Mechanical Energy Expenditures and Movement Efficiency in Full Body Reaching Movements

2010 ◽  
Vol 26 (1) ◽  
pp. 32-44 ◽  
Author(s):  
Daohang Sha ◽  
Christopher R. France ◽  
James S. Thomas
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Target Location ◽  
Mechanical Energy ◽  
The Body ◽  
Reaching Movements ◽  
Whole Body ◽  
Joint Power ◽  
Total Mechanical Energy ◽  
Full Body

The effect of target location, speed, and handedness on the average total mechanical energy and movement efficiency is studied in 15 healthy subjects (7 males and 8 females with age 22.9 ± 1.79 years old) performing full body reaching movements. The average total mechanical energy is measured as the time average of integration of joint power, potential energy, and kinetic energy respectively. Movement efficiency is calculated as the ratio of total kinetic energy to the total joint power and potential energy. Results show that speed and target location have significant effects on total mechanical energy and movement efficiency, but reaching hand only effects kinetic energy. From our findings we conclude that (1) efficiency in whole body reaching is dependent on whether the height of the body center of mass is raised or lowered during the task; (2) efficiency is increased as movement speed is increased, in part because of greater changes in potential energy; and (3) the CNS does not appear to use movement efficiency as a primary planning variable in full body reaching. It may be dependent on a combination of other factors or constraints.

Three-dimensional kinematics and limb kinetic energy of running cockroaches.

1997 ◽  
Vol 200 (13) ◽  
pp. 1919-1929 ◽  
Author(s):  
R Kram ◽  
B Wong ◽  
R J Full
Keyword(s):  
Kinetic Energy ◽  
High Speed ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Three Dimensional ◽  
The Body ◽  
Morphological Data ◽  
Fast Running ◽  
Total Mechanical Energy ◽  
Reaction Forces

We tested the hypothesis that fast-running hexapeds must generate high levels of kinetic energy to cycle their limbs rapidly compared with bipeds and quadrupeds. We used high-speed video analysis to determine the three-dimensional movements of the limbs and bodies of cockroaches (Blaberus discoidalis) running on a motorized treadmill at 21 cm s-1 using an alternating tripod gait. We combined these kinematic data with morphological data to calculate the mechanical energy produced to move the limbs relative to the overall center of mass and the mechanical energy generated to rotate the body (head + thorax + abdomen) about the overall center of mass. The kinetic energy involved in moving the limbs was 8 microJ stride-1 (a power output of 21 mW kg-1, which was only approximately 13% of the external mechanical energy generated to lift and accelerate the overall center of mass at this speed. Pitch, yaw and roll rotational movements of the body were modest (less than +/- 7 degrees), and the mechanical energy required for these rotations was surprisingly small (1.7 microJ stride-1 for pitch, 0.5 microJ stride-1 for yaw and 0.4 microJ stride-1 for roll) as was the power (4.2, 1.2 and 1.1 mW kg-1, respectively). Compared at the same absolute forward speed, the mass-specific kinetic energy generated by the trotting hexaped to swing its limbs was approximately half of that predicted from data on much larger two- and four-legged animals. Compared at an equivalent speed (mid-trotting speed), limb kinetic energy was a smaller fraction of total mechanical energy for cockroaches than for large bipedal runners and hoppers and for quadrupedal trotters. Cockroaches operate at relatively high stride frequencies, but distribute ground reaction forces over a greater number of relatively small legs. The relatively small leg mass and inertia of hexapeds may allow relatively high leg cycling frequencies without exceptionally high internal mechanical energy generation.

External, internal and total work in human locomotion.

1995 ◽  
Vol 198 (2) ◽  
pp. 379-393 ◽  
Author(s):  
P A Willems ◽  
G A Cavagna ◽  
N C Heglund
Keyword(s):  
Potential Energy ◽  
Mechanical Energy ◽  
Human Locomotion ◽  
The Body ◽  
Whole Body ◽  
Gravitational Potential Energy ◽  
Total Work ◽  
Centre Of Mass ◽  
Body Segments ◽  
Energy Transfers

The muscle-tendon work performed during locomotion can, in principle, be measured from the mechanical energy of the centre of mass of the whole body and the kinetic energy due to the movements of the body segments relative to the centre of mass of the body. Problems arise when calculating the muscle-tendon work from increases in mechanical energy, largely in correctly attributing these increases either to energy transfer or to muscle-tendon work. In this study, the kinetic and gravitational potential energy of the centre of mass of the whole human body was measured (using a force platform) simultaneously with calculation of the kinetic and potential energy of the body segments due to their movements relative to the body centre of mass (using cinematography) at different speeds of walking and running. Upper and lower boundaries to the total work were determined by including or excluding possible energy transfers between the segments of each limb, between the limbs and between the centre of mass of the body and the limbs. It appears that the muscle-tendon work of locomotion is most accurately measured when energy transfers are only included between segments of the same limb, but not among the limbs or between the limbs and the centre of mass of the whole body.

scholarly journals Walking in simulated reduced gravity: mechanical energy fluctuations and exchange

1999 ◽  
Vol 86 (1) ◽  
pp. 383-390 ◽  
Author(s):  
Timothy M. Griffin ◽  
Neil A. Tolani ◽  
Rodger Kram
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Gravitational Potential ◽  
Inverted Pendulum ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Gravitational Potential Energy ◽  
Reduced Gravity

Walking humans conserve mechanical and, presumably, metabolic energy with an inverted pendulum-like exchange of gravitational potential energy and horizontal kinetic energy. Walking in simulated reduced gravity involves a relatively high metabolic cost, suggesting that the inverted-pendulum mechanism is disrupted because of a mismatch of potential and kinetic energy. We tested this hypothesis by measuring the fluctuations and exchange of mechanical energy of the center of mass at different combinations of velocity and simulated reduced gravity. Subjects walked with smaller fluctuations in horizontal velocity in lower gravity, such that the ratio of horizontal kinetic to gravitational potential energy fluctuations remained constant over a fourfold change in gravity. The amount of exchange, or percent recovery, at 1.00 m/s was not significantly different at 1.00, 0.75, and 0.50 G (average 64.4%), although it decreased to 48% at 0.25 G. As a result, the amount of work performed on the center of mass does not explain the relatively high metabolic cost of walking in simulated reduced gravity.

scholarly journals The Possibility of Zero Limb-Work Gaits in Sprawled and Parasagittal Quadrupeds: Insights from Linkages of the Industrial Revolution

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
J R Usherwood
Keyword(s):  
Potential Energy ◽  
Industrial Revolution ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Phase Fluctuation ◽  
Vertical Axis ◽  
The Body ◽  
Mechanical Work ◽  
Gravitational Potential Energy ◽  
Pull Out

Synopsis Animal legs are diverse, complex, and perform many roles. One defining requirement of legs is to facilitate terrestrial travel with some degree of economy. This could, theoretically, be achieved without loss of mechanical energy if the body could take a continuous horizontal path supported by vertical forces only—effectively a wheel-like translation, and a condition closely approximated by walking tortoises. If this is a potential strategy for zero mechanical work cost among quadrupeds, how might the structure, posture, and diversity of both sprawled and parasagittal legs be interpreted? In order to approach this question, various linkages described during the industrial revolution are considered. Watt’s linkage provides an analogue for sprawled vertebrates that uses diagonal limb support and shows how vertical-axis joints could enable approximately straight-line horizontal translation while demanding minimal mechanical power. An additional vertical-axis joint per leg results in the wall-mounted pull-out monitor arm and would enable translation with zero mechanical work due to weight support, without tipping or toppling. This is consistent with force profiles observed in tortoises. The Peaucellier linkage demonstrates that parasagittal limbs with lateral-axis joints could also achieve the zero-work strategy. Suitably tuned four-bar linkages indicate this is feasibly approximated for flexed, biologically realistic limbs. Where “walking” gaits typically show out of phase fluctuation in center of mass kinetic and gravitational potential energy, and running, hopping or trotting gaits are characterized by in-phase energy fluctuations, the zero limb-work strategy approximated by tortoises would show zero fluctuations in kinetic or potential energy. This highlights that some gaits, perhaps particularly those of animals with sprawled or crouched limbs, do not fit current kinetic gait definitions; an additional gait paradigm, the “zero limb-work strategy” is proposed.

scholarly journals Sensitivity of Idealized Moist Baroclinic Waves to Environmental Temperature and Moisture Content

2018 ◽  
Vol 75 (1) ◽  
pp. 337-360 ◽  
Author(s):  
D. J. Kirshbaum ◽  
T. M. Merlis ◽  
J. R. Gyakum ◽  
R. McTaggart-Cowan
Keyword(s):  
Kinetic Energy ◽  
Moisture Content ◽  
Potential Energy ◽  
Diabatic Heating ◽  
Environmental Temperature ◽  
Mechanical Energy ◽  
Negative Relationship ◽  
Vertical Motion ◽  
Periodic Wave ◽  
Cloud Band

Idealized simulations are used to examine the sensitivity of moist baroclinic wave growth to environmental temperature and moisture content. With relative humidity held fixed, the surface temperature at 45°N, denoted T0, is varied from 275 to 290 K. As T0 increases, the atmospheric moisture content, moist instability, and moist available potential energy also increase. For the chosen initial configuration, moist waves develop larger eddy kinetic energy K e than corresponding dry waves, but enhanced diabatic heating at larger T0 does not further increase K e. This finding is linked to a warm-frontal cyclonic potential vorticity (PV) anomaly that strengthens and shifts downstream at larger T0 owing to increased diabatic heating along the frontal cloud band. This eastward shift feeds back negatively on the parent cyclone by increasing the downstream export of mechanical energy aloft and degrading the phasing between dry baroclinic vertical motion and buoyancy within the warm sector. The latter suppresses the conversion from eddy potential energy to K e [ C( P e, K e)], offsetting a direct enhancement of C( P e, K e) by diabatic heating. Compared to their dry counterparts, isolated moist waves (initiated by a single finite-amplitude PV anomaly) display a similar sensitivity to T0, while periodic wave trains (initiated by multiple such anomalies) exhibit a stronger negative relationship. The latter stems from anticyclonic diabatic PV anomalies aloft that originate along the warm front and recirculate through the system to interact with the upper-level trough. This interaction leads to a horizontal forward wave tilt that enhances the conversion of wave K e into zonal-mean kinetic energy.

scholarly journals The importance of Abhyanga in Dincharya in present era: A literary review.

2018 ◽  
Vol 6 (07) ◽  
Author(s):  
Ganesh Shantaram Puradakar ◽  
Arun Shankarrao Dudhamal ◽  
Disha Sharma
Keyword(s):  
The Body ◽  
Whole Body ◽  
Human Being ◽  
Science And Art ◽  
Therapeutic Procedures ◽  
Long Life ◽  
The Senses ◽  
The Right ◽  
Head Neck ◽  
Full Body

Ayurveda is a ‘science of life” which provides not only curative but also preventive principles for healthy and long life. Ayurveda is a lifestyle; a science and art of appropriate living that ensures health and longevity of human being. Abhyanga which is one among the Dincharya, is also a part of therapeutic procedures of Panchakarma therapy. As it nourishes the senses of mind and gives the strength, but if done in the region like localized in head, neck, legs etc then it is termed as  Shiroabhyanga, padaabhyanga etc. Full body massage gives strength to whole body but localized massage gives strength to that particular part of the body. Localized massage can be practiced by self. Thus it is easy to practice. But for abhyanga one need to be dependent in massage trainer. The instructions to be followed under localized massage also. It gives its benefits when it is done in the right manner only.

scholarly journals POLA LUKA PADA KEMATIAN AKIBAT PANAH WAYER DI RSUP PROF. DR. R. D. KANDOU MANADO PERIODE JANUARI SAMPAI OKTOBER 2014

e-CliniC ◽  
2015 ◽  
Vol 3 (2) ◽  
Author(s):  
Jaysen Kobstan ◽  
Johannis F. Mallo ◽  
Djemi Tomuka
Keyword(s):  
Retrospective Study ◽  
Kinetic Energy ◽  
Potential Energy ◽  
The Body ◽  
Pattern Of Injury ◽  
Vital Part ◽  
Penetrating Wound

Abstract: Panah wayer (a kind of arrow) has become a troubling incident for the citizen of Manado City. People are afraid to do activities outside, especially at night. Wound that caused by this arrow often leads to death if it is punctured into a vital part of the body. However, there are also surviving victims. This study aimed to obtain the pattern of injuries in dead victims caused by this panah wayer. This was a descriptive and retrospective study using visum et repertum as pimary data. The results showed that injuries caused by panah wayer had diverse sizes and depths, depend on the kinetic energy of the arrow itself and the potential energy of the sling itself. Injuries that caused by panah wayer look like a penetrating wound and the hook-like structure at its tip made this arrow hard to repeal and if it is pulled out forcefully a wider rupture at the area of injury can occur.Keywords: pattern of injury, panah wayerAbstrak: Panah wayer telah meresahkan warga kota Manado dan mengakibatkan ketakutan untuk beraktifitas di luar rumah, terutama di malam hari. Luka akibat panah wayer umumnya mengarah pada kematian bila tertusuk di daerah-daerah tertentu pada bagian tubuh. Penelitian ini bertujuan untuk mendapatkan pola luka pada kematian akibat panah wayer. Penelitian ini bersifat deskriptif retrospektif dengan meggunakan visum et repertum sebagai data primer. Hasil penelitian memperlihatkan bahwa luka akibat panah wayer memiliki ukuran dan kedalaman luka yang beragam berdasarkan energi kinetik dari panah wayer itu sendiri dan energi potensial dari pelontar. Luka yang disebabkan panah wayer memiliki bentuk seperti luka tusuk dan struktur seperti pengait yang terdapat di bagian ujung panah wayer meyebabkan panah wayer sulit untuk dicabut dan jika dicabut secara paksa akan menimbulkan robekan yang lebih besar pada daerah luka.Kata kunci: pola luka, panah wayer

Quantifying Segmental Contributions to Center-of-Mass Motion During Dynamic Continuous Support Surface Perturbations Using Simplified Estimation Models

2020 ◽  
Vol 36 (4) ◽  
pp. 198-208
Author(s):  
Alison Schinkel-Ivy ◽  
Vicki Komisar ◽  
Carolyn A. Duncan
Keyword(s):  
Balance Control ◽  
Center Of Mass ◽  
Three Dimensional ◽  
The Body ◽  
Whole Body ◽  
Mass Motion ◽  
Support Surface ◽  
Body Segments ◽  
Body Model ◽  
Full Body

Investigating balance reactions following continuous, multidirectional, support surface perturbations is essential for improving our understanding of balance control in moving environments. Segmental motions are often incorporated into rapid balance reactions following external perturbations to balance, although the effects of these motions during complex, continuous perturbations have not been assessed. This study aimed to quantify the contributions of body segments (ie, trunk, head, upper extremity, and lower extremity) to the control of center-of-mass (COM) movement during continuous, multidirectional, support surface perturbations. Three-dimensional, whole-body kinematics were captured while 10 participants experienced 5 minutes of perturbations. Anteroposterior, mediolateral, and vertical COM position and velocity were calculated using a full-body model and 7 models with reduced numbers of segments, which were compared with the full-body model. With removal of body segments, errors relative to the full-body model increased, while relationship strength decreased. The inclusion of body segments appeared to affect COM measures, particularly COM velocity. Findings suggest that the body segments may provide a means of improving the control of COM motion, primarily its velocity, during continuous, multidirectional perturbations, and constitute a step toward improving our understanding of how the limbs contribute to balance control in moving environments.

Mechanics of locomotion in lizards.

1997 ◽  
Vol 200 (16) ◽  
pp. 2177-2188 ◽  
Author(s):  
C T Farley ◽  
T C Ko
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Gravitational Potential ◽  
Inverted Pendulum ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Gravitational Potential Energy ◽  
Lateral Bending ◽  
Walking Gait ◽  
Bending Force

Lizards bend their trunks laterally with each step of locomotion and, as a result, their locomotion appears to be fundamentally different from mammalian locomotion. The goal of the present study was to determine whether lizards use the same two basic gaits as other legged animals or whether they use a mechanically unique gait due to lateral trunk bending. Force platform and kinematic measurements revealed that two species of lizards, Coleonyx variegatus and Eumeces skiltonianus, used two basic gaits similar to mammalian walking and trotting gaits. In both gaits, the kinetic energy fluctuations due to lateral movements of the center of mass were less than 5% of the total external mechanical energy fluctuations. In the walking gait, both species vaulted over their stance limbs like inverted pendulums. The fluctuations in kinetic energy and gravitational potential energy of the center of mass were approximately 180 degrees out of phase. The lizards conserved as much as 51% of the external mechanical energy required for locomotion by the inverted pendulum mechanism. Both species also used a bouncing gait, similar to mammalian trotting, in which the fluctuations in kinetic energy and gravitational potential energy of the center of mass were nearly exactly in phase. The mass-specific external mechanical work required to travel 1 m (1.5 J kg-1) was similar to that for other legged animals. Thus, in spite of marked lateral bending of the trunk, the mechanics of lizard locomotion is similar to the mechanics of locomotion in other legged animals.

High-resolution simulations of cylindrical gravity currents in a rotating system

2016 ◽  
Vol 806 ◽  
pp. 71-101 ◽  
Author(s):  
Albert Dai ◽  
Ching-Sen Wu
Keyword(s):  
High Resolution ◽  
Kinetic Energy ◽  
Potential Energy ◽  
Three Dimensional ◽  
Gravity Currents ◽  
The Body ◽  
Heavy Fluid ◽  
Rotating System ◽  
Maximum Radius ◽  
Inertia Forces

Cylindrical gravity currents, produced by a full-depth lock release, in a rotating system are investigated by means of three-dimensional high-resolution simulations of the incompressible variable-density Navier–Stokes equations with the Coriolis term and using the Boussinesq approximation for a small density difference. Here, the depth of the fluid is chosen to be the same as the radius of the cylindrical lock and the ambient fluid is non-stratified. Our attention is focused on the situation when the ratio of Coriolis to inertia forces is not large, namely $0.1\leqslant {\mathcal{C}}\leqslant 0.3$, and the non-rotating case, namely ${\mathcal{C}}=0$, is also briefly considered. The simulations reproduce the major features observed in the laboratory and provide more detailed flow information. After the heavy fluid contained in a cylindrical lock is released in a rotating system, the influence of the Coriolis effects is not significant during the initial one-tenth of a revolution of the system. During the initial one-tenth of a revolution of the system, Kelvin–Helmholtz vortices form and the rotating cylindrical gravity currents maintain nearly perfect axisymmetry. Afterwards, three-dimensionality of the flow quickly develops and the outer rim of the spreading heavy fluid breaks away from the body of the current, which gives rise to the maximum dissipation rate in the system during the entire adjustment process. The detached outer rim of heavy fluid then continues to propagate outward until a maximum radius of propagation is attained. The body of the current exhibits a complex contraction–relaxation motion and new outwardly propagating pulses form regularly in a period slightly less than half-revolution of the system. Depending on the ratio of Coriolis to inertia forces, such a contraction–relaxation motion may be initiated after or before the attainment of a maximum radius of propagation. In the contraction–relaxation motion of the heavy fluid, energy is transformed between potential energy and kinetic energy, while it is mainly the kinetic energy that is consumed by the dissipation. As a new pulse initially propagates outward, the potential energy in the system increases at the expense of decreasing kinetic energy, until a local maximum of potential energy is reached. During the latter part of the new pulse propagation, the kinetic energy in the system increases at the expense of decreasing potential energy, until a local minimum of potential energy is reached and another new pulse takes form. With the use of three-dimensional high-resolution simulations, the lobe-and-cleft structure at the advancing front can be clearly observed. The number of lobes is maintained only for a limited period of time before merger between existing lobes occurs when a maximum radius of propagation is approached. The high-resolution simulations complement the existing shallow-water formulation, which accurately predicts many important features and provides insights for rotating cylindrical gravity currents with good physical assumptions and simple mathematical models.

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