The Weightlifting Pull

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Here is a short edited extract from a translation carried out by Bud Charniga

in his " Weightlifting Training and Technique " book, which some of you might

find to be a useful addition to your libraries. Details of this and other

texts may be seen here:

http://www.dynamic-eleiko.com/

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Biomechanics of the Weightlifting Exercises

Ilya Pavlovich Zhekov

Fizkultura i Sport, Publishers, Moscow 1976

Optimization of the Pull with the " Squat Under "

Four Factors, Defining the Dynamics of the Pull with the Squat Under

The factors, defining the dynamics of the pull with the squat under are the:

the speed of the descent, the vertical speed, the height of the lift and the

height of the squat under.

The Speed of the Descent

Even an untrained person can lift an empty bar (20kg) to his chest, then to

straight arms overhead without resorting to a special technique. However, if

discs are subsequently loaded onto the bar, increasing the weight to 50 kg,

for example; already he is unable to successfully lift the barbell to his

chest. Initially, it forces the chest lower by 5 cm, then by 10, 29, 30, 40

cm and so forth. Finally a weight is reached that can only be lifted up to

the knees. Nevertheless, it is still possible to lift it to the chest! If it

can't be raised to the level of the chest, then the chest has to be lowered

to the level of the barbell. But how is this done?

If you hold a barbell below the level of the chest and try to lower your

chest to the bar, the bar will also be lowered. Regardless of how you try to

lower your chest to the bar, you will not meet with success. If you could

free yourself from the barbell for some time, this would be another matter.

And, the fact is that it is not difficult to do this: you need only to cease

applying force to the bar, release your hands from the bar or not release it

in order to once again not have to grasp it. But we cannot force the barbell

to remain in the same place. However, we can make it move independently.

Why are you unable to successfully lift a heavy barbell to the chest? This

can be explained as follows. The Earth's gravity generates the same

acceleration and consequently, the same amount of time for a specific descent

speed. Therefore, the chest will always be the same distance from the barbell

when you try to lower it. It (the chest) requires a larger speed in order to

catch up to the barbell. This allows the chest to catch up to the barbell as

when a runner catches up to the runner in front, during the baton pass in a

relay race, for instance.

Therefore, it is quite clear that the lifter is confronted with a very

important task: to be able to find the favorable instant during the lift in

which to lower the chest earlier than the descending barbell. If the athlete

is able to do this, then at the very instant when the barbell begins to

descend, the lifter's chest will already have a definite speed as well as a

downward direction which will enable him to not only catch up to the barbell

but to outstrip it.

It is possible for the lifter to cease trying to lift the barbell up and to

begin the " squat under " , 0.1 sec. earlier than the barbell begins to descend.

When the distance between them (the bar and the chest) is 30 cm, they begin

to descend together. The difference between the speed of the downward descent

of the athlete's chest and that of the barbell is 1 msec. This is due to the

earlier descent into the " squat under " , which in turn enables the athlete to

develop a larger speed and consequently, outstrip the barbell.

We can now make a fundamental conclusion: the lifter needs to achieve a

definite descent speed (1 msec. in our example) at the instant the barbell

reaches its greatest height, in order to successfully execute the classic

exercises. The athlete's speed of descent at the instant the barbell reaches

its maximum height is the " catch-up " speed.

The Vertical Speed

It is obvious from the just discussed characteristics of the " catch up "

speed, that the magnitude of this speed is determined by the distance of the

independent vertical movement of the barbell, which is dependent on the

barbell speed at the instant when the lifter ceases to exert a strong

influence on it. The longer this vertical movement, the greater the speed of

the " catch-up " . The portion of the lift at which the lifter communicates the

greatest vertical speed at a specific height is called the pull. The largest

speed the barbell acquires during the pull is called the maximum vertical

speed.

The Height of the Lift.

This is the height at which the barbell reaches its greatest speed during the

pull. [Comments?] Furthermore, the barbell reaches its greatest speed at the

instant when the acceleration is zero. Consequently, the height of the lift

can be defined as the distance over which the athlete communicates a positive

vertical acceleration to the barbell.

Increasing the height of the lift makes it possible to lift a barbell with

less force and with less power. However, there are two essential limitations

to increasing the height of the lift:

1. When the lifter lifts a small weight he can employ the strong muscles

(the legs, for example) to a greater extent than the weaker (the arm muscles

for instance). With the increase in the weight, the weaker muscles, already,

are not in a state to actively participate in the lifting; therefor, the

height of the lift gradually decreases.

2. An athlete primarily employs the muscles of the legs and torso to lift a

(personal) maximum weight. As these muscles contract, they increase the

angles between the levers of the lifter's kinematic chain (the shins, thighs

and the torso) up to the instant, they assume a vertical position. Therefore,

the acceleration path is defined basically as the length of the levers of the

kinematic chain. The length of the levers is constant. Therefore, the path of

acceleration of a near-limit and a limit weight for a given lifter is

practically constant. Here lies the second limitation.

Here it is necessary to point out, that we are talking about increasing only

the vertical acceleration path and no other. Any curve in the barbell

trajectory designed to increase its acceleration path, which would be the

same as increasing the time of influence on the barbell, is not considered.

Barbell speed is always directed along the trajectory and can be resolved

into two components: the vertical and the horizontal. A curve in the

trajectory increases the horizontal component which, consequently, decreases

the vertical. So, there is no advantage to using a curvilinear trajectory

that is designed to decrease the vertical component. So, there is no

advantage to a curvilinear trajectory designed to increase the time of

influence on the barbell. This curve is important to the energy relationship

and will be dealt with in a later chapter.

The Height of the " Squat Under "

It is obvious from the analysis of the speed of the descent that a decrease

in the length of its path allows the " catch up " speed to increase. Thus, the

height of the " squat under " should decrease.

Since the speed of the descent depends on the length of time of the barbell's

vertical movement, a consequence of the vertical speed, it is then obvious

that a reduction in the vertical speed will decrease the vertical movement

time, and consequently, reduce the speed of the descent. Naturally, this

forces the lifter to decrease the height of the " squat under " . However, the

height of the " squat under " cannot be decreased indefinitely. It is limited

by the athlete's kinematic links, i. e., the length of the levers and joint

mobility. When a lifter is no longer able to reduce the height of the " squat

under " , this height becomes practically constant for each athlete.

Well then, it is obvious that all four movement parameters of the

" athlete-barbell " system: the speed of the descent, the vertical speed, the

height of the lift and the height of the " squat under " are interconnected and

are necessary conditions for the successful execution of the weightlifting

exercises.

As one would expect, the height of the lift and the height of the " squat

under " are constants for highly qualified lifters. Therefore, the reserves

for improving their sport results are to be found primarily in the optimum

way of controlling the movement, by means of the vertical speed and the speed

of the descent.

The computations were presented for the purpose of simplifying the account of

the lifter's entry into the squat position, without regard to his interaction

with the barbell. The effect of this interaction on the height of the lift,

the vertical speed, the speed of the descent and the height of the " squat

under " will be discussed later.....

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Dr Mel C Siff

Denver, USA

Supertraining/