Young Adult And Adolescent Balance Control Strategies During A Dual-Task Stone-Stepping Paradigm, Emily Ford

Theses and Dissertations (Comprehensive)

Stone-stepping demands greater attention and visuomotor integration, as it requires precise foot placement. The amount of attention required during locomotion is typically assessed with a secondary task, by analyzing the dual-task cost. Adolescents are suggested to have a greater dual-task cost than young adults and demonstrate balance control impairments while dual-tasking walking. The purpose of the current study was to explore the balance control differences between adolescents and young adults during a stone-stepping paradigm. We hypothesized that adolescents would experience greater balance control deficits while performing the secondary task compared to the young adults, especially while on the uneven terrain. …

Sensory Conflict Alters Visual Perception Of Action Capabilities During Crossing Of A Closing Gap In Virtual Reality, Natalie A. Snyder, Michael E. Cinelli

Kinesiology and Physical Education Faculty Publications

The somatosensory, vestibular, and visual systems contribute to multisensory integration, which facilitates locomotion around obstacles in the environment. The joystick-controlled virtual reality (VR) locomotion interface does not preserve congruent sensory input like real-walking, yet is commonly used in human behaviour research. Our purpose was to determine if collision avoidance behaviours were affected during an aperture crossing task when somatosensory and vestibular input were incongruent, and only vision was accurate. Participants included 36 young adults who completed a closing-gap aperture crossing task in VR using real-walking and joystick-controlled locomotion. Participants successfully completed the task using both interfaces. Switch point between passable …

Exploring Upper Limb Sequence Behaviours In Egocentric And Allocentric Reference Frames, Robyn Brooke Grunberg

Theses and Dissertations (Comprehensive)

Voluntary behaviours, such as reaching, are essential for manipulating and exploring our environment. The current body of literature, however, has predominantly investigated reach behaviours through tasks such as peg-moving, tapping, dotting, and circle drawing. The objective of this study was to investigate the order and direction of reaching behaviours in a sequential tapping task in both an egocentric and an allocentric reference frame. Gaze behaviours were observed to explore intent to reach in the sequential task. Implementing reference frames in an upper limb motor control task might be of clinical importance when exploring rehabilitation techniques post-traumatic brain injury. It was …

Spinal Motor Neuron Excitability And Balance Control Changes Following Downslope Walking, Nikki Aitcheson-Huehn

Theses and Dissertations (Comprehensive)

Downslope walking (DSW) has been proposed as a rehabilitation tool for people with Multiple Sclerosis (PwMS) although there are mixed findings in young adults (YA) regarding the balance control changes, despite both populations experiencing depressed spinal motor neuron (MN) pool excitability. Our aim was to determine whether YAs could demonstrate improved balance control in conjunction with SOL H reflex depression (estimate of spinal MN excitability) following DSW. We also aimed to determine whether reciprocal inhibition was a potential mechanism for H reflex depression via conditioned SOL H reflexes. Thirty young adults (23±1.4y, 6 males) were assigned to 30-minutes of DSW …

The Task At Hand: Fatigue-Associated Changes To Corticospinal Excitability During Writing, Kezia Cinelli

Theses and Dissertations (Comprehensive)

Corticospinal excitability as measured via transcranial magnetic stimulation (TMS) is highly dependent on the task being performed at the time of stimulation. As such, this study sought out to measure corticospinal excitability during the relevant, daily task of writing and compare it to the conventional abduction task often utilized. We used single-pulse motor evoked potentials (MEPs) to provide a measure of corticospinal excitability and cortical silent period (CSP) duration, and paired-pulse conditioned MEPs to assess short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) recorded from the right first dorsal interosseous (FDI) of 19 participants on two randomized and counter-balanced days. …

Physical Fatigue Negatively Affects Decision-Making During A Closing-Gap Aperture Crossing Task When Using Joystick-Controlled Locomotion, Natalie Snyder

Theses and Dissertations (Comprehensive)

Goal-direct locomotion is made possible through the integration of sensory input from the visual, vestibular, and somatosensory system. However, changes in collision avoidance behaviours and action capabilities (i.e., affordances) may occur when a sensory conflict is introduced (i.e., via incongruent input from a sensory system). Further, changes to the person (such as physical fatigue) may have negative implications on the cognitive abilities of an individual following physically fatiguing exercise. This in turn could affect an individual’s ability to avoid collisions with objects or other individuals in their environment. Thus, the objective of this thesis was to explore how physical fatigue …

Exploring The Potential Neuromuscular Adaptations Associated With Sprint Interval Training, Samer Hassan

Theses and Dissertations (Comprehensive)

Purpose. The primary purpose of this study was to explore the acute (a single sprint interval training or SIT exercise session) and chronic (3 weeks of SIT) neural adaptations that may occur with the SIT (30 second sprint and 4 minutes of rest).

Methods. 28 recreationally active participants were pseudo-randomized into either a control group (CTRL) or training group (TR) and tested at 4 time points after baseline VO_2max testing. Participants were tested, pre-training/pre-fatigue, pre-training/post-fatigue, post-training/pre-fatigue, post-training/post-fatigue. The fatigue protocol was a SIT session (4 x 30-s sprints). The TR completed a 3-week running SIT protocol (3x/wk) progressing …

The Sidewalk Problem: An Examination Of The Avoidance Behaviours Employed During A Head-On Collision Course With An Approaching Person, Lana M. Pfaff

Theses and Dissertations (Comprehensive)

Individuals use visual information in order to guide their avoidance behaviours. More specifically, individuals may directly perceive the time prior to colliding with an approaching obstacle (i.e., time to contact, TTC) in order to determine when to avoid. However, if the path of the approaching obstacle is highly predictable, individuals do not use a consistent TTC (Cinelli & Patla, 2007). Additionally, individuals use body- and action-scaled information to control their movements (Fajen, 2013). These avoidance behaviours differ when avoiding a human obstacle compared to an inanimate object (Hackney, Cinelli, & Frank, 2015; Knowles, Kreuser, Haas, Hyde, & Schuchart, 1976). As …

Differences In Perceptions Of Aperture Crossing During A Virtual Reality Choice Reaction Task Between Non-Athletes And Varsity Athletes, Jaime Mitchell

Theses and Dissertations (Comprehensive)

Background: Vision will guide the actions and behaviors that allow us to circumvent environmental obstacles. When passing through a gap, individuals will consistently elicit a shoulder rotation (SR) if the gap is 1.4 times their shoulder width (SW) or narrower, with this behaviour being produced under various environmental conditions. Although a few studies have investigated perceptual predictions regarding gap passage, the effect of physical activity and the differences between trained and untrained athlete’s behaviours has not been examined. This study investigated the perceptual judgements of non-athletes and varsity athletes regarding the action they would utilize to pass through a dynamically …

Task-Dependent Modulation Of Cortical Excitability And Balance Control In Individuals With Post-Concussion Syndrome, Kristen Kaster, Jayne M. Kalmar Ms., Michael E. Cinelli Mr

Theses and Dissertations (Comprehensive)

In most cases, symptoms resolve between 7-10 days post-concussion. However, in 10-15% of the concussed population, symptoms can remain unresolved for months to years following the head injury. The purpose of this thesis was two-fold, and was broken up into two studies, where the same individuals participated in both studies. The purpose of the first study was to quantify the differences in balance control between individuals with PCS (i.e., had been experiencing symptoms for <30 days) and non-concussed individuals during a lower-limb reaching task. Participants completed a static balance assessment before and after a lower-limb reaching task, which incorporated a Go/No-Go paradigm. Results from this study revealed no differences in the static stability assessments, however, individuals with PCS demonstrated increased medial-lateral COP displacement as well as greater trunk pitch during the reaching task. Overall, the findings reveal persistent balance impairments in individuals with PCS, which may put this population at an increased risk of further injury. The purpose of the second study was to assess task-dependent modulation of cortical excitability prior to planned index finger abduction contractions comparing a non-concussed population to a population with PCS. The protocol in this study consisted of both single and paired-pulse transcranial magnetic stimulation (TMS) which was applied prior to the beginning of 3 different tasks (i.e., a rest condition with no plan to contract, a precision contraction, and a powerful contraction). In addition to the three tasks, participants also had to respond to a Go/No-Go cue. The results of this study revealed an increase in excitability prior to a precision contraction in both non-concussed and PCS groups. No differences in task-dependent modulation were found between the two groups with respect to intracortical facilitation and inhibition, however a negative correlation between number of symptoms reported (SCAT3 symptom evaluation) and intracortical facilitation was revealed. The increase in corticospinal excitability prior to a precision contraction was not explained by the two cortical mechanisms we assessed and may therefore be due to spinal modulation or a different cortical mechanism. Overall, based on the results from this thesis, it appears that individuals with PCS have balance impairments, which may be a result of an inability to maximally activate their postural muscles. Furthermore, it appears that those individuals who reported a higher number of symptoms had greater reductions in intracortical facilitation, likely reflecting the heterogeneity of this clinical group.

Peripheral Visual Motion Sensitivity In Previously Concussed, Asymptomatic Individuals, Alyssa Prangley

Theses and Dissertations (Comprehensive)

Background: Individuals acquire information about self-motion from the environment which specifies actions necessary to be successful (Fajen & Matthis, 2011). However, concussed individuals demonstrate residual disturbance in execution of postural movement at 30 days post injury, depicting an impaired ability to perceive self-motion in a visually conflicting environment (Slobounov et al. 2006). The objective of this thesis was to investigate the extent to which one’s behaviours on a central field of view task are influenced by the amount and type of peripheral visual movement during a collision avoidance task, as well as to determine the additive effects of changes to …

The Effects Of A Low Back Pain Vibration Modality On Trunk Postural Control, Adam R. Cornwall

Theses and Dissertations (Comprehensive)

Abstract

Introduction: Low back pain (LBP) is prevalent worldwide and is affecting even more individuals as the population ages. There has recently been an increase in production of low back pain (LBP) vibration modality belts that apply localized vibration to the lumbar region of the spine as it has shown to reduce pain. However, vibration is also known to perturb muscle spindles and thus interfere with proprioception. If a LBP vibration modality causes a proprioceptive deficit in the trunk lumbar region it could potentially increase an individual’s risk of injury due to poor postural control. Therefore, the effects of a …

Estimates Of Persistent Inward Current Decline In Human Soleus Motor Units During Fatigue, Kirby Mendes

Theses and Dissertations (Comprehensive)

Fatigue is defined as any exercise induced reduction in strength or power, and can be attributed to central and peripheral components. Many central and peripheral mechanisms have been extensively studied, but few studies have looked at the changes in the intrinsic properties of motor neurons and their contribution to fatigue. Persistent inward current (PIC) is an important intrinsic property of motor neurons responsible for setting a large increase in the gain of motor output and may contribute to fatigue. Inhibitory inputs such as reciprocal inhibition (RI) have been shown to turn off PICs and reducing the gain of output. PIC …

An Exploratory Approach To Manipulating Dynamic Stability: Investigating The Role Of Visual Control During A Precision Foot Placement Task, Russell Cg Kennedy

Theses and Dissertations (Comprehensive)

ABSTRACT

Background: The visual system provides the body with an accurate sensory system; designed to gather information at a distance and acts as a feedforward control mechanism during human locomotion. By doing so, visual information contributes coordination of the head-arm-trunk (HAT) segment and modulating foot placement. The purpose of this study was to examine the effects of a constrained pathway during a complex navigational stone-stepping task on HAT segment control and how the visual system guides locomotion during a complex foot placement task.

Methods: Nine university-aged females (Mean age: 22.5 years old +/-1.75) participated in this study. Participants …

The 2d:4d Ratio, Handedness, And Sex Across The Age Span, Helen A M Protopapas Ms.

Theses and Dissertations (Comprehensive)

The ratio of the difference between the 2nd and 4th digits of the hand (2D:4D ratio) has been demonstrated to be an indirect indicator of prenatal testosterone levels. Prenatal testosterone has been found to play a role in brain development in utero, and thus may influence lateral asymmetries, such as handedness. Consequently, one of the aims of the current study was to examine relationships between the 2D:4D ratio, hand preference, and hand performance with the factors of sex (males and females), handedness (right handers and left handers), and age considered. A total of 104 participants were tested, 90 right handers …

The Influence Of Joint-Site, Limb Preference, And Physical Activity On Joint Position Sense, Amanda N. Forsyth

Theses and Dissertations (Comprehensive)

Joint position sense provides the body with information about where limb segments are relative to one another in three-dimensional space. The ability to utilize this sense is imperative for smooth, coordinated, and accurate movement in everything from activities of daily living to competitive sport (Ghez & Sainburg, 1995). Researchers currently use joint position sense as a measure of proprioceptive acuity. However, limited research has investigated the influence of potential confounding factors on proprioception. Specifically, literature on how joint-site specificity and lateral preference influence proprioception displays several incongruent findings. Therefore, the purpose of the current study was (1) to determine if …

The Effects Of External Focus Of Attention Exercise Rehabilitation On Dual Task Walking In Parkinson's Disease, Eric N. Beck

Theses and Dissertations (Comprehensive)

Parkinson’s disease impairs control of well-learned movements, and therefore, individuals with Parkinson’s disease are forced to walk with greater conscious control. This causes difficulties while walking and completing a secondary task simultaneously (dual tasking), in that distractions from conscious control of walking increase the risk of falls and injury. Although, attention-based exercise may be a potential avenue to decrease the demands associated with walking in Parkinson’s disease. For example, an external focus of attention (on manipulated objects) has been found to recruit the networks that are important for walking with little conscious control (automatic control networks). In contrast, an internal …

Alternate Foot Placement: Investigating The Role Of Gait Parameters, Planar Obstacle Complexity, And Athletic Training, Brittany A. Baxter

Theses and Dissertations (Comprehensive)

On a daily basis modifications, based upon environmental demands and the capabilities of the individual, are made to the locomotor pattern to enable avoidance of undesirable landing areas (i.e. planar obstacles). Athletes and dancers have been suggested to have superior perception-action coupling compared to non-athletes, allowing them to perform various tasks at a greater speed without a loss of precision (Federici et al., 2005; Gerin-Lajoie et al. (2007). The current study assessed non-athletes, dancers, and field athletes to investigate whether training influences the maintenance of forward progression and stability in relation to alternate foot placement during planar obstacle avoidance. Eleven …

Estimates Of Persistent Inward Current In Human Motor Neurons During Postural Sway, Ryan Foley, Jayne M. Kalmar Dr.

Theses and Dissertations (Comprehensive)

Persistent inward current (PIC) is a membrane property critical for increasing gain of motor neuron output. In humans, most estimates of PIC are made from plantarflexor or dorsiflexor motor units with the participant in a seated position with the knee flexed. This seated and static posture neglects the task-dependent nature of the monoaminergic drive that modulates PIC activation. Seated estimates may drastically underestimate the amount of PIC that occurs in human motor neurons during functional movement. The current study estimated PIC using the conventional paired motor unit technique which uses the difference between reference unit firing frequency at test unit …

Influence Of Planning Resources On Gait Control In Parkinson’S Disease, Frederico P. Faria

Theses and Dissertations (Comprehensive)

Movement disturbances in individuals with Parkinson’s disease (PD) have been associated with difficulties to plan complex actions. Performance of simple and complex actions overloads resources for individuals with Parkinson’s disease (PD). However, it is unclear if central resources required to plan gait adjustments while walking exacerbate gait disturbances of patients with PD. More specifically, it is unclear how gait impairments, sensory processing, and the dopaminergic system influence the load on processing resources (e.g. cognitive load) during the planning of step modifications. In order to investigate the relative influence of these factors on cognitive load and its impact on gait control, …

An Athletic Approach To Studying Perception-Action Integration: Does Sport-Specific Training, And The Impact Of Injury, Influence How Individuals Visually Guide Navigation?, Carmen Baker, Jennifer Campos Ph.D, Michael E. Cinelli Ph.D.

Theses and Dissertations (Comprehensive)

The objective of this thesis was to investigate perception-action integration capabilities of individuals during a choice navigation task. This task assessed navigation strategies in open space while individuals avoided colliding with two vertical obstacles that created a body-scaled, horizontal gap, at three varying obstacle distances from the starting location (3m, 5m, 7m). The two studies completed in this thesis employed the same paradigm to assess the hypothesized group differences. Gaze behaviours and kinematics of navigation strategies were compared between: 1) athletes specifically trained in navigating in open space versus non-athletes; and 2) athletes with post-concussion syndrome (PCS) versus non-concussed, specifically …

The Effect Of Training Older Adults In Tai Chi And Compensatory Stepping On Balance Control, Hannah L. Moore Miss

Theses and Dissertations (Comprehensive)

Abstract

Introduction: In Canadian society, there is a growing prevalence of older adults and one of the main problems facing this generation today is the risk of falling. Tai Chi (TC) is a martial art that has demonstrated improvements in balance control. It uses a series of fluid movements that engage head, neck and trunk rotation while simultaneously reducing base of support. In addition, it has been demonstrated that training older adults by administering unpredictable perturbations to challenge balance better equips them to react successfully in response to balance perturbations. This study aims to determine the potential balance specific benefits …

The Application Of Hand Switch Costs Towards Understanding Bimanual Movements: An Investigation Throughout The Lifespan, Gordon Young

Theses and Dissertations (Comprehensive)

The objective of the present study was to examine the different kind of switch costs among a varied population using a modified bimanual serial reaction time task. Alternating between responses produce a cost of increased response time, which is termed a switch cost. However, not all switch costs are equal, and its effect on response time is dependent on what previous hand and digit combination was utilized. A detachable touchscreen tablet PC running a custom built JavaScript based software prompted participants to press down with their digits (2^nd-5^th) to corresponding buttons which would light up in …

The Effect Of Gvs On Path Trajectory And Body Rotation In The Absence Of Visual Cues During A Spatial Navigation Task, Tanya Karn

Theses and Dissertations (Comprehensive)

Background: The vestibular system has been shown to contribute to mechanisms of locomotion such as distance perception. Galvanic vestibular stimulation (GVS) is a tool used to perturb the vestibular system, and causes significant deviations in path trajectory during locomotion. Previous research has suggested that applying GVS during straight-line locomotion tasks is not sufficient to determine the effects of the vestibular system on locomotion. However, spatial navigation challenges one’s ability to navigate throughout the environment using idiothetic cues to constantly update one’s position. The purpose of the current study was to determine the effects of GVS on both path trajectory and …

Laterality Across The Lifespan: The Effects Of Task Complexity, Nicole Williams

Theses and Dissertations (Comprehensive)

The current study aimed to build on the work of Gooderham & Bryden (2013) by comparing the effects of task complexity on hand selection across the lifespan. It was hypothesized that the increasing complexity of a task would override a biomechanically efficient movement such that participants would use only the preferred hand to complete the task. It was also hypothesized that older adults would perform similarly to young children with respect to switch points in space. Four age groups of participants (3-7 year olds, 8-12 year olds, 18-25 year olds and adults over 70 years) completed the newly designed Hand …

Gait Initiation Mechanics In Concussed Varsity Athletes, Adam Harper

Theses and Dissertations (Comprehensive)

Concussions are a common and potentially serious injury that affects athletes across multiple sports. More than ever concussions are now at the forefront of sport-related research.

Current research indicates that in a cohort of Canadian junior hockey players examined during the 2009-2010 season showed a rate of concussion at 36.5% of all athletic injuries (Echlin et al., 2010). This rate of concussion injury indicates that proper evaluations and examination tools are key to successful management of concussions. The objective of this study was to determine whether a functional task such as gait initiation is able to quantify stability difference following …