Kinesiology and Health Sciences
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This is the collection for the University of Waterloo's Department of Kinesiology and Health Sciences. It was known as the Department of Kinesiology until January 2021.
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Item Stabilization Strategies of the Lumbar Spine in Vivo(University of Waterloo, 2002) Grenier, SylvainIn developing a method of quantifying stability in the lumbar spine Cholewicki and McGill (1996) have also broached the notion of sufficient stability, where too much stiffness (and stability) would hinder motion. Thus people highly skilled at maintaining stability may use different and optimal strategies, where sufficient stability is maintained. The purpose of this work was to explore the contributors to sufficient stability, how they coordinate and relate to injury mechanisms. This work represents a cascade of investigations where. 1) To explore the balance of various sources of stiffness and their effect on the critical load and post-buckling behaviour, simulations were undertaken where the buckled configuration of the spine was predicted and its stability in this new configuration was assessed. 2) The various sources of stiffness contributing to stability in the lumbar spine have been in some cases found to be deficient. The question of how these deficiencies place individuals at risk of instability, if at all, remains unresolved. A challenged breathing task was used to determine if there was a difference in stabilizing potential between healthy individuals and low back pain sufferers. Given that differences in stabilizing potential are apparent, several tasks which included a predetermined motor strategy, such as 3)pressurizing the abdomen and 4) abdominal hollowing vs. muscle bracing, were evaluated to determine if individuals can utilize motor strategies to augment stability. The stabilizing potential of abdominal pressure (IAP) and its interaction with muscle activation was evaluated. Some individuals are more skilled at stabilizing their lumbar spine than others. Some consciously controlled motor strategies are better stabilizers than others. These strategies highlight the relative contributions of various components (posture, passive tissue, muscle activation, and load) in that no single muscle dominates stability and IAP appears to augment stability beyond muscle activation alone. The margin of safety is considerable and depends on the task at hand, but it is possible to speculate on which tissues are at greatest risk of injury.Item The Dilemma of Proxy-Agency in Exercise: a Social-Cognitive Examination of the Balance between Reliance and Self-Regulatory Ability(University of Waterloo, 2005) Shields, Christopher AndrewSocial Cognitive Theory (SCT: Bandura, 1997) has been used successfully in understanding exercise adherence. To date, the majority of the exercise research has focused on situations of personal agency (i. e. , self as agent: e. g. , McAuley & Blissmer, 2000). However, there are a number of exercise situations in which people look to others to help them manage their exercise participation by enlisting a proxy-agent (Bandura, 1997). While using assistance from a proxy can promote the development of self-regulatory skills, Bandura (1997) cautions that reliance on a proxy actually reduces mastery experiences which can result in an inability to self-regulate one?s behaviour. Although research examined proxy-agency in exercise (e. g. , Bray et al. , 2001), the issue of reliance on the proxy at the expense of the participant?s ability to adjust to exercise without that agent has not been investigated. This potential dilemma of proxy-agency in exercise was at the core of this dissertation and was investigated in a series of three studies. Study 1 investigated whether those who differed in preferred level of proxy-contact also differed in their social-cognitions both within and outside a proxy-led exercise context. In addition, the relationships between proxy-efficacy, reliance and self-efficacy were examined. Results indicated that participants who preferred regular contact with an exercise proxy had lower self-regulatory efficacy, lower task efficacy, and weaker intentions in a proxy-led exercise context. Further, high-contact participants were shown to be less efficacious in dealing with the behavioural challenge of sudden class elimination. It was also demonstrated that higher reliance on the instructor was associated with lower self-efficacy and higher proxy-efficacy. Study 2 served to extend the findings of Study 1 through the examination of behavioural differences characteristic of differential levels of preferred proxy contact and the reasons for use of proxy-agency. It was found that exercise class participants preferring high contact with a proxy found exercising independently more difficult than did their low contact counterparts. It was also found that when faced with class elimination, those preferring high contact chose a self-managed activity alternative less frequently than did those preferring low contact. High contact participants also reported feeling less confident, less satisfied and perceived their alternative activity as more difficult than did those preferring low contact. In examining the reasons for preferring high proxy-contact, results indicated that a preference for high contact was associated with having had less experience exercising independently and allotting more responsibility for in-class participation to the class instructor as compared to preferring low proxy-contact. Study 3 used Lent and Lopez?s (2002) tripartite model of efficacy beliefs to examine the associations between relational efficacies (i. e. , other-efficacy and relation inferred self-efficacy (RISE) beliefs, proxy-efficacy) and various social cognitions relevant to proxy-agency. Results revealed that relational efficacies were distinct yet related constructs which additively predicted self-regulatory efficacy, satisfaction, intended intensity and reliance. Relational efficacies were also shown to make unique contributions to the predictions of the relevant social-cognitions. It was also demonstrated that RISE beliefs were associated with the attributions participants made. Specifically, higher RISE beliefs was associated with making more internal, personally controllable and stable attributions. These results represent the initial examination of relational efficacy beliefs in the exercise literature and provide additional evidence of the proxy-agency dilemma in exercise. Taken together, the present series of studies both support theorizing by Bandura on the dilemma of proxy-agency and represent an extension of the existing literature of proxy-agency in exercise. Results suggest that seemingly healthy, regularly exercising adults who choose to employ proxy-agency may be at risk for nonadherence in situations of behavioural challenge. The current findings have important implications for exercise leaders and interventionists as they must be aware of the balance between helping and hindering.Item An Identity Theory and Social Cognitive Theory Examination of the Role of Identity in Health Behaviour and Behavioural Regulation(University of Waterloo, 2005) Strachan, ShaelynThe self has been identified as the ?psychological apparatus that allows individuals to think consciously about themselves? (Leary & Price Tangney, 2003, p. 8). Further, the self has been identified as a worthwhile construct of investigation in relation to health behaviour (Contrada & Ashmore, 1999). Two self-related variables that have been useful in the study of health behaviour are identity (e. g. Anderson, Cychosz, & Franke, 1998; Petosa, Suminski & Hortz, 2003; Storer, Cychosz, & Anderson, 1997) and self-efficacy (Maddux, Brawley & Boykin, 1995). Identity Theory posits that individuals regulate their behaviour in a manner that is consistent with their goal identity (Gecas & Burke, 2003). Social Cognitive Theory provides a means of measuring social cognitions that may be important in behavioural regulation relative to identity. Further, self-efficacy beliefs may influence individuals? persistence at aligning their identity and behaviour. Research to date has investigated the link between identity and exercise (e. g. Anderson, Cychosz & Franke, 1998; Petosa, et al. , 2003). Further, researchers are beginning to investigate the link between identity and other health behaviours (e. g. Armitage & Conner, 1999; Kendzierski and Costello, 2004; Storer, Cychosz, & Andersen, 1997). However, research has not utilized the predictive frameworks offered by Identity Theory and Social Cognitive Theory to investigate the relationships between identity, behaviour and behavioural regulation.
Study One investigated the role of identity and self-efficacy beliefs in the maintenance of vigorous physical activity. Results were consistent with both Identity Theory and Social Cognitive Theory. Individuals who strongly identified with the runner identity expressed stronger task and self-regulatory efficacy beliefs. They also exercised more frequently and for longer durations than did those who only moderately identified with running.
Study Two further explored the relationship between exercise identity, exercise behaviour and the self-regulatory processes involved in behavioural regulation. Identity Theory and Social Cognitive Theory were used as guiding frameworks for this investigation. High and moderate exercise identity groups were compared in term of their affective and cognitive reactions to a hypothetical behavioural challenge to exercise identity. Consistent with Identity Theory, results indicated that participants appeared to be regulating their behaviour in a manner that was consistent with their exercise identity. Specifically, in response to the behavioural challenge to identity, high exercise identity participants, in contrast to their moderate counterparts, showed (a) less positive and (b) greater negative affect about the challenge, (c) higher self-regulatory efficacy for future exercise under the same challenging conditions, (d) stronger intentions for this future exercise, as well as for (e) using self-regulatory strategies to manage the challenging conditions and (f) intending to exercise more frequently under those conditions.
Study Three investigated whether identity with healthy eating could also be useful in understanding behaviour and behavioural regulation. Similar to Study Two, extreme healthy-eater identity groups? reactions to a hypothetical behavioural challenge to identity were compared. Results were similar to Study Two. Participants responded in a manner that suggested that they would regulate their future behaviour relative to their healthy-eater identity. In response to the behavioural challenge to identity, individuals who highly identified as healthy-eaters expressed less (a) positive affect, greater (b) negative affect, (c) self-regulatory efficacy for managing their healthy eating in the future challenging weeks, (d) intentions to eat a healthy diet, (e) generated more self-regulatory strategies and had (f) stronger intentions to use those strategies in future weeks under the same challenging conditions than did individuals who moderately identified themselves as healthy-eaters. Further, prospective relationships between healthy-eater identity and social cognitive variables, and healthy eating outcomes were examined. As was found in Study One in the context of exercise, healthy-eater identity and social cognitions predicted healthy eating outcomes.
Taken together, the three studies suggest that identity may be important in understanding health behaviours and the regulation of these behaviours. Also, the present findings support the compatible use of Identity Theory and Social Cognitive Theory in the investigation of identity and health behaviour.Item Determinants And Strategies For The Alternate Foot Placement(University of Waterloo, 2005) Moraes, RenatoUndesirable landing area (e. g. , a hole, a fragment of glass, a water puddle, etc) creates the necessity for an alternate foot placement planning and execution. Previous study has proposed that three determinants are used by the central nervous system (CNS) for planning an alternate foot placement: minimum foot displacement, stability and maintenance of forward progression. However, validation of these determinants is lacking. Therefore, the general purpose of the series of studies presented here is to validate and test the generality of the decision algorithm of alternate foot placement selection developed previously. The first study was designed to validate the use of a virtual planar obstacle paradigm and the economy assumption behind minimum foot displacement determinant. Participants performed two blocks of trials. In one block, they were instructed to avoid stepping in a virtual planar obstacle projected in the screen of a LCD monitor embedded in the ground. In another block, they were instructed to avoid stepping in a real hole present in walkway. Behavioral response was unaffected by the presence of a real hole. In addition, it was suggested that minimum foot displacement results in minimum changes in EMG activity which validates the economy determinant. The second study was proposed to validate the stability determinant. Participants performed an avoidance task under two conditions: free and forced. In the free condition participants freely chose where to land in order to avoid stepping in a virtual obstacle. In the forced condition, a green arrow was projected over the obstacle indicating the direction of the alternate foot placement. The data from the free condition was used to determine the preferred alternate foot placement whereas the data from the forced condition was used to assess whole body stability. It was found that long and lateral foot placements are preferred because they result in a more stable behavior. The third study was designed to validate the alternate foot placement model in a more complex terrain. Participants were required to avoid stepping in two virtual planar obstacles placed in sequence. It was found that participants used the strategy of planning the avoidance movement globally and additional determinants were used. One of the additional determinants was implementation feasibility. In the third study, gaze behavior was also monitored and two behaviors emerged from this data. One sub-group of participants fixated on the area stepped during adaptive step, whereas another sub-group anchor their gaze in a spot ahead of the area-to-be avoided and used peripheral vision for controlling foot landing. In summary, this thesis validates the three determinants for the alternate foot placement planning model and extends the previous model to more complex terrains.Item Self-efficacy theory and the self-regulation of exercise behaviour(University of Waterloo, 2005) Angove Woodgate, JenniferWhy are people unable to adhere to an exercise program? Adhering to an exercise program is complex, and exercisers struggle with a variety of challenges that require self-regulation (e. g. , making time, learning skills, changing behaviour). Bandura (1995b) has deemed the assessment of self-regulatory efficacy to manage the regular performance of health behaviours (e. g. , exercise) essential. Despite this recommendation, few components of self-regulation have been examined in the exercise and self-efficacy research to date (McAuley & Mihalko, 1998). Furthermore, major reviews of the exercise-related self-efficacy literature have demonstrated that task self-efficacy has been the predominant operationalization of the self-efficacy construct, and barriers self-efficacy has been the most prevalent operationalization of self-regulatory efficacy (Culos-Reed, Gyurcsik, & Brawley, 2001; McAuley & Mihalko, 1998). However, self-regulation of behaviour involves more than managing barriers and overcoming their limitations (Barone, Maddux, & Snyder, 1997; Brawley, 2005; DuCharme & Brawley, 1995). In order to examine other aspects of self-regulatory efficacy, self-efficacy theory was used as the underpinning for the three studies in this dissertation (Bandura, 1986, 1997).
In Study One an expanded operationalization of exercise-related self-regulatory efficacy was investigated. The construction of various self-regulatory efficacy indices was informed by self-regulation frameworks (Barone et al. , 1997; Baumeister et al. , 1994). These indices as well as barriers efficacy were used to prospectively predict self-reported exercise behaviour. The hierarchical multiple regression analysis indicated that the expanded self-regulatory efficacy variables (i. e. , scheduling, relapse prevention, goal-setting self-efficacy) explained a significant amount of variance in exercise behaviour. In addition, barriers efficacy also contributed significant, but modest, variance to the model. These results underscore McAuley and Mihalko?s (1998) recommendation that multiple measures of self-efficacy should be used to examine exercise behaviour. The findings also emphasize that a focus solely on barriers as the indicant of self-regulatory efficacy in exercise may be overlooking other aspects of the construct that contribute to prediction.
Study Two extended the descriptive findings of the first study and addressed a recognized research need (Dzewaltowski, 1994; McAuley & Blissmer, 2000; McAuley et al. , 2001). Specifically, this study examined the possibility of individual differences (i. e. , optimism, consideration of future consequences) influencing the relationship between self-regulatory efficacy and exercise behaviour. Results indicated that participants higher in optimism reported significantly greater self-regulatory efficacy and exercise intentions for intensity than did those lower in optimism. In addition, participants higher in consideration of future consequences (CFC) reported greater self-regulatory efficacy and exercise attendance than participants with moderate CFC. Finally, CFC significantly moderated the influence of various indices self-regulatory efficacy on subsequent exercise attendance. However the effect upon the prospective relationship was modest.
Whereas the first two studies examined the predictive relationship between self-regulatory efficacy and exercise behaviour, Study Three focused upon the influence of sources of self-regulatory efficacy in strengthening efficacy beliefs. This investigation concerned the effects of an acute manipulation of self-efficacy information in changing self-regulatory self-efficacy within a special population -- cardiac rehabilitation exercise program participants. According to theory, sources of self-efficacy information are common to task and self-regulatory efficacy (Bandura, 1997).
The study used a 2 (message condition) by 2 (time) design in which cardiac rehabilitation program participants were randomly assigned to conditions. Utilizing a written message employing the self-efficacy sources of verbal persuasion and vicarious experiences, self-regulatory efficacy for the scheduling of independent exercise was targeted within an ?efficacy enhancing? condition. This condition was compared to an ?information control? message of other information relevant to cardiac rehabilitation participants. As hypothesized, the efficacy-enhancing condition exhibited increased scheduling self-efficacy compared to the control condition. As well, exercise-related cognitions (i. e. , intentions for frequency, action plans, behavioural commitment to learning about independent exercise) were superior for the efficacy-enhancing condition participants compared to their control conditioncounterparts.
Taken together, the studies support and extend research on self-regulatory efficacy in the exercise domain. In part, this was accomplished by expanding the operationalization of exercise-related self-regulatory efficacy to represent more components of self-regulation than examined in the exercise literature to date. In addition, these studies extend previous descriptive research by examining the potential moderators of the influence of self-regulatory efficacy on exercise behaviour. Finally, the third study represented one of the first efforts to experimentally manipulate determinants of self-regulatory efficacy for independent exercise in a special population. It supported the hypothesis that informational determinants (i. e. , vicarious experience, verbal persuasion) can be acutely manipulated to increase self-regulatory efficacy among cardiac rehabilitation participants.Item Protective Responses during a Sideways Fall: Effects of Secondary Tasks(University of Waterloo, 2006) Shankar, SnehaFalls and hip fractures are a major public health problem among the elderly. In addition to bone strength, sideways falls and direct hip impact are important determinants for hip fracture. However, few falls actually cause serious injury in both young and older adults. Therefore, understanding how individuals facilitate a safe landing during a fall will help guide appropriate exercise-based training programs. The primary purpose of this thesis was to investigate the effects of secondary tasks on movement strategies during a sideways fall.
To address this aim, I used a tether and electromagnet to suddenly release subjects from a sideways leaning position, causing them to fall onto a gymnasium mat. I instructed subjects to "fall and protect yourself, as if you were landing on a hard surface". I acquired trials in four conditions, presented in a pseudo-random order: falling while holding a box, falling while holding an empty mug, falling while reciting spoken text, and falling with no secondary task. In most trials, regardless of condition, impact occurred to the lateral aspect of the pelvis (no secondary task = 87%, box = 82%, cognitive = 90%, mug = 79%). While the frequency of impact to both hands decreased when carrying an object (box=67%, mug=50% compared to cognitive=90% and no secondary task=85%), 40% of trials in the mug condition involved one hand contacting the ground, indicating hand impact was still common. It appears when protective movements such as impact to the knees and hands did occur, they were not used to avoid direct hip impact. Instead, they were used to help break the fall, and to avoid head impact, which was not seen in this experiment. The results from this study indicate that secondary tasks have minimal effects on fall responses and that the rare occurrence of hip fractures in the young is due to some combination of bone strength and effective use of body segments to break the fall.
In a second study, I examined how a cognitive task affected the ability of young women to rotate forward (FR) or backward (BR) during a sideways fall. Subjects were released from a sideways leaning position and were provided with a visual cue upon tether release instructing them on the desired direction of rotation. The site of impact on the pelvis (as reflected by the hip proximity angle) was closer to the lateral aspect of the hip in cognitive trials than in control trials (43 ± 18º versus 51 ± 19º in FR and 59 ± 18º versus 68 ± 18º in BR) (p=0. 0006). This was due to a longer delay in the initiation of rotation in cognitive trials (293 ± 60 ms versus 232 ± 71 ms in FR and 278 ± 87 ms versus 239 ± 60 ms), as opposed to a change in mean angular velocity. Pelvis impact velocity was similar in the two conditions (2. 6 ± 0. 3 m/s compared to 2. 7 ± 0. 3 m/s in FR trials and 2. 8 ± 0. 2 m/s compared to 2. 9 ± 0. 2 m/s in BR trials) (p=0. 0514). The results from this study indicate that involvement in a secondary task can impair safe landing responses. Secondary attentional tasks cause a delay in the initiation of fall protective responses, which alters landing configuration. However, the motor programme that governs falling, remaining consistent across condition is robust to changes in task execution at the onset of the fall.Item The Effects of 60 Days of Head Down Bed Rest on Vascular Health(University of Waterloo, 2006) Mattar, LouisThis study was designed to test the hypothesis that 60 days continuous head down bed rest (HDBR), an Earth-based analogue of the effects of space flight, would elevate factors that increase vasoconstriction and would increase markers of vascular inflammation. The study incorporated countermeasures consisting of treadmill running within lower-body negative pressure and resistive "flywheel" exercise (exercise countermeasure, EX) or an increased protein intake of 0. 6 g/kg body weight/day (dietary countermeasures, DIET) to determine whether these interventions might prevent the vasoconstrictor and inflammatory responses when compared to a control (CON) group. Markers of vascular health measured in the study include the vasoactive molecules angiotensin II (Ang II), endothelin-1 (ET-1), and nitric oxide metabolites (NOmet); and markers of inflammation including C-reactive protein (CRP), and the adhesion molecules E-selectin (E-sel), intracellular adhesion molecule-1 (ICAM), and vascular cell adhesion molecule-1 (VCAM). Twenty four women were housed at the MEDES clinic in Toulouse, France, as part of a large international study (Women International Space Simulation for Exploration, WISE) in which various experimental protocols and countermeasures were integrated into a single experimental design completed during two campaigns. Each 100 day campaign included 20 days of pre-testing (pre-HDBR), 60 days of bed rest (HDBR), and 20 days of post-testing (post-HDBR). The experimental countermeasures were applied only during the 60-day HDBR period. Following 60 days of HDBR, many changes occurred in the concentrations of the measured molecules. Specifically, the concentration of Ang II significantly increased in the CON and DIET groups (52. 9%, p = 0. 014; and 124. 4%, p <0. 0001 respectively), but not in the EX group. Also, NOmet decreased in all groups, with reductions in the EX and DIET groups (p = 0. 013, and p = 0. 056 respectively). Markers used to assess vascular inflammation increased following the HDBR. The increase in CRP in the CON and DIET groups and the decrease in the EX group from pre- to post-HDBR were not significant; however, the directional changes resulted in an interaction between group and HDBR (p = 0. 052). The adhesion molecule E-sel was significantly increased in the DIET group (p = 0. 003), and VCAM was significantly increased in the CON group (p = 0. 016) with a smaller increase in the DIET group (p = 0. 08). No changes in adhesion molecules were observed in the EX group. This study demonstrated that 60 days of HDBR by young, healthy, women caused changes in several different molecules that are beginning to emerge as risk factors for the development of cardiovascular diseases. Further, it was observed that regular, vigorous exercise during HDBR prevented these changes. These results suggest that future studies of this kind should directly monitor the effects of simulated space flight on vascular health in men and women to obtain a greater understanding of the adaptations that might occur during long term space exploration missions. HDBR can be considered an extreme model of physical inactivity and could be used to provide insight into mechanisms of disease processes associated with the sedentary lifestyle that is prevalent in Western society.Item Central Nervous System Control of Dynamic Stability during Locomotion in Complex Environments(University of Waterloo, 2006) MacLellan, MichaelA major function of the central nervous system (CNS) during locomotion is the ability to maintain dynamic stability during threats to balance. The CNS uses reactive, predictive, and anticipatory mechanisms in order to accomplish this. Previously, stability has been estimated using single measures. Since the entire body works as a system, dynamic stability should be examined by integrating kinematic, kinetic, and electromyographical measures of the whole body. This thesis examines three threats to stability (recovery from a frontal plane surface translation, stepping onto and walking on a compliant surface, and obstacle clearance on a compliant surface). These threats to stability would enable a full body stability analysis for reactive, predictive, and anticipatory CNS control mechanisms. From the results in this study, observing various biomechanical variables provides a more precise evaluation of dynamic stability and how it is achieved. Observations showed that different methods of increasing stability (eg. Lowering full body COM, increasing step width) were controlled by differing CNS mechanisms during a task. This provides evidence that a single measure cannot determine dynamic stability during a locomotion task and the body must be observed entirely to determine methods used in the maintenance of dynamic stability.Item Progressive Disc Herniation: An investigation of the mechanism using histochemical and microscopic techniques(University of Waterloo, 2006) Tampier, ClaudioAbstract Background: The process that involves the migration of the nucleus pulposus from the innermost annular layers and culminates with the final extrusion of the nucleus has been limited to a few studies. This investigation was directed towards a better understanding of the herniation process. The architecture of the annulus fibrosus and the mechanism of progressive disc herniation were analyzed, using a controlled porcine model. Microscopic and histochemical techniques were employed.
Methodology: Two studies were performed. In the first stage, the macroscopic and microscopic structures of twelve cervical intervertebral discs were compared with young human disc data from studies reported in the literature. Important structural features were studied such as annulus fibrosus thickness, number of lamellae, lamellae thickness, orientation of the lamellae fibers and blood supply. In the second study, sixteen fresh-frozen functional spine units were submitted to repetitive flexion?extension motions combined with a low compressive load in a servo-hydraulic dynamic testing system. Discograms, dissections and histochemical techniques were applied to characterize the cumulative damage. The experiment produced eight complete herniations, four partial herniations and four specimens without any microscopic detectable annular damage.
Results and Discussion: The structure of the cervical porcine disc resembles the lumbar human disc. Some differences are evident. The size of the annulus is smaller, the thickness of the lamellae is narrower and the number of layers is fewer in the pig. It is hypothesized that the flexion-extension motion combined with a low-level load produced an increased hydraulic pressure in the inner wall of the posterior annulus. This pressure and repetitive motion first produced a small cleft, spreading the collagen bundles inside the first layer. The nuclear material was "pumped" through the small cleft to the first layer filling the layer creating a fluid-filled pocket between the collagen fibers. Once the "pocket" acquired enough pressure a new cleft was produced in the weakest part of the layer allowing the nuclear material to create a new "pocket" in the second layer. This was the first stage of damage and disc herniation production. This mechanism was repeated until the nucleus traveled along the annulus reaching the posterior longitudinal ligament. At this point a complete extrusion herniation was produced.
Conclusion: The porcine model appears to be suitable as a model to understand the mechanism of disc herniation when the spine is subjected to flexion-extension motions combined with a low-level load. The first cumulative injury appears to be a cleft between the lamellae bundles produced by the nuclear hydraulic pressure. A cumulative load/cumulative injury model approach was used to create the damage that was quantified in the study.Item Locating Instability in the Lumbar Spine: Characterizing the Eigenvector(University of Waterloo, 2006) Howarth, SamuelOverloading of the back can cause instability such that buttressing the instability is a primary objective of many of the leading edge therapeutic approaches. However, a challenge lies in determining the location of the instability or the least stable vertebral joint. A mathematical analysis, based on a commonly used approach in engineering for determining structural stability, has been developed for the lumbar spine. The purpose of this investigation was to determine the feasibility of a method for mathematically locating potential areas of instability within a computer-based model of the lumbar spine. To validate this method, the eigenvector from the stability analysis was compared to the output from a geometric equation that approximated individual vertebral joint rotational stiffness with the idea that the entry in the eigenvector with the largest absolute value would correspond to the vertebral joint and axis with the lowest stiffness. Validation of the eigenvector was not possible due to computational similarities between the stability analysis and the geometric rotational stiffness method. However, it has been previously demonstrated that the eigenvector can be useful for locating instability, and thus warrants future study. Determining the least stable vertebral joint and axis can be used to guide proper motor pattern training as a clinical intervention. It was also shown in this investigation that an even distribution of fascicle force and stiffness generated stability. This supports the idea that well-coordinated efforts of muscle activation are beneficial for improving stability of the lumbar spine.Item An examination of glove attributes and their respective contributions to force decrement and increased effort in power grip at maximal and submaximal levels(University of Waterloo, 2006) Willms, KirstenGloved work has been shown to increase the effort required to perform manual tasks. In power grip tasks, these differences have been observed as reductions in strength and increases in muscular effort. Decreases in force output have been attributed to a number of factors, including loss of tactile sensitivity, glove flexibility or suppleness, thickness, changes in hand geometry, and friction at the glove-object interface. Glove research has rarely quantified glove attributes, and often compared gloves of varying material and physical properties. This research had the unique opportunity to control for a number of these properties by using three sets of identical gloves (powerline maintainers? insulating rubber gloves), differing only in thickness.
Administering the Von Frey Hair Test indicated that the gloves did indeed decrease tactile sensitivity. This research showed that increasing glove thickness led to large decreases in maximum power grip force. Small changes in hand geometry, such as increased interdigital space or grip span, affected force output. In the same hand posture, participants increased their grip force with increasing glove thickness for the object lifting task but were able to maintain a fixed submaximal force with visual feedback. The decrease in tactile sensitivity is a likely cause of this difference.
Muscular activity was affected by wearing the gloves while performing manual tasks. Inconsistent responses of muscular activation were seen in gloved maximum grip effort, while overall increases in electromyographic activity were recorded for tasks at submaximal levels when wearing gloves.
Interdigital spacing had different effects on maximal and submaximal tasks. For maximum effort power grip, interdigital spacing decreased force output by as much as 10%, with no significant changes in muscle activation. For submaximal tasks, no significant differences were seen in muscular activity or in force output. The overall force capability of the gloved user is hindered by changes in interdigital spacing at near maximal effort, but does not appear to be for tasks requiring lower grip force, such as the lifting task which required roughly 20%MVC. Overall, the effect of wearing these gloves on the users, the powerline maintainers, is a substantially increased effort to work. This research contributes to a greater understanding of why and how gloves inhibit performance.Item VISUAL INPUTS AND MOTOR OUTPUTS AS INDIVIDUALS WALK THROUGH DYNAMICALLY CHANGING ENVIRONMENTS(University of Waterloo, 2006) Cinelli, MichaelWalking around in dynamically changing environments require the integration of three of our sensory systems: visual, vestibular, and kinesethic. Vision is the only modality of these three sensory systems that provides information at a distance for proactively controlling locomotion (Gibson, 1958). The visual system provides information about self-motion, about body position and body segments relative to one another and the environment, and environmental information at a distance (Patla, 1998). Gibson (1979) developed the idea that everyday behaviour is controlled by perception-action coupling between an action and some specific information picked up from the optic flow that is generated by that action. Such that visual perception guides the action required to navigate safely through an environment and the action in turn alters perception. The objective of my thesis was to determine how well perception and action are coupled when approaching and walking through moving doors with dynamically changing apertures. My first two studies were grouped together and here I found that as the level of threat increased, the parameters of control changed and not the controlling mechanism. The two dominant action control parameters observed were a change in approach velocity and a change in posture (i. e. shoulder rotation). These findings add to previous work done in this area using a similar set-up in virtual reality, where after much practice participants increased success rate by decreasing velocity prior to crossing the doors. In my third study I found that visual fixation patterns and action parameters were similar when the location of the aperture was predictable and when it was not. Previous work from other researchers has shown that vision and a subsequent action are tightly coupled with a latency of about 1second. I have found that vision only tightly couples action when a specific action is required and the threat of a collision increases. My findings also point in the same direction as previous work that has shown that individuals look where they are going. My last study was designed to determine if we go where we are looking. Here I found that action does follow vision but is only loosely correlated. The most important and common finding from all the studies is that at 2 seconds prior to crossing the moving doors (any type of movement) vision seems to have the most profound effect on action. At this time variability in action is significantly lower than at prior times. I believe that my findings will help to understand how individuals use vision to modify actions in order to avoid colliding with other people or other moving objects within the environment. And this knowledge will help elderly individuals to be better able to cope with walking in cluttered environments and avoid contacting other objects.Item Visual Inputs and Motor Outputs as Indivduals Walk Through Dynamically Changing Environments(University of Waterloo, 2006-12-01T21:19:36Z) Cinelli, MichaelWalking around in dynamically changing environments require the integration of three of our sensory systems: visual, vestibular, and kinesethic. Vision is the only modality of these three sensory systems that provides information at a distance for proactively controlling locomotion (Gibson, 1958). The visual system provides information about self-motion, about body position and body segments relative to one another and the environment, and environmental information at a distance (Patla, 1998). Gibson (1979) developed the idea that everyday behaviour is controlled by perception-action coupling between an action and some specific information picked up from the optic flow that is generated by that action. Such that visual perception guides the action required to navigate safely through an environment and the action in turn alters perception. The objective of my thesis was to determine how well perception and action are coupled when approaching and walking through moving doors with dynamically changing apertures. My first two studies were grouped together and here I found that as the level of threat increased, the parameters of control changed and not the controlling mechanism. The two dominant action control parameters observed were a change in approach velocity and a change in posture (i.e. shoulder rotation). These findings add to previous work done in this area using a similar set-up in virtual reality, where after much practice participants increased success rate by decreasing velocity prior to crossing the doors. In my third study I found that visual fixation patterns and action parameters were similar when the location of the aperture was predictable and when it was not. Previous work from other researchers has shown that vision and a subsequent action are tightly coupled with a latency of about 1second. I have found that vision only tightly couples action when a specific action is required and the threat of a collision increases. My findings also point in the same direction as previous work that has shown that individuals look where they are going. My last study was designed to determine if we go where we are looking. Here I found that action does follow vision but is only loosely correlated. The most important and common finding from all the studies is that at 2 seconds prior to crossing the moving doors (any type of movement) vision seems to have the most profound effect on action. At this time variability in action is significantly lower than at prior times. I believe that my findings will help to understand how individuals use vision to modify actions in order to avoid colliding with other people or other moving objects within the environment. And this knowledge will help elderly individuals to be better able to cope with walking in cluttered environments and avoid contacting other objects.Item Negotiating Varying Ground Terrain during Locomotion: Insights into the Role of Vision and the Effects of Aging(University of Waterloo, 2006-12-18T16:50:15Z) Marigold, DanielWe continually encounter different ground terrain such as slippery, compliant, uneven, rocky, and irregular terrain when walking, yet we know very little about how individuals safely negotiate this type of complex environment. Furthermore, we know little about how aging affects stability in these situations despite the increased risk of falls and fall-related injuries among older adults. Paramount to our comprehension of how individuals safely traverse challenging ground terrain is to understand how visual information is utilized as vision is the first line of defense for preparing for and/or avoiding potentially hazardous terrain or obstacles. Thus, the objective of this thesis was to provide a better understanding towards how individuals negotiate different ground terrain in the environment to maintain dynamic stability and prevent the occurrence of a fall. In particular, the role of vision and the effects of aging were investigated. Three studies focused on the role of vision while negotiating varying ground terrain while two studies examined stability across these surfaces. Two main conclusions can be drawn from the results of the three studies on the role of vision. First, regardless of age individuals fixate on highly task-relevant areas (i.e. surfaces eventually stepped on) in an on-line manner and by fixating approximately two steps ahead. Second, visual information from the lower visual field is important for negotiating varying ground terrain. This latter finding has implications for older adults who wear multi-focal glasses and suggests that these individuals should be cautious when wearing these glasses in complex environments. In terms of stability, the results suggest that young and older adults demonstrate greater instability when walking across varying unstable ground terrain compared to solid level ground. Older adults are particularly more unstable in the medial-lateral direction when negotiating the challenging terrain, which may explain the frequency of laterally directed falls and increased hip-fracture risk with advancing age. Interestingly, older adults appear more stable in the anterior-posterior direction; although, this can largely be explained by the cautious gait strategy (i.e. slower walking speed and shorter steps) adopted by these individuals. The results of the studies of my thesis provide valuable insight into how individuals safely negotiate different types of challenging ground terrain when walking. Importantly, this knowledge can serve as an initial step in attempting to reduce falling among those at risk.Item Control of Dynamic Stability during Gait Termination on a Slippery Surface(University of Waterloo, 2007-01-17T19:59:35Z) Oates, Alison RobynThe purpose of this thesis is to investigate the reaction to a purely unexpected slip during gait termination and subsequent experiences stopping on the slippery surface in participants who are young and healthy, older and healthy and who have Parkinson’s disease while on traditional dopamine-replacement medication. Gait termination requires control of the forward momentum of the body’s centre of mass (COM). This forward momentum must be dissipated and the COM held within a newly formed base of support. The challenge of stopping on a slippery surface involves maintaining stability while transitioning from steady-state locomotion to steady-state stance. Experience with a slippery surface changes postural and gait characteristics to diminish the perturbing effect of the slip. The magnitude of the slip response diminishes quickly as the movement becomes more efficient. Our investigations revealed a typical slip response to a purely unexpected slip during gait termination including a lowering of the COM, an increased muscular response to support the body, a shortened step and an arm raise. Knowledge of and experience with the slippery surface quickly changed the slip response to reduce the perturbing effect of the slip and also to increase the efficiency of the response while smoothly transitioning from steady-state locomotion to gait termination. Parkinson’s disease impairs balance control, the ability to switch between motor tasks and also to stop within two steps. The need for a voluntary change in motor programs along with difficulty stopping and increased instability makes gait termination a potentially difficult task for someone with Parkinson’s disease (PD). The participants with PD used a slower, safer strategy to stop on non-slippery surfaces to compensate for their instability compared to age-matched controls. When a slip was first introduced during gait termination, the participants with PD continued to be less stable in the plane of progression than the control group. Despite the instability, the PD group was still able to integrate a balance-correcting response into a voluntary gait termination program. The ability to generate adaptive strategies to integrate the balance-correcting response into a voluntary gait termination program over multiple trials does not appear to be affected by PD; both the control group and PD group showed behavioural modifications according to repeated exposures to the slippery surface. Although participants with PD seemed slightly less stable and walked slower, their behavioural adaptations were similar to the control group.Item ROLE OF SECOND MESSENGER SIGNALING PATHWAYS IN THE REGULATION OF SARCOPLASMIC RETICULUM CALCIUM-HANDLING PROPERTIES IN THE LEFT VENTRICLE AND SKELETAL MUSCLES OF DIFFERENT FIBRE TYPE COMPOSITION(University of Waterloo, 2007-02-09T18:47:21Z) Duhamel, Todd A DThe overall objective of this thesis was to examine mechanisms involved in the acute regulation of sarcoplasmic reticulum (SR) Ca2+-handling properties by second messenger signaling pathways in skeletal and cardiac muscle. The aim of the first study (Chapter Two) was to characterize changes in the kinetic properties of sarco(endo)-plasmic reticulum Ca2+-ATPase (SERCA) proteins in cardiac and skeletal muscles in response to b-adrenergic, Ca2+-dependent calmodulin kinase II (CaMKII) and protein kinase C (PKC) signaling. The aim of the second study (Chapter Three) was to determine if insulin signaling could acutely regulate SERCA kinetic properties in cardiac and skeletal muscle. The aim of the final study (Chapter Four) was to determine if alterations in plasma glucose, epinephrine and insulin concentrations during exercise are able to influence SR Ca2+-handling properties in contracting human skeletal muscle. Data collected in Chapter Two and Chapter Three were obtained using tissue prepared from a group of 28 male Sprague-Dawley rats (9 weeks of age; mass = 280 ± 4 g: X ± S.E). Crude muscle homogenates (11:1 dilution) were prepared from selected hind limb muscles (soleus, SOL; extensor digitorum longus, EDL; the red portion of gastrocnemius, RG; and the white portion of gastrocnemius, WG) and the left ventricle (LV). Enriched SR membrane fractions, prepared from WG and LV, were also analyzed. A spectrophotometric assay was used to measure kinetic properties of SERCA, namely, maximal SERCA activity (Vmax), and Ca2+-sensitivity was characterized by both the Ca50, which is defined as the free Ca2+-concentration needed to elicit 50% Vmax, and the Hill coefficient (nH), which is defined as the relationship between SERCA activity and Ca2+f for 10 to 90% Vmax. The observations made in Chapter Two indicated that b-adrenergic signaling, activated by epinephrine, increased (P<0.05) Ca2+-sensitivity, as shown by a left-shift in Ca50 (i.e. reduced Ca50), without altering Vmax in LV and SOL but had no effect (P<0.05) on EDL, RG, or WG. Further analysis using a combination of cAMP, the PKA activator forskolin, and/or the PKA inhibitor KT5270 indicated that the reduced Ca50 in LV was activated by cAMP- and PKA-signaling mechanisms. However, although the reduced Ca50 in SOL was cAMP-dependent, it was not influenced by a PKA-dependent mechanism. In contrast to the effects of b-adrenergic signaling, CaMKII activation increased SERCA Ca2+-sensitivity, as shown by a left-shift in Ca50 and increased nh, without altering SERCA Vmax in LV but was without effect in any of the skeletal muscles examined. The PKC activator PMA significantly reduced SERCA Ca2+-sensitivity, by inducing a right-shift in Ca50 and decreased nH in the LV and all skeletal muscles examined. PKC activation also reduced Vmax in the fast-twitch skeletal muscles (i.e. EDL, RG and WG), but did not alter Vmax in LV or SOL. The results of Chapter Three indicated that insulin signaling increased SERCA Ca2+-sensitivity, as shown by a left-shift in Ca50 (i.e. reduced Ca50) and an increased nH, without altering SERCA Vmax in crude muscle homogenates prepared from LV, SOL, EDL, RG, and WG. An increase in SERCA Ca2+-sensitivity was also observed in enriched SERCA1a and SERCA2a vesicles when an activated form of the insulin receptor (A-INS-R) was included during biochemical analyses. Co-immunoprecipitation experiments were conducted and indicated that IRS-1 and IRS-2 proteins bind SERCA1a and SERCA2a in an insulin-dependent manner. However, the binding of IRS proteins with SERCA does not appear to alter the structural integrity of the SERCA Ca2+-binding site since no changes in NCD-4 fluorescence were observed in response to insulin or A-INS-R. Moreover, the increase in SERCA Ca2+-sensitivity due to insulin signaling was not associated with changes in the phosphorylation status of phospholamban (PLN) since Ser16 or Thr17 phosphorylation was not altered by insulin or A-INS-R in LV tissue. The data described in Chapter Four was collected from 15 untrained human participants (peak O2 consumption, VO2peak= 3.45 ± 0.17 L/min) who completed a standardized cycle test (~60% VO2peak) on two occasions during which they were provided either an artificially sweetened placebo (PLAC) or a 6% glucose (GLUC) beverage (~1.00 g CHO per kg body mass). Muscle biopsies were collected from the vastus lateralis at rest, after 30 min and 90 min of exercise and at fatigue in both conditions to allow assessment of metabolic and SR data. Glucose supplementation increased exercise ride time by ~19% (137 ± 7 min) compared to PLAC (115 ± 6 min). This performance increase was associated with elevated plasma glucose and insulin concentrations and reduced catecholamine concentrations during GLUC compared to PLAC. Prolonged exercise reduced (p<0.05) SR Ca2+-uptake, Vmax, Phase 1 and Phase 2 Ca2+-release rates during both PLAC and GLUC. However, no differences in SR Ca2+-handling properties were observed between conditions when direct comparisons were made at matched time points between PLAC and GLUC. In summary, the results of the first study (Chapter Two) indicate that b-adrenergic and CaMKII signaling increases SERCA Ca2+-sensitivity in the LV and SOL; while PKC signaling reduces SERCA Ca2+-sensitivity in all tissues. PKC activation also reduces Vmax in the fast-twitch skeletal muscles (i.e. EDL, RG, and WG) but has no effect on Vmax in the LV and SOL. The results of the second study (Chapter Three) indicate that insulin signaling acutely increases the Ca2+-sensitivity of SERCA1a and SERCA2a in all tissues examined, without altering the Vmax. Based on our observations, it appears that the increase in SERCA Ca2+-sensitivity may be regulated, in part, through the interaction of IRS proteins with SERCA1a and SERCA2a. The results of the final study (Chapter Four) indicate that alterations in plasma glucose, epinephrine and insulin concentrations associated with glucose supplementation during exercise, do not alter the time course or magnitude of reductions in SERCA or Ca2+-release channel (CRC) function in working human skeletal muscle. Although glucose supplementation did increase exercise ride time to fatigue in this study, our data does not reveal an association with SR Ca2+-cycling measured in vitro. It is possible that the strength of exercise signal overrides the hormonal influences observed in resting muscles. Additionally, these data do not rule out the possibility that glucose supplementation may influence E-C coupling processes or SR Ca2+-cycling properties in vivo.Item Comparison of model-predicted and measured moment arms for the rotator cuff muscles(Elsevier, 2007-07) Gatti, Christopher J.; Dickerson, Clark R.; Chadwick, Edward K.; Mell, Amy G.; Hughes, Richard E.Background The ability of mathematical models of the shoulder to accurately replicate physiological muscle moment arms is unknown. The purpose of this study was to compare model-predicted and experimentally measured moment arms for the rotator cuff muscles during arm elevation. Methods Moment arms obtained from six mathematical models and seven experimental studies were compared for the supraspinatus, infraspinatus, teres minor, and subscapularis for elevation in the scapular plane. Results All of the included models generated moment arms that generally fell within the range of experimentally measured data. Interpretation The quantitative agreement between model-predicted and experimentally measured moment arms supports the use of the included models for biomechanical shoulder analyses.Item IN VITRO AND IN VIVO BIOMECHANICAL INVESTIGATION OF THE CLINICAL PRACTICE OF DISC PROLAPSE PREVENTION AND REHABILITATION(University of Waterloo, 2007-09-10T14:07:01Z) Scannell, JoanUnderlying this thesis is the McKenzie school of thought, a physiotherapy approach that teaches clinicians to recommend particular exercises to their clients in an attempt to accelerate recovery/ prevent recurrence of disc prolapse. The recommendations are based on an untested clinical theory that movements opposite to those that cause disc prolapse can achieve reversal of disc prolapse. Little consideration has been given scientifically to the reversal of the failure process of the lumbar discs. Three in vitro and one in vivo study were designed to attain a greater understanding of both disc failure and the mechanics of its clinical treatment responses and thereby provide a foundation for evidence-based practice. The first in vitro study in this thesis compared in vitro and in vivo herniated discs in an attempt to link the two and provide a more thorough understanding of the in vitro model proposed to test the mechanical theory underlying the McKenzie derangement approach. Ten C3/4 osteoligamentus porcine specimens were repeatedly flexed or flexed and side bent to result in posterior migration of the nucleus. Three of the 10 specimens had posterior migration of the nucleus. Statistically significant (p < 0.01) and clinically significant (>33%) disc height loss occurred in all 10 specimens. The results provide a sub-classification of in vitro herniated discs that is similar to the spectrum of herniated discs that occurs in vivo. Continuing from the disc height loss sub-classification of post-herniated in vitro discs, the second in vitro study in this thesis pursues alternate methods of creating herniation with the goal of creating herniation without causing more than thirty three percent disc height loss of the specimens. Repeated flexion of porcine cervical specimens under a lower compression level (1kN) resulted in disc herniation but with loss of 50% of the pre-test disc height (p < 0.001). Re-hydrating specimens by injecting the disc after a period of failure testing with a barium sulphate nucleus mix (n = 5) or by placing the specimen in a saline bath for an extended period of time (n = 4) resulted in a significant increase of the disc height of the specimens. Further flexion testing of the specimens significantly reduced the disc height again. Intermittent saline injection of specimens (n = 3) during the failure procedure did not prevent or reduce the disc height loss that occurred in the absence of saline injections. Using higher compression levels (2 and 2.596kN, n = 4), failure testing under torque control (n = 3), non-physiologically starting the annular rupture (n = 5) and using hypolordotic thoracic porcine spines (n = 9) instead of porcine cervical spines were unsuccessful attempts at creating herniations. This study indicated that the in vitro model used in the first in vitro study displayed features from one end of the spectrum of damage seen clinically but was then the best-available. Combined these two studies provide a framework for interpretation of the results of the subsequent and third in vitro study in this thesis. The focus of the third study is the mechanical investigation of the McKenzie clinical theory of the treatment response seen in vivo in prolapsed discs, which is that movements or positioning can alter the location of a displaced portion of nucleus in a prolapsed disc. This study is a proof of the principle on which this aspect of the McKenzie approach is based and provides, to the author’s knowledge, the first scientific evidence supporting the theory that repeating movements opposite to those that caused posterior migration of the nucleus can centralize the prolapsed material. The results indicate that the McKenzie approach works on some prolapsed discs and not on others. Consideration of the changes in disc height of the specimens during the testing procedures offers some understanding of the varied success of this approach and exposes a vast area of future research that will refine the clinical approach and mechanical understanding of this specific disc pathology. The fourth study, an in vivo study, provides a first look at the kinematics and kinetics of the current in vivo application of this approach. Twenty asymptomatic subjects volunteered to participate in this study and performed frequently prescribed McKenzie exercises and a selection of activities of daily living during which a 3-SPACE Isotrak system measured their three dimensional lumbar kinemetics. One subject underwent a series of McKenzie exercises while electromyography and three-dimensional lumbar motion were measured. Mean peak extension of extension in standing and extension in lying exercises were within 3% (SD 22.33%) of each other. An additional 6.75% (SD 11.18%) of extension occurred when the extension in lying exercise was combined with a Grade 3 Maitland extension mobilization to L3, a passive physiotherapy technique that involves the therapist applying intermittent low amplitude oscillations to, in this case, the posterior aspect of the spinous process with the goal of subsequently increasing the range of active motion in the direction of the mobilization. The peak extension during the extension in lying exercise was increased after the mobilization relative to the pre-mobilization range. The mean peak right side bend in the right side glide exercise, normalized to the full right side bend range, was 61% (SD 17.4%). The L4-5 forces at the position of peak extension in extension in lying and extension in standing were 828.97N and 1368.86N respectively. The peak flexion ranges of the activities of daily living investigated match those previously used to create disc prolapse when applied at high repetitions and under moderate axial compression. The lumbar spine ranges achieved in commonly prescribed McKenzie rehabilitative and preventative exercises and those that occur in seemingly non-problematic activities of daily living were quantified. The results of this study will enhance clinical practice by providing quantitative evidence of the relative peak motion of the McKenzie exercises as well as highlighting seemingly benign activities of daily living that involve levels of flexion, side bend and rotation sufficient to cause disc damage and even prolapse. The macroscopic goal of this thesis was to attain a greater understanding of the mechanics of both disc failure and its clinical treatment responses and thereby provide a foundation for evidence-based practice, a goal that was successfully achieved. This thesis ultimately challenged and increased our understanding of pathological discs while simultaneously adding information to assist clinical decision making. Several new contributions to the existing knowledge of lumbar spine biomechanics and clinical concepts of treating disc prolapse have been made.Item Effects of Age and Experience on Memory-Guided Movements(University of Waterloo, 2007-09-14T13:35:33Z) Skakum, AmandaThe purpose of the present research was threefold: 1) to investigate whether natural aging affects the movements to remembered targets when participants make reaching movements under closed-loop feedback conditions, 2) to determine if experience with visually-guided movements facilitates memory-guided reaching and 3) to determine if age affects this facilitation. Two groups of 10 participants (healthy older and healthy younger) performed a manual aiming task with a mouse on a graphics tablet. A target appeared in one of 6 possible locations on a computer screen and participants had to make aiming movements with a visible cursor in 3 different visual conditions: full vision, immediate recall and delayed recall. In the full vision condition vision of the target was available throughout the movement. In the delay conditions the target disappeared either at the initiation of the aiming movement (immediate recall) or 2 seconds before movement onset (delayed recall). Vision of the hand (cursor) was available in all conditions. Each memory condition was divided into 2 blocks; block 1 was presented before the full vision condition and block 2 was presented after. Endpoint accuracy and variability were measured along with movement kinematics. Results showed no age differences in the kinematics in the full vision condition. For memory dependent pointing age also did not affect the movement kinematics or endpoint accuracy. Movements to remembered targets were significantly more variable in the delay recall compared to the immediate recall condition. A Block by Condition effect showed that the delay effect was present in the first block, but not in the second block, suggesting that variability did not increase with memory delay once participants had experience from full vision reaching. A Group by Condition effect showed the older adults were more variable than younger, although this difference was smaller in the delay condition due to the increase in variability as a function of delay seen in younger but not older adults. These findings suggest that aging does not affect how movements are controlled whether pointing to visible or remembered targets. They also suggest that aging does not affect the accuracy in pointing to remembered targets. Aging does affect the variability of these pointing movements. Finally, experience in pointing at targets with full vision modulates the increase in variability of pointing as a function of delay.Item Omega-3 Fatty Acid Blood Biomarkers Before and After Acute Fish Oil Supplementation in Men and Women(University of Waterloo, 2007-09-17T15:32:23Z) Metherel, Adam HenryOmega-3 fatty acids, particularly docosahexaenoic (DHA) and eicospentaenoic acid (EPA), are important mediators for cardiovascular disease, fetal/infant development, neurological disorders and inflammatory diseases. Supplementation and washout studies are important for future research on the physiological effects of omega-3 fatty acids and for determination of the proper washout period for future cross-over studies. In this study, omega-3 fatty acid blood biomarker comparisons are made for the n-3 HUFA score (% of n-3 HUFAs in total HUFAs) and omega-3 index (sum of EPA + DHA) in plasma, erythrocytes, whole blood and a novel finger-tip prick blood method (FTPB) of analysis. This FTPB method of fatty acid analysis is further tested to determine the potential for its use in fatty acid analysis. In addition, gender differences in response to omega-3 fish oil supplementation are analyzed in all four blood fractions. Nine males and seven females were supplemented with 8 fish-oil capsules per day (providing 3.2 g/day EPA and 1.6 g/day DHA) for four weeks, followed by an eight-week omega-3 washout period. Venous plasma, erythrocyte and whole blood samples were collected during weeks 0, 4, 8 and 12 and FTPB samples were collected weekly during supplementation and washout fatty acid analysis was performed. EPA and DHA incorporation is lowest in magnitude in erythrocytes relative to all other blood fractions. Omega-3 blood biomarker comparisons demonstrate that the n-3 HUFA score is a more reliable measure across all blood fractions compared to the omega-3 index. In addition, the n-3 HUFA score demonstrates no differences (p > 0.05) between FTPB and whole blood analysis, providing evidence to support its usefulness as a tool for fatty acid analysis. However, differences (p < 0.05) do exist between these methods for saturated fatty acid, monounsaturated fatty acids, omega-6 polyunsaturated fatty acids (PUFAs) and omega-3 PUFAs. Baseline fatty acid levels for DHA, and the DHA:EPA and DHA:DPA ratios tend to be higher (p < 0.05) in females, and docosapentaenoic acid n-3 (DPAn-3) is higher (p > 0.05) in males across all blood fractions. Furthermore, a gender effect (p < 0.05) is seen for the DHA:EPA ratio across all blood fractions. At baseline, female DHA:EPA is higher (p < 0.05) than males with supplementation lowering both male and female values and removing any differences (p > 0.05) between genders. Washout results in a return of levels towards baseline, however, baseline levels are not fully reached. Furthermore, while gender differences do begin to reform during washout, these differences are not significant (p > 0.05). In conclusion, omega-3 fatty acid responses, particularly DHA:EPA ratio, demonstrate significant gender differences that may be related to differences in long-chain PUFA synthesis pathways between males and females. In addition, the n-3 HUFA score may be a more valuable omega-3 blood biomarker than the omega-3 index, as the n-3 HUFA score displays more consistent levels across all blood fractions. Finally, the FTPB method of analysis may be a useful tool in the measurement of fatty acid composition, however, some microwave methylation problems do exist, specifically in the phospholipid class of lipids.