Life Sciences Commons^™

Sex Comparisons Of External, Anatomical And Methodological Factors On Motor Unit Firing Behavior, Michael James Marsala

Electronic Thesis and Dissertation Repository

Motor unit (MU) recruitment and firing rate (MUFR) modulation are the primary factors governing force control. Differences in the anatomical distributions of α-motoneurons, muscle properties, and perception of fatigue between males and females may cause sexually dimorphic MU firing behaviors. The purpose of this dissertation was to further examine external, anatomical, and methodological factors that may influence observations of sex-related differences in neuromuscular function. In chapter 2, sex differences in how mental fatigue may influence MU firing behaviors were examined. Mental fatigue did not significantly alter MU firing behavior, maximal force, or force tracing ability in either males or females. …

Assessing Copd Care Quality In A Rural Ontario Primary Care Clinic: A Retrospective Chart Review, Daniel Henke

Electronic Thesis and Dissertation Repository

Background: Primary chronic obstructive pulmonary disease (COPD) care may be worse in rural versus more urban environments.

Purpose: To evaluate the quality of COPD care in a rural Ontario primary care clinic.

Methods: A 12-month retrospective chart review study was conducted between June 2022 and January 2023 at a Goderich, Ontario primary care clinic. Electronic medical records (EMRs) were randomly selected for inclusion. Baseline sociodemographic (e.g., occupation) and health (e.g., smoking status) characteristics were extracted as well as information regarding COPD care received (i.e., Health Quality Ontario [HQO] Quality Standard [QS] indicators; n=33. The primary study outcome was overall proportion …

Cortical Activation During Mobility In An Indoor Real-World Environment: A Mobile Eeg Study, Sam Marshall

Electronic Thesis and Dissertation Repository

Human mobility requires neurocognitive inputs to safely navigate the environment. Previous research has examined neural processes that underly walking using mobile neuroimaging technologies, yet few studies have incorporated true real-world methods without a specific task imposed on participants (e.g., dual-task, motor demands). The present study utilized mobile electroencephalography to examine and compare theta, alpha, and beta frequency band power (μV2) in young adults during sitting and walking in laboratory and real-world environments. Our findings support that mobility and environment may modulate neural activity, as we observed increased brain activation for walking compared to sitting, and for real-world walking compared to …

The Effects Of Resistance Exercise Training On Insulin Resistance Development In Female Rodents With Type 1 Diabetes, Mitchell James Sammut

Electronic Thesis and Dissertation Repository

The etiology of insulin resistance (IR) development in type 1 diabetes mellitus (T1DM) remains unclear; however, impaired skeletal muscle metabolism may play a role. While IR development has been established in male T1DM rodents, female rodents have yet to be examined in this context. Resistance exercise training (RT) has been shown to improve IR and is associated with a lower risk of hypoglycemia onset in T1DM compared to aerobic exercise. Additionally, the molecular mechanisms mediating RT-induced improvements in insulin sensitivity remain unclear. Therefore, the purpose of this study was to investigate the effects of RT on IR development in female …

The Effect Of Central Chemoreceptors On The Peripheral Respiratory Chemoreflex Response To Hypoxia In Humans, Nasimi A. Guluzade

Electronic Thesis and Dissertation Repository

We measured the peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic carbon dioxide tensions (PCO₂) to determine the form of the relationship between PChS and central PCO₂. Twenty participants completed three repetitions of modified rebreathing tests with end-tidal PO₂ (P_ETO₂) clamped at 150, 70, 60, and 45 mmHg. PChS was computed at 1-mmHg intervals of P_ETCO₂ as follows: the differences in V̇_E between the three hypoxic profiles and the hyperoxic profile (∆V̇_E) were calculated; three ∆V̇_E values were plotted against corresponding calculated oxyhemoglobin …

Influence Of High-Intensity Interval Running On Femoral Cartilage Deformation In Competitive Runners, Ryan J. Evans

Electronic Thesis and Dissertation Repository

Competitive compared with recreational runners have increased odds of having osteoarthritis and running-related injury, which may be from engaging in different types of running. We compared femoral cartilage deformation in competitive runners following a continuous and high-intensity interval run and evaluated the association between running kinetics and cartilage deformation. Twenty-four competitive runners (11 females and 13 males) underwent ultrasound imaging of femoral cartilage before and after two running sessions that were one week apart in a counterbalanced order. Repeated measures 2 x 2 ANOVA revealed lateral femoral cartilage had greater deformation after interval compared to continuous running. Collapsed across conditions, …

The Ventilatory Response To Modified Rebreathing Is Unchanged By Hyperoxic Severity: Implications For The Hyperoxic Hyperventilation Paradox, Joshua D. Huggard

Electronic Thesis and Dissertation Repository

We measured the ventilatory response to hyperoxic CO₂ rebreathing with O₂ tension clamped at increasingly higher pressures. We hypothesized that the V̇_E versus PCO₂ relationship is fixed and independent of PO₂. Twenty participants (10 females; mean± SD age: 24±4 years) performed three repetitions of modified rebreathing in 4, randomized, isoxic-hyperoxic conditions: mild: PO₂=150 mmHg; moderate: PO₂=200 mmHg; high: PO₂=300 mmHg; and extreme: PO₂≈700 mmHg. For each rebreathing trial, the P_ETCO₂ at which V̇_E rose was identified as the ventilatory recruitment threshold (VRT, …

The Influence Of Knee Position And Sex On Ultrasound Imaging Of Femoral Cartilage Characteristics, Harry Battersby

Electronic Thesis and Dissertation Repository

The purpose was to examine (1) the effect of measurement position and sex on femoral cartilage outcomes, and (2) the association between gait biomechanics and cartilage outcomes. Fifty individuals participated (25 males, 25 females; Age=20.62±1.80years). Ultrasound measured femoral cartilage thickness and echo-intensity (EI) at 90º, 115º, and 140º of knee flexion. Gait outcomes included the external knee adduction and knee flexion moments. Cartilage outcomes were compared using 2(sex) x 3(position) repeated measures ANOVA. Gait and cartilage associations were assessed using stepwise regression. Cartilage was thicker when measured at 90° compared with 140°, but mainly in males. Males had thicker cartilage …

Does Acute Maximal Exercise Or Chronic Physical Activity Affect Circulating Angiotensin (1-9) Concentrations?, Kyle R. Weiman

Electronic Thesis and Dissertation Repository

Introduction: Epidemiological evidence suggests physical inactivity can increase the likelihood of hospitalization from the SARS-COV-2 virus. Further, some data indicate a greater ratio of angiotensin 1-9 to angiotensin I helps prevent severe outcomes during infection. Moreover, related hormones can enhance potentially both physical activity and health. The purpose of this study was to determine whether plasma concentrations of angiotensin (1-9) are modified after a single exhaustive exercise bout and whether sex or chronic physical activity is associated with greater plasma concentrations.

Methods: Participants (n=14) performed a graded exercise test on a cycle ergometer. Antecubital area venipunctures were performed before, immediately …

The Prevalence Of Ontario Undergraduate University Students Meeting The 24-Hour Movement Guidelines And The Role Of Perceived Social Support, Nia Contini

Electronic Thesis and Dissertation Repository

The extensive physical and mental health implications of physical activity, sedentary behaviour, and sleep are irrefutable. The COVID-19 pandemic has had drastic consequences on university students and their already poor movement behaviours. Recommendations for a healthful distribution of physical activity, sedentary behaviour, and sleep were presented in the Canadian 24-Hour Movement Guidelines for Adults. The current research sought to report the prevalence of Ontario undergraduate university students meeting the Guidelines approximately two and a half years into the pandemic and assess the association between meeting the Guidelines and perceived social support. A total of 508 undergraduate students registered at 19 …

The Neural Control Of Force Production In Response To Directional Force Challenges, Joshua W. Cohen

Electronic Thesis and Dissertation Repository

Maintenance of upright standing posture is fundamental to human mobility and requires muscular control of the body’s centre of mass over the base of support. Force production, necessary for standing, is achieved by neural activation of populations of motor units (MUs). The possibility of preferentially activating different MUs within or across synergists has been debated in the motor control literature. Accordingly, the overall objective of this dissertation was to examine the neural control of standing balance in response to different directional force challenges. High Density Surface-Electromyography (HD-sEMG) was used to observe the location of muscle activity, and signal decomposition techniques …

Plantar Flexor Dynamic Contractile Rates Are Not Dependent On Calcaneal Tendon Stiffness, Sohum Kulkarni

Electronic Thesis and Dissertation Repository

The ability to rapidly generate muscular torque and velocity is important in specialized activities and daily tasks of living. Tendon stiffness is one factor in the neuromuscular system that influences musculoskeletal torque transmission. Previous studies have reported weak-to-moderate correlations between tendon stiffness and rate of torque development (RTD). However, these correlations have been reported only for isometric contractions which may not be relevant to contractions involving joint rotation (i.e., dynamic). The purpose was to investigate the effect of calcaneal tendon stiffness on the dynamic rates of torque (RTD) and velocity (RVD) development in plantar flexor muscles. Young adult males (n=13) …

A Comparison Of Methods To Identify The Mean Response Time Of Ramp-Incremental Exercise For Exercise Prescription, Nikan Behboodpour

Electronic Thesis and Dissertation Repository

Introduction: The oxygen uptake (V̇O₂) vs power output (PO) relationship from ramp incremental exercise (RAMP) is used to prescribe aerobic exercise. As PO increases, there is a delay in V̇O₂ that contributes to a misalignment of V̇O₂ from PO making precise prescription of exercise PO untenable. Three methods of determining Mean Response Time (exponential modeling (MRT_EXP), linear modeling (MRT_LIN), and the steady-state method (MRT_SS)) were compared and evaluated for their accuracy at predicting the V̇O₂ associated with two PO below estimated lactate threshold (q_LT) and one …