Biomedical Physiology and Kinesiology - Theses, Dissertations, and other Required Graduate Degree Essays

Receive updates for this collection

Remote management of chronic heart failure patients using Internet supported technology

Author: 
Date created: 
2008
Abstract: 

Background: Heart failure results in high morbidity and mortality rates and is increasing in prevalence. Symptom and weight monitoring is essential as it has been associated with improved outcomes for patients. Purpose: To investigate the use of a website for the telemonitoring of heart failure patients, to assess its uptake, and evaluate its effect. Methods: Twenty patients were recruited and entered their daily weight and symptoms onto the website for six months. Patients were remotely monitored by a nurse and contacted as required. Results: Trends toward improvement were observed on the maintenance (p=0.039) and confidence subscales of the Self-Care of Heart Failure Index (p=0.069), Minnesota Living With Heart Failure® Questionnaire (p=0.337), six-minute walk test (p=0.124) and NT-proBNP (p=0.210). Participants and nurses demonstrated a favourable uptake of the website. Conclusions: The website was favourably accepted by both patients and nurses and its use is associated with improved outcomes.

Document type: 
Thesis
File(s): 
Senior supervisor: 
S
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

Factors affecting the efficacy of hip protectors during falls

Date created: 
2008
Abstract: 

Hip protectors represent a promising strategy for preventing fall-related hip fractures in the elderly. However, fractures still occur when wearing a protector. From a biomechanical perspective, the protective benefit of a hip protector should depend on the wearer’s body habitus, the fall orientation, and the position of the hip protector relative to the greater trochanter. This thesis is comprised of two studies designed to test this hypothesis. In the first study, I conducted experiments with human subjects which demonstrate that the reduction in peak magnitude and change in pressure distribution provided by a hip protector depends on body habitus and fall direction. In the second study, I conducted experiments with a hip impact testing system to show that force magnitude and distribution are affected by the position of the hip protector relative to the greater trochanter.

Document type: 
Thesis
File(s): 
Senior supervisor: 
S
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

Biomechanical testing of hip protectors and energy-absorbing floors for the prevention of fall-related hip fractures

Date created: 
2008
Abstract: 

The general objective of my thesis research was to characterize the stiffness and force distribution characteristics of the hip region during the impact phase of sideways falls, and to advance our understanding of the potential for external engineering interventions (e.g. hip protectors and compliant floors) to reduce hip fracture risk by reducing the force applied to the proximal femur during such falls. This thesis is comprised of five studies. In the first I characterized the degree of non-linearity in pelvic stiffness, and examined the influence of stiffness characterization methods on the accuracy of mathematical models (mass-spring and Voigt) in predicting impact dynamics during falls on the hip. In the second study I employed a pelvis release paradigm (a method of inducing low severity but clinically relevant falls) to examine whether soft shell hip protectors alter the distribution of force throughout the hip region during impact. The third study entailed a sensitivity analysis to determine the influence of mechanical test system properties on the force attenuation provided by hip protectors. In the fourth study I used pelvis release experiments to determine how the force applied to the pelvis is affected by body impact configuration and floor stiffness; I also examined the ability of a mass-spring model to predict these relationships. The final study used a mechanical fall simulator to assess the attenuation in femoral neck force provided by four low stiffness floors compared to a standard rigid floor, and assessed the influence of these floors on fall risk through a range of static and dynamic balance tests with fifteen elderly women. Overall, this thesis demonstrates that compliant floors and soft shell hip protectors substantially reduce the force applied to the proximal femur during the impact stage of sideways falls. Of equal importance, this work demonstrates the need for international standards for the biomechanical testing and market approval of these devices. These are essential steps for increasing the quality of hip protectors and compliant floors available in the marketplace, and consequently, for enhancing their ability to reduce hip fracture risk in vulnerable populations.

Document type: 
Thesis
File(s): 
Senior supervisor: 
S
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
Dissertation (Ph.D.)

Flavonoids and neuroprotection: biochemical and population-based analyses of potential neuroprotective factors related to dementia.

Date created: 
2008
Abstract: 

Dementia is a leading contributor to burden of disease in Canada and the world. With an aging population, there are projected increases in its global prevalence. Evidence suggests that some neurodegenerative disorders, such as Alzheimer’s disease, that lead to dementia are partly preventable, and that dietary intake of flavonoids may have relevant neuroprotective effects. The purpose of this study was to evaluate such potential for flavonoids using biochemical- and population-based analyses. Among 23 developed nations, negative correlations were found between rates of dementia and intake of all flavonoid groups, especially flavonols (p <0.05); these correlations were not significantly confounded by other relevant factors. The biochemical component helped elucidate possible mechanisms of flavonoid protection against heme-amyloidβ;-enhanced oxidative reactions with potential relevance to neurotoxicity. Overall, the evidence suggests that flavonoids, especially flavonols, and flavonoid-rich foods are part of a preventive dietary strategy, along with other health-promoting factors, towards decreasing rates of dementia.

Document type: 
Thesis
File(s): 
Senior supervisor: 
A
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

Electrophysiological correlates of performance monitoring and error detection in response to augmented feedback

Date created: 
2005
Abstract: 

The ability to monitor performance and detect errors is essential for intelligent behaviour. Motor behaviourists have long been interested in how information about the performance of motor skills is used to facilitate learning. Recently, cognitive neuroscientists have also been interested in studying performance monitoring, particularly after the discovery of an event-related potential (ERP) component linked to error processing. This ERP component, aptly termed the error-related negativity (ERN), is observed in response to physical errors and also upon presentation of augmented feedback indicating performance errors or monetary losses. The neural generator of the ERN is thought to be located in the anterior cingulate cortex (ACC), a structure situated in the medial frontal wall of the human frontal lobe. ERN studies along with functional imaging experiments have suggested that ACC acts as part of an error detection system. In this thesis I challenge the notion that ACC activity, as measured by feedback ERN (f-ERN), is in fact related to errors. Experiment 1 measured participants' expectation of feedback by asking them to estimate their performance on each trial of an anticipation-timing task. The results show that f-ERN is elicited by feedback indicating both correct performance and errors, so long as expected feedback does not match the actual feedback. Experiment 2 replicated the results of Experiment 1 without asking participants to estimate their performance. This was accomplished by presenting false correct feedback in situations in which participants made errors. Taken together, the results of Experiments 1 and 2 suggest that ACC might not be selectively activated by errors, and that f-ERN might not be elicited exclusively by feedback indicating performance errors and monetary losses. I propose that f-ERN is the outcome of a more general system that searches the environment for violations of expectancy.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

Retrograde transport rates in the G93A mouse model of amyotrophic lateral sclerosis

Date created: 
2005
Abstract: 

Amyotrophic Lateral Sclerosis is a late-onset, progressive neuromuscular disease involving degeneration of corticospinal tracts and motor neurons in the brain stem and spinal cord. Recently, it has been suggested that ALS results from a "dying back" axonopathy as opposed to originating in the motor neuron cell body. This is supported by a reduction of neuromuscular junctions in skeletal muscle prior to symptom onset and motor neuron death. It is known that there is a slowing of retrograde transport when comparing presymptomatic and end-stage mice; however, when during disease progression this occurs has not been clarified. By using a retrograde tracer, I sought to observe retrograde transport rates during disease progression in the G93A mouse, a murine model of ALS. Results indicate that retrograde transport is attenuated before symptom onset, loss of motor neurons, and precedes alterations in anterograde transport indicating this is one of the earliest pathological events in ALS.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

Neural mechanisms of incorporating prior knowledge of movement experience into feedforward motor commands

Date created: 
2008
Abstract: 

The central nervous system (CNS) predicts the amount of force needed so that the hands can grasp and hold objects securely. How does the CNS compute the dynamics and produce the appropriate forces required to perform tasks like holding a cup or a needle? It has been proposed that the CNS combines a priori information about the properties of a movement with sensory information from the peripheral sensory receptors, to obtain optimal force estimation. We propose a novel task that requires the subjects to experience the magnitude of a first torque pulse and subsequently estimate and compensate a second torque pulse that is equal in magnitude. By varying the magnitude of the torque pulses according to a normal probability distribution with a large standard deviation, we investigate the neural mechanisms of how the CNS combines prior knowledge of movement experience with sensory feedback, to produce accurate feedforward motor commands.

Document type: 
Thesis
File(s): 
Senior supervisor: 
T
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

The influence of voluntary movement dynamics on postural stability borders and balance recovery strategies

Date created: 
2008
Abstract: 

Falls are the number one cause of unintentional injury, and often occur during tasks such as bending and reaching. My thesis examined how the dynamic features of an ongoing task influenced one’s ability to maintain and recover balance. In study one, I conducted experiments and mathematical modeling to show there was a tradeoff between the frequency and amplitude of heel-toe rocking movements that can be performed without losing balance. The central nervous system (CNS) must account for this tradeoff in planning stable movements. In study two, I conducted experiments to perturb participants’ balance at different phases of the rocking cycle, and found that, when the initial position was constant, the velocity at the time of the perturbation influenced the kinematics and muscle activities associated with the recovery response. This indicated an ability of the CNS to adapt the postural response to the nature of the ongoing task.

Document type: 
Thesis
File(s): 
Senior supervisor: 
S
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
(Kinesiology) Thesis (M.Sc.)

Biomechanics of Postural Stability in the Elderly

Author: 
Date created: 
2004
Abstract: 

Falls cause substantial death and morbidity in the elderly. Fall risk depends on ability to maintain balance during daily activities and ability to recover balance following a perturbation such as a slip or trip. To guide the design of fall prevention programs, we need an improved understanding of the biomechanical variables that govern ability to recover balance. The aims of this thesis were to determine (1) the relative importance of strength versus speed-of-response variables in explaining age differences in balance recovery performance with the ankle strategy, and (2) the association between variables related to ability to recover balance and variables related to ability to maintain balance. To address Aim 1, young and elderly women were supported in a forward leaning position by a horizontal tether and instructed to recover an upright vertical stance by contracting their ankle muscles. The maximum initial lean angle where they could recover balance without release of the tether (which depends primarily on strength) was 19.6% smaller for elderly than young. The maximum initial lean angle where they could recover balance after the tether was suddenly released (which depends on strength and speed-of-response) was 36.1% smaller for elderly. Moreover, between-group differences in performance were related to both strength and speed-of-response. Peak ankle torque was 7.7% smaller in elderly than young during tether release trials, reaction time was 27% slower in elderly, due to a lengthened muscle response latency, and rate of ankle torque generation was 15.6% slower in elderly. These results suggest that exercise-based fall prevention programs should include balance and agility training, in addition to strength training. To address Aim 2, the same elderly subjects participated in postural steadiness experiments, where the amplitude, velocity, and frequency of their centre-of-pressure displacement were measured during quiet stance. Postural steadiness during quiet stance and ability to recover balance with the ankle strategy were not associated, perhaps because postural steadiness during quiet stance is controlled partly by anticipatory strategies, while balance recovery following a perturbation is governed by reactive strategies. These results support the need to measure both balance recovery and postural steadiness in balance assessments of the elderly.

Document type: 
Thesis
File(s): 
Department: 
School of Kinesiology - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Adaptive control of goal-oriented human arm movement

Author: 
Date created: 
2003
Document type: 
Thesis
File(s): 
Department: 
Theses (School of Kinesiology) / Simon Fraser University
Thesis type: 
Thesis (M.Sc. (Kinesiology))