THE EFFECTS OF PROLONGED RUNNING ON THE BIOMECHANICS AND FUNCTION OF THE FOOT AND ANKLE
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Running injuries have been linked to morphology and lower limb function, and changes in foot and ankle biomechanics and function within a run may contribute to the predisposition to injury. This thesis investigates the effects of prolonged running on the foot and ankle, and potential mechanisms underlying changes in foot posture. Methods: A series of studies were undertaken from field to laboratory, measuring foot posture changes after prolonged running of different durations. Further measures of ankle invertor strength and medial ankle stiffness were taken in the laboratory studies as well as kinematic and plantar pressure data captured every ten minutes to enable repeated measures analysis of pedal movement to be conducted. Reliability across the foot posture, strength and stiffness measures was also determined. The latter studies involved the development and mechanical testing of a novel foot orthosis component which was compared to a standard open cell orthotic foam. A double blind randomised controlled trial then compared how the novel and standard foam components affected foot posture, ankle invertor strength and medial and plantar soft tissue stiffness after a 30-minute run. Results: A mean drop in NH and increase in FPI-6 following the half marathon, hour long and 30-minute treadmill runs was seen, with changes decreasing as running duration reduced. Ankle invertor strength and medial ankle stiffness reduced but did not correlate to the change in foot posture. Changes in foot and ankle kinematics were seen within 30 minutes of running. Mechanical testing of the novel orthotic component and standard foam revealed characteristic differences in response to loading, and changes in foot posture measures after 30 minutes of running in the randomised controlled trial were almost identical across both conditions. Further comparison of invertor strength and medial foot and ankle stiffness revealed no significant differences, but a large difference between exertion measures was seen. Conclusion: There was an overall effect of duration of running on changes in foot posture in this thesis, and the foot posture change was moderated by two different foot orthosis conditions although the mechanism remains unclear.