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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
641

Eating disorder symptoms and exercise motivations across exercise investment levels among female distance runners

Canady, Andrea. January 2002 (has links)
No description available.
642

Variability Among Individual Male Runners Influences Cumulative Loading More Than Foot Strike Type

Trotter, Tamarie 26 June 2023 (has links) (PDF)
Foot strike type affects running mechanics and may influence overuse injury occurrence. Measuring the interaction between cumulative load and foot strike type may provide additional information that could eventually help with understanding injury mechanisms. The purpose of this study was to determine how foot strike type affects cumulative loading in runners, and to determine if individual metrics change throughout a 5-kilometer sub-maximal run. 30 participants ran on an instrumented treadmill for 5 km at 3.15 m/s with their preferred foot strike type (14 rearfoot strike, 16 non-rearfoot strike). Stride rate, foot strike angle, loading rate, per stride and per km (cumulative) vertical ground reaction force impulse, impact peak, absolute peak, knee negative work, and ankle negative work were calculated and compared across time and between groups. Per stride between-group main effects were seen for stance time (p=0.003), foot strike angle (p<0.001), and loading rate (p=0.040), all of which were greater for rearfoot strike runners. Per stride and cumulative ankle and knee negative work also showed significant differences, with ankle negative work being greater for non-rearfoot strike runners (p=<0.001 per stride, p=<0.001 cumulative) and knee negative work being greater for rearfoot strike runners (p=0.014 per stride, p=0.008 cumulative). Both loading rate and cumulative vertical ground reaction force impulse decreased significantly over time (p=0.035, p=<0.001 respectively). In summary, we found a few differences in per stride and cumulative metrics between foot strike groups, namely ankle and knee loading as previously observed. However, as a whole, individual variability in vertical ground reaction force loading patterns was more apparent than any group distinctions. We also found patterns in previous research suggesting that study design components, specifically self-selected speed and habituation, affect variables such as stride rate and peak vertical ground reaction force. The common perception that non-rearfoot strike runners have a higher stride rate was not supported in this study. Lastly, we determined that cumulative calculations can be different if taken at the beginning vs the end of a run. Quantifying injury risk is complicated and cumulative damage models should take into account individual load capacity and training session characteristics (e.g., warm-up time, length, intensity, and rest time).
643

Knowledge on the Run: Uncertainties in the Careers of Kenyan Long-Distance Runners

Biehl, Konstantin 04 February 2022 (has links)
This paper focuses on the history and future of Kenyan Long-Distance Running.
644

Koordinační změny atletického sprintu před a po provedení speciálních běžeckých cvičení / Changes of coordination of the athletic sprint before and after the performance of special running exercises

Pařík, Ondřej January 2014 (has links)
This doctoral thesis deals with the kinesiological analysis of the athletic run - sprint. The aim of the thesis is the time characteristics comparison and switching on of the muscles which are working during the sprint before and after the performance of special running exercises. It is becoming much more important to use the special training procedures during training sessions. The special running exercises are performed almost daily during training sessions of sprinters. The question is to what extent their performance is evident on the activation of muscles. The qualitative and quantitative results show the activation of muscles during sprint before and after the performance of the special running exercises. The main tool of the research was the surface EMG analysis of muscles during a 30-metre long sprint. The content of the research were two comparative analysis, where 8 proband participated - interindividual and intraindividual. During the evaluation process we considered the quantitative and qualitative components. On the basic of the reached results we may say that there is no diference between the run before and after the performance of special running exercises. Keywords: Sprint, special running exercises, electromyography, ANOVA
645

An Investigation of Compliant Over-running Ratchet and Pawl Clutches

Roach, Gregory Mark 11 March 2003 (has links) (PDF)
This thesis proposes that compliant mechanism theory can be used to design over-running ratchet and pawl clutches with reduced part count, lower assembly and manufacturing time while maintaining functionality. An extension of the theory to the micro regime is also briefly addressed. The results of the research show that the ratchet and pawl type of over-running clutch is a good choice for the use of compliance, and the clutch pawls should be loaded in compression to get the largest amount of output torque. It was found that com-pliant mechanism theory can be used to design ratchet and pawl clutches with fewer parts and lower manufacturing and assembly costs, and that these clutches perform comparable to traditional rigid-body ratchet and pawl clutches. Compliant ratchet and pawl clutches can replace traditional rigid-body clutches in some applications and now make it possible to be used in applications where it was once not economically feasible to use a over-running clutch. It was also found that these clutches function at the micro level.
646

Physiological Differences between Land and Water Treadmill Running

Rife, Rachel Kemp 21 March 2008 (has links) (PDF)
Objective: To determine if water treadmill running with (WTR-S) or without water shoes (WTR-NS) could produce similar cardiorespiratory responses as land treadmill running (LTR). Design and Setting: A repeated measures design was used to assess the differences between LTR and WTR-S and WTR-NS. All testing was done in either a research laboratory or an athletic training hydro-therapy room. Subjects: Eighteen trained runners (9 men and 9 women) volunteered for this study. All 18 subjects participated in three running conditions. Measurements: Treadmill speed, HR, and SF were assessed at four exercise intensities representing 50%, 60%, 70%, and 80% of land VO2max for all three running conditions. Results: WTR with and without water shoes produces similar cardiorespiratory responses to LTR. The VO2/HR relationship showed that at a HR of 150 bpm, VO2 was significantly less (p < 0.0001) when running on a land treadmill (34.66 ml/kg/min) compared to a water treadmill with shoes (37.51 ml/kg/min) and without shoes (37.21 ml/kg/min) were nearly identical. At a HR 150 of bpm, the VO2 in males (40.52 ml/kg/min) was 8.12 ml/kg/min higher than that of their female (32.40 ml/kg/min) counterparts. At a treadmill speed of 6 mph, stride frequency during LTR was 23.6 steps/min greater (p < 0.0001) than WTR-S and 21.8 strides/min greater than WTR-NS. VO2 was on the average 4.12 ml/kg/min higher (p < 0.0001) during WTR-S compared to WTR-NS running condition at the same treadmill speed. Conclusion: Statistical analysis indicated that 50%, 60%, 70%, and 80% of land VO2max was achieved in the water. Therefore, WTR can be used during rehabilitation of athletes unable to fully weight bear to prevent deconditioning. Wearing the AQinc water running shoe increases the metabolic demand by 4.12 ml/kg/min at any given water treadmill speed. Gender differences existed in the absolute HR/VO2 relationship but not in the relative HR/VO2 relationship among the three running conditions.
647

A Comparison of the Traditional, Swing, and Chicken Wing Arm Movements on Volleyball Blocking in NCAA Division 1 Female Athletes

Neves, Taubi J. 08 March 2010 (has links) (PDF)
Blocking is highly correlated with team success. The identification of specific techniques that produce a more successful block would be helpful knowledge for coaches and players. This study compared the traditional, swing, and chicken wing arm swings in combination with the running step footwork pattern in order to determine which arm swing enabled athletes to perform a more effective block. The time it took the athletes to get off the ground and get their hands above (vertically) the net was calculated. The distance the hand reached over the net or hand penetration (displacement between the net and finger in the anterior and vertical planes) was also measured. Lastly, jump height was calculated. High-speed videography was used to capture the blocking movements of thirteen female NCAA Division I athletes. Data were analyzed using a repeated measures ANOVA test, pairwise comparison, and co-variate analysis. The chicken wing block arm swing was quickest in getting the athlete off the ground and getting their hands above the net. The swing block was greatest for hand penetration and jump height. These results can help coaches and players decide which arm swing will benefit them most as a blocking team and as individual blockers.
648

Lower-Extremity Hip Strength Differences among Sexes and Stages of Physical Maturation in Adolescent Long Distance Runners

Stout, Brian J. January 2021 (has links)
No description available.
649

Modelling and laboratory investigations on freight wagon link suspensions with respect to vehicle-track dynamic interaction

Jönsson, Per-Anders January 2004 (has links)
The link suspension is the most prevailing suspension system for freight wagons in central and western Europe. The system design is simple and has existed for more than 100 years. However, still its characteristics are not fully understood. This thesis emphasizes freight wagon dynamics and comprises three parts: In the first part a review of freight wagon running gear is made. The different suspension systems are described and their advantages and disadvantages are discussed. The review covers the running gear standardized by UIC and the conventional so-called three-piece bogie. Additionally five improved three-piece bogies and twelve novel running gear designs are presented. The second part focuses on the lateral force-displacement characteristics in the link suspension. Results from stationary measurements on freight wagons and laboratory tests of the link suspension characteristics are presented. To improve understanding of the various mechanisms and phenomena in link suspension systems a simulation model is developed. Link suspension systems have strongly nonlinear characteristics including a hysteresis loop. The loop exhibits usually three characteristic sections with different tangential stiffnesses. The actual contact geometry of the links and end bearings has a significant influence on the characteristics. By wear in ordinary service - as well as by geometric tolerances on new components - the contact geometry may deviate considerably from nominal geometry. Further, it seems that elastic deformation in the contact surfaces has considerable effects on the suspension characteristics, in particular on the initial rolling stiffness for small displacements. Also, flexibilities in links and end bearings influence the characteristics. It is also observed that new components after a short period of dynamic testing can exhibit a very low amount of energy dissipation, a phenomenon that is also indicated in some stationary measurements on wagons. To summarize the second part, it appears that the link suspension characteristics are very sensitive to several factors being hard to control in the real world of freight wagon operations. The various stiffnesses and hysteresis loops have a considerable variation and may have a strong influence on the ride qualities of vehicles. As long as the characteristics can not be controlled within closer limits than found in this study, there is a strong need for sensitivity analysis to be made, both in predictive multibody simulations of vehicle dynamics, as well as in verification and acceptance tests. In the third part a study on the possibility to improve ride qualities of freight wagons with link suspensions is presented. Parametric studies with multibody dynamic simulations on freight wagons equipped with link-suspension bogies are performed. The effect of supplementary friction and hydraulic damping is investigated under various running conditions: speed, loading, tangent and curved track, wheel-rail contact geometry, track gauge and track irregularities. Substantial improvements of the lateral running behaviour of wagons with link suspension bogies can be achieved - both at ordinary speeds and at increased speeds - by using a proper combination of supplementary hydraulic dampers. Speeds up to 160 km/h could be realistic.
650

Dynamic Assessment of Footbridges : A designer's method to estimate running induced vibrations

Södergren, Jones, Barraza, Anton January 2018 (has links)
Dynamic problems in footbridges, such as sensible vibrations caused by human induced loading, has on a number of occasions been observed. These vibrations are rarely an ultimate limit state problem, but can be perceived as unpleasant by the pedestrian. In design guidelines there are propositions for how to asses the dynamic problem. However, they only take the walking load into account. It has been shown that, in the case of a running load, accelerations that lie above the comfort zone can occur and that running loads are more severe than walking loads in some cases. It is possible that the running load case has to be considered in future guidelines, and finding a feasible design methodology demands a lot of work. In this thesis, a method aimed to be easily used by a designer is analyzed. The amplitude of acceleration received as a result from a dynamic analysis in a commercial FEM software, was reduced by reduction factors to generate accelerations closer to reality. This could be identified and verified against recommendations.

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