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Non-contact heading mechanism (right knee). (A) At−306 ms, the player wins a heading duel while having trunk-to trunk contact in the air with his opponent. (B) At initial contact, he lands at high vertical speed on his right leg striking the pitch with the forefoot. (C) At 80 ms, being out of balance both backwards and sideways, he puts the entire load on his right leg. (D) At 186 ms, his right knee joint clearly give way in substantial abduction (dynamic valgus collapse).
