When kicking a football the action at the knee is?

Answer 1

The kicking leg undergoes a preparation stage and a kicking and follow through stage.

In a good kick from a flexible leg, the knee joint firstly bends and flexes such that the heel of the kicking foot, during the preparation phase, almost touches the buttock muscles before the lower leg begins its forward, 'kicking' motion, trajectory.

The hip joint flexes forwards as the knee extends forwards.

Foot contact is made with the ball while the knee joint is still partially in a partly-flexed position, as the foot swings forward like a pendulum, while the knee joint goes through the extension phase. The leg continues to swing forward as the knee straightens out in full extension phase, and the hip and knee joints follow through, as weight is also delivered behind the ball.