Posted on 20 Dec 2008 19:28
By Eric Troy, Ground Up Strength
The concept of the kinetic chain was purportedly introduced in 1955 by Arthur Steindler in his important book Kinesiology of the HUMAN BODY UNDER NORMAL AND PATHOLOGYICAL CONDITIONS. He wrote:
"We designate an open kinetic chain a combination in which the terminal joint is free. The waving of the hand is an open kinetic chain in which the action of the shoulder joint, the elbow joint, and the wrist joint are successively involved.
A closed kinetic chain, on the other hand, is one in which the terminal joint meets with some considerable external resistance which prohibits or restrains its free motion. Eventually, the external resistance may be overcome and the peripheral portion of the joint may move against this resistance, for instance, in pushing a cart or lifting a load; or the external resistance is absolute, in which case the proximal part moves against the peripheral, as for instance, in chinning oneself on a horizontal bar; or the limitations of the muscular effort may assert itself both peripherally and proximally and may be insurmountable, in which case no visible motion is produced. Only in the latter instance is the kinetic chain strictly and absolutely closed.
However in common use we apply the term to all situations in which the peripheral joint of the chain meets with overwhelming external resistance." 1
It is clear that there was a great deal of internal inconsistency in this original definition and this still exists since the terms have been re-defined again and again. While the problems are real - and whether the terms themselves are ultimately useful remains to be seen - there is no need for confusion for the amateur strength trainee as such idiosyncrasies serve little purpose for general strength development. It is "common use" we are concerned with, as Dr. Steindler himself points out in the quote above1
Therefore, the purpose of this explanation is to help the reader understand, in simple terms, the concept of open kinetic chain versus closed kinetic chain. As such, the complexities of the kinetic chain concept in its entirety are not discussed, for to understand this concept completely would require an entire tome as it involves more than just the bones of the body and their joint linkages but also encompasses the soft tissues such as muscle, tendon, ligament, and the nervous system.
For our purposes, here, however, we can view the body as simply a collection of bony parts linked by a series of joints. Thus a chain. A kinetic chain, therefore, is a system of linked rigid bodies which force is applied to. The mobility of the distal segment of this chain, and it's complexity, determines how it is classified whether simple or complex, open or closed.2
Open and Closed Kinetic Chain
Imagine a chain that is spread out without either one of its ends being joined to any other object or to each other. Hence the chain is open. You will see that either end or extremity of the chain can be manipulated without much effect on any other link. But if you attach one or both ends of the chain so that it is closed it is difficult to move any one link in the chain without movement in other links of the chain.
Some writers will assert that it is impossible to effect the movement of one link in a closed chain without a lot of movement in other adjoining links but I do not think this is entirely accurate, as will be discussed later.
The "distal end" is a part of the body that is furthest away from the trunk or middle. So, for instance, the hand is the distal end of the upper extremities. If you press a dumbbell or barbell the kinetic chain is open. In other words the hands are free to move freely in space and not "attached" to something immovable, such as the floor, or wall. So, the bench press or overhead press is an open chain exercise.2 Any one joint can be moved without other joints being affected significantly. You can do a wrist curl without moving your elbow or shoulder much (the proximal joints or segments). The same goes for a curl or extension, etc…This does NOT mean that there is never movement in adjoining joints in open chain exercises, it simply means that it is possible for movement to occur at any one joint without movement in the others.
But in the case of closed chain movements, where the distal end is stationary, it becomes much more difficult to move any one joint without a compensatory movement along the entire chain. Compare the press to a natural pushup. Movement in one joint cannot occur without movement in the others.
So, muscle groups are more easily isolated during open–kinetic chain exercises, whereas there is more movement of proximal segments in closed chain movements and therefore more co-contraction.
This is the general idea. However, as I stated at the beginning movement is complex and there do exist many gray areas between defining the concept of open versus closed in body movements. After all, the human body is a bit more complex than a simple metal chain. In the case of certain movements, and especially with machines, there can exist exercises that could be described as "partially" closed or open.
The difference, in my opinion, has to do with the predictability of subsequent joint movement in certain exercises. With a barbell back squat, (closed chain movement) for instance, properly performed, it is very easy to predict the movement of body segments based on body geometries, bar position, stance width, etc. But exchange that barbell, where the weight's movement is not held to a fixed plane, and replace it with a smith machine squat, and you will see that the concept of open versus closed becomes much less clear-cut. The bar in a smith machine is forced to travel in a fixed plane of motion and thus the subsequent movements of the body's segments are not easily predictable. Although a smith machine squat is, upon first glance, a closed chain movement…it resides in the gray area I mentioned above. During a squat the body needs to maintain the center of mass, which has been moved upward from the middle by the addition of the barbell. When a fixed plane of motion is introduced this natural movement can no longer occur.
A popular alternate definition of these terms is basically that "open chain" means the force applied by the body is great enough to overcome the resistance while with "closed chain movements" the force is not great enough to overcome the resistance. I find this to be a nonsense explanation which can create a lot of confusion. The idea is that, with a squat, the force is applied to the floor but, of course you can't move the floor. With bench press the force is applied to the bar which moves….
Such a nice black and white explanation would be quite handy. Too bad it makes no real sense. With either movement, body segments move and that is what is important. The "resistance" in the squat is NOT the floor. The floor is simply the surface which "closes" the distal end. The resistance that is being moved is still the bar. Remember, the distal end is the extremity and this is what determines, in simple terms, whether a movement is closed or open. But it does not determine, necessarily, where the mass to be moved rests. The explanation works better when you think of running where you apply resistance to the ground which moves the body.
It's hard to tell why this kind of explanation exists but if I could guess, it would be to help explain skill transfer in simpler terms. But this is a case of the centipede and its many legs.
To put this explanation to rest one need only consider an overhead squat.
Muscle groups may be isolated during open–kinetic chain exercises, and more co-contraction of various muscle groups occurs during closed–kinetic chain exercises.
Since the body is not merely a collection of bony links all movement cannot be explained or predicted by this model. Keep in mind that a model such as this is a simplified version of a complex system and models only serve to help us envision and understand these systems intuitively. The body could also be viewed as a collection of possible levers. It is much more difficult to view the body this way than as a simple chain! Especially since the type of lever for a given joint and muscle changes as a result of how the each part is arranged in relation to the other, and again, when the distal end is in fixed contact a new lever system is created.
The purpose of this article was to explain the concept of open versus closed chains which is related to the segmental interaction principle of biomechanics. However, whether the open/closed concept itself concept is useful as a way of classifying movement has been debated by some. Many complexities and question exist and different classification systems have been proposed, some of which are highly complex.
The remainder of this article will answer some common questions regarding whether certain exercises should be considered open or closed chain. However, keep in mind that "gray" areas do exist.
Is the Overhead Squat a Closed or Open Chain Movement?
The overhead squat is a closed chain movement. The confusion over this comes about because the weight is held overhead in the hands leading people to wonder which "end" should be considered the distal end. The fixed end does not change whether the barbell is on the back of your shoulders, the front of your shoulders, or overhead in your hands.
During overhead squats, the weight is maintained in a steady position overhead in the "pocket". It does not move nor should we be attempting to move the weight with our arms. The distal end, the feet, is closed just like with any other free-weight squat. Again, as in the explanation above, where the external load rests is not as important as where the force is applied. Just as in any squat, the force is applied to the ground and the resistance being moved is the overhead weight plus body-weight. The over-head squat is a closed chain exercise.
Are the Bench Press and Overhead (Military) Press Open or Closed Chain Exercises?
The bench press and the military press exercises, as should be clear from the article above, are both open chain movements. The distal end is the hands which are holding the barbell, dumbbells, or other free weights. This end is not fixed but is free to move about in any plane, thus the exercises are open chain movements. If another system of classification is used, or a different aspect of the kinetic chain concept is focused on the bench press could be considered closed chain by some.
Are Pullups or Chinups Open or Closed Chain Exercises?
This is a tougher question to answer. Many consider pullups and chinups to be one of those "gray areas" mentioned above. This confusion exists because of the simple fact that the body is free to move about in space while hanging from the bar. However this is needless confusion as the pullup is clearly a closed chain movement. The hands are fixed by the pullup bar and the force is being applied to the bar, which, being immoveable, results in the body being pulled up. Any subsequent movement is influenced by the fixation of the hands.
There are two simple ways to conceptualize this. One is to compare regular body weight pullups or chinups to pullups done with an assisted pullup machine. These machines support the body underneath and provide a certain degree of assistance by pushing up on the body. This fixes the lower half of the body, usually at the knees. Now that both ends are technically "fixed" we can easily see that this is a closed chain movement and also see that its fundamental nature, whether on a machine or not, is that of a closed chain movement. Regardless of whether the body segments can be moved about freely the fundamental movement is a movement that is primarily influenced by the distal end being fixed at the immobile bar. There is no practical need for imagining the pullup to be a "gray" area in terms of the kinetic chain.
Another way to understand this is to compare pullups with lat pulldowns using a cable and pulley system, which is clearly an open chain movement.
Examples of Open Kinetic Chain Exercises
- Biceps Curl
- Triceps Curl
- Leg Curl
- Leg Extension (Knee Extension)
- Dumbbell Lateral Raise
- Dumbbell Flyes
Examples of Closed Chain Kinetic Exercises
- Push Ups
- Leg Press
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This page created 20 Dec 2008 19:28
Last updated 30 Apr 2016 04:15