• 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.
    • 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.
    • Can exergaming improve mental health of university students?

      Santos, Esther; Applied Health Sciences Program
      The academic, financial, and social pressures that emerge when adults begin university may lead them to encounter mental health challenges (American College Health Association [ACHA], 2016). In Ontario, 46.2% of university/college students have reported ‘excessive’ stress whereas 64.5% report ‘overwhelming’ anxiety (ACHA, 2016). One approach that may be useful for enhancing mental health is exergaming which uses motion-sensor technology requiring players to move their bodies to complete the videogame sessions (Huang et al., 2017). However, studies focused on the effectiveness of exergaming for improving mental health of university students are scarce in number and limited in scope. The overall purpose of this dissertation was to examine the role of exergaming in relation to mental health reported by university students. In Study 1, a synthesis of published intervention research using exergaming to change well-being – a psychological concept affiliated with mental health – reported by adults was conducted. Results from Study 1 indicated that less than 50.0% of the coded studies - using either multi- or single-group (pre-post-test) research designs - reported enhanced well-being as a function of exergaming. In Study 2, the link between the amount and intensity of exergaming behaviour per week and mental health reported by university students was evaluated. Results from Study 2 indicated that university students who reported more frequent exergaming behaviour during a typical week displayed lower anxiety and stress plus higher flourishing and vitality. In Study 3, the contributions of exergaming to mental health of university students were investigated using an experimental research design that compared exergaming against other physical activity behaviours and self-management approaches. Results from Study 3 showed that ‘exergamers’ did not present higher or lower mental health scores compared against ‘traditional’ exercisers but displayed less stress and anxiety when compared against pet therapy, as well as, higher vitality plus lower stress and anxiety compared to ‘non-exercisers’. The results from these studies make it apparent that exergaming may not offer anything ‘unique’ as a stimulus beyond more traditional modes of exercise, but it fosters mental health of university students.
    • 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.
    • 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.
    • 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.
    • Designing, Testing, and Implementing BIAS (Body Image Awareness Seminars): A Positive Body Image Program

      Bailey, Kaytlin Alysse; Applied Health Sciences Program
      Dissatisfaction with the body is prevalent in North America and body image researchers have called this phenomenon a norm, suggesting it is abnormal for people to love their bodies. Positive body image programs are needed now more than ever but currently they are scarce, and this is especially true for individuals outside adolescent and university student populations. This dissertation describes the design, testing, and implementation of a new positive body image program called BIAS (Body Image Awareness Seminars). This program is unique in three ways: 1) it was created by working with participants using action research, 2) it is applicable to a diversity of people including older adults and people with physical disabilities, and 3) it was informed by positive body image research. In study 1, initial interviews and focus group meetings revealed a potential knowledge gap in understanding body image between body image researchers and the non-academic community. Participants described a need to understand body image better in order to improve their body image experiences. This study led to the conclusion that psychoeducation is an important component of a positive body image program which significantly informed the design of BIAS. Study 2 describes the creation of BIAS using action research. Very few body image programs have been designed using participatory methodologies. Instead, most body image researchers create and implement body image interventions without any participant feedback. Study 2 highlights both the advantages and disadvantages of using action research in the design, testing, and implementation of the BIAS program. Study 3 is an evaluation of the effectiveness of BIAS. Using mixed methods, qualitative and quantitative data were analyzed and both concordance and discordance of results were reported. Participants’ body image was found to significantly improve and this improvement was sustained 6-weeks later. Additional findings include participants experiencing self-compassion, greater knowledge about body image, and becoming positive body image advocates. Study contributions to both the body image and mixed methods literature are discussed.
    • Effects of Exogenous Lipopolysaccharide Exposure on Bone Outcomes in Rodent Models

      Bott, Kirsten; Applied Health Sciences Program
      Chronic low-grade inflammation has been identified as a potential contributor to the pathophysiology of osteoporosis. A key mediator may be lipopolysaccharide (LPS) released from gram-negative bacteria in the gut that can enter circulation stimulating an inflammatory response and upregulate bone resorption. Since rodent models mimic the loss of bone mineral density (BMD) and structure that occurs in humans, rodents offer an accelerated model for studying these inflammation-mediated changes. Therefore, the objective of this thesis was to characterize a rodent model of LPS-induced bone loss using repeated in vivo μCT scans to establish a time course effect of LPS longitudinally and for this purpose three studies were conducted. Study 1 & 2 were run simultaneously using the same control mice. Study 1 demonstrated that repeated irradiation had a negative impact on trabecular bone in both male and female CD-1 mice, while cortical bone was only negatively impacted in the females. In study 2, continuous delivery of exogenous LPS via osmotic pumps for 12 weeks elevated serum LPS in both male and female CD-1 mice but did not alter trabecular or cortical bone structure or BMD at any of the scanning timepoints. Results from Study 2 may in part have been influenced by the effects of repeated irradiation from the in vivo μCT scans at 4-week intervals for a total of 4 scans analyzed in Study 1. In study 3, a systematic review was conducted to better characterize a model of LPS induced bone loss and identify factors that may impact the effects of LPS on bone outcomes in rodent models. Regardless of study duration, exogenous LPS negatively impacted trabecular bone structure and BMD but not cortical bone structure, due to an upregulation in bone resorption. Together these data suggest that exogenous LPS can induce alterations in bone structure and BMD in rodent models, however a clearly defined model of exogenous LPS induced bone loss has yet to be fully characterized.
    • Effects of local muscle temperature manipulations on neuromuscular function

      Mallette, Matthew M.; Applied Health Sciences Program
      Human muscle can operate through a wide range of temperature; however optimal function may occur throughout a much narrower range. Muscle cooling results in an impairment in muscle contractile properties and maximal force, whereas heating the muscle fosters faster and more powerful contractions. However, what neural compensatory mechanisms exist such that the muscle can still function adequately throughout a wide range of temperatures are unknown and forms the purpose of this dissertation. To this end, muscle contractile and motor unit properties of the flexor carpi radialis were examined during three separate projects involving forearm temperature manipulations. Chapter 4 investigates the effects of local forearm cooling on motor unit properties during an isometric wrist flexion contraction to 50% of baseline maximal force. Chapter 5 builds upon Chapter 4 to include local heating and contraction intensities above and below the motor unit recruitment range of the flexor carpi radialis. Finally, Chapter 6 investigates how different muscle temperatures affect manual performance – assessed through a staircase isometric force tracking task. Local cooling did not affect the ability to perform voluntary contractions to 50% of baseline force, but motor control was achieved through changes in the relationship between motor unit firing rate and recruitment threshold, indicating either faster motor unit firing rates and/or earlier motor unit recruitment to accomplish a task at the same absolute force (Chapter 4). However, these differences were not present when force requirements were made relative to muscle capacity of the respective temperature conditions. We found that motor units were recruited earlier in the cold when contraction intensity was above the motor unit recruitment range (Chapter 5). The altered relationship between motor unit firing rate and recruitment threshold observed in Chapter 4 with muscle cooling at an absolute force level did not affect isometric force tracking ability (Chapter 6). Collectively, this thesis found that the motor unit recruitment threshold may be depressed in the cold due to cutaneous stimulation, and that manual function during an isometric force tracking task involving relatively light loads is not impaired with muscle temperature changes.
    • The Examination of Potential Mechanisms Underlying the Cross Education Phenomenon

      Green, Lara; Applied Health Sciences Program
      Cross education is the strength or skill gain that is found in the contralateral, homologous limb following a unilateral training program or practice. This phenomenon provides a beneficial rehabilitation model for unilateral injuries or neurologic disorders, such as stroke. Although the cross-body transfer of strength and skill are each widely studied, they are rarely examined concurrently, despite each contributing to the goal of functional movement rehabilitation. Therefore, the overall purpose of this thesis was to examine the neuromuscular adaptations of unilateral resistive exercise training contributing to the transfer of strength and skill, while employing the necessary methodological controls that have been under-examined and under-used. The assessment of neuromuscular mechanisms requires both voluntary and evoked contractions to be performed simultaneously. Therefore Manuscript 1 examined a novel electrode configuration, consisting of one electrode on the electrically identified motor point and the second electrode directly adjacent in a bipolar configuration. Both voluntary surface electromyography measures and evoked potentials were found to be reliable (ICCs > 0.75) and effective across multiple test sessions. Manuscript 2 was a comprehensive review of 90 unilateral training studies in young and older able-bodied participants and in patient populations. The cross education strength gain was estimated at 18% in young, and 17% in older able-bodied participants. The cross education strength gain was 29% in patient populations consisting of post-stroke, multiple sclerosis, osteoarthritis, and neuromuscular disorder patients. The meta-analysis identified the efficacy of electromyostimulation (EMS) training over voluntary training modalities. The magnitude of strength transfer was similar between upper and lower and between males and females. Lastly, manuscript 3 consisted of a 6-week unilateral training program resulting in contralateral strength gains of 11% in the wrist flexors and 15% in the dorsiflexors. A continued increase in contralateral strength at retention demonstrated the persistence of cross education following 6-weeks of detraining. Skill transfer in the contralateral limbs was evident in the force variability measures calculated during contractions without concurrent feedback (noKR). Agonist RMS amplitude, V-wave amplitude, and central activation ratio indicated neuromuscular adaptations; however, there was no change in motor unit firing rates at 60% of maximal force.
    • Examining Student Preparation for Certification Examination: An Exploratory Case Study

      TAYLOR, HELEN CATHERINE; Applied Health Sciences Program
      This research paper explores three university-level programs with mandatory licensing exams for graduates who wish to attain professional certification. Specifically, the study explored the affordances and constraints associated with curricular alignment and program accreditation, student success on licensure, and student satisfaction. The specific programs and the licensure exams are: the Bachelor of Science in Nursing (BScN), who are eligible to take the National Council Licensure Examination-Registered Nurse (NCLEX-RN), the Master of Applied Disability Studies (MADS), who write the Behavior Analyst Certification Board Exam, and the Bachelor of Accounting/Master of Accountancy (BAcc/MAcc), who are eligible to take the Chartered Professional Accountants (CPA) Common Final Examination (CFE). The study used a scoping review of the literature specific to the NCLEX-RN to help inform an exploratory case study of three academic programs that are offered through a University in Ontario, all leading to licensure exams. The programs are designed to ensure that students are prepared to write the licensure exams and provide more material that is integral to the practice but is not necessarily tested on the licensure exam. Using curriculum and accreditation review processes, administrators/faculty and students can provide insight into processes that could aid future students for licensure exams. When comparing the findings from analyses of transcripts from one program and documents across all three programs, it is apparent that there are many similarities across the programs despite the differences in the actual curricular goals and licenses. However, there appears to be a disconnect in the Nursing program, since they use the greatest number of the identified techniques/tools, but still have lower percentages of first-time pass rates than the other two programs. This provides an area for future study and analysis.
    • Exploring Mental Health in Sport: The Behaviors, Perspectives and Needs of Stakeholders

      Murphy, Jessica; Applied Health Sciences Program
      Student-athletes are at high risk for poor mental health. Leaders within the varsity sport environment influence athlete mental health and help-seeking. This dissertation explored the behaviors, perspectives and needs of athletes, coaches, and athletic trainers as it pertains to mental health in sport. Three studies were conducted, the first utilized the Theory of Planned Behavior to explore factors associated with coach-athlete conversations about mental health. A coach’s Attitude towards having a conversation with an athlete significantly influenced their Intention to do so. Perceived Behavioral Control (PBC) significantly influenced the relationship between Social Norms and Intention. Both PBC and Social Norms had a significant relationship with the Behavior (having a conversation about mental health with an athlete). The second study applied a conceptual model from Horn’s Working Model of Coach Effectiveness to explore how an athlete’s perception of coach behavior impacts attitudes and help-seeking behaviors. Psychological distress levels influenced an athlete’s Perception of their coach’s behavior. Openness to help-seeking was significantly related to help-seeking Behaviors and influenced the relationship between personal characteristics and help-seeking. Perception of coach behaviors influenced the relationship between psychological distress and help-seeking from a coach. The last study sought to determine the acceptance of an online varsity sport-specific mental health resource. Preliminary results were promising; The PEER Network was frequently used over the study period and participants had positive and supportive feedback. Overall, results from the three studies suggest that perceived ability and social support may influence whether coach-athlete conversations about mental health occur. Due to the effects of these variables, coach mental health training should focus on improving the skills required for these conversations and normalizing mental health in sport. As an athlete’s perception of coach behavior mediated the relationship between psychological distress and help-seeking, training should also focus on clear ways to show athletes that coaches are supportive of mental health. Athlete-specific training should try and improve attitudes towards help-seeking and highlight the value from seeking help. The PEER Network may be an easily accessible and context-specific way of achieving these educational goals for members of the varsity athletic community.
    • Exploring the Ecological Self: An Interpretive Phenomenological Analysis with Gifted Adults

      Windhorst, Eric; Applied Health Sciences Program
      The nature connectedness research suggests that (re)creating human-nature connections can address both escalating ecological issues and rising mental health concerns by fostering (ecological) self-realization. Given that the nature connectedness literature oversimplifies experience of ecological self, however, there remains a need to explore lived ecological self experience, and how this experience influences mental health and environmental behaviour. In this exploratory interpretive phenomenological analysis (IPA), I sought to flesh out the nature connectedness research by investigating ecological self experience among a small group of gifted adults (n=8) who measure relatively high in nature connectedness. Three research questions guided the study. The project’s primary research question was: How do gifted adults experience ecological self? Two secondary, theory-driven sub-questions refined the project further: 1. How does experience of ecological self influence mental health? 2. How does experience of ecological self influence environmental behaviour? Analysis of data collected via two semi-structured interviews held with each participant reveal that while ecological self experiences might often enhance mental health, nature experiences can also be intense, distressing, and/or ambivalent, and environmental concerns can precipitate anguish and anger. Findings also illustrate how experience of ecological self can be inconsistent: conceptions of the human-nature relationship varied, and experience of ecological self seemed to oscillate along with diurnal and seasonal cycles and appeared to evolve over the lifespan. Finally, results demonstrate that while ecological self experience may motivate pro-environmental behaviour, movement from experience to action is not automatic. Findings show how a variety of intra- and interpersonal factors can hinder pro-ecological engagement. Taken together, study results nuance the nature connectedness literature by illustrating the complexity of ecological self experience. While (re)creating human-nature connections can be considered one approach to addressing escalating ecological issues and rising mental health concerns, findings from this project suggest that the back-to-nature strategy is not a cure-all.
    • 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.
    • Future-proofing: Exploring the value of a therapeutic recreation positive psychology intervention for supporting youth experiencing mental health challenges

      Cripps, Lauren C.; Applied Health Sciences Program
      In Canada, suicide remains the second leading cause of death for individuals aged 15 to 24, exceeded only by unintentional injuries (accidents). In 2012, suicide accounted for 15% of deaths among youth aged 10-14 years, 29% among youth aged 15-19 years and 23% among young adults aged 20-24 (Statistics Canada, 2017). Recovery supports the development of a meaningful life (as described by the individual) that includes enhanced traits and practices that are specifically intended to maintain one’s level of satisfaction in everyday life, while supporting the management of recurring symptoms and/or changes in current life circumstances (Andresen, Oades, & Caputi, 2011; Kleiber, Hutchinson, & Williams, 2002; McCormick & Iwasaki, 2008; McCormick & Iwasaki, 2008; McCormick, 1999). This recovery-oriented project was a qualitative, interpretative phenomenological study guided by the evidenced-informed process as a framework for program design, implementation and evaluation. This project sought to critically explore mental health as it pertains to adolescents through the design, implementation and evaluation of a therapeutic recreation intervention designed for youth living in a residential treatment setting. This project provides evidence that the BYBS-Y program has the potential to support change with the participants. This project also demonstrates new learning and is an illustration of the potential connection between a strengths perspective and supporting essential tasks assigned to development and recovery. By implementing a three-phase process this research shows the value of feedback from both practitioners and clients, affirming that our greatest insights are always gained from those with lived experience. Finally, this project provides evidence for the contribution of TR services in the recovery process, suggesting that by focusing on the development of skills and capacities that are likely to generate emotion, highlight strengths, support choice and create opportunities for positive social connections, it is likely that youth can increase the resiliency necessary to buffer the effects of chronic symptoms and in turn begin to envision (and obtain) a life that includes, but is not defined by illness.
    • "(Having?) Doing it All”: A Narrative Exploration of Self-Care and Well-being for Generation X Women at Midlife

      Petty, Lisa; Applied Health Sciences Program
      Inspired by my own experiences as a woman moving through midlife, the purpose of this research was to better understand the lived experience of Generation X women. Specifically, the study investigated the relationship between self-care and well-being as the women navigate their changing bodies and negotiate, resist and/or reproduce social role expectations. Using a critical constructivist perspective and guided by the Life Course framework, this narrative study involved two reflexive, dyadic interviews with 21 Generation X women (born between 1965-1980). As part of the study, women took photographs that represented their experiences, and the images and narratives were included in the data. Use of Reissman’s (2008) narrative thematic analysis revealed four major thematic areas: (a) The Multiple Meanings of Self-Care: It’s Whatever is Important to You, (b) The Big Lie: Having Doing it All, (c) Who is she? What is this?: Changing Bodies, and (d) Navigating Self-Care: Something has to Give. Each thematic area is comprised of several subthemes that narrate the women’s experiences. Thematic areas are first presented in pastiche form, which is a representation much like a quilt that provides a weave of participants’ co-existing meanings (Ely, Vinz, Downing, & Anzul, 1997). The pastiche is then followed by written thematic analysis of the findings using verbatim quotations from participants, as well as my own personal reflections. Taken together, the findings highlight the myriad ways the social backdrop of ‘having it all’ has influenced the life experiences and well-being of these women. More precisely, findings show how the women reproduce and resist social role expectations placed on them in the practise of their self-care, and introduces the concepts of mindful connection, self-care shaming and the archetypal Crone to the self-care literature. As the experiences of Generation X women have largely been ignored in research across disciplines, this research provides important contributions to the self-care literature and its connections to well-being for women.
    • 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.
    • 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.
    • 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.
    • 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.