If you’re finding that 2BK coordination is difficult, give this a try….
The kicking practice i typically use with first timers of 2BK is simply, use both hands and hold onto the wall of the pool. Put your head in the water, and push out from the wall while still holding onto it and extend your body straight horizontal on the surface of the water.
Then practice 2BK of one leg at a time, while holding the other leg perfectly still. Do this a few times, then switch to the other leg.
As you may guess, with many people, they cannot hold one leg still while only kicking the other leg in 2BK form. Often they will move both legs.
After trying both legs and seeing difficulty, I have them stop and stand. Then I have them do a standing cross crawl exercise. This is simply: raise one leg and touch the opposite hand to the thigh or knee. Note the leg raised is bent. Imagine yourself marching but instead of raising your hand high along with the opposite leg’s knee going high, you touch the hand to the rising opposite leg. Then repeat with other leg/hand. And so on.
This improves your contralateral or crossing the midline movement pattern and stimulates the vestibular system to operate better, and what it was designed to do. Often through years of improper use (ie. walking around with a bag slung on one shoulder, or having things in your hands – essentially walking without swinging your arms) or disuse (ie. sitting too much!), the nervous system can literally forget how to enable cross body movement patterns.
I have found instantaneous results before and after doing cross crawling. I have them stand there and I cross crawl with them. I do it for 10-20-30+ times – more the better! Then I put them back on the wall for the 2BK kicking practice. Now they can do it! It just shows that with the proper nervous system reactivation and stimulus, things like 2BK can now be more easily learned.
Pro tips: For even better results, make sure your mouth is closed and your tongue is touching the roof of your mouth. If your mouth is closed, make sure your jaw is not slack in the mouth which makes it hard to touch your tongue to your roof of mouth; barely touch your teeth to make sure the jaw is not slack. Why does this help? People have found that touching the tongue to roof of mouth further enhances stimulus of the vestibular system to speed up learning and imprinting. If you find results are spotty, makes sure your mouth is closed and tongue touching roof of mouth and you may find that results are much better.
Note that the first level in the cross crawl progression is to touch your hand to the opposite rising leg, either on knee or thigh. The second level once you improve your skill, is to touch your forearm to the opposite rising leg, either on knee or thigh. The last and highest level is to touch your elbow to the opposite rising leg’s knee/thigh. This requires not only coordination but also mobility and stability as well.
A small detail, you may find better results if you dorsiflex the foot as you raise it (ie. do not point the toes down but rather bend the foot up to 90 deg or a bit higher). Dorsiflexing the foot will help you engage muscles to bring the leg up as high as possible and help enable meeting the opposite arm’s elbow/forearm/hand.
Many thanks for Original Strength for showing me this technique.