Human walking in the real world: Interactions between terrain type, gait parameters, and energy expenditure

Humans often traverse real-world environments with a variety of surface irregularities and inconsistencies, which can disrupt steady gait and require additional effort. Such effects have, however, scarcely been demonstrated quantitatively, because few laboratory biomechanical measures apply outdoors. Walking can nevertheless be quantified by other means. In particular, the foot’s trajectory in space can be reconstructed from foot-mounted inertial measurement units (IMUs), to yield measures of stride and associated variabilities. But it remains unknown whether such measures are related to metabolic energy expenditure. We therefore quantified the effect of five different outdoor terrains on foot motion (from IMUs) and net metabolic rate (from oxygen consumption) in healthy adults (N = 10; walking at 1.25 m/s). Energy expenditure increased significantly (P < 0.05) in the order Sidewalk, Dirt, Gravel, Grass, and Woodchips, with Woodchips about 27% costlier than Sidewalk. Terrain type also affected measures, particularly stride variability and virtual foot clearance (swing foot’s lowest height above consecutive footfalls). In combination, such measures can also roughly predict metabolic cost (adjusted R2 = 0.52, partial least squares regression), and even discriminate between terrain types (10% reclassification error). Body-worn sensors can characterize how uneven terrain affects gait, gait variability, and metabolic cost in the real world.

Vliv znázornění výškopisu v různých typech reliéfu na grafickou náplň map

The issue of graphic map load is currently very often overlooked. Conversely, having an objective knowledge of the level of a map load helps cartographers to assume the map’s readability and suitability for a target group of users. The aim of this study is, therefore, to use the Graphic Map Load Measuring Tool (GMLMT) and Subband Entropy script as objective metrics to evaluate the influence of terrain type (plains, hills, highlands, mountains, high mountains) and elevation representation method (contour lines, shading, colour hypsometry and their combinations) to graphic map load. The resulting map load values are visualized using multiple bar graphs and tables. Measurements performed using individual metrics confirmed the assumption that the map load of various terrain types differs the most when using contour lines. Hypsography using contour lines also reached the highest graphic map load among other methods. Hillshading and colour hypsography each also react specifically to increasing elevation differences. While graphic map load is increasing with increasing elevation differences, in the case of hillshading, map load seems to be more dependent on small terrain shapes and fragmentation of hillsides’ aspect.

Venus tesserae feature layered, folded, and eroded rocks

Tesserae on Venus are locally the stratigraphically oldest units preserved on the planet. These regions are characterized by pervasive tectonic deformation including normal faults, grabens, thrust faults, and folds. In multiple tesserae, sets of (often highly) curved, parallel linear features are also present. These features strongly resemble terracing in layered volcanic or sedimentary sequences on Earth having arcuate or sinuous outcrop patterns that follow undulating topography. Should this analogy hold for Venus, then these outcrop patterns imply some erosion of the tessera units in which these strata occur; radar-dark materials filling proximal lows might be deposits of that eroded material. This outcrop pattern is seen in geographically dispersed tessera units, so the preservation of layering could be common for this terrain type. If so, then tesserae record the culmination of volcanic and/or sedimentary deposition, folding, and erosion—complex geological histories that should be considered in future studies of this enigmatic terrain.

Research of rolling resistanceof two-wheeled vehicles

Rolling resistance of a bicycle tire is the main factor that affects the characteristics of two-wheeled vehicles. The study of rolling resistance allows better evaluating the advantages of different wheel diameters. Since rolling resistance is an indicator of the vehicle behavior on a particular terrain, it can be considered an objective parameter for comparing the characteristics of two wheel sizes (26 and 29 inches). The purpose of this study was to evaluate rolling resistance of mountain bikes, depending on several parameters: wheel diameter, terrain type, cyclist mass, tire pressure, and suspension type.

Human walking in the real world: Interactions between terrain type, gait parameters, and energy expenditure

Humans often traverse real-world environments with a variety of surface irregularities and inconsistencies, which can disrupt steady gait and require additional effort. Such effects have, however, scarcely been demonstrated quantitatively, because few laboratory biomechanical measures apply outdoors. Walking can nevertheless be quantified by other means. In particular, the foot’s trajectory in space can be reconstructed from foot-mounted inertial measurement units (IMUs), to yield measures of stride and associated variabilities. But it remains unknown whether such measures are related to metabolic energy expenditure. We therefore quantified the effect of five different outdoor terrains on foot motion (from IMUs) and net metabolic rate (from oxygen consumption) in healthy adults (N = 10; walking at 1.25 m/s). Energy expenditure increased significantly (P < 0.05) in the order Sidewalk, Dirt, Gravel, Grass, and Woodchips, with Woodchips about 27% costlier than Sidewalk. Terrain type also affected measures, particularly stride variability and virtual foot clearance (swing foot’s lowest height above consecutive footfalls). In combination, such measures can also roughly predict metabolic cost (adjusted R2 = 0.52, partial least squares regression), and even discriminate between terrain types (10% reclassification error). Body-worn sensors can characterize how uneven terrain affects gait, gait variability, and metabolic cost in the real world.

Prevalence and Associated Factors of Sever's Disease in an Athletic Population

Background: Sever's disease is a common cause of pain in growing kids. Many papers reported in the literature discuss this pathologic condition, but no consensus regarding its etiology has been found among researchers. The aim of the present study was to describe the epidemiologic profile and associated factors of 430 athletic children in a population-based sample of soccer (29.5%), basketball (48.1%), and volleyball (22.3%) players aged 6 to 14 years. Methods: Every athlete was evaluated through physical examination, the Foot Posture Index (FPI), the Oxford Ankle Foot Questionnaire, and a custom-made sports questionnaire. Results: These data show that body mass index, sex, terrain type, sports discipline, and FPI should not be considered as risk factors for calcaneal apophysitis, whereas a significantly higher risk has been found in younger individuals (P &lt; .01), in those with fewer training sessions per week (P = .02), and in those with shorter training sessions (P &lt; .01). Conclusions: The prevalence of Sever's disease in the athletic children evaluated in the present study was higher in younger and less active patients, whereas no differences were registered by sex, FPI, body mass index, terrain type, or sports discipline.