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OBJECTIVES
After completion of this chapter, the physical therapist should be able to do the following:
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Through the years, the concept of closed kinetic chain exercise has received considerable attention as a useful and effective technique of rehabilitation, particularly for injuries involving the lower extremity.1 The ankle, knee, and hip joints constitute the kinetic chain for the lower extremity. When the distal segment of the lower extremity is stabilized or fixed, as is the case when the foot is weightbearing on the ground, the kinetic chain is said to be closed. Conversely, in an open kinetic chain, the distal segment is mobile and not fixed. Traditionally, rehabilitation strengthening protocols have used open kinetic chain exercises, such as knee flexion and extension on a knee machine.2
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Closed kinetic chain exercises are used more often in rehabilitation of injuries to the lower extremity, but they are also useful in rehabilitation protocols for certain upper-extremity activities. For the most part, the upper-extremity functions in an open kinetic chain with the hand moving freely; however, there are a number of athletic activities in which the upper-extremity functions in a closed kinetic chain.3 It must be stressed that both open and closed kinetic chain exercises have their place in the rehabilitative process.4 This chapter clarifies the role of both open and closed kinetic chain exercises in that process.
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CONCEPT OF THE KINETIC CHAIN
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The concept of the kinetic chain was first proposed in the 1970s and initially referred to as the link system by mechanical engineers.5 In this link system, pin joints connect a series of overlapping, rigid segments (Figure 11-1). If both ends of this system are connected to an immovable frame, there is no movement of either the proximal or the distal end. In this closed link system, each moving body segment receives forces from, and transfers forces to, adjacent body segments and, thus, either affects or is affected by the motion of those components.6 In a closed link system, movement at one joint produces predictable movement at all other joints.5 In reality, this type of closed link system does not exist in ...