When exercising, what is a "kinetic chain"?

The word "chain" suggests a series of links held together. In the human body, this is a group of links and segments or body parts. These links and segments work together to generate a force. This force is used to hold or move a body part.

For example, when using the arm overhead in tennis or pitching, there is an entire sequence of actions needed. First, there is a ground reaction force as the foot and leg push against the ground. This force moves through the legs to the knees and hips and then into the trunk. The legs and trunk produce about half of the energy and force needed for this motion.

The trunk and scapula (wing bone) then work together to funnel this force to the shoulder, arm, and hand. This allows the smaller muscles of the arm and hand to position the hand to control the throw. Each activity has its own kinetic chain and energy. These depend on the position of the body (e.g., sitting, standing, kneeling) and where the activity takes place (e.g., on the field, in a pool).