scholarly journals Walking dynamics are symmetric (enough)

2015 ◽  
Vol 12 (108) ◽  
pp. 20150209 ◽  
Author(s):  
M. Mert Ankaralı ◽  
Shahin Sefati ◽  
Manu S. Madhav ◽  
Andrew Long ◽  
Amy J. Bastian ◽  
...  
Keyword(s):  
Steady State ◽  
Dynamical Systems ◽  
Cross Validation ◽  
Sagittal Plane ◽  
Bilateral Symmetry ◽  
Human Locomotion ◽  
Human Walking ◽  
Biological Phenomena ◽  
Systems Modelling ◽  
Walking Dynamics

Many biological phenomena such as locomotion, circadian cycles and breathing are rhythmic in nature and can be modelled as rhythmic dynamical systems. Dynamical systems modelling often involves neglecting certain characteristics of a physical system as a modelling convenience. For example, human locomotion is frequently treated as symmetric about the sagittal plane. In this work, we test this assumption by examining human walking dynamics around the steady state (limit-cycle). Here, we adapt statistical cross-validation in order to examine whether there are statistically significant asymmetries and, even if so, test the consequences of assuming bilateral symmetry anyway. Indeed, we identify significant asymmetries in the dynamics of human walking, but nevertheless show that ignoring these asymmetries results in a more consistent and predictive model. In general, neglecting evident characteristics of a system can be more than a modelling convenience—it can produce a better model.

Kinematics and Dynamic Stability of the Locomotion of Post-Polio Patients

1996 ◽  
Vol 118 (3) ◽  
pp. 405-411 ◽  
Author(s):  
Yildirim Hurmuzlu ◽  
Cagatay Basdogan ◽  
Dan Stoianovici
Keyword(s):  
Dynamic Stability ◽  
Sagittal Plane ◽  
Plantar Flexion ◽  
Bilateral Symmetry ◽  
Human Locomotion ◽  
Knee Extension ◽  
Polio Survivors ◽  
Hip Flexion ◽  
First Return Maps ◽  
Analytical Tools

The study reported in this article was conducted to propose a set graphical and analytical tools and assess their clinical utility by analyzing gait kinematics and dynamics of polio survivors. Phase-plane portraits and first return maps were used as graphical tools to detect abnormal patterns in the sagittal kinematics of post-polio gait. Two new scalar measures were introduced to assess the bilateral kinematic symmetry and dynamic stability of human locomotion. Nine healthy subjects and seventeen post-polio patients were involved in the project. Significant increases in the knee extension and ankle plantar flexion of post-polio patients were observed during the weight acceptance phases of their gait. Polio patients also exhibited highly noticeable excessive hip flexion during the swing phase of their ambulation. Using the proposed symmetry measure, we concluded that post-polio patients walked less symmetrically than normals. Our conclusion, however, was based on the bilateral symmetry in the sagittal plane only. Finally, we observed that post-polio patients walked significantly less stably than normals. In addition, weaknesses in lower extremity muscles of polio patients were found to be an important factor that affected stable ambulation.

Lower Extremity Joint Work During Acceleration, Deceleration, and Steady State Running

2017 ◽  
Vol 33 (1) ◽  
pp. 56-63 ◽  
Author(s):  
D.S. Blaise Williams ◽  
Jonathan H. Cole ◽  
Douglas W. Powell
Keyword(s):  
Steady State ◽  
Lower Extremity ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Joint Work ◽  
Negative Work ◽  
Relative Contribution ◽  
Acceleration And Deceleration ◽  
The Individual ◽  
Positive Work

Running during sports and for physical activity often requires changes in velocity through acceleration and deceleration. While it is clear that lower extremity biomechanics vary during these accelerations and decelerations, the work requirements of the individual joints are not well understood. The purpose of this investigation was to measure the sagittal plane mechanical work of the individual lower extremity joints during acceleration, deceleration, and steady-state running. Ten runners were compared during acceleration, deceleration, and steady-state running using three-dimensional kinematics and kinetics measures. Total positive and negative joint work, and relative joint contributions to total work were compared between conditions. Total positive work progressively increased from deceleration to acceleration. This was due to greater ankle joint work during acceleration. While there was no significant change in total negative work during deceleration, there was a greater relative contribution of the knee to total negative work with a subsequent lower relative ankle negative work. Each lower extremity joint exhibits distinct functional roles in acceleration compared with deceleration during level running. Deceleration is dominated by greater contributions of the knee to negative work while acceleration is associated with a greater ankle contribution to positive work.

scholarly journals Normal human locomotion

1979 ◽  
Vol 3 (1) ◽  
pp. 4-12 ◽  
Author(s):  
J. Hughes ◽  
N. Jacobs
Keyword(s):  
Gait Cycle ◽  
Sagittal Plane ◽  
Human Locomotion ◽  
Actual Situation ◽  
General Statement ◽  
Basic Principles ◽  
Significant Events ◽  
Normal Human ◽  
Pathological Gait ◽  
Muscle Actions

A study of normal locomotion requires an understanding of both the movements and the force actions involved. This is equally true in appreciating the problems of pathological gait. The gait cycle is described in terms of the significant events which occur during both the stance and swing phases. The basic principles underlying the analysis of force actions in walking are briefly described. A simple example of force actions in the elbow joint is considered and the analysis extrapolated to provide a general statement regarding locomotion. This relates to the muscle actions required to resist turning actions at joints due to the force effects in walking and the corresponding forces in the joints themselves. The conventional display of information relating to joint actions is considered and compared with the actual situation. “Stick diagrams” of motion in the sagittal plane are used to identify and discuss the actions at the joints of the leg in walking. Comparisons are made between this and pathological gait—in particular that of the above-knee amputee.

Steady-State and Transient Dynamical Systems Analysis of Uncoupled and Coupled Very Large Amplitude Roll Response of a Vessel in Regular and Random Waves

2006 ◽  
Author(s):  
Jeffrey M. Falzarano ◽  
Srinivas Vishnubhotla ◽  
Sarah E. Juckett
Keyword(s):  
Steady State ◽  
Stability Analysis ◽  
Dynamical Systems ◽  
Large Amplitude ◽  
Early Stage ◽  
Static Stability ◽  
Random Waves ◽  
The Us ◽  
Us Navy ◽  
Regular And Random Waves

This paper contains the most recent results of our analysis of the DTMB 5415 model hull. This hull is an early stage version of the US Navy’s DDG-51 and approximately represents the last traditional destroyer hull form designed, built and operated by the US Navy. Moreover, the US Navy has recently proposed an alternative simulation based approach to traditional static stability analysis for advanced hull forms. Static stability analysis has been in use by the US Navy for at least 50 years. This paper proposes an alternative analysis technique which uses modern techniques of dynamical systems to analyze the large amplitude (nonlinear) roll response of a vessel in waves. The technique considers the steady state (local) roll response, the transient (global) roll response in both regular and random waves. Moreover, the effects of coupling, damping and reduced GM are all investigated.

scholarly journals The rotary component of leg force during walking and running

2019 ◽  
Vol 16 (154) ◽  
pp. 20190105 ◽  
Author(s):  
Manish Anand ◽  
Justin Seipel
Keyword(s):  
Sagittal Plane ◽  
Human Subjects ◽  
Reaction Force ◽  
Average Power ◽  
Power Input ◽  
Human Locomotion ◽  
Strong Positive Correlation ◽  
Mass Centre ◽  
Force Magnitude ◽  
Locomotion Speed

The component of ground reaction force (GRF) acting perpendicular to the leg in the sagittal plane during human locomotion (acting in a rotary direction) has not been systematically investigated and is not well understood. In this paper, we investigate this rotary component of the GRF of 11 human subjects (mean age ± s.d.: 26.6 ± 2.9 years) while walking and speed walking on a treadmill, along with eight human subjects (mean age ± s.d.: 26.3 ± 3.1) running on a treadmill. The GRF on both legs was measured, along with estimates of the subject's mass centre and the centre of pressure of each foot to yield total leg lengths and leg angle. Across all steady walking and running speeds, we find that the rotary component of the GRF has significant magnitude (peak values from 5% to 38% of body weight, from slow walking to moderate running, respectively) and implies leg propulsion of the mass centre in the rotary direction. Furthermore, peak rotary force magnitude over stance increases with locomotion speed for both walking and running ( p < 0.05), and the time-averaged (mean) rotary force shows a slight increase with walking speed (though the mean force trend is uncertain for running). Also, an estimate of average power input from the rotary force of the leg acting at the mass centre shows moderate and strong positive correlation with locomotion speed for running and walking respectively ( p < 0.05). This study also shows that the rotary force acts differently in walking versus running: rotary force is predominantly positive during running, but during walking it exhibits both positive and negative phases with net positive force found over the whole stride.

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