Kinematic chain

Most movements involve not just one joint, but multiple joints working together. These combinations of joints are referred to as a 'kinematic chain'.

Kinematic chains can be categorized as open, closed, or semi-open.

Open kinematic chain

In an open kinematic chain, the joints() move(s) freely through the air and is/are not fixed or restricted. This type is most commonly seen in arm movements, but a kicking motion is also an example. The body part moves freely through open space.

Closed kinematic chain

In a closed kinematic chain, the joint(s) cannot move freely. The most common example of a closed kinematic chain is the stance phase during walking. Here, the foot is fixed between the ground and the rest of the body, preventing free movement. Other examples include squats and push-ups, both of which involve movement within a closed chain.

Semi-open kinematic chain

A semi-open kinematic chain falls between the two extremes. The joint(s) appear(s) to move freely through space but is/are attached at one end. Examples include thigh exercises performed on a gym machine where the feet dangle above the ground (leg extension), or arm exercises using a pulley machine.