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.

Upper Extremity Function in Running. I: Center of Mass and Propulsion Considerations

1987 ◽  
Vol 3 (3) ◽  
pp. 222-241 ◽  
Author(s):  
Richard N. Hinrichs ◽  
Peter R. Cavanagh ◽  
Keith R. Williams
Keyword(s):  
Center Of Mass ◽  
Three Dimensional ◽  
The Body ◽  
Horizontal Velocity ◽  
Distance Runners ◽  
Contact Phase ◽  
Arm Swing ◽  
Vertical Range ◽  
Body Center ◽  
Recreational Runners

Ten male recreational runners were filmed using three-dimensional cinematography while running on a treadmill at 3.8 m/s, 4.5 m/s, and 5.4 m/s. A 14-segment mathematical model was used to examine the influence of the arm swing on the three-dimensional motion of the body center of mass (CM), and on the vertical and horizontal propulsive impulses (“lift” and “drive”) on the body over the contact phase of the running cycle. The arms were found to reduce the horizontal excursions of the body CM both front to back and side to side, thus tending to make a runner's horizontal velocity more constant. The vertical range of motion of the body CM was increased by the action of the arms. The arms were found to make a small but important contribution to lift, roughly 5–10% of the total. This contribution increased with running speed. The arms were generally not found to contribute to drive, although considerable variation existed between subjects. Consistent with the CM results, the arms were found to reduce the changes in forward velocity of the runner rather than increasing them. It was concluded that there is no apparent advantage of the “classic” style of swinging the arms directly forward and backward over the style that most distance runners adopt of letting the arms cross over slightly in front. The crossover, in fact, helps reduce side-to-side excursions of the body CM mentioned above, hence promoting a more constant horizontal velocity.

scholarly journals Effect of foot–floor friction on the external moment about the body center of mass during shuffling gait: a pilot study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Takeshi Yamaguchi ◽  
Kei Shibata ◽  
Hiromi Wada ◽  
Hiroshi Kakehi ◽  
Kazuo Hokkirigawa
Keyword(s):  
Friction Surface ◽  
Center Of Mass ◽  
Young Male ◽  
The Body ◽  
Low Friction ◽  
Surface Conditions ◽  
Normal Gait ◽  
External Moment ◽  
Body Center ◽  
Floor Condition

AbstractHerein, we investigated the effect of friction between foot sole and floor on the external forward moment about the body center of mass (COM) in normal and shuffling gaits. Five young male adults walked with normal and shuffling gaits, under low- and high-friction surface conditions. The maximum external forward moment about the COM (MEFM-COM) in a normal gait appeared approximately at initial foot contact and was unaffected by floor condition. However, MEFM-COM in a shuffling gait under high-friction conditions exceeded that under low-friction conditions (p < 0.001). Therein, MEFM-COM increased with an increasing utilized coefficient of friction at initial foot contact; this effect was weaker during a normal gait. These findings indicate that increased friction between foot sole and floor might increase tripping risk during a shuffling gait, even in the absence of discrete physical obstacles.

Many-legged maneuverability: dynamics of turning in hexapods

1999 ◽  
Vol 202 (12) ◽  
pp. 1603-1623 ◽  
Author(s):  
D.L. Jindrich ◽  
R.J. Full
Keyword(s):  
Horizontal Plane ◽  
Center Of Mass ◽  
Vertical Plane ◽  
Force Production ◽  
The Body ◽  
Mean Velocity ◽  
Blaberus Discoidalis ◽  
Body Design ◽  
Reaction Forces ◽  
Straight Ahead

Remarkable similarities in the vertical plane of forward motion exist among diverse legged runners. The effect of differences in posture may be reflected instead in maneuverability occurring in the horizontal plane. The maneuver we selected was turning during rapid running by the cockroach Blaberus discoidalis, a sprawled-postured arthropod. Executing a turn successfully involves at least two requirements. The animal's mean heading (the direction of the mean velocity vector of the center of mass) must be deflected, and the animal's body must rotate to keep the body axis aligned with the heading. We used two-dimensional kinematics to estimate net forces and rotational torques, and a photoelastic technique to estimate single-leg ground-reaction forces during turning. Stride frequencies and duty factors did not differ among legs during turning. The inside legs ended their steps closer to the body than during straight-ahead running, suggesting that they contributed to turning the body. However, the inside legs did not contribute forces or torques to turning the body, but actively pushed against the turn. Legs farther from the center of rotation on the outside of the turn contributed the majority of force and torque impulse which caused the body to turn. The dynamics of turning could not be predicted from kinematic measurements alone. To interpret the single-leg forces observed during turning, we have developed a general model that relates leg force production and leg position to turning performance. The model predicts that all legs could turn the body. Front legs can contribute most effectively to turning by producing forces nearly perpendicular to the heading, whereas middle and hind legs must produce additional force parallel to the heading. The force production necessary to turn required only minor alterations in the force hexapods generate during dynamically stable, straight-ahead locomotion. A consideration of maneuverability in the horizontal plane revealed that a sprawled-postured, hexapodal body design may provide exceptional performance with simplified control.

Long bone cross-sectional geometry

2020 ◽  
pp. 307-320
Author(s):  
Christopher B. Ruff ◽  
Ryan W. Higgins ◽  
Kristian J. Carlson
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Lateral Displacement ◽  
Center Of Mass ◽  
Gait Pattern ◽  
Locomotor Behavior ◽  
The Body ◽  
Long Bone ◽  
Cross Sectional ◽  
Body Center

Long bone diaphyseal cross-sectional geometries reflect the mechanical properties of the bones, and can be used to aid in inferences of locomotor behavior in extinct hominins. This chapter considers all available long bone diaphyseal and femoral neck cross-sections of specimens from Sterkfontein Member 4, and presents comparisons of these section properties and other cross-sectional dimensions with those of other early hominins as well as modern samples. The cross-sectional geometry of the Sterkfontein Member 4 long bone specimens suggests some similarities to, but also interesting differences in, mechanical loading of these elements relative to modern humans. The less asymmetric cortical bone distribution in the Sterkfontein femoral necks is consistent with other evidence above indicating an altered gait pattern involving lateral displacement of the body center of mass over the stance limb. The relatively very strong upper limb of StW 431 implies that arboreal behavior formed a significant component of its locomotor repertoire. Bipedal gait may have been less efficient and arboreal climbing more prevalent in the Sterkfontein hominins.

Time-To-Contact Analysis of Gait Stability in the Swing Phase of Walking in People With Multiple Sclerosis

Motor Control ◽  
2015 ◽  
Vol 19 (4) ◽  
pp. 289-311 ◽  
Author(s):  
Jebb G. Remelius ◽  
Richard E.A. van Emmerik
Keyword(s):  
Multiple Sclerosis ◽  
Center Of Mass ◽  
Swing Phase ◽  
The Body ◽  
Head Movements ◽  
Gait Stability ◽  
Time To Contact ◽  
Prospective Control ◽  
Body Center ◽  
All Speeds

This study investigated timing and coordination during the swing phase of swing leg, body center of mass (CoM) and head during walking people with multiple sclerosis (MS; n = 19) and controls (n = 19). The MS group showed differences in swing phase timing at all speeds. At imposed but not preferred speeds, the MS group had less time to prepare for entry into the unstable equilibrium, as the CoM entered this phase of swing earlier. Time-to-contact coupling, quantifying the coordination between the CoM and the swing foot, was not different between groups. The projection of head motion on the ground occurred earlier after toeoff and was positioned closer to the body in the MS group, illustrating increased reliance on visual exproprioception in which vision of the body in relation to the surface of support is established. Finally, prospective control, linking head movements to the swing foot time-to-contact and next step landing area, was impaired in the MS group at higher gait speeds.

scholarly journals Symmetry Analysis of Amputee Gait Based on Body Center of Mass Trajectory and Discrete Fourier Transform

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2392
Author(s):  
Claudia Ochoa-Diaz ◽  
Antônio Padilha L. Bó
Keyword(s):  
Center Of Mass ◽  
Sine Wave ◽  
The Body ◽  
Compensatory Mechanisms ◽  
Magnitude Spectrum ◽  
Functional Aspects ◽  
Gait Mechanics ◽  
Body Center ◽  
Main Components ◽  
Amputee Gait

The calculation of symmetry in amputee gait is a valuable tool to assess the functional aspects of lower limb prostheses and how it impacts the overall gait mechanics. This paper analyzes the vertical trajectory of the body center of mass (CoM) of a group formed by transfemoral amputees and non-amputees to quantitatively compare the symmetry level of this parameter for both cases. A decomposition of the vertical CoM into discrete Fourier series (DFS) components is performed for each subject’s CoM trajectory to identify the main components of each pattern. A DFS-based index is then calculated to quantify the CoM symmetry level. The obtained results show that the CoM displays different patterns along a gait cycle for each amputee, which differ from the sine-wave shape obtained in the non-amputee case. The CoM magnitude spectrum also reveals more coefficients for the amputee waveforms. The different CoM trajectories found in the studied subjects can be thought as the manifestation of developed compensatory mechanisms, which lead to gait asymmetries. The presence of odd components in the magnitude spectrum is related to the asymmetric behavior of the CoM trajectory, given the fact that this signal is an even function for a non-amputee gait. The DFS-based index reflects this fact due to the high value obtained for the non-amputee reference, in comparison to the low values for each amputee.

scholarly journals Can explicit visual feedback of postural sway efface the effects of sensory manipulations on mediolateral balance performance?

2016 ◽  
Vol 115 (2) ◽  
pp. 907-914 ◽  
Author(s):  
L. Eduardo Cofré Lizama ◽  
Mirjam Pijnappels ◽  
N. Peter Reeves ◽  
Sabine M. P. Verschueren ◽  
Jaap H. van Dieën
Keyword(s):  
Visual Feedback ◽  
Repeated Measures ◽  
Visual Information ◽  
Postural Sway ◽  
Center Of Mass ◽  
The Body ◽  
Body Center ◽  
Explicit Feedback ◽  
Dominant Frequencies ◽  
Visual Conditions

Explicit visual feedback on postural sway is often used in balance assessment and training. However, up-weighting of visual information may mask impairments of other sensory systems. We therefore aimed to determine whether the effects of somatosensory, vestibular, and proprioceptive manipulations on mediolateral balance are reduced by explicit visual feedback on mediolateral sway of the body center of mass and by the presence of visual information. We manipulated sensory inputs of the somatosensory system by transcutaneous electric nerve stimulation on the feet soles (TENS) of the vestibular system by galvanic vestibular stimulation (GVS) and of the proprioceptive system by muscle-tendon vibration (VMS) of hip abductors. The effects of these manipulations on mediolateral sway were compared with a control condition without manipulation under three visual conditions: explicit feedback of sway of the body center of mass (FB), eyes open (EO), and eyes closed (EC). Mediolateral sway was quantified as the sum of energies in the power spectrum and as the energy at the dominant frequencies in each of the manipulation signals. Repeated-measures ANOVAs were used to test effects of each of the sensory manipulations, of visual conditions and their interaction. Overall, sensory manipulations increased body sway compared with the control conditions. Absence of normal visual information had no effect on sway, while explicit feedback reduced sway. Furthermore, interactions of visual information and sensory manipulation were found at specific dominant frequencies for GVS and VMS, with explicit feedback reducing the effects of the manipulations but not effacing these.

Body Segment Contributions to Javelin Throwing during Final Thrust Phases

1994 ◽  
Vol 10 (2) ◽  
pp. 166-177 ◽  
Author(s):  
Mero Antti ◽  
Paavo V. Komi ◽  
Tapio Korjus ◽  
Enrique Navarro ◽  
Robert J. Gregor
Keyword(s):  
High Speed ◽  
Olympic Games ◽  
Center Of Mass ◽  
The Body ◽  
Body Segment ◽  
Male And Female ◽  
Body Center ◽  
Joint Center ◽  
The Right ◽  
Release Speed

This study investigated body segment contributions to javelin throwing during the last thrust phases. A 3-D analysis was performed on male and female javelin throwers during the finals of the 1992 Olympic Games in Barcelona. The subjects were videotaped from the right sight of the throwing area by two NAC high-speed cameras operating at 100 frames per second. Both men’s and women’s grip of javelin and body center of mass displayed a curved pathway to the right from the left (bracing) foot during the final foot contact. The position of the body center of mass decreased at the beginning of the final foot contact, but after the decrease period it began to increase. Simultaneously with the increase, the peak joint center speeds occurred in a proper sequence from proximal to distal segments and finally to the javelin at release. Release speed correlated significantly with throwing distance in both male and females.

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