scholarly journals Phase analysis in maximal sprinting: an investigation of step-to-step technical changes between the initial acceleration, transition and maximal velocity phases.

2017 ◽  
Author(s):  
Hans Cristian von Lieres und Wilkau ◽  
Gareth Irwin ◽  
Neil E. Bezodis ◽  
Scott Simpson ◽  
Ian N. Bezodis
Keyword(s):  
Phase Analysis ◽  
Sagittal Plane ◽  
Maximum Velocity ◽  
Transition Phase ◽  
Maximal Velocity ◽  
Centre Of Mass ◽  
Acceleration Phase ◽  
Video Cameras ◽  
Large Step ◽  
Initial Acceleration

The aim of this study was to investigate spatiotemporal and kinematic changes between the initial acceleration, transition and maximum velocity phases of a sprint. Sagittal plane kinematics from five experienced sprinters performing 50 m maximal sprints were collected using six HD-video cameras. Following manual digitising, spatiotemporal and kinematic variables at touchdown and toe-off were calculated. The start and end of the transition phase were identified using the step to step changes in centre of mass height and segment angles. Mean step to step changes of spatiotemporal and kinematic variables during each phase were calculated. Firstly, the study showed that if sufficient trials are available, step-to-step changes in shank and trunk angles might provide an appropriate measure to detect sprint phases in applied settings. However, given that changes in centre of mass height represent a more holistic measure, this was used to sub-divide the sprints into separate phases. Secondly, during the initial acceleration phase large step to step changes in touchdown kinematics were observed compared to the transition phase. At toe-off, step-to-step kinematic changes were consistent across the initial acceleration and transition phases before plateauing during the maximal velocity phase. These results provide coaches and practitioners with valuable insights into key differences between phases in maximal sprinting.

Effects of Fatigue on Kinematical Parameters During Submaximal and Maximal 100-m Butterfly Bouts

2012 ◽  
Vol 28 (5) ◽  
pp. 599-607 ◽  
Author(s):  
Kelly de Jesus ◽  
Karla de Jesus ◽  
Pedro A. Figueiredo ◽  
Pedro Gonçalves ◽  
João Paulo Vilas-Boas ◽  
...  
Keyword(s):  
Sagittal Plane ◽  
Velocity Variation ◽  
Maximal Velocity ◽  
Stroke Length ◽  
Stroke Frequency ◽  
Kinematic Data ◽  
Video Cameras ◽  
Maximal Intensity ◽  
Vertical Displacements ◽  
Kinematical Parameters

We aimed to analyze the effects of fatigue on kinematical parameters during submaximal and maximal butterfly. Seven female swimmers performed two randomized 100-m butterfly bouts, at submaximal velocity and at maximal velocity in 25-m pool. During the 1st and 4th laps of each 100 m, kinematic data were recorded by two video cameras (above and below water) on the sagittal plane. Velocity, stroke length, stroke frequency, intracyclic horizontal velocity variation, horizontal and vertical displacements of the hand and foot and stroke phases’ duration were computed for each stroke cycle. Velocity, stroke length, stroke frequency were lower for 4th than 1st lap, at both intensities. Dropped elbow and foot vertical amplitude of 1st and 2nd downbeats were higher for 4th than 1st lap, at both intensities. At submaximal and maximal intensity, swimmers spent more time during push and recovery phases. At submaximal intensity, swimmers experienced fewer difficulties to cope with fatigue between 1st and 4th lap, which allowed the maintenance of intracyclic velocity variation. However, at maximal intensity, swimmers were probably more fatigued and, as a consequence, less mechanically efficient, showing an increase in intracyclic velocity variation.

scholarly journals Resisted Sled Sprint Kinematics: The Acute Effect of Load and Sporting Population

Sports ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 137
Author(s):  
Katja M. Osterwald ◽  
David T. Kelly ◽  
Thomas M. Comyns ◽  
Ciarán Ó Catháin
Keyword(s):  
High Speed ◽  
Sagittal Plane ◽  
Maximum Velocity ◽  
Acute Effect ◽  
Video Data ◽  
Maximal Velocity ◽  
Training Tool ◽  
Heavy Loads ◽  
The Relationship ◽  
Familiarization Session

In this study, we assessed the acute kinematic effects of different sled load conditions (unloaded and at 10%, 20%, 30% decrement from maximum velocity (Vdec)) in different sporting populations. It is well-known that an athlete’s kinematics change with increasing sled load. However, to our knowledge, the relationship between the different loads in resisted sled sprinting (RSS) and kinematic characteristics is unknown. Thirty-three athletes (sprinters n = 10; team sport athletes n = 23) performed a familiarization session (day 1), and 12 sprints at different loads (day 2) over a distance of 40 m. Sprint time and average velocity were measured. Sagittal-plane high-speed video data was recorded for early acceleration and maximum velocity phase and joint angles computed. Loading introduced significant changes to hip, knee, ankle, and trunk angle for touch-down and toe-off for the acceleration and maximum velocity phase (p < 0.05). Knee, hip, and ankle angles became more flexed with increasing load for all groups and trunk lean increased linearly with increasing loading conditions. The results of this study provide coaches with important information that may influence how RSS is employed as a training tool to improve sprint performance for acceleration and maximal velocity running and that prescription may not change based on sporting population, as there were only minimal differences observed between groups. The trunk lean increase was related to the heavy loads and appeared to prevent athletes to reach mechanics that were truly reflective of maximum velocity sprinting. Lighter loads seem to be more adequate to not provoke changes in maxV kinematics. However, heavy loading extended the distance over which it is possible to train acceleration.

scholarly journals Phase analysis in maximal sprinting: an investigation of step-to-step technical changes between the initial acceleration, transition and maximal velocity phases

2018 ◽  
Vol 19 (2) ◽  
pp. 141-156 ◽  
Author(s):  
Hans C. von Lieres und Wilkau ◽  
Gareth Irwin ◽  
Neil E. Bezodis ◽  
Scott Simpson ◽  
Ian N. Bezodis
Keyword(s):  
Phase Analysis ◽  
Maximal Velocity ◽  
Initial Acceleration

Comparative force-velocity relation and analyses of myosin of dog atria and ventricles

1982 ◽  
Vol 243 (3) ◽  
pp. H391-H397 ◽  
Author(s):  
J. Wikman-Coffelt ◽  
H. Refsum ◽  
G. Hollosi ◽  
L. Rouleau ◽  
L. Chuck ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Calcium Concentration ◽  
Maximum Velocity ◽  
Calcium Sensitivity ◽  
Myofibrillar Proteins ◽  
Maximal Velocity ◽  
Velocity Of Shortening ◽  
Force Velocity ◽  
Normal Calcium ◽  
Actin Concentration

The isolated muscle and purified myofibrillar proteins of canine atria and ventricles were compared relative to force-velocity relations and rate of adenosine 5'-triphosphatase (ATPase) activity as a function of calcium concentrations. The maximal stress development of isolated trabeculae of canine atria was similar to that of canine right ventricular papillary muscles when analyzed at saturating calcium concentrations (7.5 mM); however, stress was less in the atria when studied at normal calcium concentrations (2.5 mM). The maximal velocity of shortening of atrial trabeculae was about 2.3 times higher than that of ventricular muscle. Regulated actomyosin characterized from the myofibrillar proteins of the two tissues gave directionally similar calcium sensitivity. The maximum velocity of shortening for actin-activated atrial myosin of the dog was approximately 1.8 times higher when the latter was analyzed as a function of actin concentration. Both maximal tension of isolated muscle and regulated actomyosin ATPase activity were dependent on calcium concentration.

scholarly journals The importance of duration and magnitude of force application to sprint performance during the initial acceleration, transition and maximal velocity phases

2020 ◽  
Vol 38 (20) ◽  
pp. 2359-2366
Author(s):  
Hans C. von Lieres Und Wilkau ◽  
Neil E. Bezodis ◽  
Jean-Benoît Morin ◽  
Gareth Irwin ◽  
Scott Simpson ◽  
...  
Keyword(s):  
Sprint Performance ◽  
Maximal Velocity ◽  
Force Application ◽  
Initial Acceleration

RUNNING PATTERN GENERATION OF HUMANOID BIPED WITH A FIXED POINT AND ITS REALIZATION

2009 ◽  
Vol 06 (04) ◽  
pp. 631-656 ◽  
Author(s):  
BAEK-KYU CHO ◽  
ILL-WOO PARK ◽  
JUN-HO OH
Keyword(s):  
Fixed Point ◽  
Angular Momentum ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Maximum Velocity ◽  
Frontal Plane ◽  
Numerical Approach ◽  
Pattern Generation ◽  
Upper Body ◽  
Running Pattern

This paper discusses the generation of a running pattern for a humanoid biped and verifies the validity of the proposed method of running pattern generation via experiments. Two running patterns are generated independently in the sagittal plane and in the frontal plane and the two patterns are then combined. When a running pattern is created with resolved momentum control in the sagittal plane, the angular momentum of the robot about the Center of Mass (COM) is set to zero, as the angular momentum causes the robot to rotate. However, this also induces unnatural motion of the upper body of the robot. To solve this problem, the biped was set as a virtual under-actuated robot with a free joint at its support ankle, and a fixed point for a virtual under-actuated system was determined. Following this, a periodic running pattern in the sagittal plane was formulated using the fixed point. The fixed point is easily determined in a numerical approach. In this way, a running pattern in the frontal plane was also generated. In an experiment, a humanoid biped known as KHR-2 ran forward using the proposed running pattern generation method. Its maximum velocity was 2.88 km/h.

MR Measurement of Pulse Wave Velocity in the Spinal Canal

2008 ◽  
Author(s):  
Bryn A. Martin ◽  
Francis Loth ◽  
Wojciech Kalata ◽  
John N. Oshinski
Keyword(s):  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Velocity Gradient ◽  
Cardiac Cycle ◽  
Pulse Wave ◽  
Sagittal Plane ◽  
Maximum Velocity ◽  
Time Shift ◽  
Time Interval ◽  
Velocity Measurements

Non-invasive measurement of pulse wave velocity (PWV) in the cerebrospinal fluid (CSF) system is of interest as a potential indicator of subarachnoid space pressure and compliance, both of which play a role in the development of craniospinal diseases. However, measurement of PWV has eluded researchers primarily due to either a lack of access to CSF velocity measurements or to poor temporal resolution. Here, we present PWV measurements using a novel MR technique that acquires unsteady velocity measurements during the cardiac cycle with a time interval <10 ms. Axial CSF velocity measurements were obtained in the sagittal plane of the cervical spinal region on three patients without cranio-spinal disorders. PWV was estimated by using the time shift identified by the maximum temporal velocity gradient during the cardiac cycle. Based on the maximum velocity gradient, the mean PWV in the three cases was calculated to be 4.6 m/s (stdev 1.7 m/s, p<0.005) during systolic acceleration. The measurements of PWV agree with previously published values.

scholarly journals Centre of pressure versus centre of mass stabilization strategies: the tightrope balancing case

2020 ◽  
Vol 7 (9) ◽  
pp. 200111
Author(s):  
Pietro Morasso
Keyword(s):  
Degrees Of Freedom ◽  
Sensory Feedback ◽  
Sagittal Plane ◽  
Control Variable ◽  
Variable Number ◽  
Body Parts ◽  
Centre Of Mass ◽  
Centre Of Pressure ◽  
Feedback Controllers ◽  
Neuromotor Control

This study proposes a generalization of the ankle and hip postural strategies to be applied to the large class of skills that share the same basic challenge of defeating the destabilizing effect of gravity on the basis of the same neuromotor control organization, adapted and specialized to a variable number of degrees of freedom, different body parts, different muscles and different sensory feedback channels. In all the cases, we can identify two crucial elements (the CoP, centre of pressure and the CoM, centre of mass) and the central point of the paper is that most balancing skills can be framed in the CoP–CoM interplay and can be modelled as a combination/alternation of two basic stabilization strategies: the standard well-investigated COPS (or CoP stabilization strategy, the default option), where the CoM is the controlled variable and the CoP is the control variable, and the less investigated COMS (or CoM stabilization strategy), where CoP and CoM must exchange their role because the range of motion of the CoP is strongly constrained by environmental conditions. The paper focuses on the tightrope balancing skill where sway control in the sagittal plane is modelled in terms of the COPS while the more challenging sway in the coronal plane is modelled in terms of the COMS, with the support of a suitable balance pole. Both stabilization strategies are implemented as state-space intermittent, delayed feedback controllers, independent of each other. Extensive simulations support the degree of plausibility, generality and robustness of the proposed approach.

Thermophysical properties of mixed oxide fuel and stainless steel type 316 for use in transition phase analysis

1981 ◽  
Vol 67 (1) ◽  
pp. 57-74 ◽  
Author(s):  
T.C. Chawla ◽  
D.L. Graff ◽  
R.C. Borg ◽  
G.L. Bordner ◽  
D.P. Weber ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Phase Analysis ◽  
Mixed Oxide ◽  
Thermophysical Properties ◽  
Transition Phase ◽  
Oxide Fuel ◽  
Steel Type ◽  
Mixed Oxide Fuel

scholarly journals Energy balance studies in frog skeletal muscles shortening at one-half maximal velocity.

1984 ◽  
Vol 84 (3) ◽  
pp. 347-359 ◽  
Author(s):  
E Homsher ◽  
T Yamada ◽  
A Wallner ◽  
J Tsai
Keyword(s):  
Skeletal Muscles ◽  
Maximum Velocity ◽  
High Energy ◽  
Sartorius Muscle ◽  
Maximal Velocity ◽  
High Energy Phosphate ◽  
The Mean ◽  
S Period ◽  
High Energy Phosphate Metabolism ◽  
Frog Sartorius

High-energy phosphate metabolism and energy liberated as heat and work were measured in 3-s tetani of frog sartorius muscle at 0 degree C. Two contraction periods were studied: (a) a 0.35-s period of shortening near half-maximum velocity beginning after 2 s of isometric stimulation, and (b) a 0.65-s isometric period immediately following the shortening. There were no significant changes in levels of ATP, ADP, or AMP in the two contraction periods. The observed changes in inorganic phosphate and creatine levels indicated that the only significant reaction occurring was phosphocreatine splitting. The mean rate of high-energy phosphate splitting during the shortening, 1.60 +/- 0.23 mumol X g-1 X s-1 (n = 24), was about fivefold higher than that in the 1-s period in the isometric tetanus, 0.32 +/- 0.11 mumol X g-1 X s-1 (n = 17), observed in our previous study. The mean rate in the post-shortening period, 0.46 +/- 0.13 mumol X g-1 X s-1 (n = 17), was not significantly different from that in the 1-s period in the isometric tetanus. A large amount of heat plus work was produced during the shortening period, and this could be accounted for by simultaneous chemical changes. In the post-shortening period, the observed enthalpy was also accounted for by simultaneous chemical reactions. Thus, the present result is in sharp contrast to that obtained from a similar study performed at a shortening at Vmax, where an enthalpy excess was produced during shortening and an enthalpy deficit was produced during the period following the shortening.

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