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Kinesiology & Health Science

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  • ItemOpen Access
    Investigating the function of TRAF1 in NF-κB activation
    (2024-03-16) Tang, Yitian; Abdul-Sater, Ali
    Tumour necrosis factor receptor-associated factor (TRAF) proteins play an important role in mediating the activation of NF-κB. Dysregulation of NF-κB may be one of the potential causes of chronic inflammatory diseases. One member of the TRAF family, TRAF1, has been shown to increase the risk of rheumatoid arthritis (RA). However, TRAF1 plays opposing roles in the activation of NF-κB downstream of the tumour necrosis factor receptors (TNFR) and toll-like receptors (TLR) signalling pathways. In the TNFR pathway, TRAF1 recruits c-IAP2 to promote NF-κB activation and cell proliferation. In contrast, in TLR pathways, TRAF1 negatively regulates NF-κB by sequestering the linear ubiquitin assembly complex (LUBAC). Because of the complex role of TRAF1 in NF-κB activation, it is important to isolate and study the role of TRAF1 in each of these pathways. To better understand TRAF1 and its role in NF-κB activation, our laboratory has identified the same interaction site between TRAF1 and c-IAP2 and created a mutant TRAF1V203A that significantly reduces the interaction with c-IAP2. This study creates a working functional assay to test the effect of these mutants on NF-κB activation. We have generated TRAF1V203A knock-in monocyte THP-1 cells and demonstrated how this mutant alters signalling downstream of TLR and TNFR in monocytes. This study also shows that the production of pro-inflammatory cytokines is reduced in TRAF1V203A mutant monocytes. This study helps us to isolate effects on NF-κB activation and provides an excellent model to study the role of TRAF1 in vivo.
  • ItemOpen Access
    The association of physical activity with prediabetes/type 2 diabetes and cardiac autonomic function
    (2024-03-16) Pooni, Rubin Kaur; Kuk, Jennifer
    Three separate studies were conducted to assess the association of physical activity with prediabetes/type 2 diabetes (pre/T2D) and cardiac autonomic function. The purpose of study 1 was to examine whether using both objectively (accelerometer) and subjectively (questionnaire) measured moderate- to vigorous-intensity physical activity (MVPA) and sedentary time (SED) improves the prediction of pre/T2D using data from the Framingham Heart Study (n=4200). Logistic regression was used to examine the odds ratio of pre/T2D in groups cross-classified by subjective and objective MVPA and SED. The findings demonstrated that low objectively measured MVPA appears more closely associated with pre/T2D risk compared to subjective measures, and there does not appear to be an additive effect of SED on pre/T2D risk after accounting for MVPA. The purpose of study 2 was to examine the effects of 3-6 months of aerobic, resistance, and combined aerobic and resistance exercise training on heart rate recovery (HRR) from three previously reported randomized trials (n=147). A repeated measures ANCOVA was used to examine differences in 1-, 2-, 3-, 4-, and 5-min HRR from pre- to post-intervention and compared to control adjusting for sex, Tanner stage, ethnicity, and training duration. The findings suggest that aerobic exercise training may be a more effective strategy for improving HRR in adolescents with overweight or obesity. The purpose of study 3 was to examine the association of MVPA or SED and pre/T2D with heart rate variability (HRV) in Hispanic adults using data from the Hispanic Community Health Study / Study of Latinos (n=11 209). Multiple linear regression models were used to examine differences in RMSSD and SDNN in groups cross-classified by MVPA or SED with pre/T2D, adjusting for age, body mass index, sex, education, nutrition, smoking status, alcohol use, cardiovascular disease, and MVPA or SED where appropriate. Having pre/T2D, regardless of MVPA or SED, was associated with lower RMSSD and SDNN. There was an association of high HRV with high MVPA in individuals without pre/T2D, but it did not translate to individuals with pre/T2D. The association of MVPA and SED with HRV in individuals with pre/T2D requires further investigation.
  • ItemOpen Access
    Effects of Pseudo-Positive Ageism: A Systematized Critical Review
    (2024-03-16) Le, Matthew Hoang; Meisner, Brad
    There has been scattered research that explores so-called ‘positive’ generalizations of ageism. These ‘positive’ forms of ageism are more subtle than the negative and is often overlooked in literature and society. The aim of this systematized critical review is to synthesize the current knowledge of these ‘positive’ forms of ageism. A comprehensive literature search was performed on 8 databases to identify primary research articles on the overarching concept of positive ageism. The systematic search yielded 2,216 studies to which 5 met the inclusion criteria and were selected for full text review/data extraction. Definitions of ‘positive’ ageism featured the term benevolent ageism. ‘Positive’ ageism was found to influence the affective state of younger people and the perceptions of older people. Furthermore, intersectional analysis found one study examining the interactions between age and gender. Results may aid to inform future research and policy on ‘positive’ ageism and its implications.
  • ItemOpen Access
    Eminence in Endurance Cycling Sports
    (2024-03-16) Korf, Jesse; Baker, Joseph
    The objectives of this dissertation were to define and explore eminence in endurance cycling. To accomplish these objectives, both qualitative and quantitative approaches were used. Chapter 1 involved a narrative review of the literature and provides a historical account of the development of the body of knowledge around eminence in sport. In Chapter 2, a definition of eminence in a specific context of endurance cycling sports was explored. This was done by way of a Delphi method including two panels, the first involving athletes and the second involving technical experts such as coaches and performance directors. The next two chapters utilized quantitative designs where the research questions explored the developmental histories of athletes who met the criteria of eminence. For all quantitative analyses, the Union Cycliste International (UCI) database, which includes all UCI sanctioned race results from across the globe (~ 4.7 million race results), was interrogated. Several notable findings were revealed. In Chapter 2, criteria for the achievement of eminent status in endurance cycling sports were established, which included the need to win at least three high level races including the World Championships, Olympic Games and some sport specific races and general classifications such as the Tour de France and the Tour of Flanders in Road cycling and the World Cup general classification in Mountain Bike. Chapter 3 revealed that becoming an eminent cyclist was more strongly related to a diversified approach to racing across multiple cycling sports rather than fully specializing in a single cycling sport. Findings also revealed that those that achieved eminent status reached their first podium in elite races at a much younger age than those who did not. In Chapter 4, it was revealed that whilst junior to elite predictability varied between sports, junior performance in these cycling sports has a higher predictive value than suggested in other pieces of research on talent identification and development. In summary, this research program provides a framework for researchers to explore eminence in sport specific settings and provides guidance for administrators and coaches to increase the likelihood of athletes becoming eminent through specific selection and development approaches.
  • ItemOpen Access
    The Effect of Circular Vection on the Subjective Postural Horizontal in the Pitch Plane
    (2024-03-16) Hamam, Noor Jihad; Cleworth, Taylor
    Postural orientation assessments, including the subjective postural horizontal (SPH) test, has been demonstrated as a great tool for assessing otoliths contributions to postural orientation and balance (Beule et al., 2006). Previous work has shown that dynamic visual stimuli, in the form of circular vection (CV) in the roll plane, significantly affects the body position and horizontal orientation perception of the support surface (Cleworth et al., 2023). However, CV in the pitch plane has been shown to introduce a different form of the visual stimulus and elicit distinct postural strategies compared to the roll plane. Therefore, by altering the support surface and visual information, this study aims to examine the effect of applying pitch CV in VR, on the body response and perception of horizontal orientation of the support surface. Overall, pitch CV significantly affected SPH of the platform and body position. This thesis contributes to our understanding of the complex integration of the visual and vestibular systems during postural orientation tests and offers a potential avenue for testing postural orientation and balance deficits in clinical populations.
  • ItemOpen Access
    Evaluation of Percent Body Fat Estimates Using Different Body Composition Methods in Recreationally Active Adults Across Both Sexes
    (2024-03-16) Davis, Devon F.; Josse, Andrea
    This thesis compared percent body fat (%BF) values derived from different body composition (BC) modalities: air displacement plethysmography (Bod Pod), skinfold (SKF) prediction equations (Durnin and Womersley (DW), Jackson and Pollock (JP7), (JP3) and Yuhasz) with dual-energy x-ray absorptiometry (DXA) as the reference and compared whether they differed by sex. Utilizing data from 38 active individuals (20 females, aged 26.3±4.0 years; 18 males, aged 30.5±7.4 years), females demonstrated significant differences between all modalities with DXA (P<0.05), except for DW equations. Males demonstrated no significant differences with DXA (P<0.05), except for the Yuhasz equation. Bland-Altman (B-A) analyses found significant systematic biases (P<0.05) in females and males with magnitudes of difference ranging from -2.0% to -10% and -1.4% to -4.0%, respectively vs DXA. Significant proportional biases between different modalities and DXA were also evident in both sexes. These results highlight the importance of using the most appropriate BC approach to estimate %BF.
  • ItemOpen Access
    The Role of FoxO1 and Sex Differences in Response to a DNA-damaging Agent
    (2024-03-16) Martone, Christian Adelio; Haas, Tara
    Endothelial cell (EC) health can be disturbed in various diseases like aging, obesity, atherosclerosis and type 2 diabetes. Previously, our lab showed that female ECs retain a healthier phenotype than male ECs under obesogenic conditions and that they have higher levels of Forkhead Box O1 (FoxO1) than male ECs. The goal was to investigate whether FoxO1 inhibition enhances EC vulnerability and whether any sex differences occur in response to an oxidant insult. To achieve this, ECs were treated with a FoxO1 inhibitor and treated with cisplatin. FoxO1 inhibition promoted cell cycle arrest and antioxidant induction in both sexes while DNA damage improved only in male ECs. Unperturbed female ECs displayed higher levels of γH2AX compared to male ECs. These data provide evidence that FoxO1 inhibition is potentially protective for the male EC while also revealing a potential sex disparity in the DNA damage response pathway.
  • ItemOpen Access
    A Critical Examination of the Lived Experiences of Somali Refugees and Immigrants Diagnosed with Type 2 Diabetes and their Family
    (2024-03-16) Abdulwasi, Munira; Nakamura, Yuka
    This narrative study explores how the process of resettlement impacted the management/care of type 2 diabetes (T2D) among Somali immigrants and refugees living with T2D and/or family members of Somali immigrants and refugees living with this condition residing in Toronto. It also examines how the participants described their and/or family member/s illness. Family members were included in this study since research indicates that they can play a significant role in the care of individuals living with T2D (Black, Maitland, Hilbers, & Orinuela, 2016; Mayberry & Osborn, 2012; Protudjer, Dumontet, & McGavock, 2014). In total, 37 face-to-face interviews were conducted with 19 family members and 18 individuals living with T2D from Fall 2017 to December 2018. Data analysis involved analysis of narratives (Creswell, Hanson, Plano Clark, & Morales, 2007; Polkinghorne, 1995), which resulted in three themes across all participant narratives. These themes were then organized and presented through restorying three participant experiences. This study also included found poetry, displaying participants’ words from their interviews as a poem (Butler-Kisber, 2020). The first theme, ‘precarious settlement,’ describes the participants’ experiences dealing with stressors, such as unsafe neighbourhoods, un/underemployment, and poverty. The second theme, ‘gendering of T2D,’ illustrates the gendered ways in which the participants described T2D (as mainly a woman’s disease) and the gendered forms of care that were enacted by family members. Lastly, the third theme, ‘diabetes as bitter-sweet,’ explores how T2D was narrated and perceived by participants in this study, which included positive and negative accounts. This study recommends that further attention be placed to address the structural inequalities and barriers experienced by the participants. Mental health supports that are inclusive of the participants’ religious/cultural worldviews are also needed to support family members and individuals living with T2D in this population in dealing with diagnosis, care, and resettlement stressors that they may be experiencing.
  • ItemOpen Access
    Exercise Modifies Inflammatory Responses by Changing the Epigenetic Landscape
    (2024-03-16) Amandeep, Amandeep; Abdul Sater, Ali
    Physical inactivity and low-grade systemic inflammation are associated with chronic metabolic diseases such as atherosclerosis, insulin resistance, obesity etc. It is of great value to study the exercise mediated benefits to alleviate inflammation. Preliminary work in our lab demonstrated that exercise with a particular intensity and duration led to reduced inflammatory responses in bone marrow derived macrophages (BMDMs) by inducing persistent metabolic changes in these cells. In this thesis, we explored how exercise is causing these long-lasting changes in inflammatory responses and hypothesized that it does so by inducing changes in chromatin accessibility leading to changes in gene expression. We employed an unbiased ATAC-seq (Assay for Transposase Accessible Chromatin- sequencing) analysis in BMDMs prepared from sedentary and exercised C57BL/6N mice and obtained a list of differentially accessible chromatin regions. We also demonstrated using real-time PCR that exercise-mediated changes in chromatin accessibility cause a reduction in gene expression of inflammatory genes. Our findings suggested that exercise is protective against inflammatory responses by causing persistent changes at chromatin level.
  • ItemOpen Access
    A Fresh Perspective on Fat-Loss and Body Measurement Techniques: The Effects of Time Restricted Feeding and Exercise on Fat- Oxidation Rates and Commonly Used Fatness Measurements
    (2024-03-16) Yavelberg, Loren; Jamnik, Veronica
    Currently employed techniques for weight management consist of; extreme caloric deprivation alone or in combination with exercise, exercise alone or medically invasive procedures, all of which have proven not to provide sustainable resolutions (Brownell et. al., 1987; Kramer et. al., 1989). Due to the significance of a growing global obesity epidemic, the need for customized PA and exercise prescriptions which potentially increase fat-oxidation rate (FOR) are critical. To formulate a successful solution, examining both the acute and chronic effects of varying exercise intensities and modalities on FOR alone and in conjunction with healthier eating habits (time-restricted feeding (TRF) will be informative. A growing body of evidence suggests that TRF could be a valuable tool for improving health in the general population due to reports of improving blood lipids (Klempel et al., 2012 & 2013; Varady et al., 2011) and glycaemic control (Barnosky et.al., 2014), reducing circulating insulin (Trepanowski & Bloomer, 2010), decreasing blood pressure (Trepanowski & Bloomer, 2010; Tinsley & La Brounty, 2015; Varady & Bhutani, 2009), decreasing inflammatory markers (Farajeh et al., 2012) and reducing fat-mass (FM) even during relatively short durations (8–12 weeks) (Varady & Bhutani, 2009). Currently, little is known about the synergistic effects of TRF supplemented with varying forms of PA on FOR. In order to successfully improve FOR in individuals living with obesity and overweightness, exercise intensity, modality, and duration must be considered for successful weight loss. This series of investigations examined 1) Validated FOR at rest and during exercise, 2) The acute effects of TRF (12 & 16 hrs) and varying exercise intensities on FOR, 3) The short-term effects of intermittent fasting and continuous steady-state low-moderate intensity exercise on commonly used fatness measurements and FOR in middle-aged women, and 4) The importance of considering Body Mass Index in conjunction with VO2max when evaluating the health and wellness of frontline fire suppression personnel.
  • ItemOpen Access
    The Utility of Mobile Visuomotor Assessment for Neuropsychological Evaluation in Older Adults
    (2023-12-08) Adibmoradi, Ghazal; Sergio, Lauren E.
    Performance in complex visuomotor tasks, where guiding visual information doesn't align spatially with the required motor output, relies on the brain's ability to integrate somatosensory information for an appropriate motor response. Performance on such "cognitive-motor integration" tasks is affected in Alzheimer’s disease. We investigate the relationship between a traditional neuropsychological test battery and a tablet-based visuomotor skill performance tasks. Older adults ranging from healthy to early Alzheimer’s disease completed the neuropsychological test battery, three tablet-based tasks and a series of tasks on the KINARM. We observed that 5 of our 6 CMI outcome measures were predictive of four tests from the WMS-IV battery, once variability for sex and age were accounted for; with one outcome variable significantly correlated between the two technologies. Our findings suggest that our multi-domain remotely deployable mobile task (BrDI) may be a good first step assessment tool in order to flag at-risk individuals.
  • ItemOpen Access
    Characterization of RBL2 in Muscle Stem Cell Fate Decisions
    (2023-12-08) Campagna, Lucas; Scime, Anthony
    Skeletal muscle stem cells (MuSCs) regenerate muscle upon injury. Here, they receive activation signals from their environment and make a fate decision to make further copies (self-renew) or commit to becoming muscle (differentiate). Dysfunctional MuSC fate decisions, lead to poor muscle quality. Accordingly, retinoblastoma-like protein 2 (Rbl2) was characterized in MuSC fate decisions. Targeted deletion of Rbl2 in muscle progenitors impaired myotube formation, demonstrating its potential requirement for MuSC function. Rbl2 was analyzed during MuSC fate decisions by immunostaining cultured myofibers with Pax7 and MyoD. Rbl2 was expressed in the nucleus of only a fraction of committed MuSCs. Surprisingly, during a differentiation time course, primary myogenic progenitor cells expressed Rbl2 in the mitochondria. The Rbl2 expression in the mitochondria of differentiating MuSCs was confirmed in vivo by immunohistochemistry. These results provide novel insights for the localization of Rbl2 in MuSC fate decisions and the mechanisms driving differentiation.
  • ItemOpen Access
    Developing a Scale to Examine Aging-Related Assets Developed Through Sport in Older Adults
    (2023-12-08) Patelia, Shruti Shashikant; Baker, Joseph
    Background: Participation in sport continues to rise among older adults. Interestingly, sport is proposed as an avenue to continue development, particularly in psychosocial outcomes, across the lifespan. However, a significant limitation in this area is the lack of an appropriate measure to explore the development of psychosocial outcomes (i.e., assets) in older adults. Objective: The overarching purpose of this dissertation was to create a quantitative assessment tool to measure psychosocial assets in older adults. Methods: To achieve this aim, a mixed-method, sequential research design was applied, where the initial phases in the study helped inform and guide subsequent phases (i.e., development of the assessment tool). Study One included a scoping review that summarized our knowledge on sport and older adults since the first World Masters Games. This step was important in understanding how older athletes have been studied in prior research. Study Two, focused on examining the sport experiences and psychosocial development of older rowing athletes. Responses from eight athletes were analyzed to help confirm previous findings on psychosocial assets, report any novel assets, and examine general sport experiences in rowing. The final study used information gathered from previous studies as well as knowledge in the area of psychosocial development to create a preliminary instrument, “Psychosocial Assets Scale (PAS)”, to measure psychosocial assets in older adults. Results: The scoping review indicated most studies examined physiological outcomes with little exploration in areas such as psychosocial outcomes. Additionally, most studies did not report data on sociodemographic variables. Results from Study Two suggested sport experiences and psychosocial development of assets varies across individuals. In addition, findings indicated some negative sport experiences, which could alter development of assets. Lastly, the creation of the PAS showed emergence of nine factors: wellbeing, contribution, social support, drive/challenge, integrity, health habits, supportive family relationships, perceived safety, and desire to learn/continued learning. Conclusion: Collectively, this dissertation led to the creation of a preliminary scale to measure psychosocial assets in older adults. While the scale created in this dissertation requires further validation, the PAS allows researchers to advance in this area with implications for research, policy developers, sport advocates, and the broader society
  • ItemOpen Access
    Online Therapist-Guided Mindfulness-Based Cognitive Behavioural Therapy for Body Dysmorphic Disorder: Pilot Randomized Controlled Trial
    (2023-12-08) Kerry, Camrie Lauren; Ritvo, Paul G.
    Objective: While internet-based cognitive behavioural therapy is garnering increased empirical support, and standalone mindfulness meditation interventions provide promise, the efficacy of online mindfulness-based CBT for Body Dysmorphic Disorder (BDD) remains unknown. This study demonstrates the first effort to determine whether online CBT-M for BDD is feasible and acceptable, and whether mindfulness meditation adds to CBT treatment effects for BDD. Methodology: In this 8-week pilot RCT, 28 adults were randomly allocated to an online CBT-M or online CBT-only group. Study retention, accrual, adherence, and self-report measures for BDD, depression, anxiety and pain were collected. Results: This study was feasible to implement and deemed acceptable. Significant improvements were found on all outcome measures for both groups, and large between-group effect sizes were found for BDD (d= -0.96), depression (d= -1.06), pain severity (d= -1.12), and pain interference (d= -1.28). Conclusion: Mindfulness meditation may add to beneficial online CBT treatment effects for BDD.
  • ItemOpen Access
    Exploring the role of mitochondria and muscle function in a pertussis toxin free experimental autoimmune myositis mouse model
    (2023-12-08) Garibotti, Madison Claire; Perry, Christopher; Abdul-Sater, Ali
    Myositis is a rare autoimmune disorder characterized by skeletal muscle inflammation and weakness. Recently, mitochondrial stress has emerged as a possible disease contributor. To assess the relationship between mitochondrial stress and myopathy in myositis, evaluations of experimental models are required. Several models utilize an exotoxin, pertussis toxin(PT), coupled with foreign myosin injections. However, PT induces systemic inflammation impacting the ability to determine if the inflammatory response is consistent with myositis or a systemic response. Thus, the purpose of this thesis is to establish a modified myositis model whereby PT is excluded to exemplify the human condition, and to explore mitochondrial stress and myopathy. This modified model demonstrated no muscle atrophy occurred, but both the diaphragm and tibialis anterior(TA) displayed indices of mitochondrial stress. Additionally, the TA exhibited weakness that recovered over time. Suggesting the modified myositis model may induce a mild phenotype, highlighting the need for more robust model development.
  • ItemOpen Access
    Health care and outcomes in persons with obesity in Canada; an analysis of Canadian Institute for Health Information data 2018-2022
    (2023-12-08) Mirzadeh, Parmis; Ardern, Chris I.
    Overweight and obesity are associated with physical, functional, and mental health risks across the continuum of care. The purpose of this thesis was to quantify the ICD-10 code use for overweight and obesity (E66) in healthcare settings across Canada, and explore patient care of persons with obesity within emergency departments in Ontario. This study utilized data from the Canadian Institute for Health Information Discharge Abstract Database and National Ambulatory Care Reporting System from April 1, 2018 to March 31, 2022. Regional variations in E66 use were observed, where the highest rates of coding were seen in Manitoba, and the lowest rates in British Columbia (2018-2019) and PEI (2020-2021). Ontario was the only province to show an increase in E66 coding over time. Compared to controls matched for age, sex, and main diagnosis, patients with an E66 code had higher average length of stay, longer wait time for physician initial assessment, and higher triage scores.
  • ItemOpen Access
    Exploring the time-dependent changes to skeletal muscle macrophage redox homeostasis in Myositis
    (2023-12-08) Thuhan, Arshdeep Kaur; Perry, Christopher; Abdul-Sater, Ali
    Myositis, a rare idiopathic inflammatory myopathy (IIM), is characterized by skeletal muscle wasting and weakness. While autoimmune-mediated, the etiology is largely unknown. The focus of this thesis was to assess a modified version of a model commonly used in the literature, known as experimental autoimmune myositis. We assessed the progression of this model over time in the gastrocnemius and soleus muscles, to explore muscle specific changes in the immune response. Our findings reveal changes to ROS production in muscle macrophages, as well alterations in the expression of inflammatory related genes. However, the modified model, with the absence of pertussis toxin, does not replicate the strong disease phenotype observed in traditional EAM models. This allows us to question the extent to which pertussis toxin induces a myositis phenotype as opposed to systemic inflammation. Ultimately, there is a need to develop a comprehensive model of myositis that accurately mimics the human condition.
  • ItemOpen Access
    An examination of psychological stress and its effects on the mitochondrial DNA
    (2023-12-08) Mirzadeh, Parsa; Ritvo, Paul G.
    Background: With improvements in cellular stress measurement, current findings firmly implicate mitochondrial activity in cell stress reactions. Recent studies have highlighted the effects of psychological stress on mitochondria in terms of oxidative deterioration and crisis signalling. However, these studies have mainly assessed this relationship using the Trier Social Stress Test (TSST), while a variety of methods have been applied in blood sample analyses. This study contributes to the progression of existing studies as a partial replication that employs a different experimental stress protocol (based on the International Affective Picture System) (IAPS), a younger student population and similar blood sample analyses. Specifically, the relationship between cell-free mitochondria (via analyses of ccf-mtDNA levels following experimental stress) and acute psychological stress was evaluated in healthy female university-student participants. Methods: This study partially replicates the Trumpff et al., 2019 study. Fourteen female participants (n=14) were recruited on a university campus via posters and emails. All participants completed baseline questionnaires and two blood draws, with a 10-minute experimental stressor occurring between the pre-stress blood draw and post-stress blood draw. Blood samples were obtained at: i) baseline prior to the stressor and ii) +30 mins post stressor, to evaluate the changes in ccf-mtDNA levels associated with acute psychological stress. Results: A paired two-tailed t-test was used to assess the difference between the pre and post-blood samples, There was a statistically significant increase (P < 0.01) (a 53% increase) in ccf-mtDNA +30 mins after the psychological stressor. Conclusion: The present findings suggest that acute psychological stress is associated with a statistically significant increase in cell-free mitochondrial DNA (ccf-mt-DNA) in young healthy female university students.
  • ItemOpen Access
    Comparing fatigue induced by isometric and shortening contractions in skeletal muscle
    (2023-12-08) Andrews, Nathaniel Joel; Cheng, Arthur
    The intramuscular mechanisms causing greater fatigue-induced reduction in force during shortening compared with isometric contractions is not completely understood. The focus of this thesis was to compare fatigue in repeated shortening contractions and isometric contractions and investigate if greater force loss during repeated shortening contractions is attributed to more severe reductions in sarcoplasmic reticulum Ca2+ release. Single intact flexor digitorum brevis muscle fibres from C57Bl/6 mice were mechanically dissected and loaded with indo-1 AM fluorescent dye to assess myoplasmic free [Ca2+]. Fibres were either placed in an isometric or shortening protocol which were both stimulated at 70Hz of 600ms duration and 4 seconds rest for 50 tetani. The results of this thesis did not show that repeated shortening contractions cause greater fatigue-induced reductions in force compared with repeated isometric contractions, and there were no differences in the fatigue-induced reductions in SR Ca2+ release during the repeated contractions.
  • ItemOpen Access
    The Timing of Walking and Post-Meal Blood Sugar Levels in Adults with Type 1 Diabetes
    (2023-12-08) Turner, Lauren Victoria; Riddell, Michael C.
    Managing blood glucose excursions following a meal can pose a challenge for individuals with type 1 diabetes (T1D). This thesis examined whether, compared to being sedentary, a 20-minute moderate-intensity walk pre- or post-dinner could reduce postprandial glucose excursions. Eleven adults with T1D using hybrid closed-loop systems (HCLS) participated in this randomized, crossover real-world study. Participants undertook a 20-minute pre- or post-dinner walk for two weeks following a two-week baseline period. Continuous glucose monitoring data were analyzed using generalized estimating equations. In the 2-hours pre- to 4-hours post-dinner, pre-meal walks significantly improved percent time in 3.9-10.0mmol/L (LSM±SE=84.9±1.5%; B=5.58; p=0.01) and decreased percent time in 10.0-13.9mmol/L (LSM±SE=11.1±1.4%; B=-4.70; p=0.02) compared to baseline (LSM±SE=79.3±1.9% and 15.8±1.7%). There were no significant differences in area under the curve, peak, and nadir glucose between conditions (p>0.05). A 20-minute pre-meal walk may be a practical strategy to mitigate postprandial glucose excursions in individuals with T1D using HCLS.