scholarly journals Relationships of mass properties and body proportions to locomotor habit in terrestrial Archosauria

Paleobiology ◽  
2020 ◽  
Vol 46 (4) ◽  
pp. 550-568
Author(s):  
Peter J. Bishop ◽  
Karl T. Bates ◽  
Vivian R. Allen ◽  
Donald M. Henderson ◽  
Marcela Randau ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Whole Body ◽  
Body Proportions ◽  
Volumetric Models ◽  
Mass Properties ◽  
Body Sizes ◽  
Body Center ◽  
Biomechanical Constraints ◽  
Mass Position ◽  
Anatomical Parameters

AbstractThroughout their 250 Myr history, archosaurian reptiles have exhibited a wide array of body sizes, shapes, and locomotor habits, especially in regard to terrestriality. These features make Archosauria a useful clade with which to study the interplay between body size, shape, and locomotor behavior, and how this interplay may have influenced locomotor evolution. Here, digital volumetric models of 80 taxa are used to explore how mass properties and body proportions relate to each other and locomotor posture in archosaurs. One-way, nonparametric, multivariate analysis of variance, based on the results of principal components analysis, shows that bipedal and quadrupedal archosaurs are largely distinguished from each other on the basis of just four anatomical parameters (p < 0.001): mass, center of mass position, and relative forelimb and hindlimb lengths. This facilitates the development of a quantitative predictive framework that can help assess gross locomotor posture in understudied or controversial taxa, such as the crocodile-line Batrachotomus (predicted quadruped) and Postosuchus (predicted biped). Compared with quadrupedal archosaurs, bipedal species tend to have relatively longer hindlimbs and a more caudally positioned whole-body center of mass, and collectively exhibit greater variance in forelimb lengths. These patterns are interpreted to reflect differing biomechanical constraints acting on the archosaurian Bauplan in bipedal versus quadrupedal groups, which may have shaped the evolutionary histories of their respective members.

scholarly journals Association between Changes in Swimming Velocity, Vertical Center of Mass Position, and Projected Frontal Area during Maximal 200-m Front Crawl

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 60
Author(s):  
Sohei Washino ◽  
Akihiko Murai ◽  
Hirotoshi Mankyu ◽  
Yasuhide Yoshitake
Keyword(s):  
Inverse Kinematics ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Frontal Area ◽  
Whole Body ◽  
Swimming Velocity ◽  
Front Crawl ◽  
Motion Data ◽  
Mass Position ◽  
Shape Data

We examined the association between changes in swimming velocity, vertical center of mass (CoM) position, and projected frontal area (PFA) during maximal 200-m front crawl. Three well-trained male swimmers performed a single maximal 200-m front crawl in an indoor 25-m pool. Three-dimensional (3D) shape data of the whole body were fitted to 3D motion data during swimming by using inverse kinematics computation to estimate PFA accurately. Swimming velocity decreased, the vertical CoM position was lowered, and PFA increased with swimming distance. There were significant correlations between swimming velocity and vertical CoM position (|r| = 0.797–0.982) and between swimming velocity and PFA (|r| = 0.716–0.884) for each swimmer. These results suggest that descent of the swimmer’s body and increasing PFA with swimming distance are associated with decreasing swimming velocity, although the causal factor remains unclear.

Optimization-based subject-specific planar human vertical jumping prediction: Effect of elbow flexion and weighted vest

2021 ◽  
pp. 095441192110440
Author(s):  
Juan Baus ◽  
John R Harry ◽  
James Yang
Keyword(s):  
Center Of Mass ◽  
Elbow Flexion ◽  
The Body ◽  
Loading Conditions ◽  
Arm Swing ◽  
Design Variables ◽  
Vertical Jumping ◽  
Reaction Forces ◽  
Body Center ◽  
Mass Position

Jumping strategies differ considerably depending on athletes’ physical activity demands. In general, the jumping motion is desired to have excellent performance and low injury risk. Both of these outcomes can be achieved by modifying athletes’ jumping and landing mechanics. This paper presents a consecutive study on the optimization-based subject-specific planar human vertical jumping to test different loading conditions (weighted vest) during jumping with or without elbow flexion during the arm-swing based on the validated prediction model in the first part of this study. The sagittal plane skeletal model simulates the weighting, unweighting, breaking, propulsion phases and considers four loading conditions: 0%, 5%, 10%, and 15% body weight. Results show that the maximum ground reaction forces, the body center of mass position, and velocities at the take-off instant are different for different loading conditions and with/without elbow flexion. The optimization formulation is solved using MATLAB® with 35 design variables with 197 nonlinear constraints for a five-segment body model and 42 design variables with 227 nonlinear constraints for a six-segment body model. Both models are computationally efficient, and they can predict ground reaction forces, the body center of mass position, and velocity. This work is novel in the sense that presents a simulation model capable of considering different external loading conditions and the effect of elbow flexion during arm swing.

Does the anthropometric model influence whole-body center of mass calculations in gait?

2017 ◽  
Vol 59 ◽  
pp. 23-28 ◽  
Author(s):  
Robert D. Catena ◽  
Szu-Hua Chen ◽  
Li-Shan Chou
Keyword(s):  
Center Of Mass ◽  
Whole Body ◽  
Body Center

scholarly journals Discover Your Potential: The Influence of Kinematics on a Muscle’s Ability to Contribute to the Sit-to-Stand Transfer

2021 ◽  
Author(s):  
Sarah A. Roelker ◽  
Laura C. Schmitt ◽  
Ajit M.W. Chaudhari ◽  
Robert A. Siston
Keyword(s):  
Young Adults ◽  
Center Of Mass ◽  
Joint Kinematics ◽  
New Method ◽  
Whole Body ◽  
Muscle Strengthening ◽  
Sit To Stand ◽  
Vertical Support ◽  
Anterior Pelvic Tilt ◽  
Body Center

AbstractExisting methods for estimating how individual muscles contribute to a movement require extensive time and experimental resources. In this study we developed an efficient method for determining how changes to lower extremity joint kinematics affect the potential of individual muscles to contribute to whole-body center-of-mass vertical (support) and anteroposterior (progression) accelerations. A 4-link 2-dimensional model was used to assess the effect of kinematic changes on muscle function. Joint kinematics were systematically varied throughout ranges observed during the momentum transfer phase of the sit-to-stand transfer. Each muscle’s potential to contribute to support and progression was computed and compared to simulated potentials estimated by traditional dynamic simulation methods for young adults and individuals with knee osteoarthritis (KOA). The new method required 4-10s to compute muscle potentials per kinematic state and computed potentials were consistent with simulated potentials. The new method identified differences in muscle potentials between groups due to kinematic differences, particularly decreased anterior pelvic tilt in young adults, and revealed kinematic and muscle strengthening modifications to increase support. The methods presented provide an efficient, systematic approach to evaluate how joint kinematic adjustments alter a muscle’s ability to contribute to movement and can identify potential sources of pathologic movement and rehabilitation strategies.

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