Now showing items 21-35 of 35

    • Influence of upper limb ischaemia-reperfusion injury on the regulation of cutaneous blood flow during local thermal hyperaemia

      McGarr, Gregory Walter; Applied Health Sciences Program
      The present research was developed to investigate the effects of acute upper limb ischaemia- reperfusion (I-R) on neurovascular and endothelial control of the cutaneous micro-circulation in the forearm and finger by evaluating its influence on the magnitude and kinetics of the vasodilatory response to local skin heating. Study 1 investigated between-day reliability of the local heating response in non-glabrous and glabrous index finger skin. Study 2 investigated the effects of I-R on the local heating response in non-glabrous and glabrous skin of the index finger. Study 3 investigated within- and between-day reliability of the local heating response in non-glabrous forearm skin. Study 4 investigated the effects of I-R on the local heating response in non-glabrous forearm skin, as well as the contribution of sensory nerves in mediating the magnitude and kinetics of this response. When data were normalized for blood pressure and expressed as cutaneous vascular conductance (CVC) reliability was generally comparable across all skin sites. In non-glabrous skin reliability was superior when CVC was normalized to maximum heating. At all skin sites, normalizing CVC to baseline produced poor results. Vasodilatory onset time and time to initial peak during local heating produced moderate to good reliability for all skin sites in Studies 1 and 3. In the finger, I-R did not influence the magnitude of the local heating response for the initial peak or plateau phases in either skin type. However, I-R did cause a ~23% delay in vasodilatory onset time and a ~16% delay in time to initial peak in non-glabrous skin. In the forearm, I-R attenuated the initial peak and plateau phases by ~31% and ~34%, respectively. Vasodilatory onset time was also delayed by 34% post-ischaemia. The contribution of sensory nerves in mediating the initial peak and vasodilatory onset time were significantly reduced post-ischaemia, while sensory nerves did not influence the plateau. It is concluded that upper limb I-R impairs the local heating response in non-glabrous forearm and index finger skin. A combination of cutaneous sensory nerve impairment and reduced nitric oxide bioavailability appear to be responsible for attenuating the vasodilatory response to local skin heating under these conditions.
    • Cardiac Autonomic Assessment and Diastolic Function in Individuals with Spinal Cord Injury

      Sharif, Hisham; Applied Health Sciences Program
      The primary purpose of this thesis was to examine the validity and reproducibility of the QT-variability index (QTVI) as a measure of cardiac autonomic function in individuals with spinal cord injury (SCI). The secondary purpose was to investigate the influence of cardiac autonomic activity and blood volume on diastolic function in individuals with SCI. Results from Study 1 showed that the QTVI increased when participants performed a cardiovascular (CV) stress maneuver, and subsequently returned to baseline after blocking sympathetic outflow via metoprolol. Moreover, while participants were resting, the QTVI increased after blocking parasympathetic activity via atropine. These results suggest that the QTVI may reflect both cardiac sympathetic and parasympathetic activity in those with incomplete SCI, depending on the autonomic state of the individual. Results from Study 2 demonstrate high day-to-day reproducibility of the QTVI in participants with SCI, regardless of injury level, and also in those with high level injuries who may have reduced cardiac sympathetic regulation. Results from Study 3 showed that indices of cardiac parasympathetic activity (HRV and QTVI) were correlated with left ventricular filling in able-bodied individuals but not in individuals with SCI, suggesting a disconnect between cardiac parasympathetic activity and diastolic function after SCI. In addition, for the able-bodied group, the cold face test (CFT) increased vagal activity which was associated with bradycardia and augmentation of diastolic filling. However, for the SCI group, the increase in vagal activity during the CFT was associated with no change in heart rate and an attenuation of diastolic function. Results from Study 4 showed that although individuals with SCI were hypovolemic, resting diastolic velocities were similar compared to the able-bodied group. This maintenance of diastolic function appeared to be attributed to the cardiac atrophy that manifests following SCI. In addition, there was no between-group difference in the diastolic response to rapid saline infusion. Findings from this dissertation suggest that the QTVI is a valid and reliable tool for non-invasively estimating cardiac autonomic regulation in individuals with SCI. In addition, although the mechanical aspect of diastolic function is preserved after SCI, atypical vagal-diastolic interactions may impair ventricular filling in this population.
    • Use of micro-computed tomography to evaluate changes to bone structure due to ovariectomy and polyunsaturated fatty acid intervention in a rat model of postmenopausal osteoporosis

      Longo, Amanda; Applied Health Sciences Program
      The testing of osteoporosis-related therapies and the investigation into their mechanism of action largely relies on the use of the preclinical model of postmenopausal osteoporosis, the ovariectomized (OVX) rat. Study 1 evaluated the time-course of changes to the trabecular and cortical microarchitecture of the proximal tibia of the Sham-control and OVX rat over a 3-month period following surgery at 3-months of age, a typical period used in the testing of nutritional and/or drug intervention. This study confirmed the use of the 3-month OVX rat as a model for trabecular microarchitecture changes, but did not support its use as a model for cortical bone changes. The OVX rat was also used to test its resistance to repeated radiation exposure from micro-computed tomography (μCT), a method necessary for the longitudinal evaluation of a single animal (Study 2). The method of μCT and its scanning parameters were also investigated to confirm their use in appropriately quantifying the 3-dimensional microarchitecture of the rat hind limb both in vivo and ex vivo (Study 3). Together, findings from these methodological studies led to its use in the evaluation of changes to bone structure in response to a nutritional intervention in the OVX rat (Study 4). Previous studies of growing rats and of OVX rats suggest a benefit to bone with supplementation with a lower n-6 to n-3 polyunsaturated fatty acid (PUFA) dietary ratio, and to altered sources of n-3 PUFA, but no study has investigated the impact of these nutritional patterns over the life course. Therefore, Study 4 determined the effect of the dietary ratio and source of n- 3 PUFA on bone during periods of growth (1 through 3 months of age) and following Sham or OVX surgery (at 3 months of age). A low PUFA ratio with n-3 provided from flaxseed oil provided benefits to bone health during growth, but these changes were not maintained following OVX. These data suggest that dietary PUFA, at levels attainable in humans through a healthful diet, are not an adequate strategy for the prevention of the rapid and drastic bone loss induced by OVX.
    • Age-related errors in the assessment of children

      Veldhuizen, Scott; Applied Health Sciences Program
      Children's functioning can only reasonably be measured relative to that of other individuals of the same age. In practice, age ranges are usually used to group children for this purpose. Examples include school grades, age groups in sports, and age bands used in developmental assessments. Age grouping is associated with systematic errors, often known as relative age effects (RAEs): Within each age group, older children outperform younger ones. This type of assessment error may lead to opportunities and interventions being offered inefficiently or unfairly. This thesis comprises 5 research projects that aim to clarify underlying causes of RAEs, examine their importance in different contexts, and develop analytic methods relevant to their study. I use data drawn from two studies: A prospective cohort study including athletic performance measures (the Physical Health Activity Study Team project) and a validation study undertaken to compare measures of child development (Psychometric Assessment of the Nipissing District Developmental Screener). I develop linear models to characterize age-related variation and then use results to draw conclusions, to inform other analyses, and to generate synthetic datasets. Together, studies demonstrate a set of methods for the exploration and correction of RAEs. They also yield several concrete findings: (1) A simple mathematical interpretation of RAEs can fully explain the errors seen in real datasets, meaning that other explanations are, in at least some contexts, unnecessary. (2) RAEs have different effects in ranking and selection contexts, with ranking errors largest among average individuals but selection errors greatest when more extreme thresholds are used. (3) Age bands cause misclassification in measures of child development, and the error rate rises rapidly with the width of age bands used. (4) The use of different sets of age bands will prevent different assessments from agreeing closely. (5) Age grouping in developmental assessments will create an illusion of longitudinal instability. Finally, I demonstrate the use of alternative scoring approaches and discuss how these can reduce or eliminate errors related to RAEs.
    • Creating Space, or Just Juggling? Exploring the Adoption of Innovation in Community Sport

      Jurbala, Paul; Jurbala, Paul; Applied Health Sciences Program
      Previous research into community sport organization (CSO) has focused heavily on capacity and resource deficits and the ways in which CSOs manage under these constraints. This study explores mechanisms influencing CSOs as they adopt and implement an innovation: Long-Term Athlete Development (LTAD). A critical realist, extensive-intensive design spanning 36 months was used. The first, extensive phase of the study examines the contextual mechanisms influencing the approach of CSOs to adopting the LTAD innovation. Resource dependence and institutional perspectives are integrated to describe the forces acting on CSOs, how these manifest in structures, and how the structures channel the agency of CSO leaders as they work to balance resources and deliver programs. A contextual model of CSO operation under conflicting institutional logics is presented. The second, intensive phase examines the question of how CSOs plan, learn, and consolidate learning into structure as they integrate an innovation. Here, an engaged case study methodology was used to focus on the efforts of a single CSO over a one-year period as it worked to implement LTAD while managing multiple resource constraints. A learning cycle was used to explore processes of embedded agency resulting in structural change. CSOs are conceptualized as juggling resource constraints while balancing conflicting institutional logics: the communitarian logic promoted by resource controllers such as municipalities and Provincial Sport Organizations, and the individualist logic followed by CSO members. The results of the study demonstrate how CSOs compete for resources while balancing these institutional pressures and how when possible, CSOs manipulate institutional factors to gain legitimacy and contingent access to resources. In this competitive environment, LTAD represents a new institutional pressure. CSOs determine whether to adopt LTAD in part based on whether resource controllers signal that compliance will bring legitimacy and enhance resource access. When resource- controlling organizations introduce standards like LTAD intended to improve CSO program quality, the unintended result can be inter-CSO competition for legitimacy that can lead to the systematic privileging of large CSOs at the expense of smaller ones, driving professionalization and potentially increasing costs of sport participation.
    • Investigating the bone-muscle interaction during growth and development in children

      Ludwa, Izabella A.; Applied Health Sciences Program
      The purpose of this dissertation was to assess functional changes in the muscle-bone unit during normal growth and maturation in peri-pubertal children, and determine if changes in muscle strength are directly related to changes in bone properties. The first part of this work was a systematic review of literature on the effect of physical activity on bone development in children. It was found the best time to see large improvements in bone properties may be during the peri-pubertal years. It was not clear the best type of activity, nor which loading characteristic, should be utilized. This led to the second part of this work, where a non weight-bearing bone, the radius, was investigated in order to separate the influence of muscle properties on bone from ground reaction forces. Children and adolescents (n=172), between the ages of 8-16 years, were examined over a 2-year period. Measurements of somatic maturity, anthropometry, grip strength, bone properties (reflected by speed of sound (SOS)), physical activity (accelerometery), nutrition (24-hour recall), and bone resorption (NTX) were taken. Materials and procedures were identical between studies allowing for both a cross-sectional and longitudinal examination of the muscle-bone unit. Cross-sectionally, results demonstrated relative grip strength, maturity, dietary calcium and NTX explained 21% of the variance in radial SOS (p<0.05). Calcium intake was found to be a significant predictor only after NTX was accounted for, suggesting its effects on the muscle-bone unit may be modulated through bone resorption. In boys, the primary explanatory variables of radial SOS was NTX, followed by grip strength and maturity; where as in girls, it was maturity and dietary calcium. Longitudinally, maturity was found to have indirect effects on radial SOS mediated by grip strength. The influence of maturity on grip strength was similar between sexes, with the effect of grip strength on radial SOS being significantly greater in girls than boys (14.26 vs. 6.60; p<0.05); implying female bones maybe more responsive to muscle forces. Together, these studies provide an overview of muscle-bone unit development during peri-pubertal maturation, demonstrating radial bone properties to be appropriately adapted to muscle function and force independent of physical activity.
    • Neural and Behavioural Consequences of Chronic Inflammation following Spinal Cord Injury

      Allison, David; Applied Health Sciences Program
      This thesis investigated the influence of chronic inflammation on several neural/behavioural disorders following spinal cord injury (SCI) including depression, cognitive impairment, neuropathic pain, and somatic nerve deficits. Ample evidence exists to suggest that the immune system communicates with, and influences the nervous system both centrally and peripherally. Pro-inflammatory cytokines have been shown to influence the nervous system directly by altering ion channel kinetics, as well as indirectly by altering enzyme function thereby resulting in changes in critical neuroactive compounds. Proinflammatory mediators have been shown to up-regulate the enzyme indoleamine 2,3 dioxygenase (IDO) resulting in the accelerated degredation of serotonin precursor tryptophan (TRP) and increased production of TRP metabolites such as kynurenine (KYN). They have also been shown to upregulate the enzyme cyclooxygenase (COX) resulting in the increased production of pain inducing eicosanoids such as prostaglandin E2 (PGE2). Immune dysfunction in the form of chronic inflammation may therefore contribute to the severity of behavioural disorders such as depression and cognitive impairment, as well as neural disorders such neuropathic pain and somatic nerve deficits. SCI is typically associated with not only a state of chronic inflammation but also a drastically higher prevalence of each of the aforementioned neural and behavioural disorders. This makes SCI an ideal population to study the interaction between the immune and nervous systems, and assess the potential efficacy of novel treatment strategies which target the immune system for the management of such disorders. A 3-month anti-inflammatory diet was utilized as a treatment intervention for the purpose of reducing chronically elevated levels of pro-inflammatory mediators. This intervention allowed for the assessment of each of the outcome variables of interest at baseline (under an elevated inflammatory status) as well as at 1-month and 3-months during the intervention (under a reduced inflammatory state). Changes in inflammation were assessed by the quantification of serum pro (IL-1β, IL-2, IL-6, IFN-У, TNF-α, CRP) and anti-inflammatory (IL-4, IL-10, IL-1RA) cytokines. Cytokine-induced alterations in enzyme function and corresponding changes in neuroactive compounds were assessed by tryptophan (TRP), the competing amino acids phenylalanine (PHE), tyrosine (TYR), leucine (Leu), isoleucine (Ile), and valine (Val), the tryptophan metabolite kynurenine (KYN), and the pain-inducing eicosanoids prostaglandin E2 (PGE2) and leukotriene B4 (LTB4). In addition to such molecular indices, actual changes in each of the outcome variables of interest were assessed. Levels of depression were assessed by questionnaire via the Center for Epidemiological Studies Depression Scale (CES-D). Cognitive function (in the form of verbal learning) and memory was assessed via the California Verbal Learning Test (CVLT). Neuropathic pain was assessed via the Neuropathic Pain Questionnaire (NPQ). Somatic nerve function was assessed by EMG, including the assessment of nerve conduction velocity and signal amplitude in both motor and sensory nerves. The intervention significantly reduced serum concentrations of pro-inflammatory mediators in the treatment group (n=12) by 28%, while no significant change was found in the control group (n=8). Among other changes in amino acids, the most notable was that the change in the KYN/TRP ratio (an indicator of IDO activity) and the TRP/LNAA ratio (an indicator of TRP availability for serotonin synthesis) was significantly different between groups. The treatment group showed a significant reduction in scores of depression, as well as a significant reduction in sensory neuropathic pain scores. No significant changes were observed in regards to somatic nerve conduction and most indices of cognitive function (with the exception of the ability to avoid incorrect responses on the CVLT). These results may suggest a substantial role for chronic inflammation in depression and neuropathic pain following SCI and provide a potential alternative treatment strategy for the management of such intractable disorders.
    • The Influence of Cerebral Blood Flow and Carbon Dioxide on Neuromuscular Responses During Environmental Stress

      Hartley, Geoffrey L.; Applied Health Sciences Program
      Although reductions in cerebral blood flow (CBF) may be implicated in the development of central fatigue during environmental stress, the contribution from hypocapnia-induced reductions in CBF versus reductions in CBF per se has yet to be isolated. The current research program examined the influence of CBF, with and without consequent hypocapnia, on neuromuscular responses during hypoxia and passive heat stress. To this end, neuromuscular responses, as indicated by motor evoked potentials (MEP), maximal M-wave (Mmax) and cortical voluntary activation (cVA) of the flexor carpi radialis muscle during isometric wrist flexion, was assessed in three separate projects: 1) hypocapnia, independent of concomitant reductions in CBF; 2) altered CBF during severe hypoxia and; 3) thermal hyperpnea-mediated reductions in CBF, independent of hypocapnia. All projects employed a custom-built dynamic end-tidal forcing system to control end-tidal PCO2 (PETCO2), independent of the prevailing environmental conditions, and cyclooxygenase inhibition using indomethacin (Indomethacin, 1.2 mg·Kg-1) to selectively reduce CBF (estimated using transcranial Doppler ultrasound) without changes in PETCO2. A primary finding of the present research program is that the excitability of the corticospinal tract is inherently sensitive to changes in PaCO2, as demonstrated by a 12% increase in MEP amplitude in response to moderate hypocapnia. Conversely, CBF mediated reductions in cerebral O2 delivery appear to decrease corticospinal excitability, as indicated by a 51-64% and 4% decrease in MEP amplitude in response to hypoxia and passive heat stress, respectively. The collective evidence from this research program suggests that impaired voluntary activation is associated with reductions in CBF; however, it must be noted that changes in cVA were not linearly correlated with changes in CBF. Therefore, other factors independent of CBF, such as increased perception of effort, distress or discomfort, may have contributed to the reductions in cVA. Despite the functional association between reductions in CBF and hypocapnia, both variables have distinct and independent influence on the neuromuscular system. Therefore, future studies should control or acknowledge the separate mechanistic influence of these two factors.
    • Force potentiation as a modulator of contractile performance: Implications for control of skeletal muscle force and energetics of work

      Gittings, William J.; Applied Health Sciences Program
      This thesis investigated the modulation of dynamic contractile function and energetics of work by posttetanic potentiation (PTP). Mechanical experiments were conducted in vitro using software-controlled protocols to stimulate/determine contractile function during ramp shortening, and muscles were frozen during parallel incubations for biochemical analysis. The central feature of this research was the comparison of fast hindlimb muscles from wildtype and skeletal myosin light chain kinase knockout (skMLCK-/-) mice that does not express the primary mechanism for PTP: myosin regulatory light chain (RLC) phosphorylation. In contrast to smooth/cardiac muscles where RLC phosphorylation is indispensable, its precise physiological role in skeletal muscle is unclear. It was initially determined that tetanic potentiation was shortening speed dependent, and this sensitivity of the PTP mechanism to muscle shortening extended the stimulation frequency domain over which PTP was manifest. Thus, the physiological utility of RLC phosphorylation to augment contractile function in vivo may be more extensive than previously considered. Subsequent experiments studied the contraction-type dependence for PTP and demonstrated that the enhancement of contractile function was dependent on force level. Surprisingly, in the absence of RLC phosphorylation, skMLCK-/- muscles exhibited significant concentric PTP; consequently, up to ~50% of the dynamic PTP response in wildtype muscle may be attributed to an alternate mechanism. When the interaction of PTP and the catchlike property (CLP) was examined, we determined that unlike the acute augmentation of peak force by the CLP, RLC phosphorylation produced a longer-lasting enhancement of force and work in the potentiated state. Nevertheless, despite the apparent interference between these mechanisms, both offer physiological utility and may be complementary in achieving optimal contractile function in vivo. Finally, when the energetic implications of PTP were explored, we determined that during a brief period of repetitive concentric activation, total work performed was ~60% greater in wildtype vs. skMLCK-/- muscles but there was no genotype difference in High-Energy Phosphate Consumption or Economy (i.e. HEPC: work). In summary, this thesis provides novel insight into the modulatory effects of PTP and RLC phosphorylation, and through the observation of alternative mechanisms for PTP we further develop our understanding of the history-dependence of fast skeletal muscle function.
    • The Conceptualization and Exploration of Place Allegiance: Towards a Unified Model of Person-Place Relationships within Outdoor Recreation

      Howard, Ryan; Applied Health Sciences Program
      The academic study of place has been generally defined by two distinct and highly refined discourses within outdoor recreation research: place attachment and sense of place. Place attachment generally describes the intensity of the place relationship, whereas sense of place approaches place from a more holistic and intimate orientation. This study bridges these two methodological and theoretical separate areas of place research together by re-conceptualizing the way in which place relationships are viewed within outdoor recreation research. The Psychological Continuum Model is used to extend the language of place attachment to incorporate more of the philosophy of sense of place while attending to the empirical strength and utility of place attachment. This extension results in the term place allegiance being coined to depict the strong and profound relationships outdoor recreationists build with their places of outdoor recreation. Using a concurrent mixed methods research design, this study explored place allegiance via an online survey (n = 437) and thirteen in-depth qualitative interviews with outdoor recreationists. Results indicate that place allegiance can be measured through a multi-dimensional model of place allegiance that incorporates behaviours, importance, resistance, knowledge and symbolic value. In addition, place allegiance was found to be related to an individual's influence on life course and his/her willingness to exhibit preservation and protection tendencies. Place allegiance plays an important role in acknowledging the importance of authentic place relationships in an effort to confront placelessness. Wilderness recreation is an important avenue for outdoor recreationists to build strong place relationships.
    • Autonomic Cardiovascular Control in Children and Adolescents

      Chirico, Daniele; Applied Health Sciences Program
      This thesis investigated the impact of pubertal maturation and sex on cardiovagal baroreflex sensitivity (BRS) and arterial properties of the common carotid artery (CCA), and the relationship between CCA arterial properties and BRS. This thesis also investigated the effect of orthostatic stress on arterial properties of the CCA and carotid sinus (CS), as well as their impact on BRS in response to orthostatic stress. Children and adolescents between the ages of 8-18 years were examined. To assess pubertal maturation participants were organized into five pubertal groups based on the criteria of Tanner. BRS was assessed by transfer function analysis in the low frequency range (0.05 – 0.15Hz). Pulse pressure (PP) was measured at the CCA (PPCCA) and CS (PPCS) using applanation tonometry, and at the finger (PPFinger) using photoplethysmography. Ultrasound sonography and applanation tonometry were used to determine the distensibility coefficient (DC) at the CCA (DCCCA) and CS (DCCS). A moderate posture stimulus was implemented by passively moving participants into a 50° seated-recumbent (SR) position. The results demonstrated a sex-by-maturation interaction on BRS (p= 0.019). BRS decreased from early- to post-puberty in males (p<0.01), and remained unchanged in females. Females demonstrated greater BRS compared to males post-puberty (p<0.05). CCA distensibility was not affected by sex or maturation and was not related to BRS. PPCS was greater than PPCCA (p<0.001), while PPFinger was greater than both PPCCA (p<0.001) and PPCS (p<0.001). In response to SR, the relative change in PPFinger was significantly different than the relative change in PPCCA (p<0.001) and PPCS (p<0.001), while the relative change between PPCCA and PPCS were not different. Finally, in response to SR there was a significant decrease in DCCS (p=0.001), but not DCCCA. The relative change in BRS in response to SR was significantly correlated to the relative change in DCCS (p=0.004), but not DCCCA. The findings demonstrated an important sex-dependent maturation effect on BRS in children and adolescents that was not explained by CCA distensibility. Also, the CS and CCA responded differently to orthostatic stress. The CS was more suitable to evaluate the effect of arterial distensibility on BRS in response to posture change.
    • The Influence of Attentional Focus on the Self-Efficacy-Performance Relationship in a Continuous Running Task

      LaForge-MacKenzie, Kaitlyn; Applied Health Sciences Program (Brock University, 2015-02-04)
      The self-efficacy-performance relationship in continuous sport tasks has been shown to be significantly reciprocal yet unequal with stronger influences in the performance-to-self-efficacy pathway rather than self-efficacy-to-performance pathway (e.g., LaForge-MacKenzie & Sullivan, 2014b). Bandura (2012) suggested that sociocognitive variables may influence this relationship. Attention as a sociocognitve factor may bias the processing of performance and self-efficacy information (Bandura, 1982, 1997; Bandura & Jourden, 1991). As confidence and attention are important aspects of peak running performance (Brewer, Van Raalte, Linder, & VanRaalte, 1991), the primary purpose of the present study was to examine the self-efficacy-performance relationship under three conditions of attentional focus. The secondary purpose was to examine self-efficacy and performance as separate constructs under the same conditions of attention. Participants ran continuously for one kilometer in one of three randomly assigned attentional focus conditions: internal-focus (n = 51), external-focus (n = 50), and control (n = 49). Self-efficacy was assessed using a one-item measure every 200 meters. Path analyses examining the primary objective revealed significant self-efficacy-to-performance pathways in all conditions: external-focus (p < .05, βs ranging from -.17 to -.32), internal-focus (p < .05, βs ranging from -.26 to -.36), and control (p < .05, βs ranging from -.29 to -.42). Significant reciprocal relationships were absent in all conditions. ANOVAs examining the secondary objectives found significantly faster performance in the control condition at the start (F (2, 147) = 3.86, p < .05) and end of the task (F (2, 147) = 3.56, p < .05). Self-efficacy was significantly higher in the internal-focus condition at the end of the task (Self-Efficacy 4 (F (2, 147) = 3.21, p < .05) and Self-Efficacy 5 (F (2, 147) = 4.74, p < .05). In contrast to previous within-trial research (e.g., LaForge-MacKenzie & Sullivan, 2014b) self-efficacy-to-performance effects were more significant and robust than performance-to-self-efficacy effects. These results provided support for Bandura’s (2012) suggestion that sociocognitive factors may have the ability to alter the causal structure of the self-efficacy-performance relationship, proposing complexities in the self-efficacy-performance relationship (Sitzmann &Yeo, 2013). Results were discussed from both theoretical and applied perspectives.
    • A Narrative Study of Patient Encounter Accounts of Physicians, Nurses, and Medical Receptionists after Two Decades of a Paradigm of Patient-Centered Care

      Akseer, Riaz; Applied Health Sciences Program (Brock University, 2014-12-02)
      Despite recent well-known advancements in patient care in the medical fields, such as patient-centeredness and evidence-based medicine and practice, there is rather less known about their effects on the particulars of clinician-patient encounters. The emphasis in clinical encounters remains mostly on treatment and diagnosis and less on communicative competency or engagement for medical professionals. The purpose of this narrative study was to explore interactive competencies in diagnostic and therapeutic encounters and intake protocols within the context of the physicians’, nurses’, and medical receptionists’ perspectives and experiences. Literature on narrative medicine, phenomenology and medicine, therapeutic relationships, cultural and communication competency, and non-Western perspectives on human communication provided the guiding theoretical frameworks for the study. Three data sets including 13 participant interviews (5 physicians, 4 nurses, and 4 medical receptionists), policy documents (physicians, nurses, and medical receptionists) and a website (Communication and Cultural Competency) were used. The researcher then engaged in triangulated analyses, including N-Vivo, manifest and latent, Mishler’s (1984, 1995) narrative elements and Charon’s (2005, 2006a, 2006b, 2013) narrative themes, in recursive, overlapping, comparative and intersected analysis strategies. A common factor affecting physicians’ relationships with their clients was limitation of time, including limited time (a) to listen, (b) to come up with a proper diagnosis, and (c) to engage in decision making in critical conditions and limited time for patients’ visits. For almost all nurse participants in the study establishing therapeutic relationships meant being compassionate and empathetic. The goals of intake protocols for the medical receptionists were about being empathetic to patients, being an attentive listener, developing rapport, and being conventionally polite to patients. Participants with the least iv amount of training and preparation (medical receptionists) appeared to be more committed to working narratively in connecting with patients and establishing human relationships as well as in listening to patients’ stories and providing support to narrow down the reason for their visit. The diagnostic and intake “success stories” regarding patient clinical encounters for other study participants were focused on a timely securing of patient information, with some acknowledgement of rapport and emapathy. Patient-centeredness emerged as a discourse practice, with ambiguous or nebulous enactment of its premises in most clinical settings.
    • The role of skeletal muscle PLIN proteins at rest and following lipolytic stimulation

      MacPherson, Rebecca EK; Applied Health Sciences Program (Brock University, 2013-12-16)
      This thesis investigated the subcellular location of skeletal muscle PLIN proteins (PLIN2, PLIN3, and PLIN5) as well as protein interactions with ATGL and HSL at rest and following lipolytic stimulation. In addition, the serine phosphorylation state of PLIN2, PLIN3, and PLIN5 was determined at rest and following lipolytic stimulation. An isolated whole muscle technique was used to study the effects of contraction and epinephrine-induced lipolysis. This method allowed for the examination of the effects of contraction and epinephrine alone and in combination. Further, the soleus was chosen for investigating the role of PLIN proteins in skeletal muscle lipolysis due to its suitability for isolated incubation, and the fact that it is primarily oxidative in nature (~80% type I fibres). It has also been previously shown to have the greatest reliance on lipid metabolism and for this reason is ideal for investigating the role of PLIN proteins in lipolysis. Immunofluorescence microscopy revealed that skeletal muscle lipid droplets are partially co-localized to both PLIN2 and PLIN5 and that contraction does not affect the amount of colocalization, indicating that PLIN5 is not recruited to lipid droplets with contraction (PLIN2 ~65%; PLIN5 ~56%). Results from the immunoprecipitation studies revealed that with lipolysis in skeletal muscle the interaction between ATGL and CGI-58 is increased (study 2: 128% with contraction, p<0.05; study 3: 50% with contraction, 25% epinephrine, 80% contraction + epinephrine, p>0.05). Further PLIN2, PLIN3, and PLIN5 all interact with ATGL and HSL, while only PLIN3 and PLIN5 interact with CGI-58. Among these interactions, the association between PLIN2 and ATGL decreases with lipolytic stimulation (study 2: 21% with contraction, p<0.05). Finally our results demonstrate that PLIN3 and PLIN5 are serine phosphorylated at rest and that the level of phosphorylation remains unchanged in the face of either contractile or adrenergic stimulation. In summary, the regulation of skeletal muscle lipolysis is a complex process involving multiple proteins and enzymes. The skeletal muscle PLIN proteins likely play a role in skeletal muscle lipid droplet dynamics, and the data from this thesis indicate that these proteins may work together in regulating lipolysis by interaction with both ATGL and HSL.
    • Physical Activity and Fitness in Children with Developmental Disorder

      Rivilis, Irina; Applied Health Sciences Program (Brock University, 2012-05-17)
      Introduction: Developmental coordination disorder (DCD) is a prevalent condition characterized by poor motor proficiency that interferes with a child‟s activities of daily living. Children with DCD often experience compromised health-related fitness components such as cardiorespiratory fitness (CRF). Purpose: To better understand the physical activity and fitness characteristics of children with probable DCD (pDCD), with a particular focus on CRF. Specifically: (1) to present a synopsis of current literature; (2) to determine the longitudinal trajectories of CRF; (3) to compare the submaximal CRF of children with and without pDCD. Methods: A comprehensive, systematic literature review was conducted of the recent available data on fitness and physical activity and pDCD (Chapter 2). This review provided the background for the other two studies included in this thesis. In Chapter 3, a prospective cohort design was used to assess how CRF in children with pDCD changes over time (56 months) relative to a group of typically developing controls. Using a nested-case control design, 63 subjects with pDCD and 63 matched controls from the larger sample were recruited to participate in the lab-based component of the study (Chapter 4). In this investigation CRF was examined using the oxygen cost of work (VO2) during an incremental test on a cycle ergometer. Results: The literature review showed that fitness parameters, including CRF and physical activity levels, were consistently reduced in children with pDCD. Chapter 3 demonstrated that the difference in CRF between children with pDCD and typically developing children is substantial, and that it tends to increase over time. Results from VO2 assessments showed that children with pDCD utilized more oxygen to sustain the same submaximal workloads compared to typically developing children. Conclusions: Findings from this thesis have made several important contributions to our understanding of children with pDCD. Since differences in CRF between children with and without pDCD tend to worsen over time, this adds to the argument that interventions intended to improve CRF may be appropriate for children with motor difficulties. This thesis also presented the first evidence suggesting that DCD involves higher energy expenditure, and could help explain why children with pDCD perform poorly on tasks requiring CRF.