Problems with the Jerk
Olymp 2:29 – 32:2005
Translated by Andrew Charniga, Jr.
Analysis of the jerk portion of the clean and jerk in major competitions over the last decade show that the realization of attempts in this exercise remain low; with the number of successful lifts falling in the range of 50 – 70%.
The reason for the low results in the jerk from the chest is due, first and foremost, to incorrect technique. It has been established as far back as 40 – 50 years ago that the jerk from the chest requires approximately 30% less force than the clean. For instance, a successful clean requires an average maximum barbell speed of 1.5 m/sec, depending on the lifter’s height. A successful jerk requires a maximum barbell speed in the range of 1 m/sec. The speed of the barbell depends on the impulse force the weightlifter imparts to the apparatus, the greater this force accelerating the barbell, the greater the maximum speed. Simple calculations show that a successful jerk requires significantly less force than the clean.
It is common place to see a weightlifter make a good result in the snatch; easily clean a big weight, but be unable to fix it overhead in the jerk. The main reasons for failed jerk attempts are psychological and technical problems with the jerk portion of the exercise. We will consider only the technical problems with the jerk in this article.
The principles of proper jerk technique have been common knowledge since the time of N.I. Luchkin. These techniques have been described in sufficient detail in all of the Weightlifting textbooks published (beginning in 1972).
One of these principles is as follows: the body’s center of gravity and that of the barbell, the center of the arm and hip joints should all lie in the same vertical line from the instant the barbell is thrust from the chest and in the split position with the barbell fixed overhead. Furthermore, the feet are to be rearranged such that the general center of gravity of the “athlete – barbell” system is distributed uniformly over both feet; which ensures the minimum energy expenditure in holding the barbell and the subsequent recovery to the final position.
The fact of the matter is that over the last decade and up to the present time, the performance of the jerk from the chest of many weightlifters, is a considerable departure from the manner proscribed in the textbooks or methodological literature. We should point out that 40 – 50 years ago the weightlifters of that era performed the jerk from the chest basically as the literature proscribed; and, the reliability of this part of the clean and jerk was considerably higher.
Let’s consider the basic reasons for missed jerks in more detail. At the present time the most common mistake is jerking the barbell forward. Many highly – qualified lifters (world and Olympic champions) commit this error.
A peculiarity of this error is that it makes the recovery from the split difficult. The lifter leans forward during the recovery which in turn shifts the barbell and body in the same direction. Consequently, the forward placed leg bears a disproportionate loading of the barbell and the body. Furthermore, the rearward shift of the weight of the system to the rearward foot is insufficient.
This situation creates a loading which can exceed the strength of one bent leg. For instance, an analysis of the aforementioned posture of Hossein Reza Zadeh with his jerk attempt of 263.5 kg indicates that the loading on his forward placed leg in the split position exceeds 400 kg. This would be roughly equivalent to a 700 kg half squat with both legs. Such a position exacerbates the difficulty for the weightlifter to recover from the split while holding a barbell overhead and maintain a specific mobility in the spine and shoulder girdle.
The center of mass of the “athlete – barbell system” shifts some 10 – 20 cm forward, relative to a vertical line passing through the center of the hip joints; which in turn, creates an additional moment force for the lifter to overcome. This moment force can be significant such that the addition increases the total moments by 15 – 20% to perform such a movement. The aforementioned position is made much more difficult because of the necessity to balance the “athlete – barbell system” while lifting a limit weight under the stressful conditions, at the highest levels of competition.
A lifter is unable to overcome the combination of speed – strength and psychological loading to the nerve – muscle system, and, consequently cannot fix the barbell according to the rules.
These problems which prop – up in competition during the lifting of maximum weights are very stressful for the sportsman. These stresses are absent under normal training conditions because the athlete lifts significantly smaller weights, weighs more and has a higher level of speed – strength; consequently, the aforementioned errors are not a source of anxiety for the athlete and coach. However, these errors will cause missed attempts in competitions where the athlete has to realize his maximum speed – strength potential at that precise moment.
The aforementioned errors are exacerbated when the lifter shifts the general center of mass of the “athlete – barbell” system forward (closer to the toes) during the half squat of the jerk. Consequently, the barbell trajectory is forward instead of vertical, relative to the starting position, during the jerk proper. The athlete will only be able to move his arms, shoulders and upper trunk under the barbell because the barbell will be shifting forward. The foot placed backward in the split will end up bearing less of the load, but this is the leg which the recovery from the split usually begins, which of course shifts the full load of the “athlete – barbell system” onto the front leg such that it becomes an ineffective “ballet pose”.
However, sometimes the mistake happens even when the half – squatting is correctly performed but the shifting forward towards the toes happens anyway.
The advantages and disadvantages of the “push jerk” style versus the traditional split style of jerking have been discussed for many years. Biomechanical experiments show that the “push jerk” requires 13% more force for a successful lift than the split style. The “corridor” of a successful jerk with the “push jerk” style is about 10 – 15 cm from the center of the ankle joints to the center of metatarsal phalangeal joints. The same “corridor” can be significantly greater (up to 30 – 40 cm) with the split style of lifting, which allows some imprecision in the half squat and thrust of the barbell and still permits a successful lift in the split position.
There is a higher squat under position with the “push jerk” style; the knee angles are sharper, which increases the moment forces for extension of the knee and hip joints. Furthermore, the “push jerk” style requires a higher level of speed – strength, more precise spatial coordination of the body’ links and greater mobility in the spine and shoulder joint in comparison with the traditional split style.
When shoulder mobility is insufficient the lifter usually thrusts the barbell slightly in front of the head like David Rigert and some other athletes. However, this posture in unrealistic for the “push jerk” style, but, suffices for the split style. Splitters at the world class level have stable results which gives the advantage to the split style.
The knee and hip angles are more obtuse with the split style which makes the extension of these joints easier because of lesser moment forces. This facilitates significantly fixing the barbell overhead with a lower position under the barbell if the height of lifting is insufficient or the bar trajectory is imprecise.
Analysis of all of the aforementioned technique elements of the jerk indicates there is a greater chance of success with the split style in comparison with the “push jerk” style.
The overwhelming majority of weightlifters employ the split style and the greatest number of world records are established with the split style of jerking.
There are some young lifters who have levels of speed – strength and special mobility whom achieve good results with the “push jerk” style; but it is common knowledge (theoretical and practical experience in the physiology of sport) that the aforementioned physical qualities deteriorate faster than maximum strength.
We know of examples in weightlifting of this sort. Even the great Yuri Vardanyan was unable to compete in the 1988 Seoul Olympiad because he was unable to jerk 205 kg in a qualifying competition although he employed what you might call a “half push – jerk”, “half split style” of jerking.
A recent example was Pirros Dimas at the Athens Olympiad. He was unable to jerk 207.5 kg and failed to win his 4th gold medal even though he had lifted more than this in the past. Another example is the Moldovan lifter Fyodor Kasapu. He used the “push jerk” style with varying success but switched to the split style prior to the Barcelona Olympiad. He made his best results at this competition and won the gold medal.
Yuri Zakharevitch is another great lifter whom employed the “push jerk” style but he had his greatest success when he returned to the more reliable split style. Some coaches and athletes who advocate the “push jerk” are inspired by the phenomenal achievements of Yuri Vardanyan; but, without taking into account his mobility, speed – strength level and coordination.
Analysis of all of the aforementioned technique peculiarities of the jerk from the chest show that the slit style is a more reliable method than the “push jerk” technique. The Chinese “push jerk” technique with a deep squat is not a prospective technique because it is more like circus acrobatics and an attempt to perform a relatively simple movement in an unreasonably complex manner.
Lifters frequently make another error which is connected with the hip joint of the forward leg in the split position. Occasionally one finds lifters who arrange the backward leg such that the thigh is in the same vertical line as the trunk. The knee of this leg is significantly bent which does not permit one to fully utilize the support of this leg. This technique is a modification of the “push jerk” and is sometimes called a “half – push – jerk” a la Yuri Vardanyan.
Rather often the hip of the rearward leg is weak even when it is positioned correctly and does not provide the necessary support.
The aforementioned situations compel the weightlifter to shift the center of mass of the “athlete – barbell system” subconsciously to the forward leg which in turn creates the already discussed problems for the subsequent recovery from the split position. The “weak” fixation of the hip joint of the rearward leg is connected with the uncoordinated control of the hip muscles and a lack of strength in these muscles in the split position.
This is easy to determine in the gym. The hip muscle of the rearward leg should be tense to the touch when the rearward leg is positioned straight and forms an obtuse angle with the trunk. This indicates these muscles are activated correctly. If on the other hand, the hips are not tense, the hip joint is not fixed and consequently, cannot secure the full support on the rear leg. This in turn causes the forward leg to be overloaded at the beginning of the recovery from the split position.
We recommend the following exercise to improve the fixation in the split position. The coach instructs the lifter to pause in this deep split position for five seconds. If the static position can be held easily and it conforms to the model, the recovery can be performed correctly.
In conclusion, one should always keep in mind the model performance of the split style of jerk, so that something “new” does not displace the “old”. The jerk from the chest should be performed in the following sequence.
The general center of mass of the “athlete – barbell” system should lie in the same vertical line passing through the middle of the hip and ankle joints. The general center of mass should remain within the aforementioned vertical line during the half squat. The hip joints should shift up to 4 cm backwards during the downward movement, to compensate for the forward shifting of the knees and a small inclination of the trunk forward, i.e., or as the specialists would say, the half squat movement should be like sitting into a chair. The knees should bend to an angle of about 115° in order to prevent a pause at the bottom in switching from bending to straightening.
The half squat should be performed smoothly, gradually accelerating up to a depth of 15 – 20 cm; the last 3 – 5 cm of which should be “braked” sharply in order to maximize the elastic deformation of the tendon – muscles complex of the lifter’s legs; after which the lifter needs to switch explosively from the yielding work to the overcoming. The accumulation of force from the elastic deformation of the tendon – muscle complex by the aforementioned movement can increase the total force of the thrust by 30% because it comes on top of the metabolic force from the contracting muscles.
The barbell should rise vertically along the same line as the starting position. The trunk is leaning forward slightly during the rise from the half squat which keeps the barbell in a vertical path and slightly backward so that it can be fixed overhead or slightly behind the head.
It is possible for the barbell to be fixed slightly in front of the head. The thrust should performed flat – footed with a full straightening of the legs and trunk to a vertical position along with a rising onto the toes and elevation of the shoulder girdle to the maximum height from the support.
The switching from the thrusting to scissoring under the barbell should proceed without a pause. It is necessary to fix the barbell overhead within a very brief time (from 0.07 – 0.1 sec) in order to lock the arms with the barbell at its maximum height. Fixation of the barbell at the apex of its vertical movement is considered an indication of high sport mastery; but, the lifter should be prepared to lower further into the split position in the event of some imprecision, or as the specialists say to “fight the weight” in order to fix it according to the rules.
The rearranging of the feet into the split position is very important. The thrust should be performed such that the barbell’s center of mass, the center of the shoulder and hip joints will all lie in the same vertical line. The feet are rearranged in the fore – aft direction such that the weight of the barbell is distributed uniformly on each foot. The knee angle of the forward leg should be about 120 – 130°; the shin is vertical and the foot is turned inward slightly. The back leg is almost straight and forms an obtuse angle to the trunk. The optimum tension in the gluteus and hamstring muscles fix the hip joint of the backward leg.
It is very important to rearrange the rear foot such that the heel is raised significantly with a maximum contraction of the gastrocnemius muscle.
The rear foot should be turned inward slightly with the weight distributed on all five toes. Both feet are turned inward to secure better balance in the split position. The feet should be placed in the split position at about hip width apart. All of the technique elements of rearranging the feet in the split position are required to secure a rigid and stable support and avoid a loss of balance sideways.
The recovery from the split begins with the straightening of the forward leg tilting rearward as the athlete pushes backward toward the straight rear leg. Next, the rear foot is brought in line to complete barbell fixation. The aforementioned sequence of performing all of the technique elements of the jerk from the chest produces maximum effectiveness with the minimum of force.
The back needs to remain arched throughout the movement. This is connected with the “fixation” of the arm and shoulder joints.
The width of the hand spacing is very important in the jerk from the chest. The lifter needs to use a wide – hand – spacing if he lacks mobility in the shoulder joints, the actual width should be determined individually to make sure the arms can be fully straightened when the barbell is thrust overhead. The rules permit changing the hand spacing in the starting position; but, not all lifters exercise this option.
All of the technique elements described in this article are applicable to both sexes, since there is no essential distinction between the sexes as far as the biomechanics of the exercises is concerned. It should be emphasized that all of the problems with the jerk, as with all of the other exercises, need to be addressed in the learning stage; because, technique errors discovered later on can be difficult to eliminate, and, sometimes firmly reinforced, such that they are inappropriate to eliminate.
Only the coach’s multi – faceted systematic work to develop the lifter’s technique of the snatch and the clean and jerk combined with the constant effort to increase speed – strength will enable the athlete to achieve high, stable results in the clean and jerk and avoid annoying errors in competitions, including those of the very highest level.