The rear mount is arguably the most dominant position in grappling. When you have rear mount you can apply some very powerful chokes and locks. In MMA or self defense you can administer severe punishment without your opponent having the ability to strike you back.

The positioning of the legs in rear mount is very important because your legs allow you to follow and control your opponent’s movement. One common mistake in rear mount, made mostly by beginners, is crossing the ankles in front of the opponent’s legs: this is considered a huge no-no in BJJ and submission grappling.

Crossing your ankles and feet while rear-mounted is frowned upon because your opponent can catch you in a simple, and very painful, leglock. If he crosses his ankles (or figure 4’s his legs) on top of your ankles he can tap you out by arching his hips forward. Depending on exactly how the legs are arranged the submission may result from a pain-based Achilles tendon crush, a foot hyperextension, or a foot/knee twist. Regardless of the actual mechanism getting caught in this submission is a painful and embarrassing experience.

All this being said, I occasionally DO cross my ankles when rear mounted on an opponent. Under certain circumstances crossed ankles increase your control over your opponent (which is why people do it instinctively). I never do this for more than a second or two and always maintain a state of high alert in this position. I try to release the crossed ankles as soon as I can, returning to a more conventional rear mount position. To further minimize the risk of getting leglocked I try to cross my ankles high on his body and, if possible, slightly off to one side.

When rear-mounted you should follow the rule of not crossing your ankles at least 99% of the time. Intermediate and advanced level grapplers can sometimes break this rule, but not for very long or without a good reason!

MMA fighter Joe Doerkson displaying good form in rear mount (i.e. NOT crossing his ankles)