"Fosbury flop" high jump performance improvement technology
Фотографии:
ˑ:
Dr.Hab., Professor V.V. Antsyperov1
Dr.Hab., Associate Professor V.A. Likhodeeva1
Dr.Hab., Associate Professor V.A. Ovchinnikov2
PhD N.L. Goryacheva1
1Volgograd State Academy of Physical Culture, Volgograd
2Volgograd Academy of MIA of Russia, Volgograd
Keywords: technique, biomechanics, jump, height, movement, swing body segments
Introduction. Movement construction is subject to biomechanical laws, without knowing which it is impossible to purposefully improve the technique. An athlete controls body locomotion in space through joint movements by limiting mobility in certain joints and activating it in some others.
One of the ways to increase high jump performance is taking into account the leading biomechanical parameters in the structure of athlete’s actions and establishing their role and efficiency in achieving the final result. In order to improve the technique of every movement you need to know when, how and to what extent you should change the movement [6, 11]. So, Boloban V.N. [1] points out that a motor action will be effectively implemented if the laws of inertia are used to the maximum to move the body and its segments. Active muscle effort manifests itself therewith in the movement phases and moments, in which their influence is most appropriate. The importance of applying the inertia law in the movement construction and regulation lies in the fact that this law is the foundation underlying the whole doctrine of kinesiology.
According to experts, top results in Fosbury Flop high jump can be achieved by the optimal combination of kinematic and dynamic parameters [10, 12]. This was confirmed in a number of research studies [5, 7, 9]. It is recommended to use mathematical movement models [2], the characteristics of athlete’s poses and movements [7]. Zaborsky G.A. [5] believes that the comparison of model characteristics of the motor optimum to the structure of jumper’s take-off movement being reproduced in practice will help identify the elements of his/her technical and speed-strength skills and abilities, which, with certain correction and improvement, will form the individual optimum take-off jumping technique [8, 10].
Gaverdovsky Y.K. [3] indicates that it is the purposeful synchronized joint action that represents the maximum take-off model. Therefore, persistent work on developing the skills of synchronized operation of body swing segments at take-off is required in the jump training process. This suggests the search for the optimal combined work of body swing segments at take-off to be of special importance in high jump performance. In our opinion, this approach will help successfully influence the outcome in Fosbury Flop high jump.
Research methods: qualitative biomechanical analysis of movement.
Results: Incredible as it may seem, high jumps and gymnastic exercises have a lot in common. So, Y. Gaverdovsky [3], comparing high jump in athletics and backward rotation jumping exercises in acrobatics and gymnastics, believes that it is not only physical qualities that play a major part in them but also technique and, arm work in particular.
The jump technique has been studied well enough in athletics by now. But what can we still change in it? Analysis of high jumps at world championships and Olympic Games, carried out by gymnastics experts, put them to some confusion. Actually, it is impossible to execute a back flip with this technique of arm work in gymnastics.
With this in mind, we carried out a comparative analysis of the work efficiency of the body swing segments in the world’s top athletes - world and Olympic champions E. Slesarenko, A. Chicherova, M. Kuchina, B. Vlašić - in Fosbury Flop high jump (Figure 1).
Fig. 1 High jump performed by top female athletes
All female athletes display individual techniques of take-off and swing segments work, with no claims to swing-up leg work. The leg is drawn up to exactly horizontal position, creating rotation about a transverse axis and additional kinetic energy that is transferred to the body, which allows the whole body rise. Besides, single leg asymmetrical work contributes to body rotation around its longitudinal axis with the back turned to the bar. But, in gymnast’s opinion, the arms work is not quite rational and, consequently, ineffective. This, in turn, does not allow for a better result. Where does this inefficiency manifest itself?
It is known from biomechanics that swing movement made with body peripheral segments is an essential component of any take-off movement. In principle, it is impossible to "start" the mechanism of interaction with support without accelerated movement of peripheral segments [4]. The analysis of jumpers’ chronophotographic images makes it clearly visible that arms work is associated more with body rotation around its longitudinal axis than a take-off power increase.
As is well known, turns can be performed with or without support. The first ones (with support) are started with an initial torque force by interacting with support. You can see it clearly on chronophotographic images. Foot setting and single leg swing contribute to creating a pair of forces leading to a slight torso rotation. Arms, head and trunk are involved in this movement.
However, you can clearly see in the jump technique the actions that are typical for unsupported rotation. This manifests itself in the fact that after a take-off the athlete straightens himself up. In addition, after flapping to horizontal position the arms normally execute dissimilar movements. Next, one arm keeps moving up and down, while the other one, along the body, goes down and is swung aside in a circular movement. All this also contributes to an additional body rotation about the longitudinal axis, as it leads to a change in the body inertia moment. All these actions indicate the use of a mixed mechanism to create a rotational impulse on the support and maintain it in the flight phase.
In some publications there are method guidelines and chronophotographic images in which the arms remain passive after the swing and as the body continues to move they are drawn to the trunk. And that's where their work ends.
As is well known from biomechanics, after creation of a powerful torque it must somehow be stopped. As you can see on the chronophotographic images, to do this the athletes extend their arms sideways. In our opinion, this is not very rational. A similar description of the technique can be found in some research and methodological publications [5, 8, 9, 10].
The question arises: what should be done to improve the jump efficiency in general? How can you switch the arms work to increasing the overall performance and take-off power?! According to Y.K. Gaverdovsky [3], rotation of the body swing segments during take-off is a characteristic and rather subtle technical feature of sport movements. Whenever a movement program involves active rotation of the whole body, it is important how exactly the athlete’s swing segments function at the take-off. The author refers to a number of factors related to the swing segments work that are responsible for the take-off energy efficiency (Table 1).
Table 1. Energy efficiency of take-off swing movements (according to Y. Gaverdovsky)
Factors |
Action mechanism |
Acceleration of free segments during their swing movement |
The more the athlete’s free body segments accelerate in the first take-off phase, the more their pressure on the support is due to the reactive interaction in the kinematic chain and the more efficient and physically powerful the whole take-off is. |
Optimum range of swing movement
|
The maximum energy effect will be obtained when the swing movement of free body segments is performed only until a segment continues to gain momentum, and thus kinetic energy. |
Mass of segments involved in swing movement |
The bigger the body mass involved in the accelerated movement, the more powerful take-off is (synchronization of the take-off leg push on the ground with the free leg and arms swing) |
Deceleration of swing segments |
The sharper the deceleration of swing segments, the stronger the movement in the second phase of take-off is |
In concluding the study of tthe high jump technique it is necessary to specify the arms’ passive work after extending them sideways. This, in turn, does not contribute to the active rise of pelvis and legs above the bar and body rotation as a whole. Visually, it looks like a passive rotation about an axis passing through the general center of the body mass with lowering of head and shoulders, followed by hips and thighs. Clearing the bar ends with the feet going up by virtue of leg extension in the knee joints.
It follows from the above that while mastering the jump technique it is important to find the most efficient combination of the movement parameters, when technical extremes are excluded and an optimum solution should be selected to solve a complex motor task. In our opinion, the elimination of the above shortcomings will enable athletes to jump higher and ensure stability in the high jump performance.
Conclusions. Thus, analysis of high jumps performed by top athletes has shown that in order to improve the jump technique it is particularly important to find an optimal combination of swing segments work, taking into account the patterns of mechanical energy transmission from one segment to another.
Moreover, to solve this task it is necessary to revise the arms work technique, since the current one cannot be considered rational enough.
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Corresponding author: ua4ahp@gmail.com
Abstract: Objective of this paper was to provide a theoretical substantiation of the work of the body swing segments in high jump and substantiate the significance of individual technical skills. Analysis and evaluation of the body swing segments at the moment of take-off from the support indicated low take-off energy efficiency, inadequate arms acceleration, asynchronous functioning of free segments and the body, excessive actions taken for body rotation around the vertical axis. It was shown that an athlete can jump higher by taking purposeful synchronized joint actions with regard to the patterns of mechanical energy transmission from one body segment to another.