©Copyright 2008 by Robert Chuckrow
Is Active Muscular Extension Possible?
In my book, Tai Chi Dynamics, which was published in July, 2008, I claimed that muscles can actively extend and utilized that concept to explain a number of hitherto elusive principles in Taiji. Within weeks after publication of that book, reviews of it appeared on Amazon.com asserting the scientific impossibility of active muscular extension (AME).
First, I emphasize that my basis for accepting that muscles can actively extend is experiential and is from thirty-five years of my study of Kinetic Awareness® (KA) under Elaine Summers. KA is a system of natural movement and self-discovery originated by Summers. It should be noted that her teachings have influenced a number of other movement fields that have for decades utilized the concept that muscles can extend. Such fields are athletics, physical therapy, Yoga, Pilates, Feldenkrais, dance, bicycling, swimming, gymnastics, and weight-lifting.
About a decade or so ago, I began to realize that AME was intrinsic to what in T’ai Chi is called “correct strength” (as opposed to “awkward strength”). Read the article on Peng, Jin, and Li. This realization greatly expanded my progress in T’ai Chi—especially when I began to apply basic principles of mechanics and dynamics to movement involving AME.
The following is my attempt to explore whether AME is possible:
Hypothetical Modalities of Muscle Usage
Consider the specific example of curling a light weight with one hand. The elements of this example can easily be generalized to other actions. Let us examine possible cases that could occur if it is possible for muscles to actively extend:
Case 1. The biceps contracts, and the triceps sympathetically contracts. Here, the action of the triceps actually opposes that of the biceps, making the action awkward and inefficient. This mode of muscular action is seen in untrained people and in weight-lifters.
Case 2. The biceps contracts, and the triceps relaxes and is passively lengthened (stretched). Here, the action of the triceps opposes that of the biceps but less than in case 1—it opposes because some of the biceps’ force is used to stretch the triceps.
Case 3. The biceps contracts, and the triceps actively extends only to eliminate the resistance to being stretched but does not otherwise add any pushing force to the movement. Here, the action of the triceps does not at all oppose that of the biceps but does not add any force of its own.
Case 4. The biceps contracts, and the triceps actively extends, adding force to the movement. Here, the action of the triceps adds force of its own.
Case 5. The biceps relaxes, and the movement is caused totally by an active lengthening of the triceps. Here, the action of the triceps adds force of its own—so much so that the biceps does not assist the action.
Case 6. The biceps and the triceps both actively extend, the triceps less so than the biceps. Here, the action of the triceps opposes that of the biceps.
Note that cases 1 and 2 are not controversial because they do not involve active extension.
Questions and Responses to Them
Next, consider questions that have arisen regarding muscular extension.
How can it be that there is a new mode of muscular action when the mechanism of muscular movement is well described in cellular and molecular biology?
Not everything is known about the physiology of muscular action. Throughout the history of science and medicine, new ideas, concepts, phenomena have continually arisen that were thought to be impossible. After study, some of these have been rejected as false, but a substantial number of others were later found to be valid. Only extensive scientific investigation can rule out the possibility of something. Thus, nowadays, scientists make a statement of the impossibility of something very cautiously, only after extensive, objective, and convincing study of the allegedly impossible phenomenon. Cautiousness, dictated by the large number of things previously thought to be impossible but later found not to be so, prompts scientists to express doubt, skepticism, or curiosity instead of saying something is impossible.
Muscle cells are able to contract and shorten, so how can muscles deliver a pushing force?
Neural impulses to muscle cells within muscle fibers cause these cells to contract, and the cellular contraction shortens the muscle fibers. This is true of all muscle fibers as far as is known, and there is no disagreement about the fact that nerve impulses to muscle fibers can only cause them to contract. Thus, we are not asserting that neural impulses to muscle cells within a particular muscle fiber can ever cause that fiber to extend. Instead, we will assert the possibility that the contraction of certain muscle fibers can cause other muscle fibers, on which they impinge, to lengthen.
Consider the fact that it is unusual for all the muscle fibers of a muscle group to run all in one direction. Instead, the fibers of most muscle groups cross and weave, one into the other. Moreover, such fibers are layered one above the next. The arrangements of different muscles are different, and these varying arrangements are referred to as muscle architecture. A good example of complex muscle architecture is in the shoulder and arm. The muscles of the forearm control the flexing and opening of the fingers, rotations of the wrist, the bending forward and back of the hand, and the bending sideways of the hand. The muscles of the shoulder control the rotations of the arm and the sagittal, frontal, and horizontal motions of the arm. See the figure below, showing the superficial (outer) muscles of the shoulder and arm. In order for such motions to occur, muscles must be arranged transversely.
Superficial Muscles of the shoulder and arm. From Henry Gray and Charles Mayo Goss, Anatomy of the Human Body, Lea & Febiger, Phiadelphia, PA, 1974, p. 451.
It is not far fetched that groups of fibers might contract selectively and in such a way that they squeeze other fibers that they weave through or cross over, thereby constricting and making these other fibers longer (extension). Considering the huge number of neural connections to muscles and the ability of the brain to coordinate these impulses, it is reasonable that such a way of lengthening muscles is possible.
It appears that nothing that is known about the way muscles contract rules out the above mechanism, which is just an additional mode of contraction. Such extension is active in the sense that it results actively from neural impulses rather than passively by contraction of opposing muscles. However, it is emphasized that muscles are incapable of extending unless squeezed by others that contract.
The tongue has a very complex muscle architecture. A known example of extension produced by contraction occurs when you stick out your tongue. Such extension is understood* to occur through the contraction of muscle fibers that go across the length of the tongue, making the tongue narrower and longer. Thus, the extension of the tongue is an example of how the contraction of muscle fibers can cause muscular extension.
Even if such a muscular extension could occur, it would mean that the muscle would have to exert force to the bones by pushing the bones with the use of the tendons. A tendon is like a cable, which is good at pulling, not pushing. How can a tendon push?
A cable can exert a pushing force. Cables are used to exert pushing force in machinery and automobiles. The reason it works is that the cable is enclosed in a sheath that keeps it from buckling. In the human body, there is tissue surrounding tendons, and that tissue can well keep tendons from buckling, allowing them to push bones. From my experience, when I use AME and press on the tendon involved with my fingers, it definitely feels rigid enough to push bone. In fact, when I extend my hand (palm trailing) using AME and, at the same time, lightly place the ball of my thumb of my other hand on the inside of the wrist of the extending hand, I can feel the associated tendons activate. Alternately, when I extend my hand (palm trailing) using contraction of the muscles on the outside of my forearm and, at the same time, lightly place the ball of my thumb of my other hand on the inside of the wrist of the extending hand, I can feel the tendons sliding underneath rather than activating. Moreover, when using AME, I feel a hydraulic pressure building up, as if my wrist were swollen. I can’t help feeling that this hydraulic pressure is involved in the movement.
My first teacher, Cheng Man-ch’ing, talked about developing “tenacious strength,” or “tenacity” (Cheng Man-ch’ing, T’ai Chi Ch’uan: A Simplified Method of Calisthenics for Health & Self Defense, North Atlantic Books, Berkeley, CA, 1981, pp. 16–17.) According to Zheng, “Tenacity is the resistance or tonicity of living muscles. The muscles being relaxed, tenacity cannot involve the bones. Force, on the other hand, is derived from muscles, binding the bones together into a wooden (rigid) system.”
The following quote is from Chen Wei-Ming, T’ai Chi Ch’uan Ta Wen Questions and Answers on T’ai Chi Ch’uan, Translated by Benjamin Pang Jeng Lo and Robert W. Smith, North Atlantic Books, Berkeley, CA, 1985, pp. 57–58:
“Chin [Jin]: One of the main objectives of T’ai Chi Ch’uan is the development of Chin or internal force. Chin is contrasted with li, which refers to muscular contraction and release. Chin is said to generate power from the sinews [tendons] rather from the muscles binding together and striking with the bones. Chin is developed through circular changes while the flexations of li follow straight lines.”
As one with a scientific and KA background, I am eager to have this proposed phenomenon studied. Others in the KA community are likewise eager. For example, a scientific investigation of the existence of AME might utilize living subjects who are trained in its use. Finding such subjects should not be difficult because there are many people so-trained. If only one person in the group can exhibit AME, then it is possible. If not, then one can suspect that it is not possible.
Note that cases 4, 5, and 6 require a tendon to push a bone, but case 3 does not. Thus, even if tendons were unbable to push, that still would not rule out that muscles can actively extend!
If AME is so powerful, why are all axial skeletal muscles arranged in opposing pairs? Why not a single muscle that can do both active contraction and extension?
An analogous question can be asked of why we have two eyes, two nostrils, two ears, etc., one on each side when one will do. The answer is that functional redundancy is common in the human body. Having eyes and ears on both sides adds the perception of visual depth and auditory directionality. Similarly, having opposing muscles provides much greater strength and adds more movement options. Most of us fall far short of our full movement potential. Studying Taiji and similar arts teaches us to utilize movement options otherwise not experienced. One of the very purposes of my book is to aid the practitioner in experiencing and cultivating such movement options.
If AME is possible, wouldn’t it be possible to do a pull-up without using the biceps, and wouldn’t not being able to do a pull-up without using the biceps rule out any possibility of AME?
Not being able to do a pull-up without using the biceps only rules out case 5, not 3 or 4, and, therefore, does not rule out the existence of AME. Anyway, case 5 may not be a realistic way of doing a pull-up because it requires an inordinate amount of AME. Possibly, those skilled in this type of activity utilize some degree of AME. The extent that a pull-up is done with AME of the triceps is worthy of investigation.
I am reasonably sure that I can use AME solely to accomplish some actions that do not involve large amounts of strength and which I have practiced regularly over the decades. Perhaps others have developed AME to exert more strength than I.
Some Experiential Evidence for AME
Here are some exercises (some of which are described in my book) that you can try, which should, at the very least, make you skeptical of the conventional idea that muscles cannot extend:
1. Lie on your back on the floor, legs straight out, with heels touching each other. If you need to, place a pillow under your head to achieve an optimal alignment of the cervical vertebrae. Without moving your pelvis or the heel of one foot, extend that knee horizontally away from the axis of your body. Even if you have trouble at first, you should be able to eventually learn to move your knee an inch or so in this manner.
Consider three points: your knee k, your heel h and you hip joint j Note that these three points form a triangle. Think of the base of this triangle as the line jh. As you move you knee away from this line, each of the distances hk and jk becomes longer. There is no way that contracting a muscle (which shortens it) can accomplish such lengthening. Next, feel the muscle on the inside of your left thigh, and notice that it is activated and lengthening when you move your knee outward. Then feel (or have another person feel) the muscles on the outside and bottom of your left thigh. Those muscles should be totally relaxed. In doing this exercise, you should also be able to feel that your left thigh joint is actually opening slightly. Can there be a way for any of these things to happen by contracting (shortening) muscles?
2. Let your arm rest on a table and extend it fully. With your other hand, feel that your biceps and the tendon from the biceps to the forearm both activate.
3. Experiment with your abdominal muscles by contracting or expanding your lower abdomen. You can do both of these actions just by using the same set of muscles and no other ones.
4. When you move your bowels or urinate, pay attention to what you do with your sphincter muscles, which are normally relaxed but taut. When you excrete, you extend these muscles and can feel it directly. Next, try contracting these same muscles. Note the difference in the feeling.
5. Feel your diaphragm expand when you cough or breathe out sharply.
6. Feel your trachea (wind pipe) expand when you breathe in—and even more so when you yawn.
7. Feel your nostrils flare when you inhale.
8. Extend your head upward.
I welcome any questions, comments, and references to scientific articles that provide possible mechanisms of AME. Please email them to me.
* “Apparently, the classical anatomical techniques of gross dissection and serial sectioning are not able to unravel the complex 3-dimensional anatomy of human tongue muscles. This lack of information appears to be a large obstacle to potential tongue researchers as even the most basic histological studies, such as myofibrillar ATPase muscle fiber typing, have not yet been reported for human tongue muscles.” From http://www.uchsc.edu/sm/chs/events/vh_conf/pdfs/007.pdf
©Copyright 2009 by Robert Chuckrow
More Articles on T’ai Chi
Tai Chi Dynamics Book