Recent Submissions

  • 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.
  • Lessons learned from a critical appraisal of a fall break policy in higher education: A case study

    Pilato, Kelly A.; Applied Health Sciences Program
    The incidence, severity and persistence of mental health issues is increasing across post- secondary campuses (Zivin et al., 2009; Canada Newswire, 2012) with these students now viewed as a high-risk population (Stallman, 2010). Many Canadian universities are implementing a policy for a fall break in hopes of alleviating students’ stress and anxiety in order to improve mental health, heighten retention, and increase academic productivity. To date, there is limited empirical evidence to guide the development of policy and the delivery of effective practices to alleviate school-related stress and anxiety. This thesis is presented as a three paper, manuscript approach. The focus of this project was to appraise the development and implementation of a fall break and then evaluate its effectiveness in an effort to address rising concerns related to mental health for post-secondary students. Three thousand and seventy-one students in years one to four completed a post-break survey during one week in January of 2013, 2014, 2015. Of those, 1019 were male and 2052 female. Thirty-three students varying in years from one to four participated in focus groups in February of 2013, 2014, 2015. Of those 4 were male and 19 were female. Ten faculty from varying faculties and one informant participated in interviews in spring, 2018. Analyses from the surveys revealed that overall, students are in favour of having a fall break. Even though a small percentage of participants perceived their workload to go up before and after the break, 90% of students agree that the fall break was useful in reducing school related stress levels. However, the focus group, faculty and informant interviews revealed that the timing of the fall break had an impact on how students and faculty experienced the break and thus influenced perceptions on the impact that the break had on student mental health. Comprehensive evidence about whether a fall break policy supports or undermines the mental health of students needs to be assessed using a range of indicators before its implementation. This will help post-secondary institutions determine whether a break in the fall semester can be an effective approach to addressing students’ stress and anxiety.
  • 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 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.
  • 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.
  • Sclerostin Response to Exercise: Association with Bone Turnover, Oxidative Stress and Inflammation

    Kouvelioti, Rozalia; Applied Health Sciences Program
    The purpose of this thesis was to compare the response of sclerostin, a bone-specific glycoprotein that downregulates bone formation, to two modes (high impact vs non-impact) of high intensity interval exercise and to examine its relationship to potential exercise-induced changes in bone turnover (Study 1), oxidative stress (Study 2) and inflammation (Study 3). For the three studies included in this thesis, 40 healthy, young (18-25 years old) female and male adults performed two high intensity interval exercise trials in random order. Trials consisted of eight repetitions of 1 min high intensity running or cycling (mean heart rate 90% of maximum), separated by 1 min passive recovery intervals between repetitions. Blood samples were collected pre-exercise, and 5 min, 1h, 24h and 48h post-exercise. Sclerostin, bone turnover markers (cross linked telopeptide of type Ⅰ collagen [CTXI], procollagen type I amino-terminal propeptide [PINP]), oxidative stress markers (thiobarbituric acid reactive substances [TBARS], protein carbonyls [PC]) and inflammatory cytokines (interleukin-1β [IL-1β], -10 [IL-10], -6 [IL-6], and tumor necrosis factor-alpha [TNF-α]) were measured in serum. In the first two studies, sclerostin showed a significant time effect, but no significant exercise mode effect or interaction in both females (study 1) and males (study 2). In study 3, sclerostin showed a significant main effect for sex and a significant sex-by-time interaction. Specifically, sclerostin significantly increased from pre- to 5 min post-exercise and returned to baseline levels within 1h post-exercise with greater increase in males than females (47% vs. 34%, respectively). Furthermore, there were no correlations between sclerostin’s exercise-induced increase and the corresponding changes in bone turnover and oxidative stress markers. In contrast, sclerostin’s increase 5 min post-exercise was significantly correlated with the corresponding increase in the inflammatory cytokines, especially TNF-α, which along with sex, significantly explained 34% of the variance in its post-exercise elevation. In conclusion, in both young females and males, one session of high intensity interval exercise leads to an increase in sclerostin immediately post-exercise, and this increase is of similar magnitude following high impact and no impact exercise. Furthermore, the increase in sclerostin 5 min post-exercise seems to be associated with the exercise-induced inflammation.
  • Sex differences in the neural control of muscle

    Inglis, J Greig; Applied Health Sciences Program
    Sex-differences in muscle strength have been linked to differences in muscle size, involved limb, and daily activities. Early work has shown that sex-differences are greater in the upper compared to lower limb, making the upper limb an ideal model to investigate the best statistical approaches for sex comparison. Large differences in the upper limb reveals how biomechanical factors may impact neural control. Since males and females are more comparable with respect to strength in the lower limb, it allows for a determination of whether potential sex-differences in neural control exist without large differences in biomechanics. Understanding sex-differences allows for prescription of rehabilitation and training modalities, taking into account potential specificities in sex-related neuromuscular and musculoskeletal factors. The overall purpose was to examine neural and biomechanical differences that would account for sex-differences in neural control of muscle. Manuscript 1 examined normalization versus an ANCOVA to assess sex-differences. Sex-differences were seen in elbow flexor strength and rate of force development (RFD). Normalization by either maximum strength or neural factors couldn’t account for all sex-differences in RFD, resulting in an ambiguous interpretation. In contrast, both variables were able to be incorporated in an ANCOVA to determine their relative contribution. Manuscript 2 examined the effect of task familiarization and the contribution of maximum strength, twitch contraction time, muscle fiber condition velocity, and rate of muscle activation to sex-differences in the RFD during dorsiflexion. There were no significant differences between the sexes in muscle properties, but there were differences in neural control. Additionally, across days females exhibited a neural adaptation leading to an improvement in the RFD. Manuscript 3 directly assessed potential sex-differences in neural control during force gradation by recording motor unit activity during maximal and submaximal contractions. Females had less force steadiness (FS), which may have resulted from neural compensation for a less optimal pennation angle or a tendency towards greater joint laxity. Higher motor unit discharge rates and incidence of doublets may increase twitch force summation leading to a reduction in FS. Thus, biomechanical, not inherent sex-differences in neural drive led to neural compensation strategies manifesting as a difference in FS.
  • 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.
  • 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.
  • On the Ball Implementation of Canada Basketball’s Athlete Development Model

    Whitaker-Campbell, Tammy; Applied Health Sciences Program
    The purpose of this dissertation was to explore the perceived benefits and challenges of Canada Basketball’s athlete development model (ADM)/long-term athlete development (LTAD) by administrators, learning facilitators, and coaches at Canada Basketball to better understand the barriers to and enablers of this process. The methodological approach used for the study was an exploratory case study. Methods were established that were consistent with the iterative nature of case study. In total, 5 participants who identified as administrator/learning facilitator/coach, 6 participants who identified as /learning facilitator/coach, and 1 participant who identified as a coach participated in the study. In-depth semi-structured interviews were conducted with each participant that provided new insight into participants’ perceptions of and experiences with ADM/LTAD relative to their positions. Analysis revealed themes related to perceived (a) benefits while using ADM/LTAD; and (b) and challenges with using ADM/LTAD. These findings provide a preliminary assessment of one sport specific athlete development model and may inform research of other sport-specific athlete development programs. Several implications of the study findings are discussed and suggestions are posed for future research.
  • Mind over Matter: Exploring the Power of a Positive Body Image

    Cline, Lindsay; Applied Health Sciences Program
    This dissertation examines positive body image and its relationship with appearance-related commentary, body weight, and impression formation among young adult women. It explores how women’s unique individual experiences are constructed within social interactions. The present dissertation examined weight using a dynamic approach - weight trajectory (i.e., whether someone is gaining, losing, or maintaining weight). In study 1, body appreciation and a body image coping strategy (i.e., positive rational acceptance coping), which are characteristics associated with positive body image, were tested as mediators in the relationship between the frequency of positive appearance-related commentary and the effect elicited from those compliments. Only body appreciation produced indirect effects, as the frequency of appearance compliments only impacted the effect felt from those comments through body appreciation as the processing mechanism. In study 2, women were interviewed about their body image experiences with appearance-related commentary at differing weight trajectories. Women described how their body image was influential in filtering appearance-related commentary both while a higher and lower body weight. A more positive mindset (e.g., body acceptance), rather than weight loss, fostered positive effects from positive appearance-related commentary. Study 3 determined whether information provided about a female target’s weight trajectory and/or body image altered the participants’ impression of that target. The target described as on a weight loss trajectory compared to a weight gain trajectory was rated more favourably on certain personality and physical characteristics. Further, the target described as having a positive body image (including high self-esteem) compared to a target described as having a negative body image (including low self-esteem) was also rated more favourably on numerous personality and physical characteristics. All three studies demonstrated the value of having a positive body image both from an intrapersonal and interpersonal perspective. This has important implications for future research and body image programs designed to foster positive body image.
  • 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.

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