The kinetic chain is the sequence of joints and tissues that transmit force during movement. Force generated at one segment travels through the chain to deliver power at the end.
Mechanism: A throw starts at the foot. A squat depth limitation may live in the ankle, not the hip. Weakness or restriction at any link compromises the whole sequence.
Use case: Diagnose the chain when training a 'problem area.' Shoulder pain often traces to T-spine mobility or scapular control. Knee pain often traces to hip strength or ankle dorsiflexion.
Caveats: The model is useful but reductive. Real movement is more chaotic than the textbook chain suggests.