Browsing by Author "Jordan, Matthew James"

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    Pushing for Gold On Force Application in Bobsleigh and Cycling
    (2023-07) Onasch, Franziska Maren; Herzog, Walter; Stefanyshyn, Darren J.; Edwards, William Brent; Jordan, Matthew James; Thompson, Robert Ian; McErlain-Naylor, Stuart
    In many sports, performance is governed by an athlete’s ability to produce force paired with a given movement velocity and, thereby, generate power. The 4-man bobsled push start is an event that requires team effort, and its goal is to maximize sled velocity in the shortest possible time. Fractions of a second can decide the outcome of a race, and off-ice tests designed to assess strength and speed are used to identify the athletes that will perform best. However, the actual contributions of the team members during the push start on ice have not been measured. The objective of the first project in this thesis was to better understand the push contributions of the four athletes in a 4-man team by analyzing the components of the push start. A 4-man bobsled was instrumented to record both sled velocity and 2D push forces as applied to the sled by the athletes during the push start. Push force was observed to decrease quickly once the sled picked up speed, and the execution of the loading was discovered to be a crucial component of the push start that can affect overall performance. In project 2, a prowler sled was instrumented to measure sled velocity and push force in an off-ice push force-velocity test to be used as a training and assessment tool in bobsleigh athletes. Greater force results in greater power output – if the force is applied the right way. In project 3 we studied force effectiveness in cycling, where only pedal force directed perpendicular to the crank is effective i.e., results in propulsion, while forces parallel to the crank have been considered wasted. In our study, we aimed to determine the impact of constrained pedal force direction on force output. Constraining static pedal force to be perpendicular to the crank only was counterproductive and resulted in significantly reduced force magnitude. In summary, this thesis work contributes to the applied study of power output in sports, with instrumented devices aiding the study of force and power output in athletes, novel data, and the proposal for a new training method.
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    Tibial-fibular morphology: variation, sexual dimorphism, and mechanical implications
    (2023-05-01) Bruce, Olivia Leigh; Edwards, William Brent; Boyd, Steven Kyle; Kuo, Arthur; Roach, Koren Elaine; Jordan, Matthew James; Lenz, Amy Lorraine
    Stress fractures are common injuries among runners and military personnel associated with the mechanical fatigue of load-bearing bone. The tibia is the most frequently fractured site and females are at much greater risk than males. Bone geometry and density are hypothesized risk factors for stress fracture and are thought to contribute to the disparity in risk between sexes via their influence on bone strain magnitude which is strongly related to the rate of mechanical fatigue. However, covariation between these two complex factors and their influence on the strain environment of the tibia are not well characterised. The overarching goal of this thesis was to develop a more nuanced understanding of the mechanical implications of tibial-fibular geometry and density variations present in young active adults. A series of studies were performed utilizing a combination of advanced medical imaging, statistical approaches, gait data, and the finite element method to characterise and quantify covariations in whole-bone tibial-fibular geometry and density distributions and their influence on bone strain. Transverse diaphyseal geometry and sagittal curvature were identified as key features that likely influence stress fracture risk, demonstrating substantial effects on finite element-predicted bone strain. Additionally, the average female illustrated a narrower tibia which resulted in elevated bone strain when compared to the average male, suggesting that bone geometry likely contributes to the disparity in stress fracture risk between sexes. As we work towards improving predictive models and developing effective screening tools for stress fracture risk, these findings provide insights into key features of bone geometry and density that will need to be accurately characterised. Landmark- and anthropometric-based predictions of tibial-fibular geometry and density were not sufficiently accurate, indicating that some level of advanced medical imaging data will be necessary to generate personalised models or characterise geometry and density features associated with stress fracture risk.