Original Articles

The Foot, the Ankle Joint and An Asian Pull

The Foot, the Ankle Joint and An Asian Pull
Andrew Charniga, Jr.
Sportivnypress.com©

The arch of the foot is linked up by elastic ligaments that can store elastic energy when deformed and later reutilize it as mechanical work.” (Alexander, 1988).

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Figure 1. The re – bending of the knees occurs at what is considered pre – maturely in the Asian pull. Re – bending at this point re – introduces the extensor muscles of the thighs and shank. Moreover, this also diminishes the toppling over effect of the barbell. The re – bend occurs later in Russian pull (middle figure). Charniga photos

Questions were raised in a previous article concerning suitability of prolonging the loading on the lumbar spine, characteristic of the Russian pull technique. Also, the question as to whether knowledge of training and weightlifting techniques which were the products of research in era of special enhancement is in need of revision in light of current testing protocols.

Moreover, the question was raised as to whether an Asian pull technique, characterized by an atypically large shifting of the shoulder joints and a premature, significant rise onto the toes in the pull phase represents a significant error in technique.

In all probability, the most significant deficit in our knowledge of weightlifting sport, especially as it pertains to our acceptance of the protocol of the Russian pull is the role assigned the foot lever and the musculature of the ankle. This is not surprising since the collective role of the foot, the ankle joint, and the muscle- tendon – ligament linkage is one of, if not the least understood aspects of weightlifting.

The Initial contribution of the muscles of the shank:
Inertia coupling

Inertia coupling is an important concept to understanding the complexity of human movement. Essentially it means muscles can accelerate joints their tendons do not cross. And, this concept is very relevant to weightlifting technique.

When we think of straightening the legs in pulling the barbell from the platform, or in squatting, we automatically think quadriceps group because these four muscles cross the knee. This muscle group acts to straighten the knee joint. However, the soleus muscle and other single joint plantar flexors are virtually never mentioned in textbook discussions of knee, let alone hip extension; because they are muscles of the shank, which do not cross the knee joint. They cannot produce torque on the knee.

Either absent or very insignificant in other mammals, (Alexander, 1988) the soleus muscle is an overlooked, poorly understood, synergist of the quadriceps group. When the shin is tilted forward away from the vertical in pulling or in squatting, soleus contracts in what can be described as a reverse origin insertion action to return the shin to vertical.

Contraction of soleus pulls the shin backward assisting the straightening of the knee and even hip, because shin bones are interconnected to thigh bones and hip by means of the knee joint. Consequently, when this muscle straightens the shin, thigh and hip are accelerated into extension; because, ankle, thigh and hip are interconnected by couplings.

“In a flat –footed posture near the vertical position the soleus acts to accelerate the knee into extension twice as much as the ankle because the thigh is accelerated into extension as much as the shank, i.e., the soleus acts to accelerate the thigh clockwise as much as it acts to accelerate the shank counterclockwise.” F. E. Zajac, 1993

Soleus and the other single joint plantar flexors are very active synergists from the instant a weightlifter begins applying force to the barbell in the start position; up until the shins approach vertical. This is the initial major contribution of the shank muscles.

slide BFigure 2. Two illustrations of inertia coupling of shank muscles with quadriceps group in the pull phases of weightlifting. The photo on the left reveals activity of soleus and other single joint plantar flexors contracting in a reverse origin insertion action in synergy with quadriceps group to pull shin to a vertical disposition. The photo on the right illustrates the re – introduction of these same muscles to contribute to straightening the lower extremities.  Charniga photos.

Once the weightlifter straightens the lower extremities in the pull, i.e., the shins shift to a vertical disposition, the quadriceps – shank muscle synergy can contribute little to the upward movement of the barbell. The lifter is forced to continue raising the barbell with the muscles which straighten the trunk until the knees re – bend. In the Russian pull this involves a prolonged shifting of the shoulder joints in front of the vertical line of the bar.

Lifters react to the large moment on the hips and trunk as the lower extremities straighten, and “the toppling over moment force of gravity of the force of the barbell” (R. A. Roman, 1986) by re – bending the knees. This action re – introduces the quadriceps – shank – muscle synergy into the work of raising the barbell. When the shins tilt forward the muscles of the shank are re –introduced into the work to act in concert with the quadriceps and trunk extensors to create the most powerful disposition of the human body to complete the pull phase of lifting.

A rapid knee re – bend activates the soleus and other plantar flexors in a reverse origin insertion contraction to work in synergy with quadriceps while at the same time rapidly stretching the Achilles tendon, the body’s largest, strongest spring.

Slide 16Figure 3. World champion DENG Wei (CHN) activating knee extensors (quadriceps and shank muscles) by re – bending knees under bar. Charniga photos.

So, the muscles of the shank are employed repeatedly in the act of pulling by means of inertia coupling; all the time from a flat footed posture.

Bi – articular muscles:
Transport of Power

Many authors have studied the role of bi-articular muscles in human movement. The important question behind such research is why does the body even have such things? The tendon connections of bi – articular (also referred to as two – joint) muscles cross two joints such that as they lengthen under tension; these muscles create torque at two joints simultaneously.

Furthermore, these muscles can transfer muscle force from one part of the body to another by a process known as transport of power (Van Ingen Schenau, 1989).

The gastrocnemius portion of the triceps surae muscles are bi-articular. These muscles connect ankle and knee. The gastrocnemius muscles and soleus are relegated a relatively minor role in weightlifting technique. These muscles are expected to come into play when the athlete endeavors to raise the heels in final portion of the pull: pretty much after the knees and trunk have fully straightened.

As already noted the soleus is a very active in synergistic straightening the knee; pulling shins to a vertical disposition.

However, for the most part, the Russian pull stipulates a specific sequence:
“The execution of the explosion involves a rapid extension of the legs and trunk followed by raising onto the toes and elevating and tilting the shoulder girdle slightly backwards. An earlier inclusion of the arms and rise onto the toes will reduce the realization of strength potential.” R.A. Roman, 1974

“There is a rapid straightening of the legs and torso with a subsequent lifting onto the toes and raising of the shoulder joints up and back during the explosion.” R.A. Roman, 1986

Moreover, at least part of the rationale of the Russian technique protocol to remain flat – footed until the knees have all but ceased to straighten is the assumption a premature heel raise will have a dampening effect on the force generated by the quadriceps and trunk extensors. And, of course, this circumstance would diminish the effectiveness of the support reaction.

Consequently, according to the Russian protocol a “premature”, (before knees and trunk have all but stopped straightening) prolonged raising of the heels characteristic of an Asian pull would be considered an error of technique.

The Russian technique stipulates pulling flat footed as long as possible before rising onto the toes. This flat – footed delay of heel raise is supposed to prevent the force produced by the muscles straightening the trunk and knees from being dampened by the muscles of the shank. The same circumstances apply to a premature bending of the arms and raising the shoulders before legs and trunk have straightened.

One can even find some ambiguity of opinion among the experts:

“A full and stable rise onto the toes certainly is a technical error, because one delays the “switching” to the squat under (however, it is unclear if the athlete should forego rising onto the toes).” A. N. Vorobeyev, 1988

Some of these ideas, which actually sound good on paper; and, however well the intention, are often coupled with misguided advice:

“Beware of executing the shrug and rising onto the toes too early. If these are done before maximum hip extension is achieved, then the bar will not be pulled high enough”. (Brown, L. Baechele, T. , 2000)

In point of fact what would be considered a “premature” heel raise in the pull is not an action; it is a reaction, regardless of Russian stipulations or an Asian technique.

Research of inter-muscular coordination of the vertical jump has practical application to weightlifting, if for no other reason, power is generated in jumping and lifting over the much the same joint angles. Subjects who raised heels such that they pushed off on their toes, jumped higher in vertical jump tests than in the opposite case where feet remain flat until trunk and knees have all but straightened. (Van Ingen Schenau, 1989).

Moreover, although mathematical models would seem to affirm the correctness of remaining flat footed up until push off in jumping, the body’s protective reactive mechanisms prevent this.

Hence:
“Of course jumpers might not want to implement exactly the optimal strategy for jumping as high as possible because they might want to jump again (e.g., their joints might otherwise be seriously injured because of hyperextension.” (Zajac, 1993)

Well then, animals, vertical jumpers and weightlifters alike, can be observed generating explosive force with heels raised and knees flexed, from a base limited to the toes.

It is common knowledge the human body has geometric constraints to movement. For instance, normal full extension of knee and elbow joints is about 180º. Some are unable to achieve 180º while others, in the elbow for example, can straighten this joint beyond 180º. In this instance, an elbow joint which straightens beyond 180º is said to hyperextend. The same circumstance can also be present in the knee joint.

One of the body’s reactive protective mechanisms called anatomical constraint is activated to prevent hyperextension of joints. This mechanism slows or otherwise redistributes mechanical energy to prevent damage to joints from straightening with excessive speed.

The mechanism of transport of power is interconnected with anatomical constraint. When a jumper or weightlifter generates explosive force with the lower extremities tension is created in the lengthening biarticular gastrocnemius muscles as the knees straighten.

In weightlifting (or vertical jumping for that matter) a premature rise onto the toes with knees still flexed in the pull; in effect bends knees further. Since the heel raise stiffens gastrocnemius muscle, this action allows transport of power from the quadriceps muscles to the support.

In weightlifting this premature rise onto the toes, which can be exaggerated in the Asian pull; is both an effective reactive protective mechanism while at the same time transports (instead of braking) the power of the quadriceps to contribute to the support reaction by means of raising the heels.

Consequently, the weightlifter is using quadriceps to transport lifting power to the feet even as knees are bending:

“The work of the knee extensors “is not used for the increase of knee extension velocity but for plantar flexion since the knee extensors pull on the calcaneus via the gastrocnemius… “ in other words the gastrocnemius allows transport of power from knee to ankle joint” (Van Ingen Schenau, 1989)

This mechanism of transport of power allows the shank muscles to produce power they would otherwise be incapable:

“For jumping this transport of power is part of the explanation of the extremely high net power values found in plantar flexion (up to 2000 watts per leg).” (Van Ingen Schenau, 1989)

The power generated by means of raising the heels (plantar flexion) especially as this is displayed in the Asian pull; in theory can produce forces against the support greatly exceeding a mere rise onto the toes after legs have all but straightened.

Simulation models indicate the extremely high net power values referred to by Van Ingen Schenau are produced by a combination of transport of power from quadriceps (25%), another 25% from muscle contraction; and, the remaining power produced by recoil of elastic tissues of the shank (Bobbert, 1986), i.e., an action significantly more intricate than a mere heel raise with straight knee.

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Figure 4. Regardless of Russian or Asian pull technique weightlifters couple knee extension with plantar flexion. The main difference lies in the knee angle the shank muscles are re – introduced: later at a larger knee angle with Russian pull (photo at left and middle photo) in favor of prolonged extension of trunk; and earlier with Asian pull where the quadriceps and shank muscles are re – introduced at smaller knee angles, i.e., the loading is shifted away from muscles straightening the trunk to the lower extremities. Charniga photos.

Concepts such as inertia coupling and transport of power shed a radically different light on the role of the ankle muscles in weightlifting technique. Traditionally these muscles are assigned a rather minor role in the weightlifting literature, i.e., a heel raise at the end of the pull phase. However, the activity of these muscles is significantly more intrinsic with the thigh and trunk extensor muscles throughout the entire motion of lifting.

The single joint soleus is an important synergist with quadriceps in straightening the knee joints in a flat footed posture. The bi-articular gastrocnemius muscle likewise participates in transporting power from the quadriceps while stiffening to prevent hyperextension of the knee joint. The role of so – called triceps surae (gastrocnemius and soleus) group in weightlifting technique is far more complex than the average weightlifting coach or sport scientist has even imagined.

The minor role in the special weightlifting literature assigned the muscles of the shank is unjustified.

Consequently, an exaggerated heel raise coupled with an exaggerated shifting of shoulder joints behind the vertical line of the bar characteristic of the Asian pull, can be viewed as a shifting of the emphasis to the lower extremities to raise the barbell while reducing the role of the trunk extensors and the trapezius muscles.

SLide 5Figure 5. The rapid rise onto the toes as the shoulders move backward behind the vertical line of the bar allows the gastrocnemius muscles to deliver power from the quadriceps; shifting the emphasis of the lifting from the trunk to the lower extremities. Charniga photos

The foot as a spring:
The Windlass Mechanism

The role of the foot – lever in weightlifting sport has received insufficient attention as most of the research and focus of weightlifting technique has been on such areas barbell trajectory, power output, intermuscular coordination, goniometry and so forth.

The weightlifter activates the so -called windlass mechanism of the foot when the heels are raised in the pull; the more so, the more the big toe is bent back. This action stretches the plantar fascia activating the so-called windlass mechanism; a taut, elastic lever is formed from which the athlete is able to push the floor away.

The activation of the windlass mechanism turns the foot into a stiff lever with elastic properties to store and release strain energy against the support.

The athlete compensates for the obvious problem of balance by shifting the trunk away from the vertical; in effect, counterbalancing the athlete – barbell system. In many cases, the greater the heel raise, especially a heel elevation most weightlifting experts would consider a premature rise onto the toes, the greater the lifter’s trunk is tilted away from the vertical.

Slide 1
Figure 6. The stretched, stiffening plantar fascia of the windlass mechanism of the foot link this “spring” to the body’s largest, strongest spring: the Achilles tendon. Although the muscle forces from hip to foot do not appear linear with heels raised, knees bent and shoulder joints behind the bar, sufficient force is nonetheless delivered to the support through the rigid yet elastic foot lever. Charniga photos and Google image illustration.

In virtually all cases one can observe a “premature” heel raise even in the Russian pull. But for the most part, the athlete’s shoulder joints are over the bar. This means the center of mass of the system is moving forward. This is why many practitioners of the Russian pull are forced to hop forward in the descent under the barbell to fix the weight in the snatch or clean.

The idea to remain flat footed as long as possible to perform the Russian pull is to avoid dampening the force of trunk and knee extensor muscles through the shank. Which is much the same idea to keep the arms straight.

However, it is all but impossible to keep the feet flat in either Russian or Asian pull until the trunk and legs have all but stopped straightening, because the reactive protective mechanism known as anatomical constraint kicks in to prevent this. The gastrocnemius stiffens as the knees straighten, the athlete’s heels rise.

That being said, the exaggerated heel raise characteristic of an Asian pull takes full advantage of a typically overlooked, yet significant potential of the muscles of the shank to deliver force to the support.

Variations in strength potential relative to the weightlifter’s posture

For a long time, there has been a general consensus among the weightlifting specialists the weightlifter must effectively employ the strongest muscles to raise the barbell in the pull. This of course means the lifter should utilize the work of the thigh extensors (quadriceps group) and the extensors of the trunk with maximum efficiency.

Soviet era testing of the elite weightlifters established the strongest disposition of the body’s links in the pull. Weightlifters can develop a force (measured on a force plate) of up to 300 kg in the starting position of the clean. The largest force of up to 500 kg was recorded in the explosion position with hip angles of about 60-70º and a knee angle of about 135 – 140º.

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Figure 7. Recording static strength in the strongest positions of the pull. Figure on the left with bar below knees and on the right with bar above knees. In both cases with feet flat. (Vorobeyev, 1988).

Measurements of leg extension in a ¼ squat position (vertical trunk) with a knee angle of 135º were in the range of 265 – 300 kg for lifters in the 110 kg class

Maximum static strength is greatest when the lifter is in the pulling positions where thigh and trunk extensor muscles are working together. However, maximum force varies according to different knee angles and inclination of the trunk to the vertical. Less maximum force was recorded when the trunk is vertical and only leg extensors working.

In all three cases recordings were made with the athlete in a flat – footed posture with knees flexed.

The Russian protocol to delay the re-bending of the knees (see photos) in the pull is not in conformity with these measurements of maximum static strength. The reason being the knees are almost straight with bar above the knees, i.e., the prolonged loading is all on the trunk extensors with a prolonged moment on the lumbar spine.

By allowing the knees to re-bend sooner the lifter is able to use extensors of the lower extremities simultaneously with the extensors of the trunk to perform the explosion.

Consequently, some research data of static strength potential is part of the logic behind the protocol of the Russian pull. Less force is produced in the pulling postures with the arms bent and likewise one can logically assume less force would be produced if the measurements in the start and explosion phase positions were made with heels raised instead of flat – footed.

Slide 7

Figure 8. Figure in the center is a depiction of starting position for learning the explosion phase of the snatch, according to Druzhinin (1974), i.e., from a raised heel disposition. This a radical departure from conventional thinking; way ahead of its time in 1974. However, in the Druzhinin example shoulders are over the vertical line of the bar whereas in Asian pull the shoulders are behind.

It is highly unlikely anyone has measured an athlete’s static force potential with the subject grasping the bar in a clean grip, heels raised and trunk behind the vertical line of the bar. In all likelihood the static force produced would be less than the Russian measurements. However, this knees bent, heels raised, trunk leaning backward disposition of the body in all probability suffices to accomplish the task under the dynamic conditions of cleaning or snatching a barbell.

Conclusions
The main distinctions between a Russian pull technique and an Asian pull are the premature heel raise with knees bending and significant deviation of the trunk away from the vertical in the explosion phase of lifting.

What would be generally considered a pre – mature raising of the heels in the pull phases of the snatch and the clean on closer examination activate a complex interaction of the body’s reactive mechanisms. Concepts such as inertia coupling, transport of power through biarticular muscles and the activation of the windlass mechanism of the foot challenge long accepted ideas of the relative importance of the various muscles and levers to modern weightlifting technique.

References:
1/ Alexander, R.McN. (1988). Elastic mechanisms in animal movement, Cambridge University Press, Cambridge
2/ Novacheck, T.F., “The Biomechanics of Running”, Elsevier Science B.V., 1998.
3/ Zajac, F.E., “Muscle Coordination of Movement: A Perspective”, J. Biomechanics,26:suppl1:109-124:1993
4/ Zajac, F.E., “Understanding muscle coordination of the human leg with dynamic simulations”, J. Biomechanics; 35:1011-1018:2002
5/ Roman, R.A., The Training of the Weightlifter, Moscow, FIS, 1974; 1986. English Translation Sportivny Press, Livonia, Michigan
6/ Van Ingen Schenau, G.J., “From rotation to translation: Constraints on multi – joint movements and the unique action of bi-articular muscles”, Human Movement Science, 8:301 – 337:1989
7/ Vorobeyev, A.N., Weightlifting: Textbook for the institutes of Sport, Moscow, FIS, 1972; 1982; 1988
8/ Baechele, Earle Essentials of Strength and Conditioning, Human Kinetics publishers,. Champaign, Illinois. 2000
9/ Bobbert, M.F., Huijing, P.A., Jan Van Ingen Schenau, G., “An Estimation of Power Output and Work Done by the Human Triceps Surae Muscle – Tendon Complex in Jumping,” Journal Of Biomechanics, 19:11:899-906,1986
10/ Bobbert, M.F., Jan Van Ingen Schenau,G., “Coordination in Vertical Jumping,” Journal Of Biomechanics, 21:3:249 – 262, 1988.
11/ Bobbert, M.F., Huijing, P.A., Jan Van Ingen Schenau, G., “A Model of the Human Triceps Surae Muscle – Tendon Complex Applied to Jumping,” Journal Of Biomechanics, 19:11:887 – 898, 1986
12/ Charniga, A., “Can there be such a thing as an Asian pull?”, Sportivny press, Livonia, Michigan, 2015

13/  Druzhinin, V.A., “Teaching Snatch Technique to Beginners”, Tiazhelaya Atletika 29- 31: 1974;Translated by Andrew Charniga, Jr. Sportivny Press©

Bi – articular muscles

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