The Training Weights in the Snatch Pull
Frolov, V. I., Efimov, N.M., Vanagas, M.P.,
Tyazhelaya Atletika, Fizkultura I Sport publishers, Moscow, 1977:65 – 67 Translated by Andrew Charniga www.sportivnypress.com
During the execution of the snatch the force against the support constantly outstrips the changes in the kinematic characteristics of the movement of the barbell. This apparently, allows the neural – muscular apparatus to switch from excitation to relaxation, and vice versa, i.e., the excitation of the muscle groups takes the form of local concentrated volleys of electrical activity. It should be pointed – out that the explosion phase of the snatch is preceded by a specific preparatory phase, which involves some brief drop in the vertical force and the relaxation of some muscle groups.
Figure 1. The full extension position of the snatch pull. Charniga photo.
This period of muscle relaxation does not occur in the high pull. A lifter is unable to generate a comparable maximum force against the support in the explosion phase of a high pull as he can in the snatch. The speed of the barbell at the bordering moments of the parts of the pull is also slower in the high pull than in the snatch (p<0.01).
So, the first part of the movement in the snatch is characterized by the ability of the muscles to quickly generate an increasing starting force (in some instances a force of 140% of the weight of the barbell has been recorded). In the second part the athlete accelerates the barbell’s vertical movement. The greater the athlete’s starting strength, the faster the first peak of force against the support is achieved, and consequently, the faster the working tension of the muscles is reached; which secures the increasing speed of movement of the barbell in the second part.
The lifter generates less force against the support in the snatch pull at the instant of separation with weights in excess of 90% of the best snatch. The first peak force against the support is also smaller than in the snatch. Consequently, the noted high effect of the hetero – chronnicity sharply diminishes, which does not permit the neuro – muscular apparatus to perform within the same coordination structure necessary for the snatch.
The electrical activity of the muscles takes the form of single prolonged volleys, without a clearly expressed maximum amplitude of oscillation. The work regime of a high pull with a heavy weight is closer to an isometric than a dynamic.
Figure 2. Bending of ankle joints early in the pull for the classic snatch which is not present in snatch pulls with heavy weights. Charniga photo.
Due to an insignificant in magnitude force against the support, the lower barbell speed causes the athlete to execute a high pull with 100 and 110% weights with a different rhythm than in the snatch (table 2).
Table 2.
|
EXERCISE |
2nd part |
3rd part |
4th part |
|
90% snatch |
0.48 |
0.14 |
0.17 |
|
Snatch pull 110% |
0.63 |
0.19 |
0.18 |
|
Difference |
+0.25 |
+0.05 |
+0.01 |
|
P |
<0.01 |
<0.01 |
<0.05 |
It is of special importance to note here the changes in the rhythmic structure of the explosion. The knees shift under the bar (the third part) significantly faster in the snatch than the fourth part (the final acceleration). The reverse is true of the snatch pull, the 4 th part is shorter than the third. This ratio of the length of the 3rd and 4th parts caused by an increase in the time to shift the knees under the bar, results in the knees bending more than the ankle joints. As a result, the athlete assumes an “irrational” position at the bordering instant between the 3rd and 4th parts.
During the preliminary acceleration in the snatch, particularly at the instant it ends, the lifter’s center of gravity has shifted to the rear portion of the ankle joints. In the 3rd part of the snatch the lifter’s center of mass and that of the barbell converge rapidly (due to the bending at the ankle joints), i.e., there is a distinct shifting of the supports, which takes the form of a “snap” from the rear surface of the foot to the front. In this instance, the shoulder girdle (the key link in the athlete’s kinematic chain), shifts with a large vertical speed, such that, the muscles of the lower extremities develop significant reactive forces, facilitating the successful execution of the final acceleration. In a snatch pull with 100 – 110 weights the athlete cannot shift the knees in the same manner as in the snatch, because the transition between the first phase of the pull to the explosion is lacking.
Furthermore, a significant straightening of the knees in the preliminary acceleration causes the apparatus to shift towards the lifter significantly and the athlete subsequently “covers” the bar with his shoulder girdle to an excessive degree, which in turn, provokes the formation of significant horizontal forces and increases the moment force of gravity relative to the ankle, knee and hip joints during the movement of the knees under the bar.
Well then, our complex analysis of the technique of the snatch pull revealed that when a lifter employs a significant number lifts with limit weights in snatch pulls strength increases but there is a negative affect on the coordination structure of the classic snatch. The results indicate the necessity of employing 90% weights for snatch pulls and to strictly control the number of lifts with weights in excess of 90% of the maximum snatch (especially in the competition period).