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Humans actively interact with the world through a wide range of body movements. To understand human cognition in its natural state, we need to incorporate ecologically relevant body movement into our account. One fundamental body movement during daily life is natural walking. Despite its ubiquity, the impact of natural walking on brain activity and cognition has remained a realm underexplored. In electrophysiology, previous studies have shown a robust reduction of ongoing alpha power in the parieto-occipital cortex during body movements. However, what causes the reduction of ongoing alpha, namely whether this is due to body movement or prevalent sensory input changes, was unknown. To clarify this, study 1 was performed to test if the alpha reduction is dependent on visual input. I compared the resting state alpha power during natural walking and standing, in both light and darkness. The results showed that natural walking led to decreased alpha activity over the occipital cortex compared to standing, regardless of the lighting condition. This suggests that the movement-induced modulation of occipital alpha activity is not driven by visual input changes during walking. I argue that the observed alpha power reduction reflects a change in the state of the subject based on disinhibition induced by walking. Accordingly, natural walking might enhance visual processing and other cognitive processes that involve occipital cortical activity. I first tested this hypothesis in vision. Study 2 was performed to examine the possible effects of natural walking across visual processing stages by assessing various neural markers during different movement states. The findings revealed an amplified early visual response, while a later visual response remain unaffected. A follow-up study 3 replicated the walking-induced enhancement of the early visual evoked potential and showed that the enhancement was dependent on specific stimulus-related parameters (eccentricity, laterality, distractor presence). Importantly, the results provided evidence that the enhanced early visual responses are indeed linked to the modulation of ongoing occipital alpha power. Walking also modulated the stimulus-induced alpha power. Specifically, it showed that when the target appeared in the fovea area without a distractor, walking exhibited a significantly reduced modulation of alpha power, and showed the largest difference to standing condition. This effect of eccentricity indicates that during later visual processing stages, the visual input in the fovea area is less processed than in peripheral areas while walking. The two visual studies showed that walking leads to an enhancement in temporally early visual processes which can be predicted by the walking-induced change in ongoing alpha oscillation likely marking disinhibition. However, while walking affects neural markers of early sensory processes, it does not necessarily lead to a change in the behavioural outcome of a sensory task. The two visual studies suggested that the behavioural outcome seems to be mainly based on later processing stages. To test the effects of walking outside the visual domain, I turned to audition in study 4. I investigated the influence of walking in a particular path vs. simply stepping on auditory processing. Specifically, the study tested whether enhanced processing due to natural walking can be found in primary auditory brain activity and whether the processing preferences are dependent on the walking path. In addition, I tested whether the changed spatial processing that was reported in previous visual studies can be seen in the auditory domain. The results showed enhanced sensory processing due to walking in the auditory domain, which was again linked to the modulation of occipital alpha oscillation. The auditory processing was further dependent on the walking path. Additionally, enhanced peripheral sensory processing, as found in vision, was also present in audition. The findings outside vision supported the idea of natural walking affecting cognition in a rather general way. Therefore in my study 5, I examined the effect of natural walking on higher cognitive processing, namely divergent thinking, and its correlation with the modulation of ongoing alpha oscillation. I analyzed alpha oscillations and behavioural performance during restricted and unrestricted movement conditions while subjects completed a Guilford's alternate uses test. The results showed that natural walking, as well as missing body restriction, reduces the occipital alpha ongoing power independent of the task phase which goes along with higher test scores. The occipital alpha power reduction can therefore be an indicator of a changed state that allows improved higher cognitive processes. In summary, the research presented in this thesis highlights that natural walking can change different processes in the visual and auditory domain as well as higher cognitive processes. The effect can be attributed to the movement of natural walking itself rather than to changes in sensory input during walking. The results further indicate that the walking-induced modulation of ongoing occipital alpha oscillations drives the cognitive effects. We therefore suggest that walking changes the inhibitory state which can influence awareness and attention. Such a mechanism could facilitate an adaptive enhancement in cognitive processes and thereby optimize movement-related behaviour such as navigation. / Menschen interagieren aktiv mit der Welt durch eine breite Palette von Körperbewegungen. Um die menschliche Kognition in ihrem natürlichen Zustand zu verstehen, müssen wir ökologisch relevante Körperbewegungen in unsere Betrachtung einbeziehen. Eine grundlegende Körperbewegung im täglichen Leben ist das natürliche Gehen. Trotz seiner Allgegenwärtigkeit ist die Auswirkung des natürlichen Gehens auf die Gehirnaktivität und die Kognition weitgehend unerforscht geblieben. In der Elektrophysiologie haben frühere Studien eine robuste Reduktion der laufenden Alpha-Leistung im parieto-okzipitalen Cortex während Körperbewegungen gezeigt. Es war jedoch unbekannt, was die Reduktion des laufenden Alpha verursacht, nämlich ob dies auf Körperbewegung oder vorherrschende sensorische Eingangsänderungen zurückzuführen ist. Um dies zu klären, wurde Studie 1 durchgeführt, um zu testen, ob die Alpha-Reduktion von visuellem Input abhängig ist. Ich verglich die Alpha-Leistung im Ruhezustand beim natürlichen Gehen und Stehen, sowohl bei Licht als auch im Dunkeln. Die Ergebnisse zeigten, dass natürliches Gehen zu einer verminderten Alpha-Aktivität über dem okzipitalen Cortex im Vergleich zum Stehen führte, unabhängig von den Lichtverhältnissen. Dies legt nahe, dass die bewegungsinduzierte Modulation der okzipitalen Alpha-Aktivität nicht durch visuelle Veränderungen während des Gehens verursacht wird. Ich argumentiere, dass die beobachtete Reduktion der Alpha-Leistung eine Veränderung des Zustands der Versuchsperson aufgrund der durch das Gehen induzierten Hemmung widerspiegelt. Natürliches Gehen könnte daher die visuelle Verarbeitung und andere kognitive Prozesse, die die Aktivität des okzipitalen Cortex umfassen, verstärken. Ich habe diese Hypothese zuerst im Bereich der Vision getestet. Studie 2 wurde durchgeführt, um die möglichen Auswirkungen des natürlichen Gehens auf verschiedene neurale Marker in verschiedenen Bewegungszuständen zu untersuchen. Die Ergebnisse zeigten eine verstärkte frühe visuelle Reaktion, während eine spätere visuelle Reaktion unverändert blieb. Eine Nachfolgestudie 3 replizierte die durch das Gehen induzierte Verstärkung des frühen visuellen ereigniskorrelierten Potenzials und zeigte, dass die Verstärkung von spezifischen stimuliabhängigen Parametern abhängig war (Exzentrizität, Lateralität, Vorhandensein von Störreizen). Die Ergebnisse lieferten wichtige Hinweise darauf,dass die verstärkten frühen visuellen Reaktionen tatsächlich mit der Modulation der laufenden Alpha-Leistung im okzipitalen Cortex zusammenhängen. Das Gehen modulierte auch die stimuliinduzierte Alpha-Leistung. Insbesondere zeigte sich, dass bei Erscheinen des Ziels im fovealen Bereich ohne Störreiz das Gehen eine signifikant reduzierte Modulation der Alpha-Leistung aufwies und den größten Unterschied zum Stehzustand zeigte. Dieser Exzentrizitätseffekt deutet darauf hin, dass während späterer visueller Verarbeitungsstadien die visuelle Eingabe im Fovealbereich weniger verarbeitet wird als in peripheren Bereichen während des Gehens. Die beiden visuellen Studien zeigten, dass Gehen zu einer Verstärkung früher visueller Prozesse führt, die durch die durch das Gehen verursachte Veränderung der laufenden Alpha-Oszillation wahrscheinlich markiert werden. Allerdings beeinflusst Gehen zwar neuronale Marker früher sensorischer Prozesse, führt aber nicht zwangsläufig zu einer Veränderung des Verhaltensergebnisses einer sensorischen Aufgabe. Die beiden visuellen Studien legen nahe, dass das Verhaltensergebnis hauptsächlich auf späteren Verarbeitungsstadien beruht. Um die Auswirkungen des Gehens außerhalb des visuellen Bereichs zu testen, wandte ich mich in Studie 4 der Auditierung zu. Ich untersuchte den Einfluss des Gehens auf einen bestimmten Pfad im Vergleich zum einfachen Schritt auf die auditive Verarbeitung. Die Studie testete speziell, ob eine verbesserte Verarbeitung aufgrund des natürlichen Gehens in der primären auditorischen Hirnaktivität gefunden werden kann und ob die Verarbeitungspräferenzen vom Gehpfad abhängen. Darüber hinaus habe ich getestet, ob die in früheren visuellen Studien berichtete veränderte räumliche Verarbeitung auch im auditiven Bereich beobachtet werden kann. Die Ergebnisse zeigten eine verbesserte sensorische Verarbeitung aufgrund des Gehens im auditiven Bereich, die erneut mit der Modulation der okzipitalen Alpha-Oszillation in Verbindung stand. Die auditive Verarbeitung war auch vom Gehpfad abhängig. Darüber hinaus wurde eine verbesserte periphere sensorische Verarbeitung, wie sie in der Vision gefunden wurde, auch in der Auditierung beobachtet. Die außerhalb des visuellen Bereichs gefundenen Ergebnisse unterstützen die Idee, dass natürliches Gehen die Kognition auf eher allgemeine Weise beeinflusst. Daher habe ich in meiner Studie 5 die Wirkung des natürlichen Gehens auf höhere kognitive Prozesse untersucht, nämlich das divergente Denken, und seine Korrelation mit der Modulation der laufenden Alpha-Oszillation. Ich analysierte Alpha-Oszillationen und Verhaltensleistungen während eingeschränkter und uneingeschränkter Bewegungsbedingungen, während Versuchspersonen einen Guilford-Test für alternative Verwendungsmöglichkeiten absolvierten. Die Ergebnisse zeigten, dass natürliches Gehen sowie das Fehlen von Körperbeschränkungen die laufende Alpha-Leistung im okzipitalen Bereich unabhängig von der Aufgabenphase reduziert, was mit höheren Testergebnissen einhergeht. Die Reduktion der okzipitalen Alpha-Leistung kann daher ein Indikator für einen veränderten Zustand sein, der eine Verbesserung der höheren kognitiven Prozesse ermöglicht. Zusammenfassend hebt die in dieser Arbeit präsentierte Forschung hervor, dass natürliches Gehen verschiedene Prozesse im visuellen und auditiven Bereich sowie höhere kognitive Prozesse verändern kann. Die Wirkung kann auf die Bewegung des natürlichen Gehens selbst zurückgeführt werden, und nicht auf Veränderungen im sensorischen Input während des Gehens. Die Ergebnisse deuten weiterhin darauf hin, dass die durch das Gehen verursachte Modulation laufender Alpha-Oszillationen im okzipitalen Bereich die kognitiven Effekte antreibt. Daher schlagen wir vor, dass Gehen den hemmenden Zustand verändert, der das Bewusstsein und die Aufmerksamkeit beeinflussen kann. Ein solcher Mechanismus könnte eine adaptive Verbesserung in kognitiven Prozessen fördern und somit verhaltensbezogene Bewegungen wie die Navigation optimieren.

No / Physical inactivity causes approximately 17% of premature mortality in the UK. Walking offers a promising method for lowering risk of cardiovascular disease at population level, though a recent synthesis of evidence is lacking. This study aimed to conduct a meta-analysis of randomised controlled trials that have assessed the effect of walking on risk factors for cardiovascular disease in previously inactive adults. We searched PubMed, Web of Science, ScienceDirect, and the Cochrane Central Register of Controlled Trials for studies published in English between Jan 1, 1970, and May 31, 2012, using the following search terms: "walking", "exercise", "health", and "cardiovascular risk". Two authors identified randomised controlled trials of interventions (>4 weeks' duration) that included at least one group with walking as the only treatment and a comparator no-exercise group. Participants were inactive but otherwise healthy at baseline. Pooled results were reported as weighted mean treatment effects and 95% CIs in a random effects model. 32 articles reported the effects of walking interventions on risk factors for cardiovascular disease in participants aged 30–83 years. Mean length of interventions was 18·7 weeks (range 8–52). Duration of walking was 20–60 min on 2–7 days per week. Walking interventions reduced systolic and diastolic blood pressure (−3·6 mm Hg, 95% CI −5·19 to −1·97; −1·5 mm Hg, −2·83 to −0·26). Interventions also improved waist circumference (−1·5 cm, −2·34 to −0·68), weight (−1·4 kg, −1·75 to −1·00), body fat (−1·2%, −1·70 to −0·73), and body-mass index (BMI) (−0·5 kg/m2, −0·72 to −0·35). Walking improved aerobic fitness (3·2 mL/kg per min, 95% CI 2·57 to 3·80) but did not alter blood lipids. Significant heterogeneity (I2 statistic) was noted for aerobic fitness, BMI, weight, and percentage body fat. Many studies did not provide sufficient information to make firm judgments about risk of bias. These findings support the important role of walking in physical activity for health promotion. Health professionals involved in the primary prevention of cardiovascular disease should prescribe walking confident of the benefits it can provide in fitness, blood pressure, and adiposity. / Mary Immaculate College Research Directorate Seed Funding Scheme

Student Number : 0414012 - MSc dissertation - School of Therapeutic Sciences - Faculty of Health Sciences / Aim: The aim of this study was to quantify the level of ability and in particular walking ability of a group of stroke survivors resident in Soweto, between 3-6 months post incident. Design: Descriptive study in which comfortable walking speed over ten metres is correlated with the distance covered in six minutes and two minutes. Subjects: Forty one subjects after stroke divided into two groups. Twenty six with a Barthel Index initial score of ≤60 and fifteen with a score >60. Main Outcome Measures: Walking speed and two and six minute distance were compared between groups. In addition actual distance walked in six minutes was compared with the distance predicted by the ten-metre walking speed test and the distance predicted by normative reference equations. Heart rate was measured during the six minute walking test. Functional ability was compared using the Barthel Index within ten days post stroke and three to six months. Results: Of those who survived 90% of subjects were able to walk independently after stroke. The mean walking speed of 0.55 m/s demonstrated a strong correlation with the distance walked in six minutes (R2=0.816). However it underestimated the distance walked in six minutes by 7.4%. There were no significant differences between groups for the walking tests. The two minute walking test distance accurately predicted the results of the six minute walking test distance (R2=0.97). The average distance walked in six minutes by subjects after stroke was 40% of the distance predicted for healthy adults. For the functional walk test 95.5% of subjects had a heart rate within normal recommended limits. The functional walk test together with a measure of exertion (heart rate) may indicate an individual's ability to sustain submaximal activity. Subjects had minimal rehabilitation training. Lower limb pain did not significantly lower the walking speed (p=0.18) or distance walked in six minutes (p=0.17). Mean Barthel Index score at three to six months was 85.78 indicative of independence with minimal assistance. Although the mortality rate for the Barthel Index group with a score less than 60 is 30.7%, the prognosis of survivors was not uniformly poor. Conclusion: This study demonstrates that though a high percentage of subjects recovered independent walking after stroke in the Soweto community with minimal rehabilitation, their walking speed and distance walked are indicative of limited walking capacity. Walking speed and the two minute walking test could be used to predict functional walk test performance. Pain in the paretic lower limb though commonly reported did not appear to affect walking speed or distance walked. The use of the Barthel Index to predict activities and/or survival merits further investigation.

As a contribution toward the objective of developing useful walking machines, this dissertation considers solutions to some of the problems involved with bipedal robot development. The main area of focus involves control system design and implementation for dynamically balanced walking robots. A new algorithm “Torso Driven Walking” is presented, which reduces the complexity of the control problem to that of balancing the robot’s torso. All other aspects of the system are indirectly controlled by the changing robot state resulting from direct control of the robot’s torso. The result is literally a “top-down” approach to control, where the control system actively balances the top-most component of the robot’s body, leaving the control of the lower limbs to a passive “state-driven” system designed to ensure the robot always keeps at least one leg between the torso and the ground. A series of low-cost robots and simulation systems have been constructed as experimental platforms for testing the proposed new control system. The robots have been designed to balance on “point” feet, and so the control system must be able to dynamically maintain balance, while moving at a variable velocity. The Torso Driven Walking control system achieves a fully dynamic, variable speed walking behaviour that does not rely on maintaining a stable supporting polygon for balance. In addition, the system exhibits a high degree of tolerance for low frequency “bias” or “drift” errors. These measurement errors are commonly encountered when using sensors for detecting torso inclination.

abstract: Background: Postprandial hyperglycemia can increase levels of oxidative stress and is an independent risk factor for complications associated with type 2 diabetes. Purpose: To evaluate the acute effects of a 15-min postmeal walk on glucose control and markers of oxidative stress following a high-carbohydrate meal. Methods: Ten obese subjects (55.0 ± 10.0 yrs) with impaired fasting glucose (107.1 ± 9.0 mg/dL) participated in this repeated measures trial. Subjects arrived at the laboratory following an overnight fast and underwent one of three conditions: 1) Test meal with no walking or fiber (CON), 2) Test meal with 10g fiber and no walking (FIB), 3) Test meal with no fiber followed by a 15-min treadmill walk at preferred walking speed (WALK). Blood samples were taken over four hours and assayed for glucose, insulin, thiobarbituric reactive substances (TBARS), catalase, uric acid, and total antioxidant capacity (TAC). A repeated measures ANOVA was used to compare mean differences for all outcome variables. Results: The 2hr and 4hr incremental area under the curve (iAUC) for glucose was lower in both FIB (2hr: -93.59 mmol&#8729;120 min&#8729;L-1, p = 0.006; 4hr: -92.59 mmol&#8729;240 min&#8729;L-1; p = 0.041) and WALK (2hr: -77.21 mmol&#8729;120 min&#8729;L-1, p = 0.002; 4hr: -102.94 mmol&#8729;240 min&#8729;L-1; p = 0.005) conditions respectively, compared with CON. There were no differences in 2hr or 4hr iAUC for glucose between FIB and WALK (2hr: p = 0.493; 4hr: p = 0.783). The 2hr iAUC for insulin was significantly lower in both FIB (-37.15 &#956;U &#8729;h/mL; p = 0.021) and WALK (-66.35 &#956;U &#8729;h/mL; p < 0.001) conditions, compared with CON, and was significantly lower in the WALK (-29.2 &#956;U &#8729;h/mL; p = 0.049) condition, compared with FIB. The 4hr iAUC for insulin in the WALK condition was significantly lower than both CON (-104.51 &#956;U &#8729;h/mL; p = 0.001) and FIB (-77.12 &#956;U &#8729;h/mL; p = 0.006) conditions. Markers of oxidative stress were not significantly different between conditions. Conclusion: A moderate 15-minute postmeal walk is an effective strategy to reduce postprandial hyperglycemia. However, it is unclear if this attenuation could lead to improvements in postprandial oxidative stress. / Dissertation/Thesis / Doctoral Dissertation Physical Activity, Nutrition and Wellness 2015

Current state-of-the-art walking controllers for humanoid robots use simple models, such as Linear Inverted Pendulum Mode (LIPM), to approximate Center of Mass(CoM) dynamics of a robot. These models are then used to generate CoM trajectories that keep the robot balanced while walking. Such controllers need prior information of foot placements, which is generated by a walking pattern generator. While the robot is walking, any change in the goal position leads to aborting the existing foot placement plan and re-planning footsteps, followed by CoM trajectory generation. This thesis proposes a tightly coupled walking pattern generator and a reactive balancing controller to plan and execute one step at a time. Walking is an emergent behavior from such a controller which is achieved by applying a virtual force in the direction of the goal. This virtual force, along with external forces acting on the robot, is used to compute desired CoM acceleration and the footstep parameters for only the next step. Step location is selected based on the capture point, which is a point on the ground at which the robot should step to stay balanced. Because each footstep location is derived as needed based on the capture point, it is not necessary to compute a complete set of footsteps. Experiments show that this approach allows for simpler inputs, results in faster operation, and is inherently immune to external perturbing and other reaction forces from the environment. Experiments are performed on Boston Dynamic's Atlas robot and NASA's Valkyrie R5 robot in simulation, and on Atlas hardware.

Current state-of-the-art walking controllers for humanoid robots use simple models, such as Linear Inverted Pendulum Mode (LIPM), to approximate Center of Mass(CoM) dynamics of a robot. These models are then used to generate CoM trajectories that keep the robot balanced while walking. Such controllers need prior information of foot placements, which is generated by a walking pattern generator. While the robot is walking, any change in the goal position leads to aborting the existing foot placement plan and re-planning footsteps, followed by CoM trajectory generation. This thesis proposes a tightly coupled walking pattern generator and a reactive balancing controller to plan and execute one step at a time. Walking is an emergent behavior from such a controller which is achieved by applying a virtual force in the direction of the goal. This virtual force, along with external forces acting on the robot, is used to compute desired CoM acceleration and the footstep parameters for only the next step. Step location is selected based on the capture point, which is a point on the ground at which the robot should step to stay balanced. Because each footstep location is derived as needed based on the capture point, it is not necessary to compute a complete set of footsteps. Experiments show that this approach allows for simpler inputs, results in faster operation, and is inherently immune to external perturbing and other reaction forces from the environment. Experiments are performed on Boston Dynamic's Atlas robot and NASA's Valkyrie R5 robot in simulation, and on Atlas hardware.

The influence of a 60-day strength training regime on the flat walking Tennessee Walking Horse (TWH) yearling performance was determined using behavioral, physiological, and biomechanical measurements. Four TWH yearlings participated in a 60-day strength training regime. Documentation was made on behavioral responses, and measurements were taken on respiratory rates and standing and flat walking kinematics. Means (SD) were determined for physiological and biomechanical variables, and paired t-tests (P=0.05) were performed. Morphometrics, kinematics, and temporal variables remained constant through training. The flat walk shared similar kinematics and temporal variables with the walk, except for the rhythm, bipedal support, head displacements, and hind fetlock joint motion. While respiratory rates were not significantly different in training response, the TWH yearling demonstrated more efficient respiration compared to the non-gaited trot. Training impact was limited to improved, desirable behavioral responses. Through survey responses by TWH trainers, additional training variables were indicated for future training protocols.