School of Public Health

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

Note: Prior to July 1, 2007, the School of Public Health was named the College of Health & Human Performance.

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    Neural Modulation of Leg Stiffness in Response to Neuromuscular Fatigue
    (2016) Chu, Edward; Shim, Jae Kun; Miller, Ross H; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The spring-mass model is able to accurately represent hopping spring-like behavior (leg and joint stiffness), and leg and joint stiffness changes can reveal overall motor control responses to neural and muscular contributors of neuromuscular fatigue. By understanding leg stiffness modulation, we can determine which variables the nervous system targets to maintain motor performance and stability. The purpose of this study was to determine how neuromuscular fatigue affects hopping behavior by examining leg and joint stiffness before and after a single-leg calf raise fatiguing protocol. Post-fatigue, leg stiffness decreased for the exercised leg, but not for the non-exercised leg. Ankle and knee joint stiffness did not significantly change for either leg. This indicates that leg stiffness decreases primarily from muscular fatigue, but was not explained by ankle and knee joint stiffness. The decrease in leg stiffness may be an attempt to soften landing impact, while at the same time maintaining performance.
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    Probing Postural Stability Mechanisms in Locomotion
    (2009) Logan, David Michael; Jeka, John J; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    It is not currently known if those upright stability mechanisms utilized in standing posture are present in locomotion. In this investigation, subjects walked or stood on a treadmill in three speed conditions (posture, 1 km/h, 5 km/h) in front of a visual scene consisting of randomly oriented triangles. The triangles translated in the Anterior-Posterior (A/P) direction in either a low or high amplitude condition. Frequency response functions (FRFs) of both the A/P displacement of bilateral kinematic markers and their corresponding segment angles in response to the visual scene translations were computed. Gain and phase of these FRFs had consistent responses in high amplitude visual conditions in the trunk (hip and shoulder displacements, trunk angle), which motivated further comparisons within the trunk during posture and locomotion. In doing so, the postural processes of orientation and equilibrium control were teased apart during locomotion.