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artículo sobre la trayectoria en el press de banca

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artículo sobre la trayectoria en el press de banca

Mensaje por .:überfranz:. » 12 Jun 2019 13:14

artículo escrito por Boris Sheiko.

Sheiko Boris Ivanovich – powerlifting head coach of Bashkortostan,
Lukyanov Boris Georgievich – Candidate of Technical Sciences
Fetisov Vladimir Stanislavovich– Doctor of Technical Sciences, professor

First results of the biomechanical analysis of the bench press

technique

For the achievement of the top results in sport the efficient technique is necessary
- the most rational and efficient way of the competition exercises execution. On the all
sporting way from a beginner to the world-class athlete, a sportsman must constantly
work upon the improvement of his technical skill.
Technical preparation of athletes is impossible without the analysis of the sports
exercises performing. The biomechanical analysis is the most objective and substantial.
The question about its efficiency has particularly sharply got up at the present stage of
the sport development: the exercises technique getting more and more complicated,
high requirements to the technical skill, the enormous incandescence of the sport
fighting compels to mobilize the available reserves of the training information.
The exact quantitative biomechanical analysis of the exercise execution presents
itself a powerful instrument of the researches in the sport field. This form of the
analysis is necessary for revealing and setting the standards of competition exercises
execution, for decision on a matter of the building of the motion, for determination of
the biomechanical regularities of moving functions. This kind of analysis allows to
understand the reasons and essence of technical mistakes of making physical exercises,
first of all the athletic ones, to find the way to remove such mistakes, to select the
variant of the efficient individual interpretation of the exercise technology and at the
same time to save wholeness of the rational base of the technique. The biomechanical
analysis presents the unit, which is called to link the biomechanics organically with
sport training.
In modern sport the approach to the estimation of the sport exercise technique,
either as many factors of the organism of the athlete, remains basically empirical. Very
often the working of the researcher on analysis of facts about moving functions and
their comparison carries the stale nature, particularly if serial experiment is conducted
with many tested persons. Meantime with the information technologies development it
became possible to automate the researcher’s work, save him from the need to process
manually the immense amounts of data. In particular, the tempestuous development of
thу video and computer technologies of the video files processing makes much more
expedient the using of these achievements in the analysis of the sport moving functions.
In such sports as powerlifting at present time there is the deficiency in
information about the biomechanical parameters of the competition exercises execution
technique. During the studying of the scientifically-methodical literature the authors did
not discover any works with detailed description of the rational technology of exercises
execution in powerlifting, of the possible changes of this technology depending on
different factors (such as athlete’s antropometric parameters, the level of physical
preparedness and athletic skill, the presence of the special equipping and others).
Thereby, the undertaking of the studies in specified directions is very actual. All this
can give more valuable information to the coaches and sportsmen in the field of skill
revealing and rational management of the training process.

The goal of our research is a study of the sport exercises technique in
powerlifting with attraction of modern technical facilities. The detailed knowledge of
the features of the motion will considerably help to elaborate the recommendations for
the technique improvement methods of powerlifters of the different sport qualification.
The given article describes some results of our work on studying of one of the three
sport exercises - "bench press".
The priority problems of this study were:
1) the statistical observations of the bench press execution technique by the
athletes with different techniques and qualification in competition conditions;
2) the categorization of the received kinematic features;
3) the comparison of the received features with success of the current attempts
and the athlete’s achievements in longer retrospective review.
In our study we have used the kinematical analysis elements of the human
physical actions, in which the following motion features are usually studied as
trajectories, displacement, velocities and speed-up time-bases. At this stage of the
studies, for the bench press technique analysis in powerlifting we used the motion
trajectory of the centre of the barbell’s butt, as well as the time-bases of changes of the
vertical coordinate of this point.

Pict.1. Typical graphs of the trajectory of the centre of the barbell’s butt and of the time-bases of its

vertical displacement, velocity and speed-up

(on the graphs the black point designates the position of the current observable shot)

As basically all barbell’s points move relatively to the athlete in planes, which are
parallel to his sagittal plane, so in order to make an analysis of the motion of any point
of the biokinematical system "athlete-barbell" it is particularly important to know two
strands of its motion: vertical and horizontal, whose the integral factor is the motion
trajectory of some point of the barbell. The trajectory of the barbell’s center of gravity
is one of the most important features of quality of the competition exercises technique
in powerlifting, giving corresponding idea of vertical and horizontal spatial
displacements of the whole system. Under certain admissions it is possible to think that
the trajectory of the centre of the barbell’s butt (CBB) repeats the trajectory of the
barbell’s center of gravity (BCG).
The study was conducted on the base of the School of the highest sportsmanship
of the Republic of Bashkortostan (city of Ufa). The bench press execution by the
athletes of different level was analyzed (Candidate master -30 persons, Master of sports
of Russia – 70 persons, World-class athletes – 20 persons). The observations were

conducted at the period of 2006-2007 during the competitions of regional and all-
Russian levels: the Cup of the Republic of Bashkortostan (2006), the bench press

championship of the Republic of Bashkortostan (2006), the Ural and Volga regions’
championship (2007), the championship of the Republic of Bashkortostan (2007), the
Russian junior championship (2007), the Cup of Russia (2007). During the studies in
the purpose of video filming we have used the digital Sony HDR-HC3E video camera
with shooting speed of 25 frames per second. For the video clip’s digital conversion we
have used the base plate of the frame capture and software package Pinnacle Studio
10.0; the frame format - .avi, 720х576 pixels. For the video segments’ computer
analysis the authors have elaborated the software product Motion Trace / PowerLifting.
The authors have analyzed more than 250 exercise execution attempts by the

athletes of different level and different weight categories with the analysis of the above-
mentioned kinematical features of the CBB’s motion.

The bench press technique analysis was conducted on the base of the bench press
phase structure [5, 6] (Table 1).

Phases of the bench press execution

Table 1
Phase 1 Phase 2 Phase 3 Phase 4 Phase 5 Phase 6 Phase 7
The prior
start
position
Start
position
(fixing the
weight on
the straight
hands)

Descent the
weight to the
chest after the
referee’s
command
«start»

The pause
fixing
with the
weight on
the chest

The bench
pressing
after the
referee’s
command to
press

Fixing the
apparatus
in the
final
position

Putting the w
weight to
the supports
after the
referee’s
command
«to the
supports»
According to the technical competition rules, the 1st and the 7th phases are
executed by the athletes by the means of assistants [7], that’s why the bench press
technique analysis directly from the 3rd to 5th phases provokes the most interest.
Phase 3. Descent the weight to the chest

After the acoustical signal "start", which is given by the main referee, an athlete
lowers the barbell on his chest (the chest, according to the present rules, ends beside the
base of the breastbone) [7]. The time of the barbell’s descent on the chest depends on
athlete’s anthropometric particularities of the (the lengths of hands), the width of the
grip, the height of the "bridge", the lowering velocity and the barbell’s weight, as well
as it depends on the bench press shirt quality. After more than 250 graphs of the
barbell’s vertical moving in the descent phase were being analyzed, it was revealed that
the duration of the descent phases varied from 0.6 up to 3.0 seconds that at the average
has formed 1,28 seconds.
Phase 4. The pause fixing with the weight on the chest
After the barbell’s descent on the chest, the athlete must keep it in still position
on the chest [7]. The barbell’s still position on the chest means the stop. At the analysis
of the vertical displacements graphs it was revealed that the athletes’ pauses are
different, not only in its duration, but also in its execution. Along with athletes, who
begin the barbell’s press execution from the same point, where they have lowered it (for
example see pict.7 and pict.8), we can meet the considerable amount of sportsmen,
whose barbell is displaced during the pause on the chest. The barbell can be displaced
onward (from the head) or back (for example see pict.11).
The minimum fixed pause duration made 0,3 seconds, the maximum pause
duration was equal to 1,5 seconds. The average pause was 0,70 seconds.
Phase 5. Bench press
After the command "press" of the main referee the athlete must press the barbell
upwards on straight hands without the surplus (too strong) uneven unbending of the
hands [7].
All paths of the bench press execution can be conditionally divided upon their
form into several groups, differing by the typical elements. The each of the pictures 2-
11 presents one typical example of the each trajectory group that we have noted.
For all trajectories presented in the given work, the athlete’s head must be
situated on the left. The criterias of the clusterization on groups are: presence or absence
of the intersection with the vertical, getting through the trajectory’s beginning (which is
shown by means of the vertical line on graphs); presence or absence of the loop;
presence of the trajectory’s vertical area, presence or absence of the lower flat area (the
offset of the bar onward or back before the beginning of the ascent of the barbell from
the chest).

We shall consider the typical trajectories groups and their elements that we have
detected:
1. The trajectory of the type 2 (picture.2). The trajectory of the phase of the ascent
(strictly the press) practically repeats the trajectory of the phase of the barbell’s descent.
There is no any intersection with the initial vertical. The trajectory is often nearly
straight. The distant point of the stop from the vertical tells that the athlete has lowered
the barbell far on his belly that is forbidden by the competition rules.
2. The trajectory of the type 3 (picture 3). The trajectory of the phase of the
ascent once crosses the initial vertical and vastly deviates from the trajectory of the
phase of the barbell’s descent aside the athlete’s heads.
3. The trajectory of the type 4 (picture 4). The trajectories of the barbell’s descent
and ascent phases don’t cross with each other and with the initial vertical; herewith they
slightly disperse from each other. The entire trajectory is situated on the right from the
initial vertical.
4. The trajectory of the type 5 (picture 5). The trajectory of the ascent phase is
slightly displaced onward from the trajectory of the descent phase and returns nearly in
the source point. There is no any intersection with the initial vertical.
5. The trajectories of the type 6 (picture 6) are characterized with the presence of
the loop in the lower part of the trajectory, moreover the ascent phase beginning is
displaced to the right (up to the athlete’s legs) relatively to the descent phase end. The
trajectory of the ascent phase can cross or can not cross the initial vertical.
6. The trajectories of the type 7 (picture 7) are also characterized with the
presence of the loop, but it is higher than in the previous trajectory. The ascent phase
Pict. 2. Trajectories of the 1st type Pict. 3. Trajectories of the 2nd type

beginning is displaced to the left (to the athlete’s head) relatively to the descent phase
end. The trajectory of the ascent phase doesn’t cross the initial vertical.

Pict. 4. Trajectories of the 3rd type Pict. 5. Trajectories of the 4th type

Pict. 6. Trajectories of the 5th type Pict. 7. Trajectories of the 6th type

7. The trajectories of the type 8 (picture 8). The ascent phase trajectory once or
twice crosses the initial vertical. On the picture 8 we can see that after the barbell’s stop
the athlete has done the indention of the bar in the chest that is forbidden by the rules.
8. The trajectories of the type 9 (picture 9) are characterized with the presence of
the typical "stumbling block" (hereinafter - "dead point") on the area of the ascent
phase. This area is the most uncomfortable for the manifestation of active muscular
power of the athlete. This zone is one of the main factors, limiting the sport result. The
correlative analysis has shown that the height and the time of the "dead point"
manifestation is individual for each athlete. Their amounts depend on the qualification,
gender, percentage of the apparatus weight and the individually-maximum result in the
press. The trajectory of the ascent phase can cross or can not cross the initial vertical.
9. The trajectories of the type 10 (picture10) are characterized with the nearly
vertical descent of the barbell with a possible (single or double) intersection of the
initial vertical. The ascent of the barbell is possible either on the trajectory with forming
the loop, or on the trajectory, wholly lying to the left of the initial vertical.
10. The trajectories of the type 11 (picture 11) are characterized with the presence
of the offset of the bar to the left or to the right in the lower part of the trajectory.

Pict. 8 Trajectories of the 7th type Pict. 9. Trajectories of the 8th type

The juxtaposition of the trajectories configuration with the average number of
ascents successfully executed by the athletes of different qualifications has shown that
the trajectories on the pictures 1-4 are characteristic most of all for the athletes who
have got high and stable results in the competitions.
The duration of the phase of the press from the chest were also quantitatively
evaluated. This phase has a wide scatter of values in time: from 0,5 seconds up to 5,0
seconds, at the average duration of 1,4 seconds.
We can notice an observable repeatability of elements which are typical for the
concrete athlete, so it makes sense to carry out the technique analysis, the estimation of
the athlete’s current condition, the forecasting of the following results and the loads’
correction, having a set of statistical matters on the given athlete. We were, in
particular, gathering the information on trajectories and temporary unrolling of the
CBB’s vertical displacement, supplied by the materials about the weight of the athlete
and of the apparatus, the attempt success and the factors, which can influence upon the
result.
For example, on the pictures 11 and 12 we see the trajectories as well as the time
sweep of the CBB’s vertical displacement and the relative CBB’s motion velocity for
the two different athletes. On the left of each of these illustrations there are the graphs
for the attempt with weight, corresponding to 80-85% of the limit load, and on the right
- for the attempt with weight, very close to the limit. Black points on the graphs mark
the positions, corresponding to the spike of the barbell’s ascent velocity. The graphs
give the visual presentation about the technique particularities of each athlete.
So, the athlete A.Fyodorov (pic.12) is typified by the fluent beginning of the
descent phase (about 3 seconds), by the delay in lower position (about 0,6 seconds), and
then by the uniform quick ascent (nearly 1 second). When the barbell’s weight is close
to the limit loads, the uniformity of the ascent is broken: on the time sweep we see the
Pict. 10. Trajectories of the 9th type Pict. 11. Trajectories of the 10th type

evident "dead point" between the 7th and the 8th seconds, and the ascent velocity graph
becomes "double-humped". We can observe this fact beside the majority of athletes
during the limit loadings. The corresponding areas can be also often seen on the
trajectory graph (see the picture 8).

Pict. 12. Trajectories and time sweeps of the CBB’s vertical displacement for the two attempts of
A.Fyodorov (Candidate Master, born in 1978, his own weight 100 kg, the Bashkiria’s Cup

17.12.2006)

Pict. 13. Trajectories and time sweeps of the CBB’s vertical displacement for the two attempts of
D.Kashuba (Master of Sports, born in 1987, his own weight 135 kg, the Bashkiria’s Cup 17.12.2006)

The technique of D.Kashuba (pic. 13) is characterized by the considerably stable
trajectory, by the minor deformation during the loads increasing, the uniform ascent and
descent, nearly equal in time and forming 1,5 - 2,0 seconds, a short (≈ 0,4 seconds)
delay in lower position. The load increasing also causes a certain deceleration of the
second half of the ascent phase and a narrowing of the positive surge on the velocity
graph, but it is not very much expressed.
It makes sense to recommend the use of the quantitative information about the
degree of the trajectory deformation during the barbell’s weight increasing and about
the deceleration in the medium of the ascent phase in order to make the operative
estimation of the athlete’s possibilities of the and to plan the trainings.
The time sweeps of the vertical displacement also allow to check the refereeing
quality during the competitions, as they can clearly show good and bad barbell’s ascent
attempts of the athlete. As example, the picture 14a demonstrates the graph for the
occasion, when the press delay during the ascent has the critical value, but the attempt is
usually scored as the good one, because there is no practically the negative vertical
displacement. On the picture 14b we see the area with the negative offset (the offset
downwards on the 4th second), because of which the attempt is scored as bad one in
spite of the fact that the athlete pressed the barbell by himself.

Pict. 14. Time sweeps of the CBB’s vertical displacement during the athletes’ unsuccessful

attempts of the apparatus ascent in the bench press

The analysis of the typical deceleration occasions during the ascent allows to
make a conclusion that the attempt is usually scored as bad one, if the ascent velocity at
the beginning of this phase doesn’t exceed 10 cm/sec or the duration of the flat area in
the medium of the phase exceeds 1 second, and the barbell’s weight is close to the limit.
The pictures 14c and 14d show the graphs for the occasions, when the barbell is already
put on the stances by assistants.
In the course of this research we have realized the biomechanical analysis of the
execution of the bench press competition exercises that has allowed to reveal the
factors, defining the differences in technique of these exercises, and to make objective
estimations of them.
The high-class athletes with the fully formed technique are typified by their own
stable and unique trajectory type, as well as by the type of the time sweeps of the
vertical displacement and velocity.
The trajectory analysis allows to draw conclusions concerning the motion
rationality and the presence of the evident mistakes while doing an exercise.
The revealed kinematical particularities of the exercises performing can be used
in creating the models of the rational (master) powerlifting exercises techniques.
The obtained results of the studies allow to make a qualitative express-analysis of
the motion during the trainings or competitions, even without the accumulated video
segments base on the concrete weightlifter.
Comparing the space-temporary and dynamic features of the motor actions of the
athletes of different sport skill during performing the exercise, we can get a foretaste of
mistakes of the athlete with the lower skill level and of the master technique parameters,
required for the high results achievement.

Literature

1. Zhekov I. The biomechanics of weightlifting exercises. – Moscow: Physical
culture and sport, 1976. – 192 p. (in Russian).
2. Roman R. Methods of kinogrammes processing at the studying of the push and
jerk techniques// Weightlifting: yearly periodical. – 1978. – Moscow: Physical culture
and sport, 1978. – P.39-49. (in Russian).
3. Petrov V., Gagin Y. The mechanics of sport motion. – Moscow: Physical
culture and sport, 1974. – 232 p. (in Russian).
4. Cedov R., Dolgov V., Macko A. The analysis of the trajectory of the barbell’s
centre of gravity in the bench press in powerlifting / Works of the Institute for scientific
research of the physical culture and sport problems KubGafk. – Krasnodar, 1999. (in
Russian).
5. Sheiko B. Bench press technique. // Olipm. – 2002. - No3-4. P.20-25. (in
Russian).
6. Sheiko B. Powerlifting: Study guide. – Moscow: Published in ZAO «ЕАМ
Sport Service», 2005. – 544 p. (in Russian).
7. Shantarenko S. Powerlifting. Technical rules. Omsk. Published in FPR, 2007.
– 64 p. (in Russian).



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Autor del Tema
.:überfranz:.
Intermedio
Intermedio
Mensajes: 84
Registrado: 02 May 2019 18:29
Ubicación: Oslo
Género:
Italia

Re: artículo sobre la trayectoria en el press de banca

Mensaje por .:überfranz:. » 12 Jun 2019 13:14

el problema es que no puedo postear las imágines...

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Autor del Tema
.:überfranz:.
Intermedio
Intermedio
Mensajes: 84
Registrado: 02 May 2019 18:29
Ubicación: Oslo
Género:
Italia

Re: artículo sobre la trayectoria en el press de banca

Mensaje por .:überfranz:. » 12 Jun 2019 13:36

quizá de esta manera?

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