scholarly journals Intra-Segment Coordination Variability in Road Cyclists during Pedaling at Different Intensities

2020 ◽  
Vol 10 (24) ◽  
pp. 8964
Author(s):  
Rezvan Mehri ◽  
Ali Abbasi ◽  
Shahram Abbasi ◽  
Mehdi Khaleghi Tazji ◽  
Kianoush Nazarpour
Keyword(s):  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
Transverse Plane ◽  
Overuse Injuries ◽  
Knee Extensors ◽  
Plantar Flexors ◽  
Valgus Stress ◽  
Road Cyclists ◽  
Propulsion Phase

Background: The purpose of this study is to examine the lower extremity intra-segment coordination and variability of road cyclists during pedaling at different intensities. Methods: Eleven semi-professional road cyclists perform four trials at workloads of 50%, 75%, 100%, and 125% of their maximum power output in a randomized order. Thigh, shank, and foot range of motions (ROM) and the coordination and variability of these segments are compared across different pedaling intensities. Results: Foot ROM in the sagittal plane and shank ROM in the transverse plane are significantly different between different pedaling intensities. Moreover, specific coupling patterns and variabilities are observed across the pedaling cycle; however, they were not significantly different across different pedaling intensities in four pedaling phases. Conclusion: The results highlight the role of knee extensors and plantar flexors during the first and second half of the propulsion phase of pedaling, respectively. Thigh abduction dominancy with faster movement compared to the shank indicates a more valgus stress during the propulsive phase of pedaling, which can increase the risk of overuse injuries in the knee. Moreover, the smaller variability during the transition between the propulsive and recovery phases indicates a reduction in degrees of freedom and may increase the risk of overuse injuries.

Functional Role of the Superior Articular Facets of the Atlas in the Enhancement of Craniovertebral Junction Stability

2010 ◽  
Author(s):  
Richard C. Hallgren ◽  
Erik Cattrysse ◽  
Jesse M. Zrull
Keyword(s):  
Cervical Spine ◽  
Sagittal Plane ◽  
Craniovertebral Junction ◽  
Transverse Plane ◽  
Automobile Accidents ◽  
Automobile Accident ◽  
Significant Difference ◽  
Posterior Translation ◽  
Developmental Variations

Whiplash distortions of the cervical spine, occurring during the retraction phase of a rear end automobile accident, are known to cause posterior translation of the head relative to the chest and shoulders [1,2]. This anteroposterior shear produces sagittal plane rotation of the cervical spine which results in relative flexion between the occiput and the atlas (Fig. 1). This study demonstrates that there is a significant difference between the average angles of the anterior aspects and the posterior aspects of the superior facets of the atlas with respect to a horizontal (transverse) plane at P<0.01. We hypothesize that developmental variations in some individuals will allow excessive posterior translation of the head during rear end automobile accidents, and that this excessive motion may increase the risk of sustaining a whiplash-type injury for some individuals.

The Effect of Impaired Plantar Sensation on Gait in People with Multiple Sclerosis

2009 ◽  
Vol 11 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Kevin J. Kelleher ◽  
William D. Spence ◽  
Stephan E. Solomonidis ◽  
Dimitrios P. Apatsidis
Keyword(s):  
Multiple Sclerosis ◽  
Sensory Feedback ◽  
Sagittal Plane ◽  
Gait Pattern ◽  
Knee Extensors ◽  
Control Group ◽  
Plantar Flexors ◽  
Gait Patterns ◽  
Ambulatory Ability ◽  
Reaction Forces

People with multiple sclerosis (MS) often experience debilitating motor and sensory dysfunction. The aim of this study was to determine whether impaired plantar sensation affects gait patterns in MS patients, as it does in other patient populations such as those with diabetes mellitus. Sixteen patients with MS were recruited and divided into two groups according to their ambulatory ability. Ten healthy subjects made up a control group. Plantar sensation thresholds were measured and kinematic and kinetic gait data were collected for both MS groups and the control group. The MS patients had less sensation than the control group at all plantar sites tested. Gait speed and hip, knee, and ankle joint sagittal plane excursion were significantly lower in both MS groups than in the control group. Braking and push-off ground reaction forces were significantly lower in both MS groups than in the control group, and patients were found to carry the limb through the swing phase using the hip flexors and knee extensors owing to insufficient push-off from the ankle plantar flexors. The reduced plantar sensation in MS patients is likely to be a significant factor in this “cautious” gait pattern. Improving sensory feedback from the sole of the foot through the prescription of specialized footwear and orthoses may facilitate gait in people with MS.

scholarly journals Torque and Force Production during Shoulder External Rotation: Differences between Transverse and Sagittal Planes

2008 ◽  
Vol 24 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Joelly Mahnic de Toledo ◽  
Roberto Costa Krug ◽  
Marcelo Peduzzi Castro ◽  
Daniel Cury Ribeiro ◽  
Jefferson Fagundes Loss
Keyword(s):  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
External Rotation ◽  
Force Production ◽  
Transverse Plane ◽  
Resultant Force ◽  
Shoulder Abduction ◽  
Isokinetic Dynamometer ◽  
Shoulder External Rotation ◽  
The Moment

In joints with 3 degrees of freedom, such as the shoulder joint, the association of different movements results in changes in the behavior of the moment arm of the muscles. The capacity of torque production for the same movement can be changed when movements take place in a different plane. The objective of this study is to quantify differences between torque production and resultant force estimated during the shoulder external rotation in two movement planes: the transverse and sagittal planes (with 90° of shoulder abduction). Eight individuals were evaluated using an isokinetic dynamometer and an eletrogoniometer for movements in the transverse plane and six individuals for movements in the sagittal plane. The results showed that the execution of the external rotation in the sagittal plane allowed greater torque magnitudes and resultant force compared with those in the transverse plane, probably owing to a prestretching of infraspinatus and teres minor.

Body balance in a free-standing position in road and off-road cyclists

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Paulina Hebisz ◽  
Rafal Hebisz ◽  
Marek Zaton
Keyword(s):  
Sagittal Plane ◽  
Standing Position ◽  
The Body ◽  
Free Standing ◽  
Body Balance ◽  
Eyes Closed ◽  
Road Cycling ◽  
Progressive Exercise ◽  
Before And After ◽  
Road Cyclists

AbstractBackground: The purpose of this study was to compare body balance in road and off-road cyclists, immediately before and after the racing season.Material/Methods: Twenty individuals participated in the study and they were divided into two groups: specialists in road-cycling (n = 10) and in off-road cycling (n = 10). Immediately before and after the five-month racing season stabilographic trials were carried out (at rest and after progressive exercise). In assessing body balance the distance and velocity of the centre shifts (in the anterior-posterior and left-right direction) were analysed. The tests were performed with the cyclists’ eyes open, eyes closed, and in feedback.Results: After the racing season, in the off-road cyclists’ group, distance and velocity of the centre of pressure shifts increased after a progressive exercise.Conclusions: In the off-road cyclists’ group the balance of the body in the sagittal plane deteriorated after the racing season. Moreover, after the racing season off-road cyclists were characterized by a worse balance of the body, compared to road cyclists

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

scholarly journals Dzyaloshinskii–Moriya interaction in noncentrosymmetric superlattices

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Woo Seung Ham ◽  
Abdul-Muizz Pradipto ◽  
Kay Yakushiji ◽  
Kwangsu Kim ◽  
Sonny H. Rhim ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Degrees Of Freedom ◽  
Orbit Coupling ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Band Formation ◽  
Research Activities ◽  
Moriya Interaction

AbstractDzyaloshinskii–Moriya interaction (DMI) is considered as one of the most important energies for specific chiral textures such as magnetic skyrmions. The keys of generating DMI are the absence of structural inversion symmetry and exchange energy with spin–orbit coupling. Therefore, a vast majority of research activities about DMI are mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report an asymmetric band formation in a superlattices (SL) which arises from inversion symmetry breaking in stacking order of atomic layers, implying the role of bulk-like contribution. Such bulk DMI is more than 300% larger than simple sum of interfacial contribution. Moreover, the asymmetric band is largely affected by strong spin–orbit coupling, showing crucial role of a heavy metal even in the non-interfacial origin of DMI. Our work provides more degrees of freedom to design chiral magnets for spintronics applications.

scholarly journals A Superfluid Perspective on Neutron Star Dynamics

Universe ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 17
Author(s):  
Nils Andersson
Keyword(s):  
Neutron Star ◽  
Degrees Of Freedom ◽  
Temperature Scale ◽  
Fluid System ◽  
Fluid Core ◽  
State Of Matter ◽  
Entrainment Effect ◽  
Neutron Component ◽  
The Impact

As mature neutron stars are cold (on the relevant temperature scale), one has to carefully consider the state of matter in their interior. The outer kilometre or so is expected to freeze to form an elastic crust of increasingly neutron-rich nuclei, coexisting with a superfluid neutron component, while the star’s fluid core contains a mixed superfluid/superconductor. The dynamics of the star depend heavily on the parameters associated with the different phases. The presence of superfluidity brings new degrees of freedom—in essence we are dealing with a complex multi-fluid system—and additional features: bulk rotation is supported by a dense array of quantised vortices, which introduce dissipation via mutual friction, and the motion of the superfluid is affected by the so-called entrainment effect. This brief survey provides an introduction to—along with a commentary on our current understanding of—these dynamical aspects, paying particular attention to the role of entrainment, and outlines the impact of superfluidity on neutron-star seismology.

scholarly journals Higher spins from exotic dualisations

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Nicolas Boulanger ◽  
Victor Lekeu
Keyword(s):  
Infinite Number ◽  
Arbitrary Number ◽  
Degrees Of Freedom ◽  
Young Tableaux ◽  
Spacetime Dimension ◽  
Massless Field ◽  
Free Level ◽  
Higher Spins

Abstract At the free level, a given massless field can be described by an infinite number of different potentials related to each other by dualities. In terms of Young tableaux, dualities replace any number of columns of height hi by columns of height D − 2 − hi, where D is the spacetime dimension: in particular, applying this operation to empty columns gives rise to potentials containing an arbitrary number of groups of D − 2 extra antisymmetric indices. Using the method of parent actions, action principles including these potentials, but also extra fields, can be derived from the usual ones. In this paper, we revisit this off-shell duality and clarify the counting of degrees of freedom and the role of the extra fields. Among others, we consider the examples of the double dual graviton in D = 5 and two cases, one topological and one dynamical, of exotic dualities leading to spin three fields in D = 3.

scholarly journals Biologically Inspired Design and Development of a Variable Stiffness Powered Ankle-Foot Prosthesis

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Alexander Agboola-Dobson ◽  
Guowu Wei ◽  
Lei Ren
Keyword(s):  
Lower Limb ◽  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
Frontal Plane ◽  
Variable Stiffness ◽  
Plane Motion ◽  
Biologically Inspired ◽  
Passive Rotation ◽  
Ground Conditions ◽  
Biologically Inspired Design

Recent advancements in powered lower limb prostheses have appeased several difficulties faced by lower limb amputees by using a series-elastic actuator (SEA) to provide powered sagittal plane flexion. Unfortunately, these devices are currently unable to provide both powered sagittal plane flexion and two degrees of freedom (2-DOF) at the ankle, removing the ankle’s capacity to invert/evert, thus severely limiting terrain adaption capabilities and user comfort. The developed 2-DOF ankle system in this paper allows both powered flexion in the sagittal plane and passive rotation in the frontal plane; an SEA emulates the biomechanics of the gastrocnemius and Achilles tendon for flexion while a novel universal-joint system provides the 2-DOF. Several studies were undertaken to thoroughly characterize the capabilities of the device. Under both level- and sloped-ground conditions, ankle torque and kinematic data were obtained by using force-plates and a motion capture system. The device was found to be fully capable of providing powered sagittal plane motion and torque very close to that of a biological ankle while simultaneously being able to adapt to sloped terrain by undergoing frontal plane motion, thus providing 2-DOF at the ankle. These findings demonstrate that the device presented in this paper poses radical improvements to powered prosthetic ankle-foot device (PAFD) design.

Incidence and risk for traumatic and overuse injuries in top-level road cyclists

2012 ◽  
Vol 30 (10) ◽  
pp. 1047-1053 ◽  
Author(s):  
Nieves De Bernardo ◽  
Carlos Barrios ◽  
Pablo Vera ◽  
César Laíz ◽  
Michal Hadala
Keyword(s):  
Overuse Injuries ◽  
Road Cyclists
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