Human Physiology Theses and Dissertations

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Browsing Human Physiology Theses and Dissertations by Author "Becker, James N. M., 1979-"

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    Effects of Two Marker Placement and Data Analysis Methods on Running Gait Analysis
    (University of Oregon, 2010-03) Becker, James N. M., 1979-
    This study evaluated the effects of two marker placement methods and two data analysis methods on running gait analysis. Markers placed on the shoe heel counter were compared with markers placed directly on the calcaneous and visible through heel windows cut into the shoe. When analyzed using a traditional group design no significant differences were found between marker conditions for rear foot eversion excursion, percent stance at which peak eversion occurred, maximal instantaneous eversion velocity, or maximal instantaneous vertical loading rate. Ankle frontal plane variability was significantly different between conditions. When analyzed with a single subject design some individuals demonstrated significant differences between conditions while others did not. In some individuals the heel windows condition revealed previously masked coupling parameters thought to be related to injury. The results of this study suggest the heel windows method and single subject analysis should be used for a longitudinal study of runners.
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    Towards an Understanding of Prolonged Pronation: Implications for Medial Tibial Stress Syndrome and Achilles Tendinopathy
    (University of Oregon, 2013-10-03) Becker, James N. M., 1979-; Chou, Li-Shan
    Epidemiologic data suggest 25% to 75% of all runners experience an overuse injury each year. Commonly cited biomechanical factors related to overuse injuries such as Achilles tendinopathy or medial tibial stress syndrome include excessive amounts or velocities of foot pronation. However, there is conflicting evidence in the literature supporting this theory. An alternative hypothesis suggests it is not necessarily the amount or velocity of pronation which is important for injury development; rather it is the duration the foot remains in a pronated position throughout stance that is the important variable. This project examined this hypothesis by first identifying biomechanical markers of prolonged pronation. Second, it assessed whether individuals currently symptomatic with injuries typically attributed to excessive pronation instead demonstrate the biomechanical markers of prolonged pronation. Finally, musculoskeletal modeling techniques were used to examine musculotendinous kinematics in injured and healthy runners, as well as healthy runners with prolonged pronation. The results suggest the two most robust measures for identifying individuals with prolonged pronation are the period of pronation and the eversion of the rear foot at heel off. Individuals with prolonged pronation can also be identified with a set of clinically feasible measures including higher standing tibia varus angles, reduced static hip internal rotation range of motion, and increased hip internal rotation during stance phase. Finally, individuals with prolonged pronation display a more medially located center of pressure trajectory during stance. Compared to healthy controls, individuals currently symptomatic with Achilles tendinopathy or medial tibial stress syndrome did not differ in the amount or velocity of pronation. However, they did demonstrate the biomechanical markers of prolonged pronation. Injured individuals also demonstrated greater average musculotendinous percent elongation than healthy controls, especially through mid and late stance. Currently healthy individuals demonstrating prolonged pronation exhibited musculotendinous percent elongations intermediate to the healthy and injured groups. As a whole, the results from this study suggest prolonged pronation may play a role in the development of common overuse running injuries. It is suggested future studies on injury mechanisms consider pronation duration as an important variable to examine. This dissertation includes unpublished co-authored material.