The Double Ankle Sweep, and in particular, this variation is sometimes referred to as the "Kick Variation", is a great way to knock someone down who's in your guard, and decides to try to pick you up and choke/slam you.
In order to do this, the attacker has to first bring their feet up by your sides (around waist or rib level). Then, they start lifting their hips to pick you up off the ground.
When you feel that, you actually should hold on for a moment, to make them think they will be accomplishing this, which then gets them to commit more to it.
Once their hands have gotten inside to choke you, and/or you've gotten off the ground an inch or so, RELEASE the head and arm control guard position, and simultaneous grab both ankles (thumbless grip, and get your feet on their hip flexors.
You may just want to train that portion, to develop the sensitivity to that indicator. Once you feel comfortable getting into the position, then we do the actual sweep/takedown.
What the sweep/takedown requires is you pulling on their ankles, pushing with your feet on their hip flexors simultaneously. Once you have chopped them down, it is important that you do the Technical Get-Up, which is basically putting your hands on one side of you, slightly behind you, putting your weight on them, and shooting your legs back. This is also known as "Base Get Up" or "Getting Up in Base".
It's a very real possibility that someone might get themselves in that position while in your guard, and their objective might not be to choke, or slam you, but rather, to strike you. The advice here is is to block your face, and when you feel the moment is right, to quickly grab their ankles and insert your feet. It will instantly put them on the defensive.
Note for the training partner - practice your backwards break falls. To do a backwards break fall, you squat, roll back, slap the mat/floor with your palms down, arms extended, and keep your head up, not connecting with the floor.
So please go slowly with your partner, especially if they are not used to doing backwards break falls.
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