Friday, May 2, 2008

Open Chain Versus Closed Chain Exercises

Open Chain Versus Closed Chain Exercise

In addition to different types of muscle contraction, you can use two basic types of movement to elicit those contractions. Each has pros and cons, and you may need to analyze an activity to decide if you want to include it in your program. The names of these types of movement, open chain and closed chain, come from the science of biomechanics. They refer to whether or not the extremity is fixed at the distal end during an exercise, meaning whether the hand or foot stays in contact with either a stable surface or a piece of equipment that moves in a predetermined way. An open chain activity is one in which the extremity can move in any direction, because it is not attached at the end. For example, if you raise one of your feet off the ground, you can move that leg in any direction or sequence of movements. A closed chain activity, on the other hand, fixes the distal end of the extremity either to the ground or to a device that has a predetermined motion. When you keep your feet on the ground while you bend or straighten one joint, the other joints move in a predictable, set manner.

Open chain exercises do a good job of targeting one set of muscles for strengthening, but they increase the forces transmitted to the involved joint. Closed chain activities transmit less force to the joint (although they too can be stressful) and often are more functional movements. Another benefit is that when you perform closed chain exercises, you often strengthen several muscle groups.

Because of the increased stress on joints, keep open chain activities to a minimum. Exercises such as biceps curls are simple and usually do not cause too many problems. On the other hand, knee extension exercises that use an open chain motion produce a lot of stress to the knee and will probably increase your pain. If you opt for an open chain activity, keep the resistance lower around an arthritic joint. For example, you might do a knee extension in an open chain manner using rubber tubing, but keep away from knee extension machines. If you want to use a machine, the leg press is a better option; it is a closed chain activity and you can usually modify your position to further decrease the stress to your knees.


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