Fig. 6. Tibial bending during a kick. Selected images from a kick captured at 2000 images s^–1 and with an exposure time of 1/4000 s. Before the extension movement (–5 ms), the semi-lunar process is fully bent. The semi-lunar process remains fully bent during the initial part of tibial extension (–3 ms) and only unfurls when the tibia is partially extended and moving rapidly (–1 to –0.5 ms). At full extension (0 ms), inertial forces cause the tibia to bend at its proximal plane of weakness. As the tibia rebounds from full extension (+0.5 ms), it is still bent.