In a closed chain, the end of the chain farthest from the body is fixed. A good example is the squat, in which your feet are fixed on the floor and the rest of the leg chain (and torso) moves. In open-chain exercises, the end is free, such as during a seated leg extension. During open-chain exercises, your hand or foot is free to move, such as when performing a triceps extension or a hamstring curl.

Muscle actions that occur during open kinetic chain activities are usually reversed during closed kinetic chain activities. In open kinetic chain exercise, the origin is fixed and muscle contraction produces movement at the insertion. In closed kinetic chain exercise, the insertion is fixed and the muscle acts to move the origin.

In open kinetic chain exercises, the segment furthest away from the body — known as the distal aspect, usually the hand or foot — is free and not fixed to an object. In a closed chain exercise, it is fixed, or stationary.