Regulation of Forward Angular Impulse in Tasks With Backward Translation

2021 ◽  
Vol 37 (6) ◽  
pp. 601-610
Author(s):  
Witaya Mathiyakom ◽  
Rand Wilcox ◽  
Jill L. McNitt-Gray
Keyword(s):  
Sagittal Plane ◽  
Center Of Mass ◽  
Reaction Force ◽  
Knee Extensor ◽  
Whole Body ◽  
Impulse Generation ◽  
Body Center ◽  
Total Body ◽  
Trunk Orientation ◽  
Angular Impulse

Studying how elite athletes satisfy multiple mechanical objectives when initiating well-practiced, goal-directed tasks provides insights into the control and dynamics of whole-body movements. This study investigated the coordination of multiple body segments and the reaction force (RF) generated during foot contact when regulating forward angular impulse in backward translating tasks. Six highly skilled divers performed inward somersaults (upward and backward jump with forward rotation) and inward timers (upward and backward jump without rotation) from a stationary platform. Sagittal plane kinematics and RFs were recorded simultaneously during the takeoff phase. Regulation of the forward angular impulse was achieved by redirecting the RF about the total body center of mass. Significantly more backward-directed RF was observed during the first and second peak horizontal RF of the inward somersaults than the inward timers. Modulation of the horizontal RF altered the RF direction about the center of mass and the lower-extremity segments. Backward leg and forward trunk orientation and a set of relatively large knee extensor and small hip flexor net joint moments were required for forward angular impulse generation. Understanding how the forward angular impulse is regulated in trained individuals provides insights for clinicians to consider when exploring interventions related to fall prevention.

Regulation of Angular Impulse during Two Forward Translating Tasks

2007 ◽  
Vol 23 (2) ◽  
pp. 149-161 ◽  
Author(s):  
Witaya Mathiyakom ◽  
Jill L. McNitt-Gray ◽  
Rand R. Wilcox
Keyword(s):  
Sagittal Plane ◽  
Center Of Mass ◽  
Reaction Force ◽  
Impulse Generation ◽  
Biarticular Muscles ◽  
Leg Coordination ◽  
Body Center ◽  
Total Body ◽  
Angular Impulse

Angular impulse generation is dependent on the position of the total body center of mass (CoM) relative to the ground reaction force (GRF) vector during contact with the environment. The purpose of this study was to determine how backward angular impulse was regulated during two forward translating tasks. Control of the relative angle between the CoM and the GRF was hypothesized to be mediated by altering trunk–leg coordination. Eight highly skilled athletes performed a series of standing reverse somersaults and reverse timers. Sagittal plane kinematics, GRF, and electromyograms of lower extremity muscles were acquired during the take-off phase of both tasks. The magnitude of the backward angular impulse generated during the push interval of both tasks was mediated by redirecting the GRF relative to the CoM. During the reverse timer, backward angular impulse generated during the early part of the take-off phase was negated by limiting backward trunk rotation and redirecting the GRF during the push interval. Biarticular muscles crossing the knee and hip coordinated the control of GRF direction and CoM trajectory via modulation of trunk–leg coordination.

Modification of Impulse Generation During Pirouette Turns With Increased Rotational Demands

2016 ◽  
Vol 32 (5) ◽  
pp. 425-432 ◽  
Author(s):  
Antonia M. Zaferiou ◽  
Rand R. Wilcox ◽  
Jill L. McNitt-Gray
Keyword(s):  
Statistical Methods ◽  
Center Of Mass ◽  
Reaction Force ◽  
Force Plate ◽  
Design Tools ◽  
Impulse Generation ◽  
Force Magnitude ◽  
Subject Specific ◽  
Reaction Forces ◽  
Angular Impulse

This study determined how dancers regulated angular and linear impulse during the initiation of pirouettes of increased rotation. Skilled dancers (n = 11) performed single and double pirouette turns with each foot supported by a force plate. Linear and angular impulses generated by each leg were quantified and compared between turn types using probability-based statistical methods. As rotational demands increased, dancers increased the net angular impulse generated. The contribution of each leg to net angular impulse in both single and double pirouettes was influenced by stance configuration strategies. Dancers who generated more angular impulse with the push leg than with the turn leg initiated the turn with the center of mass positioned closer to the turn leg than did other dancers. As rotational demands increased, dancers tended to increase the horizontal reaction force magnitude at one or both feet; however, they used subject-specific mechanisms. By coordinating the generation of reaction forces between legs, changes in net horizontal impulse remained minimal, despite impulse regulation at each leg used to achieve more rotations. Knowledge gained regarding how an individual coordinates the generation of linear and angular impulse between both legs as rotational demand increased can help design tools to improve that individual’s performance.

Upper Extremity Function in Running. II: Angular Momentum Considerations

1987 ◽  
Vol 3 (3) ◽  
pp. 242-263 ◽  
Author(s):  
Richard N. Hinrichs
Keyword(s):  
Angular Momentum ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Vertical Component ◽  
The Body ◽  
Lower Trunk ◽  
Body Center ◽  
Recreational Runners ◽  
Total Body ◽  
Angular Impulse

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 contributions of the arms to the total-body angular momentum about three orthogonal axes passing through the body center of mass. The results showed that while the body possessed varying amounts of angular momentum about all three coordinate axes, the arms made a meaningful contribution to only the vertical component (Hz). The arms were found to generate an alternating positive and negative Hzpattern during the running cycle. This tended to cancel out an opposite Hzpattern of the legs. The trunk was found to be an active participant in this balance of angular momentum, the upper trunk rotating back and forth with the arms and, to a lesser extent, the lower trunk with the legs. The result was a relatively small total-body Hzthroughout the running cycle. The inverse relationship between upper- and lower-body angular momentum suggests that the arms and upper trunk provide the majority of the angular impulse about the z axis needed to put the legs through their alternating strides in running.

scholarly journals The Relationships Among Sagittal-Plane Lower Extremity Moments: Implications for Landing Strategy in Anterior Cruciate Ligament Injury Prevention

2009 ◽  
Vol 44 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Yohei Shimokochi ◽  
Sae Yong Lee ◽  
Sandra J. Shultz ◽  
Randy J. Schmitz
Keyword(s):  
Anterior Cruciate Ligament ◽  
Lower Extremity ◽  
Sagittal Plane ◽  
Center Of Pressure ◽  
Cruciate Ligament ◽  
Center Of Mass ◽  
Knee Extensor ◽  
Whole Body ◽  
Plantar Flexor ◽  
Anterior Cruciate

Abstract Context: Excessive quadriceps contraction with insufficient hamstrings muscle cocontraction has been shown to be a possible contributing factor for noncontact anterior cruciate ligament (ACL) injuries. Assessing the relationships among lower extremity internal moments may provide some insight into avoiding muscle contraction patterns that increase ACL injury risk. Objective: To examine the relationships of knee-extensor moment with ankle plantar-flexor and hip-extensor moments and to examine the relationship between knee moment and center of pressure as a measure of neuromuscular response to center-of-mass position. Design: Cross-sectional study. Setting: Applied Neuromechanics Research Laboratory. Patients or Other Participants: Eighteen healthy, recreationally active women (age  =  22.3 ± 2.8 years, height  =  162.5 ± 8.1 cm, mass  =  57.8 ± 9.3 kg). Intervention(s): Participants performed a single-leg landing from a 45-cm box onto a force plate. Kinetic and kinematic data were collected. Main Outcome Measure(s): Pearson product moment correlation coefficients were calculated among the net peak knee-extensor moment (KEMpk), sagittal-plane ankle (AM) and hip (HM) net internal moments, and anterior-posterior center of pressure relative to foot center of mass at KEMpk (COP). Results: Lower KEMpk related to both greater AM (r  =  −0.942, P < .001) and HM (r  =  −0.657, P  =  .003). We also found that more anterior displacement of COP was related to greater AM (r  =  −0.750, P < .001) and lower KEMpk (r  =  0.618, P  =  .006). Conclusions: Our results suggest that participants who lean the whole body forward during landing may produce more plantar-flexor moment and less knee-extensor moment, possibly increasing hip-extensor moment and decreasing knee-extensor moment production. These results suggest that leaning forward may be a technique to decrease quadriceps contraction demand while increasing hamstrings cocontraction demand during a single-leg landing.

scholarly journals Changes in human walking dynamics induced by uneven terrain are reduced with ongoing exposure, but a higher variability persists

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jenny A. Kent ◽  
Joel H. Sommerfeld ◽  
Nicholas Stergiou
Keyword(s):  
Flat Surface ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Reaction Force ◽  
Movement Pattern ◽  
Transverse Plane ◽  
The Body ◽  
Whole Body ◽  
Uneven Terrain ◽  
Walking Dynamics

AbstractDuring walking, uneven terrain alters the action of the ground reaction force from stride to stride. The extent to which such environmental inconsistencies are withstood may be revealed by the regulation of whole-body angular momentum (L) during walking. L quantifies the balance of momenta of the body segments (thigh, trunk, etc.) about their combined center of mass, and remains close to zero during level walking. A failure to constrain L has been linked to falls. The aim of this study was to explore the ability of young adults to orchestrate their movement on uneven terrain, illustrated by the range of L (LR) and its variability (vLR). In eleven male adults, we observed significant increases in sagittal plane LR, and vLR in all three planes of motion during walking on an uneven in comparison to a flat surface. No reductions in these measures were observed within a 12-minute familiarisation period, suggesting that unimpaired adults either are unable to, or do not need to eliminate the effects of uneven terrain. Transverse plane LR, in contrast, was lower on immediate exposure, and then increased, pointing to the development of a less restrictive movement pattern, and would support the latter hypothesis.

Towards Robustly Stable Musculo-Skeletal Simulation of Human Gait: Merging Lumped and Component-Based Modeling Approaches

2012 ◽  
Author(s):  
Justin Seipel
Keyword(s):  
Inverted Pendulum ◽  
Dynamic Models ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Human Model ◽  
Whole Body ◽  
Human Gait ◽  
Slip Model ◽  
Spring Loaded Inverted Pendulum ◽  
Low Dimensional

The objective of work presented in this paper is to increase the center-of-mass stability of human walking and running in musculo-skeletal simulation. The approach taken is to approximate the whole-body dynamics of the low-dimensional Spring-Loaded Inverted Pendulum (SLIP) model of locomotion in the OpenSim environment using existing OpenSim tools. To more directly relate low-dimensional dynamic models to human simulation, an existing OpenSim human model is first modified to more closely represent bilateral above-knee amputee locomotion with passive prostheses. To increase stability further beyond the energy-conserving SLIP model, an OpenSim model based upon the Clock-Torqued Spring-Loaded-Inverted-Pendulum (CT-SLIP) model of locomotion is also created. The result of this work is that a multi-body musculo-skeletal simulation in Open-Sim can approximate the whole-body sagittal-plane dynamics of the passive SLIP model. By adding a plugin controller to the OpenSim environment, the Clock-Torqued-SLIP dynamics can be approximated in OpenSim. To change between walking and running, only one parameter representing the preferred period of a stride is changed. The result is a robustly stable simulation of the center-of-mass locomotion for both walking and running that could serve as a first step toward increasingly anatomically accurate and robustly stable musculo-skeletal simulations.

EVALUATION OF A COMPUTER-SIMULATION MODEL FOR HUMAN AMBULATION ON STILTS

2004 ◽  
Vol 04 (03) ◽  
pp. 283-303 ◽  
Author(s):  
CHRISTOPHER S. PAN ◽  
KIMBERLY M. MILLER ◽  
SHARON CHIOU ◽  
JOHN Z. WU
Keyword(s):  
Computer Simulation ◽  
Ground Reaction Force ◽  
Center Of Mass ◽  
Reaction Force ◽  
Construction Workers ◽  
Whole Body ◽  
Vertical Ground Reaction Force ◽  
Actual Measurement ◽  
Increased Risk ◽  
Vertical Ground

Stilts are elevated tools that are frequently used by construction workers to raise workers 18 to 40 inches above the ground without the burden of erecting scaffolding or a ladder. Some previous studies indicated that construction workers perceive an increased risk of injury when working on stilts. However, no in-depth biomechanical analyses have been conducted to examine the fall risks associated with the use of stilts. The objective of this study is to evaluate a computer-simulation stilts model. Three construction workers were recruited for walking tasks on 24-inch stilts. The model was evaluated using whole body center of mass and ground reaction forces. A PEAK™ motion system and two Kistler™ force platforms were used to collect data on both kinetic and kinematic measures. Inverse- and direct-dynamics simulations were performed using a model developed using commercial software — ADAMS and LifeMOD. For three coordinates (X, Y, Z) of the center of mass, the results of univariate analyses indicated very small variability for the mean difference between the model predictions and the experimental measurements. The results of correlation analyses indicated similar trends for the three coordinates. Plotting the resultant and vertical ground reaction force for both right and left feet showed small discrepancies, but the overall shape was identical. The percentage differences between the model and the actual measurement for three coordinates of the center of mass, as well as resultant and vertical ground reaction force, were within 20%. This newly-developed stilt walking model may be used to assist in improving the design of stilts.

Acute exposure to foot orthoses affects joint stiffness characteristics in recreational male runners

2015 ◽  
Vol 11 (3) ◽  
pp. 183-190 ◽  
Author(s):  
P.J. Taylor ◽  
H. Vincent ◽  
S. Atkins ◽  
J. Sinclair
Keyword(s):  
Sagittal Plane ◽  
Reaction Force ◽  
Joint Stiffness ◽  
Knee Extensor ◽  
Foot Orthoses ◽  
Vertical Ground Reaction Force ◽  
Mass Model ◽  
Peak Knee ◽  
Recreational Runners ◽  
Stiffness Characteristics

Commercially available foot orthoses are advocated for the treatment of chronic running injuries, such as patellofemoral pain, yet the mechanisms behind their effects are not well understood. This study aimed to examine the limb and joint stiffness characteristics when running with and without orthotics. Twelve recreational runners ran at 4.0 m/s. Limb stiffness was obtained using a spring-mass model of running by dividing the peak vertical ground reaction force (GRF) by the amount of limb compression. Knee and ankle joint stiffness’s were calculated by dividing the peak sagittal plane joint moment by the joint angular excursion. Differences between orthotic and non-orthotic running conditions were contrasted using paired samples t-tests. The results indicate that both peak knee extensor moment (orthotic = 2.74±0.57 and no-orthotic = 3.12±0.62 Nm/kg) and knee stiffness (orthotic = 5.56±1.08 and no-orthotic = 6.47±1.40 Nm/kg rad) were significantly larger when running without orthotics. This study may give further insight into the mechanical effects of commercially available foot orthoses. The current investigation provides some evidence to suggest that orthoses may be able to improve patellofemoral pathologies in recreational runners although further investigation is required.

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