The concept of the kinetic chain originated in 1875, when a mechanical engineer named Franz Reuleaux proposed that if a series of overlapping segments were connected via pin joints, these interlocking joints would create a system that would allow the movement of one joint to affect the movement of another joint within the kinetic link. Dr. Arthur Steindler adapted this theory in 1955, and included an analysis of human movement. Steindler suggested that the extremities be viewed as a series of rigid, overlapping segments and defined the kinetic chain as a "combination of several successively arranged joints constituting a complex motor unit." The movements that occur within these segments present as two primary types—open and closed. Open-chain Movement Steindler defined open kinetic chain is defined as a combination of successively arranged joints in which the terminal segment can move freely. In an open-chain movement, the distal aspect of the extremity, or the end of the chain farthest from the body, moves freely and is not fixed to an object. Here are some examples of open-chain exercises: Seated leg extension Leg curl Bench press Dumbbell biceps curl Lat pull-down Closed-chain Movement Steindler defined closed-kinetic chain exercise as a condition or environment in which the distal segment meets considerable external resistance and restrains movement. In a closed-chain movement, the distal end of the extremity is fixed, emphasizing joint compression and, in turn, stabilizing the joints. Closed-chain exercises, such as the examples below, are considered to be more functional than open-chain exercises. Squat Wall slides Lunges Elliptical training Stair stepper Versa Climber Push-ups Understanding how the body and all of its segments work together is essential for developing effective exercise programs. Furthermore, knowing the difference between open- and closed-chain movements can help you to select appropriate exercises based on the individual needs of each client. References Ellenbecker, T.S., and Davies, G.J. (2001). Closed Kinetic Chain Exercise: A Comprehensive Guide to Multiple Joint Exercises, (1st ed.). Champaign, Ill.: Human Kinetics.