Thesis (M.S.)--East Carolina University, 2009. / Presented to the faculty of the Department of Exercise and Sport Science. Advisor: Paul DeVita. Title from PDF t.p. (viewed May 4, 2010). Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 424-439). Available also in a digital version from Dissertation Abstracts.

To understand how falls occur during walking in older adults, we need to understand how the nervous system maintains stability, and how aging affects walking. Four studies were conducted to better understand the effect of age on gait. Older adults display higher gait variability compared to young adults, possibly because of their slower walking. We compared gait stability at multiple controlled walking speeds. Greater gait variability in healthy elderly existed independent of slower walking. Their diminished strength and flexibility partly explained this difference. To explain slower walking in the elderly, some have suggested that muscle weakness and stiffness may force people to walk slower. Others have suggested that people choose to walk slower to be more stable. We compared dynamic stability of gait at multiple speeds. Healthy older adults also exhibited more stability at slower speeds, yet walked at speeds comparable to young adults despite the lower strength and flexibility. Therefore, weakness and stiffness may not force healthy older adults to walk slower. The goal of the nervous system during walking may be to maintain stability of superior segments. We tested whether superior segments are more stable than inferior segments during walking. Superior segments exhibited less orbital stability during preferred walking speed, in contrast to previous suggestions. This highlighted the importance of trunk control during gait. The effects of aging on the fluctuations in the muscle activity during gait are not well understood. We quantified the stride-to-stride fluctuations of EMG as a measure of muscle activation patterns in state-space. Variability increased with speed except in the gastrocnemius. Orbital stability was less in older adults, suggesting that deviations in the EMG amplitude pattern were not readily corrected. Less local stability was seen in older adults, suggesting that older adults were more sensitive to perturbations. Together, these findings suggest that trunk control is important during gait. Strength and flexibility deficits help explain higher variability and lower stability in older adults. Future work will need to address the effect of strength interventions, neurophysiological decline on gait stability and fall risk.

Spinal adaptive response in the frontal plane was investigated in relationship to pelvic unleveling during gait. Kinematic data were collected from 10 healthy adult subjects (5 male, 5 female) for walking and running on the treadmill at self-selected speeds. Spine and pelvic kinematic patterns and ranges of motion (ROM) were investigated with gender, speed and slope as factors. Speed and slope had the greatest impact on changes in the amplitude of the spine's kinematic patterns. Interaction effects were seen for speed and slope for the ROM, particularly of the greater trochanter (p < .047), PSIS (p < .011) and for the shoulders (p < 0.077). Gender presented more changes in the pelvic kinematics than the spine's kinematics. A significant trend in the females of greater ROM for T8 with increases in speed and slope was shown (p < 0.001). From this study it was concluded that speed, slope and gender were significant factors that affect the spine's ability to adapt to pelvic unleveling. In all conditions there was a coupled relationship found between the thoracic spine, lumbar spine and pelvis. In particular there was an oppositional movement found within the spine such that as the lumbar spine had convexity towards the swing leg then the thoracic spine had the opposite convexity. Hence, these factors are important when assessing posture and biomechanics of running and walking.

No description available.

As more adults with cerebral palsy (CP) are surviving longer (1) an intervention is needed to help reduce spasticity and increase overall strength to improve mobility, and therefore life quality. Adults with CP are lacking a form of independent exercise that allows them to maintain or improve their ambulation skills (1, 2). A new approach to increase muscle strength and flexibility is called whole-body vibration (WBV). The goal of the current study was to determine the acute effects of using an individualized frequency (I-Freq) approach to WBV therapy on gait in adults with CP. In this study, eight adults with CP (age 20-51 years, six men, two women) participated in two sets of testing: the first set was used to determine their I-Freq and the second set to perform a 3D gait analysis before and after a WBV treatment. The WBV was administered in five sets of one minute of vibration followed by one minute of rest. The gait analyses included collection of kinematic and EMG data. Subjects experienced a significant increase in walking speed (P=0.047), stride length (P=0.017) and dynamic ankle range of motion (P=0.042) after the acute bout of WBV. These data show that WBV treatments at I-Freq could help adults with CP maintain their range of motion and overall mobility through an independent and cost effective means. 1. Murphy KP. The adult with cerebral palsy. Orthop Clin North Am2010 Oct;41(4):595-605. 2. Murphy KP, Sobus K, Bliss PM. The Adult with Cerebral Palsy: A Provider-Consumer Perspective. Physical Medicine and Rehabilitation Clinics of North America2009 Aug;20(3):509-+. / School of Physical Education, Sport, and Exercise Science

Thesis (MAppSc in Physiotherapy)--University of South Australia, 1997

This thesis investigates walking patterns in healthy young people and in people with an increased risk of falling, and determines the physiological contributions to walking stability. First, a review of the relevant literature on techniques for assessing walking stability, age-related changes in balance and gait, and the contributions of vision, vestibular function, peripheral sensation and strength was undertaken. In response to a critical analysis of these findings, a new technique and protocol for the assessment of walking stability was developed. This involved measuring and analysing head and pelvis accelerations while subjects walked on a level surface and an irregular surface. Gait patterns were studied in 30 young healthy subjects and two groups known to be at increased risk of falling - 100 subjects over the age of 75, and 30 subjects with diabetic peripheral neuropathy. A series of vision, sensation, strength, reaction time and balance tests were also undertaken to identify subjects??? physiological abilities and risk of falls. Acceleration patterns of the head and pelvis differed according to physiological risk of falling, particularly when walking on the irregular surface. Those with a high risk of falling walked with a reduced velocity, cadence and step length, and exhibited less rhythmic acceleration patterns at the head and pelvis. Gait patterns were significantly associated with leg strength, peripheral sensation and reaction time. It is concluded that subjects with a high physiological risk of falling exhibit characteristic patterns of walking that indicate an impaired ability to control the movement of the pelvis and head, which may predispose to loss of balance.

Thesis (MAppSc in Physiotherapy)--University of South Australia, 1997

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.