Now showing items 1-20 of 3266

    • "Absent Students: A Critical disabilities studies approach to accessibility services "

      Williams, Stacyann; Social Justice and Equity Studies Program
      This thesis explored the experiences of students with auditory disabilities that affect learning in university settings. The objective was to examine services offered to university students with auditory disabilities from the perspective of the students receiving the services. This included an examination of how services were delivered, what processes were related to success and what gaps existed between the services available and the actual needs of student learners who are living with disabilities. Qualitative interviews were conducted with students with auditory disabilities who receive services from the accessibility office on a university campus in southern Ontario. Grounded theory methodology with a critical disability studies framework was used. Each interview was analyzed using an open coding, axial coding, and selective coding progression. The analyses revealed the following prominent themes: 1) participants felt respected as a person but did not get what they needed as a learner; 2) participants experienced emotional tension – they liked the people they worked with but still felt frustrated and disappointed; 3) participants felt that their learning needs were not understood-- people in accessibility services are kind but kindness does not equal disability knowledge; 4) participants felt that SAS staff are kind, but wait times are still too long; and 5) participants were tired of being grateful but don't want to be mean to staff. Recommendations included paying more attention to student self advocacy and institutional ableism.
    • Fog Connectivity Clustering and MDP Modeling for Software-defined Vehicular Networks

      Penghan, Yan; Department of Computer Science
      Intelligent and networked vehicles cooperate to create a mobile Cloud through vehicular Fog computing (VFC). Such clouds rely heavily on the underlying vehicular networks, so estimating communication resilience allows to address the problems caused by intermittent vehicle connectivity for data transfers. Individually estimating the communication stability of vehicles, nevertheless, undergoes incorrect predictions due to their particular mobility patterns. Therefore, we provide a region-oriented fog management model based on the connectivity through vehicular heterogeneous network environment via V2X and C-V2X. A fog management strategy dynamically monitors nearby vehicles to determine distinct regions in urban centres. The model enables a software-defined vehicular network (\Gls{SDVN}) controller to coordinate data flows. The vehicular connectivity described by our model assesses the potential for vehicle communication and conducts dynamic vehicle clustering. From the stochasticity of the environment, our model is based on Markov Decision Process (MDP), tracking the status of vehicle clusters and their potential for provisioning services. The model for vehicular clustering is supported by 5G and DSRC heterogeneous networks. Simulated analyses have shown the capability of our proposed model to estimate cluster reliability in real-time urban scenarios and support effective vehicular fog management.
    • The COVID-19 Pandemic: A Cross Sectional Analysis of Canadian University Students' and Student-Athletes' Mental Health

      Celebre, Joshua; Applied Health Sciences Program
      Student-athletes have shown to display poorer mental health than student non-athletes, typically due to the unique stressors of participating in collegiate sport. During the COVID-19 pandemic and with the implementation of public health response measures Şenışık et al. (2020) discovered that depression and anxiety symptoms were significantly lower in Turkish professional athletes than non- athletes, and similar among genders and sport types. Further research is required, and this study aims to identify differences among Canadian university student-athletes and non-athletes, males and females, and team and individual sport athletes on symptoms of depression, anxiety, stress, and distress during the 2019/2020 academic year. The Depression Anxiety Stress Scale – 21 and Impact of Events Scale – Revised were completed by 349 student-athletes (241 male and 108 female) and 142 non-athletes (77 male and 65 female). There were no main effects for gender or sport type, but student-athletes scored significantly higher than student non-athletes in depression (p < .001), anxiety (p = .014), stress (p < 0.001), and distress (p = .001). Interestingly, female team sport athletes reported greater levels of each measure than female individual sport athletes (p = .011). In conclusion, Canadian university student- athletes reported significantly higher levels of mental distress than student non-athletes during the 2019/2020 academic year, and there were no differences by gender or sport type. Although, female team sport athletes reported higher symptoms of depression, anxiety, stress, and distress than female individual sport athletes. This data was inconsistent with Şenışık et al. (2020), highlighting the need for more research to be done comparing post-secondary students and student-athletes to identify how the COVID-19 pandemic affected them, and how academic institutions can mitigate, and aid mental health disturbances caused by events of this nature.
    • Mobile Learning Activities for Students’ English Learning Engagement in China

      Huang, Min; Department of Graduate and Undergraduate Studies in Education
      Although mobile-assisted language learning (MALL) activities have the potential to foster student engagement, few studies have investigated the influence of such activities on undergraduate students’ engagement in College English learning in China, particularly in a newly developed, post-pandemic hybrid learning environment. This study adopted a mixed methods design to examine the influence of mobile learning on student engagement and explored students’ lived experiences of using MALL activities for English learning. For the study’s quantitative data collection, 206 students completed an online questionnaire that included questions regarding motivation and active learning strategies. Ten students participated in the photo-production visual method and semi-structured personal interviews. Findings show that MALL activities enabled a unique opportunity to enhance students’ active engagement and knowledge construction by multiple ways of information sharing and language practices. Easy access and effective ways of communicating on learning apps intrinsically motivated students to participate in language learning. Through mobile learning platforms, students were scaffolded by their instructor or more knowledgeable peers in a more instant, visual, specific, and affective manner. Collaboration among students was not exemplified among undergraduate learners and the challenge of self-regulation in using cellphones was uncovered. These findings are significant for educators and decision-makers to lessen the stereotype of cellphones for learning and recognize the benefits of making use of personal devices for catering to individual learners’ needs, fostering connections, elevating engagement, and increasing English skills. A new MALL model is put forward.
    • Understanding Emerging Adults’ Decision-Making Process When Selecting a Smoking Cessation Approach: A Grounded Theory Study

      Barkans, Meagan E.; Applied Health Sciences Program
      Rates of cigarette smoking have been markedly reduced in recent decades, but young adults (or emerging adults) continue to have the highest rate of tobacco use in Ontario, Canada. Though preventing smoking initiation is optimal, positive outcomes of cessation early in the lifespan make it clear that cessation support for smokers in this age group is critical. Despite research into the effectiveness of quitting approaches and smokers’ preferred approaches to quitting, it remains largely unclear how smokers characterized as emerging adults (Arnett, 2000) make and act upon “real-world” decisions about which cessation approach to use. To learn more about this important aspect of the quitting process, this study investigated emerging adults’ experiences of choosing their approach to quitting. Twenty-six recent quitters between the ages of 19-29 participated in semi-structured interviews. Grounded theory methods were used to develop a framework explaining the decision-making process successful quitters engaged in when choosing a smoking-cessation approach. The newly proposed “Choosing How To Quit” Framework shows a decision making process that includes three distinct phases: Awareness of Approaches; Personal Reflection; Making a Choice. Successful emerging-adult quitters chose a quitting approach by drawing on a variety of sources for information and exploring personal facets including their past experiences, real-life daily-living considerations and an understanding of their present and future-selves. The Framework offers emerging adults and cessation supporters new realistic avenues to consider or explore when making the decision about a cessation approach, potentially leading to a greater likelihood of success. As a preliminary theory, the CHQ Framework requires further investigation, including into which components may be most essential to the decision-making process.
    • Exploring people-place relationships through place attachment and subjective wellbeing in the context of the abrupt social and ecological change associated with the COVID-19 pandemic

      Stuart, Savannah; Environmental Sustainability Research Centre
      The COVID-19 pandemic has disrupted patterns of daily life and drastically altered social norms. The ensuing stresses have impacted mental health and wellbeing. As a key driver of positive mental health, human-place interactions have assumed increasingly important roles. Simultaneously, complex, and abrupt change emerged in places due to COVID-19 restrictions and mandates. This thesis aims to understand if and how the abrupt changes associated with COVID-19 impacted human relationships with place through place attachment, wellbeing, and the valuation of community assets. To address this question, two studies of people-place relationships were conducted in two separate settings. The first study was conducted in the Town of Lincoln, a municipality in Niagara. The second study was conducted within the Niagara Parks, a series of protected areas used for outdoor recreation. In the Town of Lincoln, a greater proportion of individuals indicated the way in which they value assets had changed since the onset of the pandemic. This was supported by pre- and post-pandemic data, which found that two categories of community assets, both indoor community assets, were valued less in 2021 than they were in 2019, whereas other community assets were valued comparably from 2021 to 2019. Two categories of community assets were found to contribute most to both place attachment and wellbeing: waterfront/beaches and recreational trails/pathways. In Niagara Parks, 85% of natural area users described observing changes to the natural areas since the onset of the pandemic. Of these participants, 61% found that system change in the natural areas impacted their experience of wellbeing while using the natural areas, and 33% of individuals reported that their attachment to the place was impacted. This thesis explores if and how change can influence the relationship between person and place. With the system variability of climate change already experienced locally and globally, it is increasingly important to understand the dynamics of people-place relationships.
    • Do disparities in suicide-related behaviour across sexual orientations differ by neighbourhood deprivation? A discrete-time survival analysis in Ontario, Canada (2007-2017)

      Azra, Karanpreet; Applied Health Sciences Program
      Background Prior research on the disparities of suicide-related behaviours (SRB) across sexual orientation has been limited by the use of surveys and self-reported data, leading to possible survival bias. Furthermore, there have been no studies examining how neighbourhood deprivation modifies the effects of sexual minority status on SRB. Sexual minority individuals in deprived areas may face unique challenges and stressors that exacerbate their risk of SRB. This study investigates the association between sexual minority status and clinical SRB, and examines whether the effect of neighbourhood deprivation differs across sexual orientation. Methods A population-representative survey sample (weighted n= 8,778,120) was linked to administrative health data in Ontario, Canada to measure SRB-related events (emergency department visits, hospitalizations, and deaths) from 2007 to 2017. Neighbourhood-level deprivation was measured using the Ontario Marginalisation (ON-Marg) index measure of material deprivation at the dissemination area (DA) level. Discrete-time survival analysis models, stratified by sex, tested the effects of neighbourhood deprivation and sexual minority status, while controlling for individual-level covariates. Results Sexual minority males had 2.79 times higher odds of SRB compared to their heterosexual counterparts (95% CI 1.66 to 4.71), while sexual minority females had 2.14 time higher odds (95% CI 1.54 to 2.98). Additionally, neighbourhood deprivation was associated with higher odds of SRB: males in the most deprived neighbourhoods (Q5) had 2.01 times higher odds (95% CI 1.38 to 2.92) of SRB compared to those in the least deprived (Q1), while females had 1.75 times higher odds (95% CI 1.28 to 2.40). No significant interactions were observed between sexual minority status and neighbourhood deprivation levels. Conclusion In both males and females, sexual minority status and neighbourhood deprivation on SRB are independent risk factors for SRB. Despite the lack of effect modification, sexual minorities living in the most deprived neighbourhoods have higher chances of SRB. Future investigations should evaluate interventions and policies to improve sexual minority mental health and address neighbourhood deprivation.
    • Modulation of Voltage-Gated Ca2+ Channels by Retinoic Acid Signaling

      de Hoog, Eric; Department of Biological Sciences
      Retinoic acid (RA), the active metabolite of vitamin A, has an established role in development of the nervous system, but has recently emerged as a critical regulator of adult nervous system function. RA is important for learning and memory in both vertebrates and invertebrates. It is also important for synaptic plasticity at rodent hippocampal synapses and is known to interact with Ca2+ signaling to regulate receptor expression and influence synaptic transmission. How RA signaling might mediate plasticity in an invertebrate nervous system has not yet been studied. Voltage-gated Ca2+ channels (CaV) represent a ubiquitous means of Ca2+ entry into a cell, and which regulate neuronal functioning (such as gene expression and neurotransmitter release). As such, CaV channels represent a potentially important locus for inducing plasticity in both vertebrates and invertebrates. It is not known in any species, whether RA might mediate changes in neuronal communication by influencing the functional properties of CaV channels. Here I show, utilizing cultured neurons from the molluscan pond snail, Lymnaea stagnalis, that RA signaling modulates CaV channel function. RA signaling inhibited CaV channel function by shifting the voltage dependence of channel activation to more depolarized potentials. I found that RA also produced spike broadening and activity-dependent complex spiking, an effect I determined was mediated by RA-induced inhibition of delayed rectifier voltage-gated K+ channels (KV), (and enhanced inactivation of these KV channels). Paradoxically, the effect of RA to induce spike broadening and activity-dependent complex spiking, enhanced Ca2+ influx through CaV channels. However, the concurrent inhibition of CaV2 channels limited this enhanced Ca2+ influx. I also provide evidence that constitutive/basal retinoid receptor signaling upregulates CaV channel function. I show that a retinoic acid receptor (RAR) antagonist produced G-protein-mediated voltage-dependent inhibition of CaV channels, a ubiquitous form of presynaptic plasticity that occurs at vertebrate synapses. I also show that a retinoid X receptor (RXR) antagonist produced a novel G-protein-independent form of voltage-dependent inhibition of CaV channels. Overall, my study indicates that retinoid signaling diversely regulates CaV channel function in this invertebrate species and provides insights into the mechanisms by which RA signaling might mediate neuronal and/or synaptic plasticity.
    • Understanding the Mental Health Experiences of Student-Athletes Throughout University

      Budgell, Taylor; Applied Health Sciences Program
      There are many factors that contribute to the mental health experience of student-athletes such balancing school and varsity sports, the transitioning process from high-school to university and creating social relationships with a variety of groups. These factors can lead to negative experiences such as stress, anxiety, and depression, but also positive experiences like belonging, confidence and excitement. Generally, there are limited studies that discuss the changes of these experiences throughout a period of time, specifically through four years of a post-secondary institution. Thus, this study took a thematic analysis approach based on the model by Braun and Clarke (2006) to explore the various experiences of student-athletes that affected their mental health across all four years of university. Those experiences were organized into themes that defined each year to demonstrate how those contexts related and affected the mental health experiences of student-athletes. Nine student-athletes were recruited (4 male and 5 female) to participate in a semi-structured interview that lasted an average of twenty-five to thirty-five minutes. Nine themes arose and were organized into each year where they were most prominent. Themes included the transitioning experience (first year), establishment on team (second year), growth as a student-athlete (third year) and responsibilies with athletic experience (fourth year). Additional themes included dealing with Covid-19 and online learning, and help-seeking. Overall, the experiences of student-athletes are unique and worthwhile to look into further, especially when considering the challenges they face throughout four years of university.
    • Economic Evaluation of the Pediatric Tele-resuscitation Intervention Pilot Study

      Pace, Alex; Applied Health Sciences Program
      Background: Pediatric Telemedicine Connecting Hospitals (Peds–TECH), a pediatric tele-resuscitation intervention, was developed in partnership with Niagara Health, Brock University and McMaster Children's Hospital. This network aims to enhance pediatric outcomes for infants and children who present to NH hospitals' emergency departments using telemedicine (TM). Objectives: This study aimed to (i) identify out-of-pocket (OOP) costs and time/productivity losses for parents of pediatric patients seeking care at the emergency department (ED); (ii) calculate financial spending within the Peds-TECH intervention and estimate health resource utilization (HRU) costs; (iii) determine the clinical effectiveness of the Peds-TECH intervention on emergency transfers to a tertiary care hospital, and survival/mortality outcomes; and (iv) estimate an incremental cost effectiveness ratio (ICER) of Peds-TECH intervention compared to usual care (i.e., conventional means of providing resuscitation in ED). Methods: A mixed methods quasi-experimental research design was used for this project that included quantitative and qualitative methods in the economic evaluation. This study used qualitative research in the form of interviews, to explore OOP expenses incurred by parents of pediatric patients treated with the Peds-TECH intervention, and quantitative research when determining costs related to health technology and HRU. The ICER represents the incremental costs (Canadian dollar) relative to the years of life lost (YLL) averted in the intervention compared to usual care. The willingness-to-pay (WTP) threshold of $50,000 was considered to interpret the cost-effectiveness of the Peds-TECH intervention. Results: Qualitative interviews with parents revealed OOP expenses pertinent to personal transportation, food/meal, and time/productivity losses. In terms of OOP costs, the largest category in terms of both overall cost ($435) and response rate (5/5) was travel/parking costs. The next most common response to expenses incurred was the cost of food/meals ($80) with a response rate of 3/5. One participant did report paying for hotel accommodations for one day ($120). The odds ratio (OR) for mortality among cases was 0.498 (95% CI, 0.173, 1.43) compared to controls (i.e., usual care), indicating that the intervention was protective against mortality. An ICER of $64.61 per YLL averted was determined from the CEA, which represents the cost for an additional life-year saved in the intervention group compared to the control. In the deterministic sensitivity analysis, the ICER ranged as low as (- 138.72) and as high as (489.75) per YLL averted. The probabilistic analysis indicated 96.1% probability that Peds-TECH is cost-effective under a $5K WTP threshold, which is much lower than the standard $50K WTP threshold. Conclusion: This study acknowledged gaps surrounding the OOP costs associated with pediatric emergencies in the Niagara Region. The Peds-TECH intervention is considered clinically effective in preventing mortality among pediatric patients compared to usual care. As well, it was determined that the Peds-TECH intervention is highly cost-effective with an ICER of $64.61 per YLL averted. Further research is warranted to assess the long-term costs and health outcomes of pediatric patients undergoing the Peds-TECH intervention.
    • Exploring the Transition of University Professors to Positions of Additional Responsibility (PAR)

      Auld, Shernett; Department of Graduate and Undergraduate Studies in Education
      Effective leadership by academic administrators is an area of significant relevance to self-governing institutions of higher education (Dean et al., 2021; Weaver et al., 2019). Universities’ success depends upon a high degree of competent performance from professors and researchers of varying ranks, particularly those who assume positions of additional responsibility (PAR), including deans, associate deans, department chairs, and program directors. Most universities do not adequately prepare faculty for the challenges of PAR, leading newly appointed academic administrators to experience needless stress and to be less effective administrators, particularly in their early years in PAR (Armstrong & Woloshyn, 2017). Although the higher education literature contains an abundance of research about university presidents, academic deans, and department chairs (White, 2014), studies that focus specifically on these role transitions are sparse. This study explores six faculty members’ transitional experiences to PAR at a southern Ontario university, how they were prepared for their administrative roles, what challenges they faced, and how they were supported in their role. Participants revealed that they were unprepared for their respective PAR, they faced challenges related primarily to “human and people” and budget administration, and the support they received was varied and lacking. Participants also provided recommendations regarding how universities can better support their transitions.
    • Is the association between sleep and internalizing symptoms mediated by student and parent-related pressures?

      Mitchell, Jessica; Applied Health Sciences Program
      Objectives: Inadequate sleep has been afforded relatively little attention, despite known declines over adolescence, a critical period for the onset of mental ill-health. There remains a need for population-level longitudinal studies to better understand links with internalizing symptoms and in managing relevant pressures among adolescents. We examined the bidirectional relationships between sleep and depression and anxiety symptoms, and whether the relationships are mediated by school- and parent-related pressures. Measures: We used 2-year linked prospective data from 25,722 Canadian secondary school students that participated in the COMPASS study in the 2017-18 and 2018-19 school years. Path analysis models tested autoregressive and cross-lagged relationships between sleep duration and depression and anxiety symptoms. Bootstrap method of indirect effects was used to test school and parent pressures as mediators. Results: Results supported the hypothesized bi-directional relationships between sleep duration and depression and anxiety symptoms across one year. Shorter sleep predicted greater internalizing symptoms, and vice versa. In females, both parental and school pressures mediated the association between sleep duration and depression and anxiety symptoms, and in the reverse direction, parental but not school pressures mediated the association between depression and sleep. In males, school pressures mediated the association between sleep and depression symptoms. Conclusions: This study provides new insights into the nature and directionality of associations between sleep and internalizing symptoms over time and differences by sex. Results further strengthen calls that short sleep should be taken seriously. Interventions promoting regular sleep schedules in adolescence may help mitigate risk for stress-related psychopathology.
    • Using Self-Compassion and Teacher Identity to Examine the Transition from Teacher to Teacher Educator

      Briggs, Spencer; Applied Health Sciences Program
      There has been considerable research regarding teacher identity and the challenges involved with the transition from teacher to teacher educator, yet there is little existing literature that addresses how to manage or mitigate these challenges. In my research, I describe the influences on my identification process and use the concept of self-compassion as a tool to support the transition from teacher to teacher educator. Self-compassion “involves offering nonjudgmental understanding to one’s pain, inadequacies and failures, so that one’s experience is seen as part of the larger human experience” (Neff, 2003b, p. 87). Data gathering and analysis were informed by self-study methodology and consisted of personal reflections and conversations with a critical friend. From the ensuing analysis, I developed three themes. First, the challenges I faced included differentiating pedagogy, returning to academia, and my perspectives of others’ perceptions. Each of these factors influenced my identification process during my transition. Second, through conversations with a critical friend, we came to see my product over process mindset, which prompted a new way of conceptualizing and acting upon these challenges. Lastly, supportive others and engaging with self-study provided a means to better understand how I practiced self-compassion and shift my mindset about challenges in new ways. Implications for this research may resonate with others who undergo similar transitions; the findings may also be informative to others making personal and professional transitions in a broader context.
    • Is the association between sexual minority status and suicide-related behaviours modified by rurality? A discrete-time survival analysis using longitudinal health administrative data

      Nielsen, Andrew; Applied Health Sciences Program
      While self-reported data shows that lesbian, gay, and bisexual individuals have a greater risk of suicide-related behaviours (SRB), little is known about how rurality may amplify the risk of SRB associated with sexual minority status. Sexual minority individuals in rural areas may experience unique stressors due to stigma and a lack of LGB-specific social and mental health services. This is the first study to use a population-representative sample to investigate the contribution of sexual minority status and rurality on clinical SRB outcomes, and whether rurality modifies the association between sexual minority status and SRB risk. A nationally representative survey linked to administrative health data was used to construct a cohort of individuals (unweighted n=169,091; weighted n=8,778,115) in Ontario, Canada, and captured all SRB-related emergency department visits, hospitalizations, and deaths between 2007-2017. Rural status was captured using three measures which reflect different dimensions of rurality: the Rurality Index of Ontario, the Metropolitan Influenced Zones classification, and the Index of Remoteness. Sex-stratified discrete-time survival analyses were used to examine the interaction between rurality and sexual minority status on SRB risk while controlling for potential confounders. Sexual minority men had 2.18 times higher odds of SRB compared to their heterosexual counterparts (95%CI 1.21 to 3.91), while sexual minority women had 2.07 times higher odds (95%CI 1.48 to 2.89). The Rurality Index of Ontario and the Index of Remoteness were associated with the odds of SRB in a dose-response manner. No significant interactions were observed between rural status and sexual minority status. Rural status and sexual minority status both independently contribute to an elevated likelihood of SRB. Differences in access to healthcare between urban and rural areas appears to be strongly associated with SRB in both sexual minority and heterosexual populations. Future studies should consider incorporating measures of urban-rural status that capture access to healthcare, such as the Rurality Index of Ontario, to predict rural health disparities. This study highlights the need to evaluate the effectiveness of interventions and policies to reduce SRB in both rural and sexual minority populations.
    • Bridging the Gap: Examining Perceptions of a Telemedicine Network for Pediatric Emergency Medicine

      Mateus, Lidia; Applied Health Sciences Program
      This research aimed to evaluate the perceived effectiveness of a telemedicine program (Peds-TECH) in delivering care to critically ill pediatric patients in the emergency department by exploring the experiences of parents/caregivers and physicians. Sequential explanatory mixed methods were employed, in which quantitative methods of inquiry were followed by qualitative methods. Data was collected through the use of a survey and semi-structured interviews, in accordance with positivist and constructivist-interpretivist paradigms respectively. Results outline perceptions of telemedicine within 5 themes developed for each participant group. Among parents/caregivers themes were: Confident in the Care Environment, Forever Grateful, The Way of the Future, The Experience of Being Transferred, and Trouble Connecting. Among physicians themes were: Support and Validation, Team Effort, Providing Visual Perspective, Institutional Understanding, and Communicating Expectations. The findings describe positive perceptions of telemedicine for emergency department pediatric care, as well as barriers and facilitators to its use. The research also discusses implications for practice and policy, with recommendations for overcoming barriers and leveraging facilitators when implementing telemedicine programming.
    • The Effect of Self-Controlled Versus Fixed Post-KR Delay on Motor Performance and Learning

      Harten, Dylan; Applied Health Sciences Program
      Previous research has explored the effects of participants self-controlling components of practice, but little evidence exists as to the relationship between self-control and post-KR delay duration. The purpose of this study was to identify whether motor learning and performance are differentially impacted by having control, versus not having control, over the post-KR delay duration. Participants performed a five key serial-timing task with a goal time of 2500ms for 80 acquisition trials following a 10-trial no-feedback pre-test. They then returned after 24-hours for a 10-trial retention test, a 10-trial sequence transfer test, and a 10-trial duration transfer test, all performed without feedback. Due to Covid-19 restrictions a preliminary sample was collected, and the results based on descriptive statistics of the self-controlled KR + self-controlled post-KR delay group follows. Findings showed that participants decreased their absolute constant error and variable error compared to their pre-test. Participants had longer decision durations prior to requesting KR, while the opposite was found in the post-KR delay where participants had a longer duration after requesting KR. Participants also preferentially requested KR after lower absolute constant error trials. These results are incongruent with self-reports whereby they reported requesting KR after both perceived good and bad trials equally, while also spending a shorter duration in the post-KR delay after perceived good trials. These findings add novel contributions to the post-KR delay and inter-trial interval literature, highlighting dynamic contextual changes in post-KR delay durations. However, due to limitations presented by Covid restrictions, further research is required.
    • Reliability of Isometric Knee Extensor Strength and Evoked Outcomes in Boys and Men

      Jenicek, Nicole; Applied Health Sciences Program
      Volitional and evoked strength are outcomes often used in both adults and children. However, the reliability of these measurements is sparse. Emerging reliability studies utilize a robust analysis, which includes “consistency” of scores and “stability” of group means. This study aimed to assess the reliability of volitional and evoked muscle strength outcomes of the knee extensors in boys and men. Twelve boys and twelve men participated in the study. Participants completed ten maximal isometric knee extensions (MVCs) on three separate days. On days two and three, quadriceps muscle belly stimulation was introduced in the 6th-10th MVC. The stability of group means was determined through a repeated measures Analysis of Variance (ANOVA) model, while consistency was determined through a fully nested ANOVA model. High reliability was observed in both, men and boys in volitional torque production, as reflected by the ICCs (Men R = 0.97 and 0.98, boys R = 0.91 and 0.92) and true score variance. The group means were stable in both, men and boys, especially in 1st-5th MVC. Twitch amplitudes were stable across days and demonstrated good reliability, as reflected by high ICCs (Pre-MVC twitch: men R = 0.78 and 0.83, boys R = 0.98 and 0.99; post-MVC twitch: men R = 0.84 and 0.85, boys R= 0.98 and 0.99), and true score variance. PAP demonstrated acceptable reliability in both boys and men, although it was lower compared to the other outcomes. PAP in the 1st-5th MVCs in men showed low reliability, while PAP in the 6th-10th MVCs showed high reliability in men and boys, as reflected by the high true score variance, ICC, and stable means. The results support using volitional torque and evoked outcomes in adults and children. Future research could examine the reliability of other evoked variables and different volitional exercise protocols.
    • Post-Activation Potentiation and Potentiated Motor Unit Activation Patterns in Boys and Men

      McKiel, Andrew; Applied Health Sciences Program
      Post-activation potentiation (PAP) describes the enhancement of twitch torque following a conditioning contraction in skeletal muscle. In adults, PAP is greater in muscles with a higher percentage of type-II fibres and PAP-related augmented contractility is accompanied by a decrease in motor unit (MU) firing rates (MUFRs). Children may have lower PAP due to lower type-II muscle fibre composition and lower activation of their higher-threshold (type-II) MUs compared to adults. Changes in potentiated MU activation have not been examined in children. Therefore, the purpose of this study was to determine whether there are child-adult differences in PAP and MU activation patterns of the potentiated knee extensors. Twenty-three boys (10.5±1.3 years) and 20 men (23.1±3.3 years) completed familiarization and experimental sessions. In the experimental session, knee extensor maximal volitional contraction (MVC) torque (Biodex System 3) was first determined. Maximal isometric evoked-twitch torque (Digitimer stimulator model DS7AH) and MU activation patterns during submaximal contractions (20% and 70% MVC) were then recorded before and after a conditioning contraction (5s MVC). PAP was calculated as the percent-increase in evoked-twitch torque after the conditioning contractions. MU activation patterns were examined during submaximal contractions before and after a 5s MVC, using Trigno Galileo surface electrodes (Delsys Inc) and decomposed into individual MU action potential (MUAP) trains (NeuroMap, Delsys Inc). PAP was higher in men than in boys (98.3±37.1% vs. 68.8±18.3%, respectively; p=0.002). In both the 20% MVC and 70% MVC contractions, boys and men displayed a reduction in MUFRs for a given MU size (MUAPamp), specifically in the higher-threshold MUs. This reduction was greater in the boys than the men in the 70% MVC contractions, and may be due to their greater fatigue resistance, as well as to a lower impact of potentiation at higher intensities.
    • Exploring the role of glycogen synthase kinase 3 in murine soleus unloading with real and simulated microgravity

      Baranowski, Ryan; Applied Health Sciences Program
      Prolonged microgravity exposure causes muscle atrophy and fiber type transformations from a slow oxidative to the fast glycolytic phenotype. Glycogen synthase kinase-3 (GSK3) is a serine/threonine kinase and known negative regulator of NFAT and Wnt/β-catenin signaling. Together, NFAT and Wnt/β-catenin signaling pathways can activate the slow-oxidative myogenic program and muscle regeneration. Part 1 of this thesis examined soleus muscles from male and female C57BL/6 mice from three separate missions (NASA RR9 [male, n=10 per group, 35 days in space], NASA RR1[female, n=4 per group, 37 days in space], BION-M1 [male, n=4 per group, 30 days in space]) to examine GSK3 activation via western blotting. I examined total and inhibitory serine9 phosphorylated GSK3 and β-catenin content in Flight, Ground Control (GC) and Vivarium control (VIV) soleus muscles. I found that ~1 month of spaceflight led to significant reductions in total GSK3. Changes in serine9 phosphorylated GSK3 varied across missions. When examining β-catenin, we found that the RR9 group showed a significant reduction in the flight group compared with GC and VIV. We also showed a collective slow-to-fast fibre type shift via MHC analysis. Part 2 of this thesis examined the effects of muscle-specific GSK3 knockdown (GSK3mKD) in male mice during hindlimb suspension (HLS) – a simulated model of microgravity. Through western blot analysis we showed a 50% reduction of GSK3 in soleus muscles from GSK3mKD mice. After subjecting the mice to 7 days of HLS, DXA analysis showed that GSK3mKD mice maintained body weight throughout the 7 days and had more lean mass compared to GSK3flox control mice. Additionally, soleus muscles from GSK3mKD mice had greater soleus muscle mass and cross-sectional area after HLS compared with GSK3flox HLS mice; and force production was not different from mobile control GSK3flox mice. Together my thesis found that GSK3 content was consistently reduced in soleus muscles from spaceflight, and that muscle specific GSK3 knockdown can increase soleus muscle size and force production.
    • The Effect of Sclerostin on Myotropic Response to Exercise

      Stoikos, Joshua; Applied Health Sciences Program
      This study is the first to examine the effect of exogenous sclerostin injection on myotropic responses to sedentary behaviour and an aerobic exercise intervention. Specifically, changes in myosin heavy chain isoform distribution, muscle mass and myofiber cross sectional area were studied in response to sedentary behaviour and to a 5-week aerobic exercise intervention. Mice (n=24) were assigned to either remain sedentary (SED, n=24), or assigned to a 4-week exercise training program (EXT, n=24) and further spit into their final groupings with sedentary control (SED+C) and exercise control (EXT+C) groups receiving saline injections and sedentary sclerostin (SED+S) and exercise sclerostin (EXT+S) groups recombinant sclerostin. Soleus and extensor digitorum longus muscle were then extracted and analyzed via fluorescent immunohistochemistry and Western blotting. Sclerostin injection led to a significant reduction in soleus MHCI, MHC1/IIA, MHCIIA/X and MHC IIB cross-sectional area (p < .5) along with trending declines in MHC IIA (p = .1). In contrast to this, there was no effect of sclerostin injection on MHC IIX or MHCIIXB CSA. In EDL tissue there was a trend towards a decrease in tissue necropsy weight in the sclerostin injection group (p = .1). Sclerostin appeared to have no effect on total MHC protein content or in the examined markers of Wnt signaling (GSK3β, β-catenin) as detected in both soleus and EDL muscle tissue via western blot. Our findings demonstrate that sclerostin negatively influences muscle tissue via decreases in myofibril cross-sectional area and these decreases trend towards a significant reduction in muscle mass.