[Truncated abstract] In cricket, the bowler propels a ball using a straight arm (permitted minimal extension) in an overhead fashion to a batsman situated approximately 20m away, who attempts to strike the ball in order to score runs for their team. Cricket bowling can be generalised by two types of bowlers; fast bowlers, who primarily use high ball speed, and spin bowlers that attempt to impart spin on the ball causing it to bounce in different directions. There has been numerous studies investigating the kinematics of fast bowling in cricket, but there is a paucity of objective literature on the spin bowling action due to the complex rotations of the upper limb necessary to develop ball velocity and rotation. One primary reason is that three dimensional (3D) analysis of upper limb movement is difficult due to the high degrees of freedom and ranges of motion of the associated joints. Furthermore, existing methods do not allow measurement of the kinematics of this highly dynamic task to be performed in an ecologically sound environment. The complexity is further compounded as the upper limb does not perform regular cyclical movements like the lower limb does with gait. Therefore, this makes it difficult to determine what

Thesis (Ph.D.)--Victoria University (Melbourne, Vic.), 2008.

abstract: According to the CDC in 2010, there were 2.8 million emergency room visits costing $7.9 billion dollars for treatment of nonfatal falling injuries in emergency departments across the country. Falls are a recognized risk factor for unintentional injuries among older adults, accounting for a large proportion of fractures, emergency department visits, and urgent hospitalizations. The objective of this research was to identify and learn more about what factors affect balance using analysis techniques from nonlinear dynamics. Human balance and gait research traditionally uses linear or qualitative tests to assess and describe human motion; however, it is growing more apparent that human motion is neither a simple nor a linear task. In the 1990s Collins, first started applying stochastic processes to analyze human postural control system. Recently, Zakynthinaki et al. modeled human balance using the idea that humans will remain erect when perturbed until some boundary, or physical limit, is passed. This boundary is similar to the notion of basins of attraction in nonlinear dynamics and is referred to as the basin of stability. Human balance data was collected using dual force plates and Vicon marker position data for leans using only ankle movements and leans that were unrestricted. With this dataset, Zakynthinaki’s work was extended by comparing different algorithms used to create the critical curve (basin of stability boundary) that encloses the experimental data points as well as comparing the differences between the two leaning conditions. / Dissertation/Thesis / Masters Thesis Bioengineering 2016

INTRODUCTION: Muscle activity and timing of the swing phases may contribute to the differences we see in athletes at different skill levels. The purpose of this study is to analyze the differences between mean muscle activity, peak muscle active and time to peak muscle activity for select muscles in the lower extremity as well as the differences between start times for swing phases and bat velocity prior to impact for a skilled and recreational group. METHODS: Twelve healthy subjects were split into two groups based on competitive level and analyzed hitting off of a tee. RESULTS: No significant differences were seen between muscle activity or the start time for the landing and swinging between groups. The skilled group did have a faster time to peak muscle activation for the front leg biceps femoris (p = 0.024), start the shifting (p = 0.12) and stepping (p = 0.11) phases significantly earlier as well as had a higher bat velocity prior to ball contact (p = 0.42) than the recreational group. CONCLUSION: Mean and peak muscle activity trends to be lower for skilled hitters than recreational hitters. Evidence of the skilled group starting the shifting and stepping phase earlier as well as having a higher bat velocity prior to impact could be important in separating hitters into skill level.

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Several methods have been used in the scientific literature to study the weightlifting pull. Broadly, these methods are used to measure kinematic or kinetic variables exhibited by the lifter, the barbell, or the lifter-barbell system. However, there is an apparent disconnect between weightlifting research and coaching practice that may reduce the perceived benefits of technique analysis among coaches and present some challenges for coaches who seek to incorporate technique analysis into their coaching practice. Differences and trends in the technique of competitive weightlifting performances are apparent from the available literature. However, there are also gaps in the literature due to infrequent analyses that are limited to narrow subgroups of the weightlifting population. Therefore, the purposes of this dissertation were to 1) update to the scientific knowledge of weightlifting technique and performance, 2) improve coaches’ ability to conduct and interpret technique analysis, and 3) enhance transferability of weightlifting in training to improve sport performance. A review of methods used to evaluate the weightlifting pull provides some practical guidance for coaches on the application and interpretation of weightlifting technique analysis. Video analysis is recommended as the most practicable method for coaches to implement technique analysis themselves. Methods used to study 319 lifts by women and men from two major international competitions demonstrate the feasibility and usefulness of video analysis as an inexpensive, time-efficient, and user-friendly method for coaches to conduct reliable technique analysis. The results of this dissertation suggest that a variety of techniques can be used to achieve international weightlifting success and provide some evidence of changes in weightlifting technique since at least the mid-1980’s. These results also indicate that a stereotypical technique profile among elite international weightlifters does not exist, which further support the notion that strength is a primary determinant of weightlifting ability.

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No description available.