Independent living requires the navigation of a surrounding environment which is often cluttered with obstacles. When walking around an obstacle in the travel path, safe clearance requires some degree of body-segment reorientation. While body-segmental coordination strategies have been well studied for steering tasks that require moving the body in a new walking direction, it has never been established just what coordination strategies are used in different walking tasks. To address this issue, the current study was designed to investigate the timing of body segment coordination strategies and whole-body anticipatory locomotor adjustments employed when circumventing an obstacle placed in the travel path. Six healthy adults were asked to walk at their natural pace during unobstructed walking, as well as during avoidance to the right or left of a cylindrical obstacle (OBS) located in the travel path. Data analyzed were center of mass (COM) clearance from the OBS, forward velocity, step length and width, yaw angles of the head and trunk, roll angle of the trunk, and medial-lateral COM displacement. Onset of change in these variables from unobstructed walking was calculated as the time from OBS crossing. Avoidance involved two equally used strategies: lead limb close to or away from the OBS during the crossing step. Medial-lateral COM deviations were controlled by changes in step width without changes in trunk roll. There were no differences in the onset times of body segment reorientation for path deviation. These results are in contrast to previous studies on change in travel direction where the head segment initiates the body reorientation. Contrary to a steering task, circumventing an obstacle requires a different coordination for a transient change in COM trajectory with the underlying travel-direction maintained.

Activities of daily living often require us to negotiate several obstacles in the travel path. To date, there is little work investigating how adults accomplish such tasks, and there is even less known about multiple obstacle avoidance strategies used by children. The current work will expand our knowledge about the role of vision in adults and children when avoiding two obstacles placed in their travel path under altered ambient lighting. Healthy 7-year old children (n=10; aged 7.51+/-0.2 years) and adults (n=10; aged 22.76+/-1.7 years) were instrumented with infrared markers (Optotrak, NDI) placed on anatomical landmarks and asked to walk along a ten meter path under three conditions: unobstructed, single obstacle, or double obstacle. These trials were performed under two lighting conditions: Full (simulating standard office lighting) and Low (simulating a dark hallway lit by nightlights). Data analyses included lead and trail clearance values, step length, step width and step velocity, take-off distance and Horizontal toe Displacement at Apex (HDA) which was defined as the distance between the horizontal position of the toe to the leading edge of the obstacle when the toe reaches its peak height. Adults were able to maintain consistent behaviour regardless of the number of obstacles in the travel path. Children, however, adjusted their foot placement for the second obstacle. This indicates that having multiple obstacles in the travel path is a more challenging task for 7-year old, and suggests that children at this age may not have fully developed anticipatory locomotor strategies. Children had larger clearance values than adults for the lead foot crossing the obstacle under all obstacle and lighting conditions, and consistently used larger HDA values than adults. Together, these findings suggest that children adopt more cautious strategies than adults in complex environments. Additionally, children decreased walking velocity, increased step width and decreased their step length in a Low light environment. These changes are all indicators of a more careful avoidance strategy, which implies that children at this age rely heavily on visual information to guide foot placements in a complex environment.

NCT02223234.

The aim of this research was to describe age-related changes in locomotor adjustments during obstructed gait and expand and build from the current body of literature describing single obstacle avoidance strategies by including trials in which the subjects stepped over two identical obstacles placed in series. We observed young adults (YA: N = 8; aged 23.1 +/- 2.0 years) and older adults (OA: N = 8; aged 76.1 +/- 4.3 years) as they walked along a 5 m long instrumented pathway (GAITRite) and stepped over one or two obstacles that were scaled to their lower leg length. Infrared markers, tracked using the Optotrak motion analysis system (60 Hz; Northern Digital Inc, Canada), were fixed to subjects' trunk and feet, and several anatomical landmarks were digitized for each segment (e.g. toes). Data analyses included lead and trail toe clearance values, take-off and landing distance, step time, length, width and velocity, and three-dimensional trunk angles. Both age groups were able to successfully complete the obstacle avoidance task, and the presence of a second obstacle did not affect clearance strategies of either OA or YA. OA crossed the obstacles with a reduced step velocity and stepped closer to the trailing edge, although take-off distances were not different between the age groups. Additionally, OA used similar ranges of trunk motion as YA when crossing the obstacle, but did so while using smaller step lengths and step widths compared to YA, effectively, using a narrower base of support. Together, these findings suggest that older adults adopted a more cautious crossing strategy in that they reduced their crossing step velocity. However, other aspects of the avoidance strategy used by the older adults, specifically the shortened landing distances and the use of similar ranges of trunk motion within a narrowed BOS, could potentially put them at risk for tripping or imbalance when stepping over an obstacle.

OBJECTIVE: To establish differences between lean and obese subjects in subjective reports of predominant taste and texture attributes of`foods as eaten', and the relationships of these qualities to hedonic preference and objective measures of dietary intake and composition. DESIGN: Free-living subjects received instruction in a laboratory and kept diaries of foods eaten at home. SUBJECTS: 41 lean (body mass index (BMI) 20 ± 25 kgam 2 ) and 35 obese (BMI !30 kgam 2 ), non-dieting healthy adults. MEASUREMENTS: Subjects kept four-day weighed dietary intake records, simultaneously assigning ratings for perceived pleasantness and predominant sensory attributes (taste and texture) of food eaten, and completed the Dutch Eating Behaviour questionnaire (DEBQ). Anthropometric measures included body composition assessed by bioelectrical impedance. RESULTS: By all anthropometric measures (except height) the obese group was signi®cantly larger than the lean group, but no signi®cant differences were found for DEBQ scores. There were no signi®cant group differences between pleasantness scores overall, nor for foods classi®ed by predominant taste. Whilst macronutrient intakes did not differ, the obese group's mean dietary energy density was signi®cantly higher, and they reported signi®cantly greater dietary energy from`salty' foods. For the obese group, the percentage of`salty' foods eaten correlated strongly with energy density. A strong positive association was found between`liking extremely' and`sweet' foods for the lean group, but no clear associations were found for any particular taste and hedonic rating for the obese group. Whilst both groups used similar texture descriptors, there were not clear or unambiguous differences in their assignment or association with other measures. CONCLUSIONS: The results suggest that obese and lean subjects do not self-select diets with markedly different perceived sensory or hedonic attributes. However obese subjects appear to consume a diet higher in energy density, which is particularly associated with intakes of saltyasavoury (rather than sweet) food items.