|
Year |
2005 |
|---|---|
|
Question Number |
22. |
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Category |
Rehabilitation |
Question
The rehabilitation term "open chain" refers to exercises best characterized as
1- weight-bearing.
2- isometric.
3- isotonic.
4- concentric.
5- moving terminal appendage.
Figures
Answer (click for answer)
PREFERRED RESPONSE: 5
During open chain activities, the distal extent of the extremity is free to move. Movement is produced by contraction of the agonist muscle. During closed chain activities, the distal aspect of the extremity is fixed, and motion occurs simultaneously at all joints that compose the kinetic chain. Movement is produced by co-contraction of muscles. Closed chain exercise simulates functional demands placed on the extremity during a variety of activities.
Isometric refers to an exercise in which the muscle length remains the same, i.e. pushing against an immovable object.
Isotonic describes constant muscle tension throughout the range of motion, i.e. biceps curls with free weights.
Concentric is when the muscle shortens during the contraction. Opposite of eccentric contraction in which the muscle lengthens during the contraction.
Using mechanical engineering concepts, the kinetic chain concept was described first by Steindler in 1955. Steindler sought to describe various types of exercise conditions with this new concept. The mechanical engineering definition of the kinetic chain describes a series of interconnected joints, fixed proximally and distally. In this system, movement of one joint has an effect on all joints above and below. Steindler separated the mechanical engineering definition into two states, open and closed kinetic chain. He described the open chain state as a peripheral extremity able to move freely, such as waving the hand or the swing phase of the gait pattern. The closed kinetic chain state was described as the distal segment meets considerable resistance, as it does with a pull-up or squat.
Reference: RECOMMENDED READINGS: DeLee JC, Drez D Jr, Miller MD (eds): Orthopaedic Sports Medicine: Principles and Practice, ed 2. Philadelphia, PA, WB Saunders, 2003, pp 319-439.
Steindler A: Kinesiology of the human body under normal and pathological conditions. Springfield, IL, Charles C Thomas, 1955.
Sullivan JA, Anderson SJ (eds): Care of the Young Athlete. Rosemont, IL, American Academy of Orthopaedic Surgeons and American Academy of Pediatrics, 2000, pp 267-280.