Ankles are like doors. A door rotates on a limited axis relative to its wall. Push it past that axis and the hinge breaks. The mechanics are the same in ankles; flex your foot past its axis and you’ll inflict damage. Cue the ankle lock: a submission in which the ankle is forced into plantar flexion (toes pointing away from your head) and the Achilles tendon is compressed beyond capacity. Submissions like these are useful in MMA combat and street fights because they can be applied in any scenario. Where can you learn such submissions, you ask? Just visit coach Clem (pictured inflicting the ankle lock below) at his 7pm no gi course tomorrow.