The Application of Force to the Barbell - The Pull
|No matter how constant the increase in strength, weightlifters cannot fully realize it because of the limited time determined by the amplitude of the task which the working links in the kinematic chain have to execute for the competition exercises (Y.V. Verkhoshansky, 1972).
Muscular force lifts the barbell (36). The forces which raise a barbell in the snatch and the clean and jerk, when all is said and done, begin and end with pressure applied through the feet. The force of the feet pressing into the floor creates an equal and opposite force. This is the so called "support reaction." The muscular force which creates the "support reaction" is the lifting force of the barbell.
In other words, the forces which raise the barbell in the snatch and the clean and jerk are generated through the feet. The vertical force created by the "support reaction" ultimately is transferred to the barbell.
That being said, "The most important fact to remember is that the support reaction should always exceed the static weight of the athlete and barbell because this force, which exceeds the static weight of the athlete and barbell, is the lifting force which constantly increases the vertical speed of the barbell" (3).
A weightlifter should seek the best method of generating the most effective "support reaction" during the lifting of a maximum weight in the snatch and the clean and jerk. This method should become the center point of a lifter's technique.
How should one go about most effectively producing the forces to lift a maximum weight? Force plate analysis of the pull produced the following conclusion: "Those athletes who possess high mastery strive to constantly exert maximum effort on the barbell in all phases"(3).
Start to Lift Fast to Move Fast
"The weightlifting exercises require the most strength in the least amount of time" (V. M. Zatsiorsky, 1966; D. Kharre, 1971) (18).
When one takes into consideration the physiological and kinematic limitations of the human body, with respect to the distance and time available to generate a sufficient lifting force to the barbell, a weightlifter should begin the snatch and the clean with a large weight as fast as possible. The athlete should strive for maximum acceleration of the body as a whole and its individual links in the effort to accelerate the barbell.
A lifter should not begin the lifts with a slow "first pull", then make a conscious effort to perform the so called "double knee bend", or to "brush the thighs" at a specific point of the pull, as is commonly practiced. These actions should be considered incorrect given the concrete requirements of the snatch and the clean as a whole. They are conscious efforts to execute the exercises in parts and not as a whole. These "conscious efforts" are too slow and inefficient for the weightlifting exercises where the speed of muscular contraction and speed of movement are crucial.
The Speed of the Initial Effort
The potential of the main lifting muscles (the extensors of the legs and trunk) to generate vertical force on the barbell is altered by the shifting inclination of the shins, thighs and trunk relative to the vertical. The greatest vertical can be produced over the first few centimeters of the lift from the platform at the instant of barbell separation up to the first full extension of the legs (2, 20, 24). Over the first few centimeters of the lift, the barbell is moving slowly. The conditions are static or close to static so more time is available to generate force, i.e., to realize a larger portion of the absolute strength of the legs.
Once the barbell achieves some vertical velocity, it can move upward under its own inertia. There is less time for the muscles to produce force on the barbell because the athlete is trying to both "lift it and chase it" at the same time.
A fast start is an opportunity to overcome the barbell's resting inertia and, at the same time, take advantage of the favorable mechanical conditions to accelerate it. Starting strength is "the muscles' ability to rapidly display a working force at the onset of tension" (27). A weightlifter employs starting strength to quickly overcome the resting inertia of the barbell.
The fast, explosive start of lifting activates the lifting muscles quickly so as to initiate the speed of muscular contraction necessary to accelerate the moving barbell as fast as possible. "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; this secures the increasing speed of movement of the barbell in the second part" (11). It is necessary to begin to lift fast through the speed of muscular contraction because the athlete will have to move much faster than the barbell is moving since it will be moving in the same direction of the force the athlete is applying to it. The lifter's mechanical advantage to accelerate the barbell from the instant of barbell separation (IOS) quickly diminishes as the shins straighten.
The Acceleration of the Barbell up to the Explosion
Once the barbell has been separated from the platform and has achieved some vertical velocity, it can continue moving upward slightly under its own inertia. The significance of the speed of muscular contraction is the crucial element in accelerating a moving object. In effect, the weightlifter has to not only "catch up" to the moving mass, but he has to significantly outstrip its inertial movement in order to continue to accelerate it over the short distance and the brief time available to do so.
There is less than one second to effectively generate a lifting force to the barbell in the pull portion of the snatch and clean before a weightlifter has to switch directions to receive the barbell. A "slow first pull" is a waste of time, effort and a lost opportunity of to take advantage of favorable biomechanical and physiological conditions.
According to Vorobeyev (20), "A rational distribution of force in the first phase of the pull resolves 65 to 75% of the motor task; the final results of which are achieved by the explosion."
This means a quick, powerful beginning effort to lift the barbell is combined with maximum effort to accelerate the barbell upward the instant the knees shift under. This strategy diminishes the effort required in the explosion to produce the necessary barbell speed of a successful lift. On the other hand, the less work accomplished at the start and in the preliminary acceleration or second phase of the pull, the more effort required in the explosion phase to achieve the necessary barbell speed.
The Approach in Jumping and The Second Phase of the Pull
Similar conditions to the preliminary acceleration or second phase of the pull exist in other sports where the movements are brief and explosive. For instance, the lift up to the instant the knees are moved under the bar during the pull is analogous to the approach in the long jump or the high jump. The take - off phases of these jumps involves similar conditions to the explosion phase of the pull.
The plant times of the take - off leg of top athletes in the long and high jump are in the range of 120 and 200 milliseconds, respectively. The plant time is the total time the jumper's take off foot is in contact with the take off board. Jumpers have an incredibly short period of time to convert the horizontal kinetic energy of the approach to vertical lift. The take off leg flexes and straightens extremely fast to produce the lift which propels the jumper out into the long jump pit or over the cross bar for the high jump.
A slow run up translates into less horizontal kinetic energy and longer plant times necessary to produce sufficient take - off forces; this is not very effective. Greater power is developed with a fast approach and a fast bending and straightening of the plant leg within a relatively small range of motion. If this were not the case, one would see long jumpers, for instance, jog up to the take off board.
A "slow first pull," like a slow approach for jumping, does not create the best conditions for the "explosion" phase and squat under phases of the snatch and the clean. With " a slow first pull," a lifter does not utilize "creatively" the mechanical advantage of the starting position where the conditions for the leg muscles are close to isometric. The ability to quickly generate vertical force on the moving barbell diminishes as the shins approach the vertical position. This compels the lifter to try and "make up for lost time" in the subsequent lifting; consequently, he is simply unable to utilize his maximum potential.
For instance, the optimum length of phase II of the snatch (from the instant of barbell separation to the first maximum straightening of the knees) is 400 to 500 milliseconds (3). One should not "artificially" lengthen this time with a "slow first pull". This is not conducive to a technically proficient snatch or clean.
The rational for this assertion is simple. The snatch, the clean and the jerk are brief, bi-directionally explosive movements. Each exercise involves a brief preliminary lifting phase which has to be completed effectively within the available range of movement of the body's links. The "lifting" phase is the preparation for the subsequent, more complex and difficult "receiving" phase. A prolonged, inefficient lifting phase (from the IOS through the explosion) will not adequately prepare the lifter to effectively "receive" the barbell.
The pull phase of weightlifting is much shorter than the approach for the long or high jump. The explosion phase (the flexing and straightening of the knees) is also very brief; it is a total time in the range of 270 to 340 milliseconds for technically efficient lifters. It should further be emphasized that this movement is carried out by an athlete holding onto a heavy barbell. The weight of the barbell affects what is already a very fast motion. For example, the knees shift under the bar slower in the clean than in the snatch because the weight is bigger and moving slower.
Despite considerable data from biomechanical analysis and widespread acknowledgement of the importance of speed of muscle contraction and the role of speed strength in weightlifting, the speed with which the weightlifter begins to lift has long been and continues to be a controversial topic.
Consider this example: "The slower the initial speed of the lift up to the explosion phase, the higher the realization of the strength potential in the explosion.... The Japanese world record holder Y. Miyaki is a good example of this technique. He raises the barbell slowly and then exerts maximum force in the explosion and limit speed" (23). Author A. K. Samusevitch cites this practical example as a rational for employing this strategy of a deliberate "slow first pull," but he does not offer a biomechanical or physiological explanation.
On the surface, this argument has some basis in fact. It is true that a person can generate more force on a slow moving object because there is more time to recruit more muscle fibers, i.e., the conditions are close to isometric. Therefore, a lifter can produce the most force in the explosion position. So, a lifter has time to generate more force on a barbell moving very slowly through the strongest disposition of the ankle, knee and hip joints (the explosion position).
However, the snatch and the clean are bi-directional explosive movements consisting of two fundamental but inseparable actions: lifting and receiving. A lifter has to complete the lifting portion in such a manner as to have the time and the wherewithal to instantaneously stop lifting and effectively receive the barbell in the squat position. This means the barbell has to move fast enough as a result of the acceleration applied in the second phase of the pull for the lifter to apply force to it very briefly in the explosion phase. Then the lifter will be able to begin switching directions at the right time instead of reacting to a barbell moving too slowly by continuing to try to lift it higher.
It is highly unlikely a lifter can produce the required barbell velocity in the "explosion" preceded by a "slow first pull" with a big weight. In fact, "athletes who have relatively high results in the snatch generate significantly larger impulse forces in the 2nd part than in the 3rd and 4th parts" (26). As it has already been pointed out, the knees bend under the bar slower in the clean because the barbell is heavier and moving slower. The slower movement of the body's links (the shins, thighs and trunk) produces less force on a moving object (8,19).
So, a purposeful slowing of the barbell's movement in the lift from the floor to the beginning of the shifting of the knees under the barbell would not contribute to the quick, explosive nature of the bending and straightening of the knee, hip and ankle joints in the final part of the pull. One could therefore expect less force generated in the explosion from a "slow first pull" because the knees would tend to shift under a slower moving barbell. This means the thigh extensor muscles would be stretched slower. Consequently, the legs would straighten at a slower speed and, therefore, produce less lifting force on the barbell (24). It is common knowledge that the faster the knees bend and switch to straightening, the greater the force produced (2, 20, 24).
So, back to our example of Miyaki who, apparently, employed a "slow first pull," set numerous world records in the snatch in the triathlon era of the 60s. He eventually achieved a best of 125.5 kg in the 60 kg class in 1969. At the 1988 Olympics in Seoul, Naim Suleymanoglu set a world record of 152.5 kg in the snatch in the 60 kg class. He employed an obvious fast as possible starting effort. Despite the obvious, that the lifts were made in different eras of weightlifting (triathlon vs. biathlon), Suleymanoglu's lift, nevertheless, reflects a huge disparity in results. His results are indicative of the superiority of modern "reactive" technique where the key components are the speed of muscular contraction and the speed of moving the body.
The Speed of Activation of Muscles
All of the scientifically defined separate parts of the snatch and the clean are inter conditional and interdependent. Any effort to consciously "perform" them separately compromises the integrity of these exercises as a unified whole.
As far as the speed of the initial effort in the pull is concerned, the literature does not offer an explanation as to the effectiveness of "switching" the speed of contraction in a fraction of a second for one and the same muscle group. There is no argument that speed is an integral component of weightlifting technique. But, a "two speed" rhythm of contraction from the thigh extensors cannot be efficient.
If the weightlifter begins the lift slowly, there has to be a quick resignaling of the thigh extensors to speed up or else the lifter will simply be unable to impart enough velocity on the barbell to effectively lift it. So, instead of concentrating on developing a single explosive contraction from the legs, the lifter who begins to lift the weight slowly at the start apparently initiates a "slow" muscular contraction then "speeds" up, all in a fraction of a second while holding onto a big weight. There are too many factors for the human body to do effectively in too little time.
I.P. Zhekov (20) developed a mathematical model to determine the most effective application of force to the barbell in the pull. Subsequent scientific experiments to determine the method of applying force to the barbell confirmed his theory. He concluded that the lifter should begin to lift with a powerful effort much like the first stage of a rocket. According to Zhekov, the support reaction of athletes who have high results in the snatch and the clean and jerk increases sharply at the beginning of the lift from the floor (24).
Therefore, an explosive effort to begin the lift contributes to and is an integral part of the final effort in the pull. A fast start is the key to a "timely", fast finish (2,12,20,22). "The larger the preliminary acceleration, the greater the acceleration in the final part" (22).
The Application of Force to the Barbell: The Explosion
The explosion phase of the pull consists of the shifting of the knees under the bar and the final extension of the knee, hip and ankle joints.
The effort to lift a barbell primarily with the muscles which straighten the legs and the trunk creates the conditions which lead to a natural shifting of the knees forward and down under the bar during the pull phase of the snatch and the clean.
There is not now and there never has been a "double knee bend" in weightlifting technique. The reason is that one should not perceive the so called "double knee bend" as a conscious effort from the athlete during the lifting of the barbell. It should be perceived as the lifter unconsciously following the path of least resistance balances the athlete and barbell as a unit and to employ the strongest muscles repeatedly to lift the barbell. An attempt to consciously control this natural reaction would diminish its efficacy.
Once the legs have ceased to straighten at the end of the second phase o f the pull, the technically proficient lifter shifts the knees under the bar (the bending of the knees and tilting of the shins away from the vertical) in 110 to 140 milliseconds. Furthermore, the time from the end of this phase to full extension (phase IV) is 160 to 200 milliseconds. The brevity of this action precludes an effectively conscious effort. A conscious effort to "scoop" the knees under would invariably slow the movement. A slower bending of the knees means a slower stretching of the leg muscles which translates into less force produced by these muscles and a lower barbell velocity.
A fast approach in the jumping events produces greater horizontal kinetic energy which the jumper can convert to greater vertical velocity at take off. The better lifters execute phases I and II of the pull quickly. The optimum acceleration of the barbell preceding the explosion phase, like the fast approach in jumping, creates better conditions for the subsequent lifting because "It is necessary to aggressively execute the preliminary acceleration in order to achieve a powerful explosion" (10).
If the barbell and the lifter's body are moving with sufficient speed, the involuntary shifting of the knees under the bar is carried out quickly. The subsequent contraction of the muscles which straighten the legs is involuntary. The faster the contraction the more power produced.
The training which develops the "reactive" nature of the shifting of the knees under the bar in the snatch and the clean is somewhat less than deliberate. "There is an unconscious perfectionism of this skill to move the knees under the barbell in the training process. The master of sport completes this phase in an average of 0.11 seconds; the classified lifter does it in an average of 0.16 seconds "(4). Therefore , the special literature devoted to the training process by which a weightlifter works to improve results in the snatch and the clean and jerk never mentions the "unconscious" improvement of the skill to shift the lower extremities faster from one position to another.
Once again, any effort to brush the thighs with the bar at a specific spot introduces a conscious effort to control the "reactive" nature of the explosion, i.e., one tries to plan and deliberately execute a "double knee bend." The "reactive" shifting of the knees under the bar must be more effective than any conscious effort to execute a "double knee bend." A conscious effort to rebend the knees is an unrealistic expectation for the weightlifter to accomplish in the span of an eye blink.
The Shifting of the Knees Under the Barbell
The shifting of the knees under the barbell in the snatch and the clean is a quick reaction:
- to counter the "toppling over" effect of the barbell on the weightlifter barbell system (10);
- to reduce the increasing moment force relative to the ankle, knee and hip joints as the legs straighten (10);
- to draw closer together the center of mass of the barbell and the body in order to improve the mechanical efficiency of the working joints by shortening the force arm of the barbell (10);
- to re - introduce the "already working" thigh extensor muscles in order to further accelerate the barbell (24);
- to prevent a significant drop in barbell speed (4).
The shifting the knees under the barbell serves to diminish the forces opposing the movement of the so - called "athlete barbell" system. For many years and up to the present time, athletes and coaches have believed that the shifting of the knees under is a conscious effort to bend the knees under the bar in order to "kick" the barbell up with the legs.
The muscles which straighten the legs essentially contract involuntarily, with great speed, immediately following an extremely fast stretch from the bending of the knees. It is a reaction to the knees flexing in as little as 110 milliseconds. Any effort to consciously execute it in parts would slow it down and compromise the efficiency of the entire lift. One would have to call this portion of the lift something else because it would no longer be "explosive" in nature.
Therefore, a "double knee bend' is something one consciously endeavors to perform; whereas, a "shifting of the knees under the bar" is a reaction to the conditions which force it to occur. The biomechanical/physiological distinction between what constitutes an action and a reaction, is lost on one who draws conclusions based on observation of the knees bending under the bar in still pictures or slow motion video.
Of the previously mentioned five basic reasons (causes) for the shifting of the knees under the barbell, the effort to "re - utilize" the legs is obvious.
The "toppling over" effect is less apparent. In simple terms, the "pull" of the significantly larger mass of the barbell (relative to the athlete's bodyweight) is diminished by the lifter drawing his center of mass closer to the barbell.
The shifting of the knees under the bar helps prevent a significant loss in barbell speed caused by the drop in the support reaction as the ankle joints reach a vertical disposition. A vertical disposition of the shins means the quadriceps, the strongest muscles of the body, are no longer working to lift the barbell, i.e., the vertical force produced by the torso straightening is not as powerful as the legs or the legs and torso straightening simultaneously.
Without the timely introduction of the muscles which straighten the legs, the weightlifter would have to finish lifting the barbell primarily by "energetically" straightening the trunk, raising the heels and shoulders. The stress on the muscles of the rear of the thighs and the other muscles which straighten the trunk would be excessive. The lifter's ability to apply force to the barbell would be greatly reduced.
One must think of attempting a vertical jump by leaning over at the waist with the legs almost straight. The athlete would have to jump upward primarily by rotating the trunk and pushing off with the feet. So, the timely utilization of the "already working" thigh extensor muscles is crucial to a successful snatch or clean. Therefore, the rapid shifting of the knees under the bar solves multiple tasks.
Theory and Practice
The speed with which the knees are shifted under the barbell is crucial for achieving sufficient barbell height to successfully execute the snatch and the clean. For instance, according to Martyanov's et al (22) data from analysis of the clean: "The height of the lift is greater, the lesser the reduction in barbell velocity during the knee shift under the bar." And, "The higher the athlete's mastery, the smaller the drop in barbell velocity during the knee shift under the bar" (22).
It is imperative that one avoid a significant loss in barbell speed during the pull. It takes additional time and unnecessary additional effort to make up for lost barbell speed in order to impart sufficient acceleration to the barbell in the very short time available and with the limited leverage available, once the knees have shifted under the bar.
The faster the athlete moves his body and the individual kinematic links (shins, thighs, trunk) through the phases of the snatch and the clean and jerk, the more force is applied to the barbell and the smaller the decrease in barbell speed (19,22,24,30,31,32).
With that statement in mind, it is of interest to examine the technique of a select few athletes who are widely acknowledged to be among the greatest weightlifters in history; this further illustrates the advantage of shifting the knees under the bar quickly.
R. A. Roman (31) analyzed three snatch attempts of Y. Zhakarevitch (USSR) with 188 kg success, 192.5 kg miss and 192.5 kg success. Zhakarevitch shifted his knees under the bar for the explosion in some 80 milliseconds. Of the three attempts analyzed, the "moving of the knees under was shortest with the successful attempts"(31). The knee angles changed during the shifting of the knees under by 16° and 17° on the successful attempts and by 20° on the unsuccessful 192.5 kg. On his successful attempts, "Zakharevitch flexed his knees significantly less than the average for other athletes (the average is 25°)" (31).
Zakharevitch's knees flexed faster (in a shorter time) because the joint movement was less than the "norm." So practice re-affirms theory that "It is natural that the lifter barbell should move in such a way that the joint movements are as small as possible" (24).
The lesser bending of the knees is faster which means more power is developed, but also the barbell loses less speed because the "shifting of the body's gears" from low to high is accomplished very quickly.
This element of Zakharevitch's technique is an integral component of technical efficiency. "Minimal knee flexion (as the knees move under the bar) is a technique peculiarity of this athlete because a significant decrease in barbell velocity is avoided. Thus, on the first and third attempts, barbell velocity decreased by 0.04 m/sec, whereas on the second attempt, where the knee flexion was great, it decreased by 0.07 m/sec '' (31).
It is no coincidence that three of the most prolific world record setters in weightlifting history share this "technique peculiarity." In his analysis of the clean and jerk of Yuri Vardanyan, Roman wrote "The moving of the knees under the bar is executed faster than other athletes, but the legs bend less at the knees. As a result, while shifting from the first phase of the pull to the second or the explosion, the athlete loses less velocity"(29).
David Rigert like Zakharevitch and Vardanyan shifted his knees under the bar faster and with less bend than the "norm" (32). The same observation was made from an analysis of V. Marchuk's (30) world record in the clean and jerk.
Therefore, despite the widely acknowledged "individualization" of the technique of the world's strongest weightlifters, these athletes share this common technique trait. This technique trait, common to these distinguished athletes, confirms the importance of preventing loss of barbell velocity during the crucial "shifting of gears" in the pull. The virtually unconscious and involuntary nature of smaller joint movement at faster speed is the most effective technique variant.
These three phenomenal record makers (Rigert, Zakharevitch and Vardanyan) lifted their "bigger weights" to lower than normal heights (in comparison with other athletes of the same height and weight class), with smaller movements in the joints of the lower extremities, with a smaller loss of barbell speed, i.e., with greater economy of effort. All of this is indicative of how these great lifters set the number of records they did and successfully lifted such fantastic weights so many times.
The Dynamics and Kinematics of the Explosion
It is common knowledge that the weightlifter's potential to generate the fundamental lifting forces on the barbell change along with the disposition of the shin, thigh and trunk, relative to the vertical (2,15,20,24).
The explosion phase begins with the knees shifting under the barbell and ends when the knee, hip and ankle joints stop straightening. The maximum force produced in the explosion occurs over the first few centimeters of the straightening of the knees, i.e., when the ankle between the shins and vertical has receded by one half (2,15,20,24). This conforms with what is common knowledge of sport exercises that "the largest force is developed at the beginning part of the amplitude of movement and it recedes at the end" ( 27). The barbell reaches maximum speed at about two thirds of the way from the maximum bend in the knees to the maximum extension of the knee, hip and ankle joints; this happens extremely fast (2,20,24).
In effect, the explosion is over at the instant the barbell reaches maximum velocity because the weightlifter is unable to further increase the speed of the barbell or even maintain the achieved maximum speed. This occurs before the legs and trunk have reached full extension and "long" before one would wait to elevate the shoulders and rise onto the toes. Therefore, the lifter should begin to switch directions before the full extension of the legs and trunk in order to effectively move under the barbell.
If the lifter begins to switch from lifting to descending under the barbell correctly, the barbell will continue to rise under the combined influence of its own inertia and the lifter's mass by moving energetically in the opposite direction (2,8,19,20, 24).
The pull phase of the snatch and the clean should be executed as fast as possible from start to finish. The pull portion of the snatch and the clean and jerk is an inseparable part of the whole of these exercises, but it should not be perceived as the principal focus of one's attention, i.e., the weightlifter should not to try to lift the barbell as high as possible by straightening the legs and trunk from the starting position up to the full extension of the knee, hip and ankle joints.
There is a definite shifting of gears in the pull phase of the snatch and the clean. But the correct "shifting of gears" in the pull is more unconscious and reactive in nature in comparison to what must be considered a plodding effort to sequentially lift to knee height, "scoop the knees under the bar," fully straighten the legs and trunk, rise up on the toes and shrug the shoulders, then "drop under" the barbell.
If one were to use the analogy of a drag racer shifting gears in a race car, but with the understanding the weightlifter should be "shifting" in the pull almost unconsciously, one could paint the following picture.
A racer begins a race like the weightlifter begins the pull by releasing the clutch in first gear and flooring the gas pedal. As the car reaches the maximum velocity, it can achieve in first gear (likewise when the lifter's shins are or almost vertical in the second phase of the pull), the racer shifts gears as fast as possible (the lifter shifts the knees under the bar to "engage" the legs) to further accelerate the car in the next gear.
The racer shifts by "popping the clutch" and flooring the gas pedal as fast as possible to accelerate and prevent loss of speed; the lifter shifts the knees under and instantaneously begins straightening them as fast as possible to once again accelerate the barbell and prevent loss of speed.
In an instant, relatively speaking, the car, like the barbell at the beginning of the explosion, reaches the maximum speed in second gear. If the racer were a weightlifter, he would shift the car into reverse at this instant. The weightlifter, unlike the drag racer who would go flying through the windshield after shifting into reverse, continues to lift the barbell by descending in the opposite direction.
The Application of Force to the Barbell in the Squat Under
It is a common misconception that the lifting portion of the snatch, the clean, and the jerk is carried out completely by the active extension of the knee, hip and ankle joints and finally the shoulders during the pull of the snatch and the clean. The idea that one should concentrate on lifting the barbell as high as possible and then drop under it is lacking in scientific or practical substantiation.
It is necessary for the weightlifter to prepare to switch directions before the knee, the hip and the ankle joints have ceased straightening at the end of the pull portion of the snatch and the clean. This fact is not widely recognized.
In fact, it is crucial to prepare to switch from lifting to receiving the barbell in advance of the "end of the pull". Preparing to switch directions in advance means that the lifter should not make a conscious effort to "complete the pull" by fully straightening the knee, hip and ankle joints, raising the heels and shoulders before descending under the barbell.
The most important component of an effective squat under the barbell is connected with the right instant to begin switching directions. When an athlete continues to actively lift the barbell past the point of diminishing returns, he significantly reduces the effectiveness of the descent under and the "receiving" of the barbell.
Another crucial component of the squat under is the speed of the descent. The energetic pulling of the body down with the arms (or pushing the body away from the barbell in the jerk) plays an important role in achieving the optimum descent speed in squatting under the barbell, even though the maximum strength of the arms and shoulders is not required. "The instant of squatting under does not require maximum force from the arms as the barbell continues to move under its own inertia"(8).
The muscles of the arms and shoulders do actually participate in lifting the barbell. However, these muscles are best employed to "lift" the barbell when they are actively engaged in "pulling" the lifter under the barbell.
The kinetic energy of the lifter's descending body is effectively communicated to the barbell through the hands grasping it. The faster the descent, the more force applied to the still rising barbell (19). In physics, force is defined as the product of mass x acceleration i.e., F = ma
The optimum, unconscious timing of the descent, the forceful thrusting of the feet to rearrange them in the squat position, combined with the energetic flexing of the arms and shoulders during the squat under, effectively raises the barbell as the lifter descends.
The so called "freeing up" instant refers to that moment when the barbell is still rising as a result of its own inertia from the velocity built up in the pull. During this same instant, the lifter is descending and continues to "lift" the barbell on the way down by energetically flexing the arms and raising the shoulders.
In addition to communicating a vertical acceleration on the barbell (with the arms) in the act of descending, a lifter increases the effectiveness of this action by explosively switching directions. A weightlifter needs to forcefully "jump" down into the squat position while at the same time "pulling" his body energetically with the arms in the same direction.
For instance, L.N. Sokolov (19) determined that 82.5 kg lifters were able to produce a force of 200 kg while switching from the explosion in the snatch. This is an indication of the potential "lifting" force a weightlifter can generate while descending into the squat position.
An optimum combination of three fundamental actions produce an effective lifting force on the barbell during the descent:
- The athlete begins the squat under by using some of the effort in the explosion phase to "pull" the body under the barbell and in doing so generates great force and speed in the descent.
- The athlete "tears the feet" explosively from the platform to begin the descent.
- The athlete actively flexes the shoulders, the wrists and the arms during the descent.
Consider the following two examples which produce the same result but with slightly different outcomes.
In his analysis of Y. Zakharevitch, Roman (31) writes "When he jumps from the platform, the interaction is even more significant and it once again receives additional acceleration. So, the weightlifter should place his legs in the squat under as fast an energetically as possible...he arranges his legs quickly and forcefully"(31). Zakharevitch raised the barbell in the snatch to "the minimal possible height of the lift lifters of his height can raise a barbell and still successfully fix it overhead" (31).
In this example, Zakharevitch contributed to the barbell's vertical movement by forcefully rearranging his feet while at the same time interacting with the barbell with his arms and shoulders. These actions allowed him to lift a record weight to the lowest possible height which is the essence of technical efficiency. There is no better illustration of the profound significance of an effective descent under the barbell.
The bigger the weight one tries to lift, the lower the velocity one can impart to it and obviously the lower height to which it can be lifted. These facts effectively stipulate the necessity to lower the body in the most mechanically efficient manner to successfully lift a maximum weight.
On the other hand, according to Roman (30), Marchuk lifted the barbell to a great height in the clean by "brilliantly executing the squat under." This is an athlete who is stronger than Zakharevitch but has less mobility. However, he takes advantage of the same opportunity "to lift while descending." The physics of the Marchuk "descent strategy" are obvious; "At exactly the same time he very actively interacts with the barbell and not only quickly moves his torso under the barbell but raises it quickly" (30).
Analysis of still pictures or slow motion video of weightlifting is often misleading. This is especially true with regards to the extension of the legs and trunk in the pull or the jerk. The reason is that it is almost impossible to determine what the athlete "is doing" during those fractions of second where he appears to be lifting the weight but is, in actuality, already making the effort to move under it.
Therefore, an effective squat under and receiving of the barbell produces the forces which continue to raise the barbell briefly as the lifter descends (2,19,24).
- From Sovietsky Sport Publishers, Publication #239:1988
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- Quote attributed to Charlie Francis on the Internet, 2002.
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