<p> The motor driven treadmill is often used in research as a convenient tool for simulating overground running. There has been varied opinion in the literature regarding the accuracy of this assumption. The major difference that has been quantified is the variation in treadmill belt speed as a result of the forces applied by a runner. In comparison, the earth does not vary its speed during overground running. The aim of the present study was to more clearly define the causes of treadmill belt-speed variation and to elucidate its effects on running mechanics. </p> <p> An in-lab fabricated tachometer was used to determine accurate treadmill belt speed while the treadmill was challenged by five subjects weighing 55.2 to 99.6 kg running at four speeds of 2.6, 3.1, 3.5 and 4.0 m/s. The actual running velocity was found on average to be 0.62% higher than the treadmill display setting. The intra-step belt-speed variation ranged from 4.2 to 8.6 % of average belt velocity. Linear regression analysis showed that 86 % of the variance in intra-step belt-speed variation was attributed to total body mass and a further 10 % attributed to running speed. </p> <p> The effect that this variation had on running mechanics was determined from the power transfer between the foot and belt, as calculated from the product of the change in belt speed and the horizontal ground reaction force. The horizontal force, as calculated using a segmental acceleration approach, did not show complete agreement with simultaneously recorded forceplate data. It was found that an average of 4.49 J flowed to the treadmill during the eccentric phase of running and 3.37 J of energy flowed to the runner during the concentric phase of running. Despite inaccuracies in the calculation, the mathematical approach used in this study permitted insight into the theoretical benefit of belt-speed variation in treadmill running. </p> / Thesis / Candidate in Philosophy

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No description available.

No description available.

Twenty-five sedentary female volunteers, 18-30 years of age, were studied to determine the effects of an endurance running program on leg strength gains from a weight training program. Subjects were randomly assigned to one of three groups: a weight training group (W), a weight training plus running group (RW), or a control group (C). The subjects trained three days per week, approximately one hour per day, for nine weeks. The RW group ran for 25 min then weight trained for 30 min, whereas the W group weight trained for one hour. Subjects were tested for one-repetition maximum (l-RM) pre-training, at two week intervals during training, and post-training. Thigh girth (midpoint [MG] and 1.18 cm above the patella [AP]) and percent body fat were measured pre- and post-training, only weekly on a calibrated scale. Body weight was measured. Significant improvements in isotonic leg strength of 56% for W and 66% for RW were observed, with no difference between the groups. W and RW also achieved a significantly greater isotonic leg strength than the C group. The experimental groups had a significantly greater posttest AP as compared to the C group. No significant differences were observed over the experimental period in MG, percent body fat and body weight of any of the groups. In conclusion, the running program used in the present study did not interfere with leg strength or girth gains achieved through weight training. These results are in contrast to those reported in other studies which found that aerobic training impaired strength gains. / Master of Science

Purpose: Race has rarely been the focus of biomechanics investigations, despite affecting the incidence of musculoskeletal injury and disease. Existing racial differences in movement mechanics could drive disease development and help identify factors contributing to racial health disparities. This study aimed to 1) Identify racial differences in walking, running, and landing mechanics between African Americans and white Americans and 2) Determine whether racial differences can be explained by anthropometric, strength, and health status factors. Methods: Venous blood samples, anthropometric measures, lower extremity strength, and a health status assessment were collected for 92 participants (18-30y) in an IRB approved study. After measuring self-selected walking speed, 3D motion capture and force plate data were recorded during 7 trials in the following conditions: regular walking (1.35m/s), fast walking (1.6m/s), running (3.2m/s), and drop vertical jump (31cm box height). Fundamental gait measures and running and landing measures associated with overuse and impact injury risk were extracted using Visual3D and custom Matlab scripts. Multivariate and post-hoc univariate ANOVA models were fit to determine main and interaction effects of gender and race (JMP Pro 15, α=0.05) after which data was separated by gender. Stepwise linear regression models evaluated whether anthropometric, strength, and health status factors explained racial effects. Results: Several racial differences in walking, running, and landing mechanics were observed in both men and women, but differed between genders. Effect sizes of observed racial differences indicate the potential for both statistical and clinical significance. Although several racial differences during all tasks were explained by anthropometric, strength, and health status factors in women, none were explained by these factors in men. In women, explanatory factors were a combination of innate and modifiable. Conclusion: Future steps should include the development of racially diverse databases and the identification of potential factors to target in interventions aimed at reducing racial health disparities. / Doctor of Philosophy / Purpose: Race has rarely been the focus of biomechanics studies, but several injuries and diseases occur at different incidence rates between racial groups. This study aimed to 1) Identify racial differences in walking, running, and landing between African Americans and white Americans and 2) Determine whether racial differences are explained by body proportion, strength, and health status factors. Methods: Blood samples, body proportion measures, lower extremity strength, and a health status assessment were collected for 92 participants (18-30 years old). Motion analysis data was recorded and analyzed during the following tasks: regular walking, fast walking, running, and drop vertical jump. Biomechanical measures were compared between racial groups and genders. When racial differences were found, we evaluated whether the differences could be explained by body proportion, strength, and health status factors. Results: Several racial differences were found during walking, running, and landing tasks in both men and women, but were dependent on gender. Several observed racial differences in women could be explained by body proportion, strength, and health status factors, but no racial differences could be explained in men. In women, some of the factors that explained racial differences were structural and could not be altered while others were potentially modifiable by exercise or were the product of social environment. Conclusion: Based on these findings, biomechanical data should be collected from racially diverse populations. Some factors able to explain racial differences could be targeted to reduce racial health disparities.

"Hot-tests" form a vital facet towards the end of the production line of modern automotive plants, where the condition of the engine is checked by running it for a short period of time, to ensure its performance under standard operating conditions. The duration of hot-tests for small engines varies from 20-75 seconds. In the conventional procedure, about 10-30 grams of lubricant (for pre-coating) is used with about 650ml of standard oil for engine testing. However, about 1-3 oz. of oil is lost per engine, as it cannot be sucked out of the crankcase after the hot tests. The loss of 1-3 oz. of oil leads to a significant loss in revenue, over the large number of engines manufactured. It also causes a potential safety and environmental hazard due to leakage of lubricant during shipping or upon first use in a particular application. The goal of this project is to conduct "no-oil" hot tests using less than 10 grams of specially formulated lubricants for pretreatment. Implementation of this procedure for conducting the hot tests in the manufacturing facility would save revenue and eliminate potential hazards mentioned above in addition to cutting down on manpower and/or machinery used for handling the engine oil. An experimental study of pre-treatment of interacting interfaces of engine components, with specially formulated lubricants, for no-oil hot tests is presented. This study includes sixteen tests performed on the production line of Tecumseh's small engine manufacturing plant. The formulated lubricants were made up of tribopolymer formers, i.e., monomers, which were used in previous tribopolymerization studies. Tribopolymerization is defined as the planned or intentional formation of protective polymeric films directly and continuously on rubbing surfaces to reduce damage and wear by the use of minor concentrations of selected compounds capable of forming polymeric films in situ. This study entailed the investigation of the anti-wear properties of the formulated lubricants on a high temperature pin-on-disk machine and subsequent selection of lubricants exhibiting superior performance for use in the engine tests. The no-oil hot-tests performed at Virginia Tech and on the assembly line exhibited the superior anti-scuffing/anti-wear properties of the specially formulated lubricants, to warrant their use on the production line in the near future. / Master of Science

The purpose of this study was to use the Eating Disorder Inventory (EDI), Negative Addiction Scale (NAS) and other measured characteristics to determine differences between consistent runners and sedentary controls. 38 male and 23 female local non-team related runners of more than 9 miles per week were studied. They completed the EDI and NAS. 31 male and 30 female nonexercisers completed the EDI. They were drawn from college classes and participated in less than one hour per week of physical activity. Height, weight and body fat were determined for both groups. As compared with anorectics, none of the EDI subscale averages for runners or controls were higher than the 38th percentile. Body dissatisfaction was less for runners than controls. Females scored higher on drive for thinness and body dissatisfaction. Female runners scored significantly higher on drive for thinness than all other groups. The mean NAS score was 78 for the females and 74 for the males. Significant body dissatisfaction subscale differences found between runners and controls were probably due to the runners' lower body fat and weight. In looking at the male/female differences, females typically have a stronger concern about weight and are less satisfied with their bodies. It is believed that in the group of runners studied, severe eating disorders did not exist. / Master of Science

Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disease affecting 1 in every 3500 boys. The disease is characterized by the absence of the dystrophin protein from the sarcolemma of muscle cells. Muscle cells lacking dystrophin go through cycles of degeneration and regeneration and are considered susceptible to contraction-induced injury 144. Eventually, the satellite cell proliferative capacity is exhausted and the muscle fibers are replaced by connective and adipose tissue that yields a progressive loss of force generating capability. DMD patients typically die by their early 20's, primarily due to respiratory or cardiac failure. The precise role of dystrophin is not presently known. However, its absence suggests that it may play a role in both cellular calcium regulation and oxidative stress 152. Recent studies suggest increased reactive oxygen species (ROS) may precede the initial wave of wasting that marks disease onset 49. Therefore, it is possible oxidative stress may contribute as a pathogenic mechanism of DMD. Strategies to reduce the deleterious effects of oxidative stress could be an effective therapeutic approach. Regular exercise is known to increase antioxidant capacity in humans and mice 146. Green tea extract (GTE) is a powerful antioxidant that is easily supplemented in the diet 83. The purpose of this study was to test the hypotheses that (1) voluntary endurance exercise alone, (2) a diet supplemented with 0.05% (wt/wt) GTE alone, or exercise and GTE combined will blunt the effects of ROS and improve muscle strength and endurance in young mdx mice. Male mdx mice at age 21-days were randomly divided into one of 4 treatment groups: Run Normal diet (RunNorm; n=8), Sedentary Normal diet (SedNorm; n=8), Run GTE diet (RunGTE; n=10), and Sedentary GTE diet (SedGTE; n=8). RunNorm and RunGTE mice were given free access to a running wheel for 3 weeks while SedNorm and SedGTE mice were restricted to normal cage movement. At the end of 3 weeks, mice in each treatment group were sacrificed and assessed for daily and weekly running distances, content of actin and myosin proteins and fiber type distribution (tibialis anterior), contractile/mechanical and fatigue properties (extensor digitorum longus), creatine kinase levels and antioxidant capacity (serum), lipid peroxidation (gastrocnemius), and citrate synthase and beta-hydroxyacyl-CoA dehydrogenase activities (quadriceps and soleus). The key findings of this study were: In normal diet running mice (RunNorm), average daily distance run was increased 300% (from 0.5 to 2.1 km/d, P<0.05) from week 1 to week 3. In GTE diet (RunGTE) compared to RunNorm mice, total distance over the 3 weeks was markedly improved 128% (61.2 vs. 26.8 km, P<0.0001). Running, independent of diet increased EDL muscle tetanic stress (18%), serum antioxidant capacity (22%), citrate synthase activity (35%), and beta-oxidation (37%; all P<0.05). GTE, independent of running decreased lipid peroxidation (gastrocnemius:-64%; heart: -29%) and serum creatine kinase (-36%), and increased citrate synthase activity (59%; all P<0.05). These findings in dystrophic mice suggest that voluntary endurance exercise with or without GTE supplementation blunted the deleterious effects of ROS. If similar positive effects are evident in human DMD patients, then these approaches may be beneficial therapies either alone or in combination. / Master of Science

El trabajo de tesis se concreta en el estudio de los nuevos usos no planificados del espacio público urbano. Nuevas formas libres y espontáneas de utilizar el espacio público surgen constantemente en las ciudades actuales, por iniciativa de los ciudadanos, sin haber sido previamente pensadas o planificadas. Estos nuevos usos o nuevas formas de entender el espacio público, rápidamente se difunden y comparten entre los usuarios de una ciudad y entre las distintas ciudades. Un buen ejemplo representativo de la situación actual es el uso del espacio público urbano para realizar actividades relacionadas con el deporte. En realidad, son los propios ciudadanos los que eligen utilizar algunos espacios de la ciudad en lugar de otros para practicar su actividad deportiva y no siempre estos espacios preferidos son los asignados por los planes de desarrollo urbano creados por el gobierno de la ciudad. En consecuencia, las ciudades se enfrentan a un doble reto: por un lado, adaptar y mejorar sus infraestructuras y equipamientos existentes para que estos nuevos usos puedan desarrollarse; y por otro, escuchar a los ciudadanos y posibilitar su intervención en los procesos de planificación urbana que gestionan la distribución de los diferentes usos en la ciudad. Con este propósito, el principal objetivo de esta investigación es el diseño de una metodología que permita, por un lado, identificar los espacios elegidos por los ciudadanos en su práctica deportiva diaria; y por otro, caracterizar estos entornos urbanos, desde el punto de vista cualitativo, para comprender las razones, factores y elementos que llevan a los ciudadanos a preferirlos. De esta manera, este conocimiento puede ser tenido en cuenta, de forma prioritaria, en los procesos de toma de decisiones cuando se interviene en la ciudad. Este trabajo de tesis se centra específicamente en el estudio del fenómeno del “running” que, más allá de una moda, se ha establecido como un movimiento social. En este sentido, las tecnologías de la información y las comunicaciones tienen mucho que ver con el auge experimentado. Cada vez más, los ciudadanos comparten información en las redes sociales sobre nuevas rutas o lugares en los que, por sus características adecuadas, escogen realizar su actividad deportiva diaria. Es evidente que esta información sobre el uso que los ciudadanos hacen del espacio público, sobre sus necesidades y preferencias, no puede quedar fuera del proceso de la planificación y el diseño inteligente de las ciudades actuales. En resumen, el objetivo general de esta investigación es estudiar las ciudades como escenario de las nuevas formas libres y espontáneas de utilizar el espacio público, por iniciativa de los ciudadanos, sin haber sido previamente pensadas o planificadas. En particular, el trabajo tiene como objetivo analizar el uso del espacio público urbano escogido por los ciudadanos para realizar actividades relacionadas con el "running". Para ello, se lleva a cabo un análisis a partir de los datos geolocalizados recuperados de redes sociales del deporte. Los resultados de la investigación se concretan, en primer lugar, en la identificación de los espacios urbanos frecuentados por los ciudadanos; y en segundo lugar, en la caracterización y comprensión de los mismos, con el objeto de poder ser adaptados y mejorados. Desde la convicción de que este conocimiento de la ciudad, obtenido de la propia experiencia del ciudadano, no puede quedar fuera del proceso de planificación y diseño inteligente de las ciudades actuales, esta investigación pretende avanzar en el desarrollo de métodos para introducir este enfoque en los procesos de planificación urbana.