface (GUI) is created that enables users to control and adjust the settings based on the user preferences. The system was tested and trained by 12 healthy participants and reviewed by 15 PwP who suffer from frequent FOG episodes. The results showed the possibility of employing the system as an indoor and on-demand visual cue system for PwP that does not rely on the subject's input or introduce any additional complexities to operate. Despite limitations regarding its outdoor use, feedback was very positive in terms of domestic usability and convenience, where 12/15 PwP showed interest in installing and using the system at their homes.

This thesis reports research on analysis of the variance of surface electromyogram (sEMG) for healthy participants and people suffering with Lower Back Pain (LBP) when they are walking and running. SEMG signal recorded when the participants were walking and running on a treadmill. The strength and duration of the muscle activity for each heel strike were the features. The results indicate that there was no significant difference in the variance and in the change of variance over time of the amplitude between the two groups when the participants were walking. However when the participants were running, there was a significant difference in the two cohorts. While there was an increase in the total variance over the duration of the exercise for both the groups, the increase in variance of the LBP group was much greater (order of ten times) compared with the participants with healthy backs. The difference between the two groups was also very significant when observing the change of variance over the duration of the exercise. From these results, it is suggested that variance of sEMG of the muscles of the lower back, recorded when the participants are running, can be used to identify LBP patients.

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: James G. Richards, College of Health Sciences. Includes bibliographical references.

Walking and running are essential tasks people take for granted every day. However, these are highly complex tasks that require significant neural control. This is complicated by the inherent redundancy of the nervous system and by physiological noise. Humans may adopt different control strategies to achieve different goals (environmental or task specific). More specifically, walking/running on a treadmill only requires that one not walk off the treadmill. Of the many possible strategies that can achieve this goal, humans attempt to maintain a constant speed from each stride to the next (Dingwell, John et al. 2010). However, how humans alter the stride-to-stride regulation of their gait when the task goals change (e.g., by maintaining stride length and/or time, during running, or during a predicted walk to run transition speed) has not yet been demonstrated. In the first two of three experiments conducted, healthy adults either walked or ran on a motorized treadmill at a comfortable speed under the following conditions: constant speed, constant speed with the stride length goal (targets on the treadmill), constant speed with the stride time goal (metronome), or constant speed with both stride length and stride time goals. In a third experiment, subjects walked and/or ran at a comfortable speed and also at their predicted theoretical walk to run transition speed. Goal functions derived from the task specifications yielded new variables that defined fluctuations either directly relevant to, or irrelevant to, achieving each goal. The magnitude of the variability, as well as the stride-to-stride temporal fluctuations in these variables, were calculated. During walking, subjects exploited different redundancy relationships in different ways to prioritize certain task goals (maintain stride speed) over others (maintain stride length or stride time) in each different context. In general, subjects made rapid corrections of those stride-to-stride deviations that were most directly relevant to the different task goals adopted in each walking condition. Thus, the central nervous system readily adapts to achieve multiple goals simultaneously. During running, subjects exhibited similar adaptations to walking, but over-corrected to prioritize maintaining stride speed even more strongly. This suggests that stepping control strategies adapt to the level of perceived risk. This purposeful adaptability of these stride-to-stride control strategies could be exploited to developing more effective rehabilitation interventions for patients with locomotor impairments. During the predicted walk-to-run speeds, subjects were able to largely exploit the redundancy within task goal, and effectively operated at “uncomfortable” speeds. These results suggest that the stride speed control is robust even with additional novel tasks and uncomfortable, abnormal speeds of locomotion. / text

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The components and alignment of a prosthesis have a large influence on the gait of an above knee amputee. The present criteria for determining the optimum alignment are mainly subjective, based on visual observation of the amputee's gait and by considering his/her comments. These comments however, are not always helpful. It has been reported that a range of alignments is acceptable to the patient and to the prosthetist, and it is believed that the optimum alignment can be selected from the range of acceptable alignments using biomechanical analysis. The socket is an important component in an above knee prosthesis and can affect the gait of the amputee. While the conventional socket is the quadrilateral, several problems have been reported with this type of socket. These include instability in the coronal plane, discomfort and restriction of the stump muscles causing limitations in the function of the prosthesis. In an attempt to overcome these problems the ischial containment (IC) socket was introduced in 1985. The biomechanical characteristics of the IC socket have, however, not been objectively assessed and compared with those of the quadrilateral socket. In this study, the effect of alignment adjustments on the gait variables for eight above knee amputees wearing quadrilateral sockets was investigated. Three of these amputees were also tested wearing IC sockets. The alignment of the prosthesis was systematically changed at the ankle, knee and socket. The primary aim of this project was therefore, to systematically vary the alignment of the prosthesis and to study the effects on the gait, and to compare the performance of amputees wearing IC and quadrilateral sockets. The ultimate goal of this research work is to provide a method for the determination of the optimum alignment from a range of acceptable alignments. A socket axis locator and a coordinate measuring system were used for measuring the prosthetic alignment accurately. Three TV cameras and two Kistler force plates were operated simultaneously and synchronously at a rate I of 50 Hz to acquire the displacements of the body segments and the ground reaction forces. All angular movements at the joints, moments and the temporal-distance parameters were calculated for both the prosthetic and the sound legs of the amputees, and for the right and left legs of ten normal subjects. The movement of the upper body was also recorded. Computer programs were developed to calculate and graphically present the above parameters in three dimensions. It was found that alignment changes affected the gait parameters of the whole body. At the prosthetic joints, certain changes in the alignment of the prosthesis resulted in specific alterations in the gait pattern. These effects were repeatable. The anterior-posterior (AP) joints moments and the fore-and-aft ground reaction force were found to be the most sensitive variables to alignment changes. The trunk rotations in the AP and medio-lateral planes, and the torso rotation in the transverse plane were also found to be sensitive to alignment changes, and the trunk was the main compensating element for any misalignment. At the sound side, the alignment changes resulted in noticeable changes in the AP joints moments and fore-and-aft ground reaction force. In the coronal and transverse planes, changes in the gait patterns that were analysed were not always consistent. These changes mainly depend on the method of compensation which is adopted by the patient. The IC socket showed improvements in the patient's performance in terms of higher speed of walking, comfort, improved symmetry in the two legs and the gait parameters are more comparable with those of normals.