INTRODUCTION: The detection of a second inorganic phosphate (Pi) resonance, a possible marker of mitochondrial content in vivo, using phosphorus magnetic resonance spectroscopy (31P- MRS) at 3T is technically challenging, which may prevent its reproducible quantification. PURPOSE: To determine the reproducibility of resting alkaline inorganic phosphate (Pialk) measurement using 31P-MRS in human skeletal muscle at 3 tesla (T). METHODS: Resting 31P- MRS of the quadriceps muscles was acquired on two separate visits, within seven days, in 13 healthy, sedentary to moderately active young adults using a whole-body 3T MR system. Measurement variability related to coil position, shimming procedure, and spectral analysis were also quantified. 31P-MRS data were acquired with a 31P/1H dual-tuned surface coil positioned on the quadriceps using a pulse-acquire sequence. Test-retest absolute and relative reproducibility were analyzed using coefficient of variation (CV) and intra-class correlation coefficients (ICC), respectively. RESULTS: Pialk demonstrated a within-subject reproducibility marginally greater then the 10% cutoff (CV: 10.6 ± 5.4%; ICC: 0.80), but still appropriate given its small concentration in relation to other 31P metabolites. Proximo-distal change in coil positioning along the length of the quadriceps induced large variability in Pialk quantification (CV: 21.1%). In contrast, measurement variability due to repeated shims on consecutive scans from the same muscle sample (CV: 6.6%), and the automated spectral processing procedure, were minor (CV: 2.3%). Both metrics of absolute and relative reproducibility of Pialk were of similar magnitude to other well-resolved metabolites (e.g., phosphocreatine, Pi, and phosphodiester). CONCLUSION: Using multiple metrics, the present study established the high reproducibility of Pialk quantification by 31P-MRS using a surface coil on the quadriceps muscle at 3T. However, large variability in Pialk quantification can originate from positioning the coil on the most distal part of the quadriceps, which should be avoided due to shimming inhomogeneity.

The objective of this dissertation was to examine the action profiles of elite field hockey players in relationship to the 2015 FIH rule change. The following are major findings of the dissertation: The following are major findings of the dissertation: Study 1 – Relative action profiles before the rule change revealed that defenders work at a lower meter per minute (m/min) when compared with all other positions, and that forwards, midfielders, and screens perform similar m/min during a game. Examination of pre rule change difference from the 1st to the 2nd half play showed that elite level field hockey players are able maintain high-intensity actions in zone 6 throughout the game by increasing actions in zones 1 and 2, and decreasing actions in zones 4 and 5. Study 2 – Action profiles after the rule formatting change revealed the team was unable to match the percent of distance covered in zones 4 and 5 during the 1st quarter all in subsequent quarters. The low intensity actions in zone 1 and 2 gradually increased, while m/min gradually declined. However the percent of distance covered in zone 6 showed no statistically significant change. When positional differences were examined forwards covered the greatest percent of distance in zones 5 and 6, followed by midfielders, screens, and defenders. This pattern varies for zone 4, within which the midfielders possesses the greatest percent distance covered. 3 Study 3 – Relative action profile comparisons for the team, pre to post the 2015 rule change did not indicate a significant change in zones 2, 3, 4, 5, and 6. However zone 1 experience a statistically significant decrease. Positional analysis showed statistically significant changes for midfielders only. The changes were a decrease in zone 1, and increase in zone 5 and 6 during the first half of the game, and decrease in zone 1 and m/min during the second half of the game. A major focus of the US Women’s National Team is to develop the athletes’ physical capacity to maintain and repeat high intensity actions. The combination of physical preparation and tactical strategies allow the team to express high m/min and numerous high intensity actions throughout a match.

The purpose of this dissertation is to shed light on the physical demands of women’s soccer at the NCAA division I college level. Though research does exists describing the physical demands of women’s soccer, the vast majority seeks to explain the physical demands association with the professional and international level. This dissertation sought to: 1) examine the physical demands of NCAA division I women’s soccer and 2) observe changes in physical demands of two NCAA division I women’s soccer players over a four-year career using a case study approach. Study 1 examined the physical demands of twenty-three athlete from a single NCAA division I team using Global Positioning System devices during four competitive seasons. Total distance, high-speed running distance and sprinting distances were analyzed for comparison against previously established physical demands associated with higher standards of play as well as for positional differences. Differences were found regarding total distance covered between standards of play. However, more pronounced differences were identified between high-speed running activities and standard of play, with higher standards requiring greater demands for high-intensity activities. Additionally, attacking players were demonstrated to cover greater total distance and high-intensity distance compared to the other position groups. Study 2 was a case study, observing seasonal variation in match physical demands of two high-level collegiate players during their 4-four college careers. Each player was tracked using GPS devices to record total distance, high-speed running distance and sprint distance. Seasonal variation in physical demands were found for each player, however, no consistent trends were found for both players. Interestingly, lower physical demands were identified during each player’s final season of play in comparison to all previous seasons, possibly demonstrating an increased tactical awareness resulting in improved playing efficiency. Nevertheless, future examination including additional data such as fitness testing results, tactical formations, and technical skill assessment are warranted. With little research available detailing the physical demands of women’s soccer at the division I collegiate level, our findings will provide further insight into the physical demands required for division I female players. By understanding the specific physical demands associated with competitive matches, as well as various positions, coaches and sports scientists can be equipped with objective data unique to women’s college soccer at the NCAA division I level. Our findings will empower practitioners with valuable information necessary to guide more informed decision making with regard to training structure and prescription, to enhance performance and minimize injury risks.

Substantial evidence exists regarding how skeletal muscles use energy and how this affects muscular performance. What remains unclear is how characteristics of muscle energetics affect whole-body energetics during daily living, and what effects this may have on mobility. The goal of this study was to determine the associations between muscle and whole-body energetics including the relationships between: 1) muscle PCr depletion (∆PCr) in response to light intensity isotonic contractions and the oxygen deficit at the onset of a 30-min treadmill walk (30MTW), and, 2) muscle oxidative capacity and excess post-exercise oxygen consumption (EPOC; 30MTW), respiratory exchange ratio (RER; 30MTW), and peak oxygen consumption (VO2 peak) from a graded treadmill test. Eight healthy young (28.4 ± 3.5 years) male participants were studied. Muscle energetics were measured via 31-Phosphorus magnetic resonance spectroscopy (31P-MRS). Muscle ∆PCr was determined as the change in PCr during 2-min of isotonic knee extensor contractions. Muscle oxidative capacity was determined as the rate constant (kPCr) of a PCr recovery following 24-s of maximal isokinetic knee extensor contractions. Whole-body energetic responses to the 30MTW were measured via indirect calorimetry. Oxygen deficit and EPOC were determined as the time constants of the change in oxygen consumption at the onset and offset of the 30MTW, respectively. Respiratory exchange ratio was determined as the mean RER during minutes 7-30 (RER L23), 25-30 (RER L5), and 29-30 (RER L1). Peak oxygen consumption was the highest 30-s average of oxygen consumption during a graded treadmill test, normalized to total mass and lean mass measured by dual-X-ray absorptiometry. Spearman rank correlation coefficients (rs) were calculated to evaluate the associations between independent variables (muscle ∆PCr and oxidative capacity) and dependent variables (oxygen deficit, EPOC, RER, and VO2 peak). Muscle ∆PCr had a positive association (rs = 0.46, p = 0.30) with oxygen deficit. Muscle oxidative capacity had a negative association with EPOC (rs = -0.64, p = 0.14), RER L23 (rs = -0.64, p = 0.14), L5 (rs = -0.68, p = 0.11), and L1 (rs = -0.74, p = 0.07). Muscle oxidative capacity had a positive association with VO2 peak per lean mass (rs = 0.64, p = 0.10), but not VO2 peak per total mass (rs = 0.14, p = 0.75). These results provide promising preliminary evidence that muscle energetics are associated with whole-body energetic response to daily-living type exercise.

Introduction: Fall-related injuries are exceptionally prevalent in occupational settings. While endangering the workers’ health, falls cause poor productivity and increased economic burden in the workplace. Hence, identifying these threats and training workers to achieve proper postural control is crucial. Purpose: Study 1: To investigate the ankle joint kinematics in unexpected and expected trip responses during single-tasking (ST), dual-tasking (DT), and triple-tasking (TT), before and after a physically fatiguing exercise. Study 2: To investigate the impact of virtual heights, DT, and training on static postural stability and cognitive processing. Methods: Study 1: Twenty collegiate volunteers (10 males and females, one left leg dominant, age 20.35 plus-minus 1.04 years, height 174.83 plus-minus 9.03 cm, mass 73.88 plus-minus 15.55 kg) were recruited. Ankle joint kinematics were recorded while treadmill walking during normal gait (NG), unexpected trip (UT), and expected trip (ET) perturbations with DT and physical fatigue. Study 2: Twenty-eight collegiate volunteers (14 males and females; all right leg dominant; age 20.48 plus-minus 1.26 years; height 172.67 plus-minus 6.66 cm; mass 69.52 plus-minus 13.78 kg; body mass index 23.32 plus-minus 3.54 kg/m2) were recruited. They were exposed to different virtual environments (VEs) over three days with and without DT. Postural sway parameters, lower extremity muscle activity, heart rate, and subjective anxiety parameters were collected. Results: Study 1: Greater maximum ankle angles were observed during UT compared to NG, MDT compared to ST, and TT compared to ST, while greater minimum ankle angles were observed during ET compared to NG and during post-fatigue compared to pre-fatigue. Study 2: Greater postural decrements and poor cognitive processing were observed in high altitudes and DT. Discussion & conclusions: Study 1: Trip recovery responses are different between during DT, TT, and fatigue. Study 2: Static postural stability deteriorates at higher virtual altitudes and with DT, while it improves with a two-day training. Virtual height exposure reduces cognitive performance. Importance: The findings of these studies will provide insights into the biomechanics of falls in ergonomic settings and aid in designing functional and convenient fall prevention programs.

Introduction: Persons with Parkinson’s disease (PD) experience changes cortically, subcortically and behaviorally. This dissertation examines the asymmetry of motor behavior to explore the role of asymmetry in persons with PD and its connection to clinical symptoms. Purpose: Project 1: To assess the hand asymmetry difference in young adults versus older adults. Project 2: To investigate the difference in hand asymmetry in older adults and persons with PD. Project 3: To explore the correlation between function and clinical symptoms of persons with PD. Methods: 55 right-handed participants [Young Adults (YA) = 20, Female = 10; Older Adults (OA) = 20, Female = 10; Persons with PD = 15, Female = 5] were recruited and performed motor tasks: Purdue Pegboard test, grip strength test, response task, thumb opposition task, tapping task, three variations of timed-up-and-go test (TUG), single leg stance task (SLS), Weight Distribution test and Limits of Stability test. The two-way ANOVA was conducted to examine a variance between YA and OA. A separate two-way ANOVA was conducted comparing variance between OA and persons with PD. The purpose was to explore asymmetries, characterized by a significant difference between groups’ left and right sides. Pearson’s correlation was implemented to examine connection of clinical symptoms and motor behavior. Statistics: IBM SPSS 24 software was used. Two 2-way ANOVAs with the between group factor of group (Young vs. Older in Project 1; Older vs. PD in project 2), and within group factor of hand (Right vs. Left in Study 1 & Study 2) were used to examine if age (or PD) changes hand asymmetry. Pearson’s correlation coefficient was used to determine correlations between Unified Parkinson’s Disease Rating Scale (UPDRS) and motor tasks in PD patients (Study 3). Results: Project 1: Results indicate asymmetry reduces with age in fine motor tasks containing speed, dexterity and strength components. Project 2: The basal ganglia dysfunction does not overall further exacerbate the reduced asymmetry with age. Project 3: Clinical symptoms of PD measured by the UPDRS are generally not associated with fine motor tasks of this study.

The current investigation was an examination of the kinetic and kinematic characteristics of the back squat using accentuated eccentric loading (AEL) and cluster set programming strategies. Trained male subjects (age = 26.1 ± 4.1 years, height = 183.5 ± 4.3 cm, body mass = 92.5 ± 10.5 kg, back squat to body mass ratio = 1.8 ± 0.3) volunteered to complete four different load condition sessions involving traditionally loaded straight sets (TL), traditionally loaded cluster sets (TLC), AEL cluster sets (AEC), and AEL straight sets where only the first repetition of each set used eccentric overload (AEL1). The use of AEL increased eccentric work (WECC) and eccentric rate of force development (RFDECC) but did not result in the expected potentiation of subsequent concentric output. Interrepetition rest, however, appears to have the largest influence on concentric peak power (PP), rate of force development (RFDCON), and average velocity (MV). Additionally, the current study was an investigation of the efficacy of novel methods of ultrasonography technique that can be applied to monitoring training response. Compared to lying measures of the vastus lateralis (VL), standing ultrasonography measures of muscle thickness (MT), pennation angle (PA), and cross-sectional area (CSA) were more strongly and abundantly correlated with dynamic and isometric strength performance. Finally, the present study was an exploration of the genetic underpinnings of performance outcomes and muscle phenotypic characteristics. The polymorphisms of two candidate genes (ACTN3, ACE) typical of strength-power athletes were used. ACTN3 RR tended to result in greater type II fiber CSA and alter maximal strength, while ACE DD tended to influence RFD through the presence of more favorable type II-to-type I CSA ratios. Overall, the current investigation provided valuable insight into the characteristics of advanced programming tactics. Furthermore, the ultrasonography measurement and genetic aspects of the current investigation may serve as a framework to inform monitoring practice and generate hypotheses related to the training process.

Transfemoral amputees around the world experience increased difficulty in climbing stairs due to lack of muscle, balance, and other factors. The loss of a lower limb greatly diminishes the amount of natural force generation provided that is necessary to propel oneself up stairs. This study investigated possible solutions to the problem of stair ascension for transfemoral amputees by the means of designing and developing an externally attachable device to a prosthesis. The number of amputations from military service has greatly increased since 2008, which shows there is a clear need for assistive devices (Wenke, Krueger, & Ficke, 2012). With the number of amputations rising and no current externally attachable products on the market to aid in stair ascension for transfemoral amputees, the need for this specific device has become more prominent. Research, previous work, and preliminary testing provided a basis for design and development of a new prototype. Bench top testing was conducted to review concepts in the prototype and provide data for further modifications. Results from testing of previous work, as well as testing of new concepts and modifications, provided a framework for designing a new externally attachable device for assistance in stair ascension. A new prototype was then designed, manufactured, and tested with bench models as well as real-time testing with amputees. Success of the device’s performance was based on bench top results and feedback from amputees, noting both the advantages and shortcomings of the new prototype. Testing provided results and feedback that the device was well built and functioned properly, but did not perform satisfactorily, particularly in the categories of force generation and balance.

<p>Multiple sclerosis (MS) is an immune-mediated neurodegenerative disease that results in a myriad of physical and mental symptoms. Current disease-modifying therapies do not prevent long-term disability accumulation and are particularly ineffective for patients with a progressive disease onset. Exercise may represent an alternative strategy for managing symptoms and disability accumulation, particularly in progressive MS.</p> <p>Whereas the benefits of exercise have been established primarily in ambulatory MS patients with a relapsing disease course, few studies have investigated the benefits of exercise for patients with progressive MS with greater impairment. Therefore, the purpose of this dissertation was to determine the short-term, long-term, and maintenance effects of adapted exercise interventions for patients with progressive MS of high disability which was addressed by conducting two adapted exercise interventions.</p> <p>The first intervention examined the effects of 24 weeks of body weight supported treadmill training (BWSTT) on outcomes of physical and mental functioning, fatigue, quality of life, and brain health. Outcomes were evaluated at baseline, 12, and 24 weeks following the intervention, and again 12 weeks post-intervention. The second intervention evaluated and compared the effects of 12 weeks of total-body recumbent stepper training (TBRST) to BWSTT on outcomes of safety, physical and mental functioning, fatigue, quality of life, and equipment preference.</p> <p>Safety of BWSTT and TBRST was established. Significant improvements in fatigue and QoL were observed with both training modalities; however, neither significantly improved physical function. There was some evidence to suggest long-term BWSTT may improve cognitive performance and brain health, and that TBRST was the preferred exercise modality. Furthermore, most beneficial effects of long-term BWSTT tended not to be maintained when exercise was discontinued.</p> <p>This dissertation established evidence for the potential benefits of BWSTT and TBRST in patients with progressive MS with high disability. BWSTT and TBRST may represent viable alternative strategies for disease management.<strong></strong></p> / Doctor of Philosophy (PhD)

<p>Temporal order judgment (TOJ) refers to one’s ability to successively report the temporal order of two tactile stimuli delivered to independent skin sites. The brain regions involved in processing TOJ remain unclear. Research has shown that TOJ performance can be impaired with a conditioning background stimuli and this phenomenon, known as TOJ synchronization (TOJ-S), is suggested to be mediated by inhibitory neural mechanisms within the primary somatosensory cortex (SI) that create perceptual binding across the two skin sites. Continuous theta-burst stimulation (cTBS) over SI impairs tactile spatial and temporal acuity. This dissertation examines the effects of cTBS on TOJ and TOJ-S performance on the hand. In Experiment 1, TOJ and TOJ-S were measured from the right hand before and for up to 34 minutes following 50 Hz cTBS over SI. In Experiment 2, same measurements were obtained bilaterally for up to 42 minutes following 30 Hz cTBS over SI. Compared to pre-cTBS values, TOJ was impaired for up to 42 minutes on the right hand following 30 Hz cTBS. TOJ-S performance was improved for up to 18 minutes on the right hand following 50 Hz cTBS. These experiments reveal two major findings. First, cTBS act upon different inhibitory circuits that are suggested to mediate TOJ and TOJ-S. Second, cTBS parameters may dictate cTBS effects over SI excitability. The findings of this work not only emphasize the significant contributions of SI on tactile temporal perception, it provides novel insight of the underlying neural mechanisms of cTBS effects on SI cortical excitability.</p> / Master of Science in Kinesiology