scholarly journals Kinematic Effects of the Target on the Velocity of Taekwon-Do Roundhouse Kicks

2021 ◽  
Vol 80 (1) ◽  
pp. 61-69
Author(s):  
Jacek Wąsik ◽  
Dariusz Mosler ◽  
Dorota Ortenburger ◽  
Tomasz Góra ◽  
Jarosław Cholewa
Keyword(s):  
Maximum Velocity ◽  
Motor Preparation ◽  
Technical Training ◽  
Lateral Side ◽  
Tennis Ball ◽  
Maximal Velocity ◽  
Body Parts ◽  
Table Tennis ◽  
Adult Males ◽  
Different Shapes

Abstract The phenomena of target kinematic effects under different striking conditions and applying different techniques constitute one of the fields of research for sports biomechanics. However, the influence of some kinematic variables which change under different strike conditions for specific parts of the lower limb remains unknown. The aim of this study was to extend the knowledge on how targets of different shapes or the lack of a physical target would affect maximal velocity registered by a marker placed on the foot, knee and hip during the execution of a roundhouse kick. In total, 15 adult males were included in this study. All participants were taekwon-do elite athletes. The displacement of markers placed on the lateral side of the foot, knee and hip during movement execution was registered by a stereophotogrammetry apparatus. Participants performed taekwon-do roundhouse kicks for three target types (into the air, a table tennis ball and a training shield) applying either a sport or a traditional style. The highest maximal velocity was obtained for kicking into the training shield. When applying the sport style, the highest maximal velocity of foot markers for the executed kicks was registered. Kicking into air resulted in higher velocities for proximal body parts than kicking into a tennis ball, but the effect was reversed for the foot marker. In conclusion, a large resistance target is suitable for athletes’ motor preparation as it allows the highest maximum velocity to be reached. Small non-resistant targets are recommended for technical training.

scholarly journals Physiotherapeutic Applications of Biomechanical Opposing Indicators – Based on Measurements of Taekwon-Do Athlets

2017 ◽  
pp. 212-215
Author(s):  
Jacek Wąsik ◽  
Dorota Ortenburger ◽  
Tomasz Góra
Keyword(s):  
Green Light ◽  
Maximum Velocity ◽  
Standing Position ◽  
Tennis Ball ◽  
Table Tennis ◽  
Everyday Functioning ◽  
Kinematic Effect ◽  
The Road ◽  
Average Maximum ◽  
Left And Right

Background. In everyday life people constantly face the dilemma of speed and accuracy. The aim of the cognitive quantification was to increase the knowledge about kinematic effect of a target. The practical aim would be to apply kinematic effect of a target in clinical situations, to supply for physiotherapeutic programs. Material and Method. The analysis was performed 14 taekwondo ITF athletes. During research they performed front left and right kicks in a lateral standing position: into the air (without a physical target), to a table tennis ball hanging on a line and a training target. The laboratory for the analysis of movement named HML was used here. Results. The highest average maximum velocity was obtained by the kicks without a physical target (10,78 - 1,32 m/s for men and 8,51 - 1,50 m/s for women)(p<0,05), then to the shield (9,98 - 1,40 m/s for men and 8,28 - 1,59 m/s for women) (p<0,05) and to the ball (9,63 -0,94 m/s for men 7,73 - 2,01 m/s for women) (p<0,05). Discussion.The obtained results provided the argument supporting the thesis that the type of target influences on the method of solving the dilemma: the velocity of movement and its precision during a frontal kick. Both, in the case of women and men who practisetaekwon-do, lowering the velocity of a kick, performed towards a precisely established target, in comparison with the velocity of a kick without a precisely established physical target (into the air) was observed. For many people with the dysfunctions of the movement organs, everyday functioning, especially related to movement, makes a challenge. In such a case crossing the road at the green light in particular time or stepping on the escalator (the examples of such barriers are numerous) are the tasks that reveal the dilemma of velocity and precision. There are many factors that may support the efficiency of these efforts. One of them may be the feeling of the efficiency of activity that has a psychological character.

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.

Conspecifics of the Striped Lava Lizard are able to distinguish sex and male colour morphs in apparently homogeneous dull dorsal colouration

2019 ◽  
Vol 40 (2) ◽  
pp. 149-162 ◽  
Author(s):  
Andre C. Bruinjé ◽  
Mauricio O. Moura ◽  
Bruno S. Maggi ◽  
Vinicius A. São-Pedro ◽  
Daniel M.A. Pessoa ◽  
...  
Keyword(s):  
Body Region ◽  
Body Parts ◽  
Adult Males ◽  
Intraspecific Interactions ◽  
Body Regions ◽  
Animal Colouration ◽  
Colour Morphs ◽  
Lava Lizard ◽  
Uv Reflection ◽  
Colour Classes

Abstract Animal colouration plays a key role in inter and intraspecific interactions, pre-eminently in mate signalling. When multiple types of colouration occur within sexes it is possible that they show alternative reproductive strategies. In lizards, most colouration studies do not incorporate how colour is perceived by conspecifics. Here, we used unbiased colour analysis methods (spectrophotometry and visual modelling) to test for sexual dimorphism and within male dichromatism in the Striped Lava Lizard. We found that males express two distinct colourations that are different from females in several dorsal and ventral body regions. Our results showed UV reflection at the throat, an important body region for signalling. Ventral patches, the coloured badge seen in adult males of Tropidurus spp., have two distinct colour classes within males (Y and B males). Morphs are best discriminated by blue and yellow chroma, and brightness. Body size had little influence on colouration, suggesting that colour may be linked to inheritance rather than growth. Our study clearly shows sexual dichromatism and the existence of colour morphs in this species. Moreover, morph differences in colouration are perceptible by conspecifics. These differences are not only between ventral patches, but also in other body parts such as the dorsum, previously considered as cryptic by human observers. We suggest that colouration at the ventral patches and throat might play a role in intraspecific interactions. Patches increase colour intensity during breeding season and are likely to be costly by pigment-based expression, whereas throat’s UV reflection might have a cost infringed by conspicuousness.

scholarly journals Table Tennis Ball Impacting Racket Polymeric Coatings: Experiments and Modeling of Key Performance Metrics

2019 ◽  
Vol 9 (1) ◽  
pp. 158 ◽  
Author(s):  
Renaud G. Rinaldi ◽  
Lionel Manin ◽  
Sébastien Moineau ◽  
Nicolas Havard
Keyword(s):  
Performance Metrics ◽  
Incident Angle ◽  
Mechanical Analysis ◽  
Tennis Ball ◽  
Table Tennis ◽  
Polymeric Coatings ◽  
Compression Tests ◽  
Compliant Behavior ◽  
The Impact

The performance of a table tennis racket is often associated with subjective or quantitative criteria such as the adhesion, the control and the speed. Overall, the so-called performance aims at characterizing the impact with the ball. Ultimately, the polymeric layers glued onto the wooden blade play a key role, as evidenced in a previous work where the normal linear (no spin) impact of a ball onto polymeric layers was experimentally and numerically investigated. In this work, more realistic loading conditions leading to varying the incident angle and spin of the ball, were explored. While the sole linear restitution coefficient was determined in the anterior normal impact study, new physical metrics were identified to describe fully the trajectory of the reflected ball after impact. A companion 3D finite elements model was developed where the polymeric time-dependent dissipative compliant behavior measured with dynamic mechanical analysis and compression tests was accounted for. The confrontations with the experimental data highlighted the key role of the polymer intrinsic properties along with the friction coefficient between the ball and the polymer external layer.

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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