The kinetic chain is a model that treats the body as a series of linked segments, such as the foot, shank, thigh, pelvis, trunk, arm, and hand. Because the segments are connected at joints, motion and force at one segment influence the segments next to it.
The term is used in two common ways in sport and exercise science.
Open and Closed Kinetic Chain
- Closed kinetic chain: The distal segment is fixed or supported, such as the feet on the ground in a squat or the hands on the floor in a push-up. Movement at one joint is coupled to movement at others.
- Open kinetic chain: The distal segment moves freely, such as the lower leg during a seated knee extension or the arm during a throw.
These categories are simplifications. Many real movements combine both, and classification can depend on how a task is defined.
Sequencing in Throwing and Striking
In many fast skills, segments tend to reach peak speed in a proximal-to-distal order: the pelvis, then the trunk, then the arm, then the hand or implement. A well-timed sequence allows each segment to contribute to the speed of the next, helping produce high velocity at the end of the chain. This pattern is commonly described in pitching, golf, tennis serves, and kicking.
Observing It in Video
Video is well suited to studying sequencing and timing. Frame-by-frame review can show when the hips begin to rotate relative to the shoulders, when the elbow extends, and when the implement reaches release or contact. Side-by-side or overlay comparison can show how sequencing differs between attempts or athletes. In KineVision, skeleton overlays and joint angle tracking can help mark segment positions across a movement.
Limits and Pitfalls
- Video shows the order and timing of segment motion, not the forces or energy transferred between segments
- Terms such as "energy leak" are coaching metaphors rather than measured quantities
- Rotation toward or away from the camera is easily misread in a single 2D view
- A problem visible at one segment may originate elsewhere in the chain, so conclusions about cause should be made cautiously
The kinetic chain is a practical framework for looking beyond a single joint when analyzing technique.