Coordination of trunk and foot acceleration during gait is affected by walking velocity and fall history in elderly adults

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.Background: Falling is a significant concern for many elderly adults but identifying individuals at risk of falling is difficult, and it is not clear how elderly adults adapt to challenging walking. Aims: The aim of the current study was to determine the effects of walking at non-preferred speeds on the coordination between foot and trunk acceleration variability in healthy elderly adults with and without fall history compared to healthy young adults. Methods: Subjects walked on a treadmill at 80% to 120% of their preferred walking speed while trunk and foot accelerations were recorded with wireless inertial sensors. Variability of accelerations were measured by root mean square, range, sample entropy, and Lyapunov exponent. The gait stability index was calculated using each variability metric in the frontal and sagittal plane by taking the ratio of trunk acceleration variability divided by foot acceleration variability. Results: Healthy young adults demonstrated larger trunk accelerations relative to foot accelerations at faster walking speeds compared to elderly adults, but both young and elderly adults show similar adaption to their acceleration regularity. Between group differences showed that elderly adult fallers coordinate acceleration variability between the trunk and feet differently compared to elderly non-fallers and young adults. Discussion: The current results indicate that during gait, elderly fallers demonstrate more constrained, less adaptable trunk movement relative to their foot movement and this pattern is different compared to elderly non-fallers and healthy young. Conclusions: Coordination between trunk and foot acceleration variability plays an important role in maintaining stability during gait.NIH T32 HD057850Frontiers Pilot and Collaborative Studies Funding Program (UL1TR000001)School of Health Professions Pilot Research Gran

Biomechanical characterization of slipping on pervious and traditional concrete walking surfaces

Title from PDF of title page, viewed on June 22, 2012Thesis advisor: Gregory W. KingVitaIncludes bibliographic references (p. 46-49)Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2012Pervious concrete is a porous material that may provide superior slip resistance due to its ability to exfiltrate melted ice and other slippery surface contaminants. The purpose of this study was to analyze slip-related biomechanical characteristics during gait on pervious and traditional concrete in dry and icy conditions. The hypothesis tested was that pervious concrete, compared to traditional, would exhibit improved frictional characteristics that are less likely to cause slipping events. Both pervious and traditional concrete slabs were manufactured, and misted water was frozen on the surface of the icy slabs. Ten participants completed walking trials across traditional and pervious concrete in both dry and icy conditions. Ground reaction forces were captured by a force platform beneath each concrete surface and used to determine friction usage, which was defined as the ratio of peak utilized shear to normal force normalized to static coefficient of friction. An analyses of variance (ANOVA) was performed on the resulting data. A statistically significant decrease in friction usage was found for pervious concrete compared to traditional. Pervious concrete exhibited significantly smaller levels of friction usage for icy conditions, suggesting its potential utility in reducing slipping events.Introduction -- Background -- Methods -- Results -- Discussion -- Appendi

Theories of schizophrenia: a genetic-inflammatory-vascular synthesis

BACKGROUND: Schizophrenia, a relatively common psychiatric syndrome, affects virtually all brain functions yet has eluded explanation for more than 100 years. Whether by developmental and/or degenerative processes, abnormalities of neurons and their synaptic connections have been the recent focus of attention. However, our inability to fathom the pathophysiology of schizophrenia forces us to challenge our theoretical models and beliefs. A search for a more satisfying model to explain aspects of schizophrenia uncovers clues pointing to genetically mediated CNS microvascular inflammatory disease. DISCUSSION: A vascular component to a theory of schizophrenia posits that the physiologic abnormalities leading to illness involve disruption of the exquisitely precise regulation of the delivery of energy and oxygen required for normal brain function. The theory further proposes that abnormalities of CNS metabolism arise because genetically modulated inflammatory reactions damage the microvascular system of the brain in reaction to environmental agents, including infections, hypoxia, and physical trauma. Damage may accumulate with repeated exposure to triggering agents resulting in exacerbation and deterioration, or healing with their removal. There are clear examples of genetic polymorphisms in inflammatory regulators leading to exaggerated inflammatory responses. There is also ample evidence that inflammatory vascular disease of the brain can lead to psychosis, often waxing and waning, and exhibiting a fluctuating course, as seen in schizophrenia. Disturbances of CNS blood flow have repeatedly been observed in people with schizophrenia using old and new technologies. To account for the myriad of behavioral and other curious findings in schizophrenia such as minor physical anomalies, or reported decreased rates of rheumatoid arthritis and highly visible nail fold capillaries, we would have to evoke a process that is systemic such as the vascular and immune/inflammatory systems. SUMMARY: A vascular-inflammatory theory of schizophrenia brings together environmental and genetic factors in a way that can explain the diversity of symptoms and outcomes observed. If these ideas are confirmed, they would lead in new directions for treatments or preventions by avoiding inducers of inflammation or by way of inflammatory modulating agents, thus preventing exaggerated inflammation and consequent triggering of a psychotic episode in genetically predisposed persons