Exercise Science Commons^™

Role Of Fat Content On The Structure And Function Of Human Skeletal Muscle, Joseph A. Gordon Iii

Doctoral Dissertations

Muscle size does not fully explain variations in muscle strength. Fat content has been implicated in muscle weakness, though this relationship remains unclear. The relationship between fat and strength may vary between scales (e.g., cellular, organ, and organism). The goal of this dissertation was to clarify the role of fat in the structure and function of muscle using in vitro and in vivo techniques across multiple scales in adults 21-45 years old. Study 1 tested the agreement of intramyocellular lipid (IMCL) content between oil red o (ORO) and magnetic resonance spectroscopy (MRS) techniques. These measures of IMCL were also compared …

Psychological Determinants Of Physical Activity And The Prediction Of Physical Activity Levels In African American Men, Alvin L. Morton Iii

Doctoral Dissertations

African American (AA) men experience disproportionally higher rates of non-communicable, chronic diseases (e.g., cardiovascular, type 2 diabetes, and renal failure) than White men. Physical activity (PA) is known to reduce the progression of CVD, type 2 diabetes, and renal failure. National statistics illustrate that AA men are less likely to get sufficient levels of PA to obtain health benefits. Although many factors (e.g., biomedical, socio-cultural) influence participation in PA, the psychological factors at the individual level are essential to beginning and maintaining activity. Therefore, understanding the psychological determinants of PA in AA men and their associations with meeting national guidelines …

Musculoskeletal Modeling Analysis Of Knee Joint Loading During Uphill And Downhill Waling In Patients With Total Knee Replacement, Tanner A. Thorsen

Doctoral Dissertations

The purposes of these studies were to determine differences in total (TCF), medial (MCF) and lateral (LCF) tibiofemoral compartment compressive forces and related muscle forces between limbs (replaced, non-replaced, and control), and different slopes during uphill [0° (level), 5°, 10°], and downhill [0° (level), 5° 10°] using statistical parametric mapping (SPM). Static optimization was used to determine muscle and compressive forces for 9 patients with total knee arthroplasty (TKA) and 9 control participants during walking trials. Total , loading-response, and push-off TCF impulse were calculated. A 3×3 [Limb (replaced, non-replaced, control] × Slope (0°, 10°, 15°)] SPM[F] repeated measures ANOVA …

Lower Extremity Muscle Contributions To Acl Loading In Healthy And Acl-Reconstructed Females, Shelby Peel

Doctoral Dissertations

Females are 16 times greater to sustain a second ACL injury compared to their healthy female counterparts. Many of these females return to play their respective sport after an ACL-reconstruction (ACLR). However, little is known about the influence fatigue in sport has on lower extremity mechanics of ACLR females. The purpose of this study was to investigate the influence muscular fatigue may have on lower extremity mechanics in healthy and ACLR females. It was hypothesized that 1) healthy control and ACLR females would demonstrate different hip, knee, and ankle mechanics, regardless of fatigue, 2) fatigue would influence hip, knee, and …

Examining The Physical Activity Levels Of Youth With Intellectual And Developmental Disabilities During Physical Education And Recess, Vincenzo Nocera

Doctoral Dissertations

Introduction: It is currently believed that children with intellectual and/or developmental disabilities (IDD) are less physically active than their peers. The school setting may offer a promising solution to allow children with and without IDD to engage in physical activity (PA). However, the current school-based PA levels of this population remain unclear. Therefore, the purpose of this investigation was to compare the PA levels and related context of youth with and without IDD during the total school day, physical education, and recess. Methods: A total of 13 children (n = 3 with IDD) enrolled in first- and second grade participated …

Bioenergetic Mechanisms Of Age-Related Differences In Muscle Fatigue, Liam F. Fitzgerald

Doctoral Dissertations

Muscle fatigue is defined as the reduced capacity to produce torque or power in response to contractile activity. Previous work has observed greater fatigue in older than young adults in response to high-velocity contractions, but similar fatigue with age in response to moderate-velocity contractions. The mechanisms for these age-related differences is not clear. One potential explanation is a greater accumulation of putative agents of fatigue (e.g., Pi, H₂PO₄^-, and H⁺) in older than young muscle during high- but not moderate-velocity contractions. Older muscle may accumulate these metabolites to greater extent because of deficits …

Mechanisms That Limit Oxidative Phosphorylation During High-Intensity Muscle Contractions In Vivo, Miles F. Bartlett

Doctoral Dissertations

Skeletal muscle oxidative capacity plays a critical role in human health and disease. Although current models of oxidative phosphorylation sufficiently describe skeletal muscle energetics during moderate-intensity contractions, much is still unknown about the mechanisms that control and limit oxidative phosphorylation during high-intensity contractions. In particular, the oxygen cost of force generation is augmented during exercise at workloads above the lactate threshold. Presently, it is unclear whether this augmentation in muscle oxygen consumption is driven by increased rates of oxidative ATP synthesis (ATP_OX) or by decreases in the efficiency of ATP_OX due to mitochondrial uncoupling. To address this …

Changes In Muscle Control And Coordination In Novel Task Learning, Sangsoo Park

Doctoral Dissertations

Learning many daily life motor skills is critical for survival and the quality of living in humans. As children, we develop walking and running patterns to move the body from point A to B without falling, and we learn to grasp a wide variety of objects during activities of daily living. Motor skills can be properly performed by appropriate muscle activations which are controlled by the central nervous system. How does the central nervous system develop and fine-tune its control strategy to learn a new motor skill? The aim of this dissertation was to better understand how human participants alter …

Cardiovascular Disease Risk And Menopause: Effects Of Cardiorespiratory Fitness, Exercise, And Follicle Stimulating Hormone, Corinna Serviente

Doctoral Dissertations

Menopause is associated with adverse changes in cardiovascular disease risk factors. A reduction in estrogens is most commonly associated with changing cardiovascular disease risk; however, recent observations suggest that the increase in follicle stimulating hormone that accompanies menopause may also influence risk, potentially through its influence on lipid levels. The changes in cardiovascular disease risk factors may adversely affect endothelial cell function, a pre-clinical marker for cardiovascular disease. Whether cardiorespiratory fitness is protective of endothelial health in this population, thereby mitigating the changes in risk that accompany menopause, is unclear. This dissertation evaluated differences in endothelial health and endothelial responses …

Observing The Molecular Basis Of Thin Filament Activation With A Three Bead Laser Trap Assay, Thomas Longyear

Doctoral Dissertations

Muscle contracts after calcium (Ca++) is released into the muscle cell, resulting from a cascade of events which result in myosin, the molecular motor of muscle, to produce force and motion. Myosin cyclically binds to a regulated thin filament, using the chemical energy of ATP to produce force and motion. Perturbations in muscle, such as a build-up of metabolic by-products or point mutations in key contractile proteins, can inhibit these functions in both skeletal and cardiac muscle either acutely or chronically. Despite the many years we have studied skeletal and cardiac muscle, we still do not have a clear picture …

A Comprehensive Validation Of Activity Trackers For Estimating Physical Activity And Sedentary Behavior In Free-Living Settings, Albert R. Mendoza

Doctoral Dissertations

The aim of study one of this dissertation was to compare consumer activity trackers (ATs) with the research-grade ActiGraph™ GT3X-BT accelerometer (AG) in estimating energy expenditure (EE) and steps during orbital shaking at different frequencies. To address this aim, we utilized an electronic orbital shaking protocol (twenty-four, 3-minute trials; 2-hour trials). For all comparisons, the AG served as the reference measure. In the 3-min protocol, we showed that on average, the NL-1000 pedometer (NL) produced the lowest error (-9 steps/3-min) at 0.9 Hz (corresponding to moderate intensity). The magnitude of the error for the NL was 14 steps/3-min at a …

Effect Modification Of The Association Between Aerobic Physical Activity And Diabetes-Related Mortality By Race-Ethnicity: A Population-Based Prospective Study Using Nhanes Iii And 1999-2006 Nhanes, William Robert Boyer Ii

Doctoral Dissertations

Purpose: To examine potential effect modification by race-ethnicity of the relationship between physical activity (PA) and diabetes-related mortality risk using a sample of U.S. adults from the Third National Health and Nutrition Examination Survey (NHANES III). Methods: The sample (n=10,717) included adults (≥20 years) who attended the Mobile Examination Center (MEC). An age-standardized PA score (PAS) was calculated from the self-reported frequency and intensity of 12 leisure-time aerobic activities. The PA scores were then grouped into three categories: inactive (PAS = 0), insufficiently active (PAS >0 - Results: There was no interaction between PA and race-ethnicity (p=0.83). Compared to inactive …

Interfacing Continuous Measurement Of Glucose And Physical Activity To Predict Glycemic Control In Individuals With Type 2 Diabetes, Jennifer Blankenship

Doctoral Dissertations

Physical activity is a cornerstone in the management of hyperglycemia and risk of cardiovascular disease in type 2 diabetes (T2D). However, the dose response relationship between physical activity and glucose regulation is not well defined. The overall goal of this dissertation was to assess the magnitude and timing of changes of daily glucose concentrations in response to continuous and intermittent light physical activity in T2D. Through utilizing continuous glucose monitors (CGM) and physical activity monitoring concurrently, we were able to assess the glycemic impact of physical activity and sedentary behavior in the free-living environment. Study 1 aimed to examine the …

Effects Of Television Viewing On Psycho-Physiological And Behavioral Outcomes, Brittany Star Overstreet

Doctoral Dissertations

Purpose: To determine the effects of television viewing during exercise on 1) preference for exercise and 2) treadmill walking time. Methods: Twenty-five insufficiently active adults (mean±standard deviation; age: 46±12 years; Body mass index: 31±5 kilogram/squared meter (kg/m²) were recruited for this study. In part 1, participants performed three randomized 1/3-mile walking bouts at an intensity equivalent to 70% of their oxygen consumption at ventilatory threshold (VO₂-at-VT). During these exercise bouts, individuals viewed 1) their favorite television program (FavTV), 2) a standardized nature program (NatTV) or 3) no-TV program (NoTV). A behavioral choice paradigm was used to …

Feasibility Of A Combined Physical Activity And Sleep Education Intervention For Girls Living In A Low Socioeconomic Status Urban Community, Cory J. Greever

Doctoral Dissertations

Declining sleep duration and poor sleep quality is a public health epidemic disproportionately effecting elementary age girls living in low socioeconomic status urban communities. The Girls Dancing and Sleeping for Health (Girls DASH) program was designed to test the feasibility, acceptability, and efficacy of a combined physical activity and sleep education program in this population. In combination with baseline data from a previously conducted intervention in elementary age urban girls living in a low SES community in Springfield, MA, results from a cross-sectional analysis indicated that greater screen time was positively associated with parental reports of child’s sleep quality. Additionally, …

Molecular Mechanisms Underlying The Contralateral Repeated Bout Effect (Crbe) In Human Skeletal Muscle, Ling Xin

Doctoral Dissertations

Eccentric (muscle lengthening) exercise induces temporary muscle damage that can lead to long-term muscle adaptation, a process known as the repeated bout effect where subsequent exercise results in less damage. The existence of a contralateral repeated bout effect (CRBE) has been controversial. The primary goals of this study were to: 1) validate the existence of the CRBE; and 2) define the underlying molecular mechanisms. Thirty-six young men performed 100 maximal eccentric actions of the knee extensors using one leg (bout 1) and repeated the exercise with the contralateral leg five weeks later (bout 2). Vastus lateralis muscle biopsies were …

Psycho-Physiological Effects Of Television Viewing During Exercise, Brian Carl Rider

Doctoral Dissertations

Purpose: To examine the effects of television (TV) viewing on psychological and physiological variables during a moderate-intensity exercise bout. Methods: 28 insufficiently active adults participated in this study. Each participant performed three separate 30-minute walking bouts on a motorized treadmill. The bouts were separated by 48 hours and the majority of participants completed all bouts within three weeks. During each bout, participants watched a program they selected (self-selected TV condition), a British Broadcasting Corporation (BBC) nature program the investigators selected (standardized TV condition), and one bout involved no TV viewing (no TV condition). Variables measured during exercise were: …

The Role Of The Extracellular Matrix In Mediating Muscle Soreness, Karen L. Riska

Doctoral Dissertations

The goal of this dissertation was to examine the role of the extracellular matrix (ECM) in muscle soreness. Study 1 examined how the disruption of the ECM from a minor surgery (e.g. muscle biopsy) affected muscle soreness. Study 1 showed that soreness levels increased at 24 h post-biopsy compared to baseline and resolved within 96 h. However, the level of muscle soreness at 24 h post-biopsy (20 mm) was lower than that reported for performing a strenuous and naïve exercise (40–80 mm). These results will help review boards at institutions where muscle biopsies are performed understand how a muscle biopsy …

Knoxville Moves: Log-In And Get Mobile, Courtney Marie Monroe

Doctoral Dissertations

This dissertation evaluated 1) the efficacy of a course-based Internet-technology intervention rooted in social cognitive theory (SCT) for increasing step counts in university faculty and staff, and 2) the effect of online social support tools on step counts among adults using a randomized control trial.

Thirty-six sedentary/insufficiently active university faculty and staff participated in an eight-week, Internet-delivered walking intervention. They received an Omron HJ-720ITC pedometer, personal step goals, and access to a Blackboard LearnTM website comprised of SCTbased features. Outcomes included daily steps, social support, self-regulation, self-efficacy, and outcome expectations. Participants significantly increased their average daily steps (p < 0.001) between baseline and week 1 by 1800. A similar increase in daily steps was observed between baseline and all other intervention weeks (p < 0.001). Social support and self-regulation significantly improved (p < 0.001). These findings helped inform the design of the second study.

In this …

Active Families In The Great Outdoors: A Family-Centered Program To Increase Physical Activity Levels, Perceptions, And Behaviors, Jennifer Irene Flynn

Doctoral Dissertations

Physical activity levels of adults and children are low, and the amount of time children spend being active outdoors is decreasing. Parents play a critical role in developing health behaviors of children and ways to increase physical activity and encourage an active family culture are needed. Promotion of family outdoor physical activity, which includes at least one parent and one child from a home engaging in physical activity together, is understudied. Therefore, the purpose of this dissertation was to 1) describe the type, frequency, and duration of family physical activity, 2) determine whether changes in the duration and number of …

Associations Of Total Activity Counts And Physical Activity Intensity Levels With The Metabolic Syndrome: A Structural Equation Modeling Approach, Dana Lizbeth Wolff

Doctoral Dissertations

To clarify the protective benefits of physical activity (PA), epidemiologists and public health researchers continue to seek improved methods of assessing PA. In particular, accelerometers have gained acceptance with researchers as they provide reliable estimates of PA and can record both the amount and intensity of ambulatory movement. However, there is concern that accelerometer data reduction techniques may not provide quantitatively accurate measurements of time spent in various PA intensity categories. One way to circumvent these inaccuracies is to use the accelerometer-derived total activity counts (TAC), which is a more direct expression of what the monitor records.

In order to …

"When Are You Going To Get A Real Job?": An Experiential Sport Ethnography Of Players' Experiences On The Men's Pro Tennis Futures Tour, Jacob Cannon Jensen

Doctoral Dissertations

In this experiential sport ethnography, I examined the experience of former NCAA college tennis players competing on the International Tennis Federation (ITF) Men’s Pro Futures Tour, the entry level of professional tennis. Limited research has focused on players competing on this tour, especially former top-level NCAA players transitioning from collegiate to professional tennis. The contributions of ethnographic studies are gaining greater recognition in sport psychology literature, and I conducted a year-long experiential ethnography in which I entered the field as a participant and researcher. I gained access to Futures tournaments and players by participating in the qualifying rounds and collecting …

The Effects Of Augmented Attentional Focus On The Performance With Practice Of A Closed Perceptual-Motor Task For Individuals Who Differ In Task Mastery, John Allen Richards

Doctoral Dissertations

The purpose of this study was to investigate the effects of augmented attentional focus on the performance with practice, of a closed perceptual-motor task for individuals who differ in task mastery. Sixty-four male volunteers were assigned to either the beginning or advanced task mastery group (n = 32) based on bowling averages (≤ 130, ≥ 150 respectively). Each subject in the task mastery groups was randomly assigned to one of four augmented focus of attention conditions, i.e., focus on: (a) environmental results of the movement that was performed (KR); (b) the movement that was performed (KP); (c) self via presence …