scholarly journals External mechanical work done during the acceleration stage of maximal sprint running and its association with running performance

2019 ◽  
Vol 222 (5) ◽  
pp. jeb189258 ◽  
Author(s):  
Akifumi Matsuo ◽  
Mirai Mizutani ◽  
Ryu Nagahara ◽  
Testuo Fukunaga ◽  
Hiroaki Kanehisa
Keyword(s):  
Mechanical Work ◽  
Running Performance ◽  
Sprint Running ◽  
Work Done

scholarly journals Crystallization of Polymers under the Influence of an External Force Field

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2078
Author(s):  
Rajdeep Singh Payal ◽  
Jens-Uwe Sommer
Keyword(s):  
External Force ◽  
Melting Behavior ◽  
Mechanical Work ◽  
Stem Length ◽  
Heat Of Fusion ◽  
Strong Increase ◽  
Lamellar Thickness ◽  
Equilibrium System ◽  
External Force Field ◽  
Work Done

We simulated the crystallization and melting behavior of entangled polymer melts using molecular dynamics where each chain is subject to a force dipole acting on its ends. This mimics the deformation of chains in a flow field but represents a well-defined equilibrium system in the melt state. Under weak extension within the linear response of the chains, the mechanical work done on the system is about two orders of magnitude smaller as compared with the heat of fusion. As a consequence, thermodynamic and simple arguments following the secondary nucleation model predict only small changes of the crystalline phase. By contrast, an increase of the stem length up to a factor of two is observed in our simulations. On the other hand, the lamellar thickening induced by the external force is proportional to the increase of the entanglement length in the melt prior to crystallization as measured by the primitive path method. While the mechanical work done on the system is only a small perturbation for thermodynamics of polymer crystallization, the change of the primitive path is large. This suggests that a strong increase in the lamellar thickness induced, by external deformation, a topological rather than a thermodynamic origin.

scholarly journals The theory of the chain fountain revisited

2021 ◽  
Vol 2090 (1) ◽  
pp. 012166
Author(s):  
Dragos-Victor Anghel
Keyword(s):  
Energy Transfer ◽  
Kinetic Energy ◽  
Significant Role ◽  
Mechanical Work ◽  
Scientific Consensus ◽  
Energy And Momentum ◽  
Work Done

Abstract We analyze the chain fountain effect-the chain siphoning when falling from a container onto the floor. We argue that the main reason for this effect is the inertia of the chain, whereas the momentum received by the beads of the chain from the bottom of the container (typically called “kicks”) plays no significant role. The inertia of the chain leads to an effect similar to pulling the chain over a pulley placed up in the air, above the container. In another model (the so called “scientific consensus”), it was assumed that up to half of the mechanical work done by the tension in the chain may be wasted when transformed into kinetic energy during the pickup process. This prevented the chain to rise unless the energy transfer in the pickup process is improved by the “kicks” from the bottom of the container. Here we show that the “kicks” are unnecessary and both, energy and momentum are conserved-as they should be, in the absence of dissipation-if one properly considers the tension and the movement of the chain. By doing so, we conclude that the velocity acquired by the chain is high enough to produce the fountain effect. Simple experiments validate our model and certain configurations produce the highest chain fountain, although “kicks” are impossible.

Effect of Short-term Altitude Training on Sprint Running Performance

2017 ◽  
Vol 49 (5S) ◽  
pp. 148
Author(s):  
Yasuhiro Suzuki ◽  
Hirohiko Maemura ◽  
Toshiyuki Ohya ◽  
Masahiro Hagiwara
Keyword(s):  
Altitude Training ◽  
Short Term ◽  
Running Performance ◽  
Sprint Running

Acute ingestion of beetroot juice does not improve short-duration repeated sprint running performance in male team sport athletes

2020 ◽  
Vol 38 (18) ◽  
pp. 2063-2070 ◽  
Author(s):  
Ciara M. E. Reynolds ◽  
Mark Evans ◽  
Catherine Halpenny ◽  
Caoimhe Hughes ◽  
Stephen Jordan ◽  
...  
Keyword(s):  
Short Duration ◽  
Team Sport ◽  
Beetroot Juice ◽  
Running Performance ◽  
Sprint Running ◽  
Repeated Sprint ◽  
Acute Ingestion

48 THE RELATIONSHIP OF INDIVIDUAL TORQUE-VELOCITY CURVE SHAPES TO SPRINT RUNNING PERFORMANCE

1990 ◽  
Vol 22 (2) ◽  
pp. S8
Author(s):  
Everett Harman ◽  
Peter Frykman ◽  
Michael Rosenstein ◽  
Michael Johnson ◽  
Richard Rosenstein
Keyword(s):  
Velocity Curve ◽  
Running Performance ◽  
Sprint Running ◽  
Relationship Of ◽  
The Relationship

Effect of Caffeine and Rest Time on Repeated Sprint Running Performance

2015 ◽  
Vol 47 ◽  
pp. 372
Author(s):  
Julia Falkenklous ◽  
Jessica Alsup ◽  
Michael Ryan ◽  
Paul Reneau
Keyword(s):  
Running Performance ◽  
Sprint Running ◽  
Repeated Sprint ◽  
Rest Time

External mechanical work done by each leg during walking in stroke patients

2006 ◽  
Vol 39 ◽  
pp. S171-S172
Author(s):  
G.G. Stoquart ◽  
C. Detrembleur ◽  
T.M. Lejeune
Keyword(s):  
Mechanical Work ◽  
Stroke Patients ◽  
Work Done
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