• 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.
    • 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.
    • 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.
    • A Narrative Study of Patient Encounter Accounts of Physicians, Nurses, and Medical Receptionists after Two Decades of a Paradigm of Patient-Centered Care

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

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

      McKinlay, Brandon; Applied Health Sciences Program
      The overall purpose of this thesis was to examine the role of post-exercise dairy protein consumption (isolated and whole-food) on recovery indices (performance and muscle damage) and inflammation following intense exercise within the context of different ecologically valid sporting environments, i.e., acute competition and a short-term period of intensified training, in competitive youth athletes. For this, two studies were conducted. Study 1 (Chapter 3) investigated the effect of whey protein consumption following a high-intensity interval swim session (HIIS) among adolescent swimmers on subsequent performance, muscle soreness, plasma creatine kinase and inflammatory cytokines, compared with isoenergetic carbohydrate and flavoured water in the acute (0–8 h) and short-term (8–24 h) recovery periods. Study 2 (Chapter 4) examined the effects of increased protein consumption, via plain Greek yogurt, compared with an isoenergetic carbohydrate control on performance recovery, inflammation, and muscle damage, during a 5-day simulated soccer training camp in competitive adolescent female soccer players. The collective findings indicate that during both acute and short-term periods of intensified exercise, the provision of dairy protein regardless of form (isolated or whole food), provided no added benefit at enhancing performance recovery or ameliorating muscle damage above that of energy matched carbohydrates. However, it does appear that the consumption of calories, regardless of type (e.g., carbohydrates or dairy protein), when rapid recovery is required, offers greater performance retainment than water. Therefore, during periods of intensified exercise that may be accompanied by inadequate recovery, the replenishment of energy should be the primary focus. Further, in both studies the consumption of dairy protein following exercise leads to an augmented anti-inflammatory response (i.e., increased IL10), not observed in the control conditions (i.e., water or energy-matched carbohydrates). Thus, it is possible that dairy protein consumption post-exercise may benefit the acute immune response. This possibility requires further study.
    • The role of skeletal muscle PLIN proteins at rest and following lipolytic stimulation

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

      McAlpine, Michael D.; Applied Health Sciences Program
      The consumption of tea has many proposed health benefits thought to likely be the result of an abundance of unique polyphenols. In particular, one exciting potential health benefit of tea is its capacity to have bone supportive effects when consumed throughout life. Prior to testing the potential bone supportive effects, it was important to characterize several types of tea and determine the ideal steeping time for each tea, maximizing the quantity of polyphenols while also maintaining taste (Study 1). Results from this study were congruent with manufacturer’s recommendations. Following this, several types of teas and tisanes were tested in an in vitro osteoblast model to determine if there were any alterations in quantity of mineral produced (Study 2). Findings demonstrated that all teas effectively increased mineralization at a dietary concentration of polyphenols, but red rooibos tea appeared to produce the greatest effects. The next important aspect which needed to be clarified was if there was an optimal concentration of red rooibos tea that elicited maximal results (Study 3). To determine this, a dose response study was conducted in the same osteoblast model as study 2 and mineral quantity was measured. From this study a positive dose-dependent response was observed without any signs of toxicity, suggesting that high concentrations may be beneficial. Following the initial in vitro studies it was important to test red rooibos tea in a physiologically relevant model of elevated bone turnover, pregnancy and lactation (Study 4). Female Sprague-Dawley rats were randomized to one of the following groups: PREG TEA (pregnant and received a supplemental level of red rooibos: ~2.6 g /kg body weight/day in water), PREG WATER (became pregnant and received water), or NONPREG CON (age-matched, non-pregnant control) from 2 weeks prior to pregnancy (age 8 weeks) through to 4 months post-lactation. Results demonstrated that there were immediate losses of both trabecular and cortical bone following lactation. However, cortical bone rapidly recovered in both pregnancy groups while the majority of trabecular outcomes only partially recovered and appeared to have permanent reductions. When comparing the two pregnancy groups, there were no differences in cortical bone post-lactation but there were significant improvements in several of the trabecular outcomes in rats that received red rooibos herbal tea. The findings from this thesis demonstrated in progressively more complex and physiologically relevant models that tea does have the capacity to be bone supportive, particularly during periods of high turnover.
    • Teachers’ Experiences of Implementing a Pedagogical Approach for Meaningful Physical Education

      Beni, Stephanie; Applied Health Sciences Program
      Dominant forms of physical education (PE) have been criticized for their inability to promote lifelong movement, with many scholars arguing in favour of an approach oriented toward meaningful experiences in PE. The Meaningful PE approach has been designed in response to this but has yet to be tested extensively in practice. The purpose of this dissertation has been to study teachers’ experiences of learning about and implementing the Meaningful PE approach. Five teachers based in Ireland and 12 teachers based in Canada participated in two separate studies lasting eight weeks and across two school years, respectively. Qualitative data were collected in the form of semi-structured interviews, non-participant observations, community of practice (CoP) meeting transcripts, and reflections. Results of this dissertation are presented in four articles. Article One highlights the experiences of Irish primary classroom teachers, demonstrating preliminary support for the approach from classroom teachers with little background in PE. Article Two focuses on Canadian elementary teachers’ experiences of implementing the Meaningful PE approach with their students and on the factors that influenced their implementation decisions. Primary factors influencing implementation included teachers’ prior experiences and beliefs, students’ responses to the implementation process, and external organizational pressures. Article Three focuses on Canadian teachers’ experiences of learning about Meaningful PE through a professional (PD) initiative designed around characteristics of effective PD outlined in the literature. Teachers were most supportive of the use of a CoP and modelling of the approach to foster their learning about Meaningful PE, while also highlighting several tensions between ideal and practical forms of PD, taking personal and organizational barriers into account. Article Four focuses on my experience of becoming a facilitator of teachers’ PD through facilitating a CoP for teachers. This article highlights the important role of identity in the process of learning to become a facilitator and navigating the tensions associated with that process. Collectively, this dissertation makes a significant contribution to the literature by a) informing the refinement of the Meaningful PE approach, b) offering insights into educational implementation research, and c) adding to the literature on teachers’ professional learning when being introduced to innovations.
    • 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.