Open and closed kinetic chain exercises
Another important classification of exercises is the kinetic chain. This can be defined as the combination of several successively arranged joints working together to successfully complete a desired motor task of the body.
A closed kinetic chain exercise is one in which the terminal joint meets with considerable resistance that prohibits or restricts its free movement – i.e. the distal (terminal) joint is stationary. Lower body closed kinetic chain exercises (such as the squat, leg press, deadlift) have often been classified as a more functional form of exercise when compared with open kinetic chain exercises (see below). When performing the squat, the feet are ‘fixed’ to the floor and do not move, providing a firm base upon which movement occurs.
Closed kinetic chain exercises have several advantages. These include increased joint stability and functional movement patterns (joints do not usually work in isolation but rather work together with adjacent joints and surrounding muscles).
An open kinetic chain exercise is a combination of successively arranged joints in which the terminal joint is free to move (such as the leg extension and leg curl machines). These exercises allow for greater concentration on an isolated joint or muscle. During the leg extension exercise, the feet and lower legs can move freely, although the exercise allows greater concentration on the quadriceps at the knee joint. Whereas the squat (a closed kinetic change exercise) which also uses the quadriceps muscles and knee joint, also relies on muscle activity at both the hip and ankle joints.
Although closed kinetic chain exercises are often viewed as more functional, most activities involve both open and closed kinetic chain movements. In sprinting, for example, while one leg is on the ground (closed kinetic chain), the other is in the air (open kinetic chain), which means that both types of movements can occur simultaneously.