Tuesday, April 14, 2009

Banish the Popcorn Knees

I typed this up in response to a question on Trifuel's forums about how to do a proper flutter kick. I thought it might be helpful to share some of this info here, in case kicking is anyone's personal bugaboo (all you triathletes out there who always train with pull buoys, maybe???)

If you're having trouble with the freestyle kick, chances are, you’re doing one of two things. You’re either bending your knees too much when you kick, which is the most common kicking mistake people make, or you’re not bending your ankles/feet enough.

First, the “popcorn knees” (I call it that because if you flip over and kick on your back, your knees will look like popcorn popping out of the water). It’s only natural to do this, we humans bend our knees to do everything else, but in the pool it costs us a lot of extra energy and drag to do so. To see if this is your issue, kick on your back holding the end of a kickboard very loosely in your hands with the kickboard itself extending (floating) over the tops of your thighs and knees. If your knees hit the board, you have popcorn knees. But wait, some people cheat by simply bending their knees but keeping their feet underwater. So what you need to do is kick with your feet breaking the surface but without your knees hitting the board, then you will start fixing this issue. I like this drill because you can tell what you’re doing and whether you’re getting better without a coach there, it’s self-correcting.

In order to kick correctly without the knee bending, you should be feeling it in the tops of the backs of your legs (upper hamstrings) and in your glutes. You can stand at the end of the pool and tense those muscles and then start kicking and try to feel the same muscles firing.

Second, the ankle/foot flexibility. Usually when people start trying to kick with straighter legs, they also lock their feet/ankles up. This is the pat-your-head-rub-your-tummy syndrome. As you try to bend one thing less, you also bend the other thing less. To counter this, stand on the pool deck and kick one foot as if you’re trying to kick peanut butter off of your toes, in a toe-flipping kind of motion. Notice how your leg doesn’t bend much but your foot flops around. This is the sensation you want while kicking – very little knee bend, lots of up and down with the foot. Now get in the pool and stand at the end and do the same peanut-butter-toe-flick. Then start kicking. Chances are, you’ll be moving quite a bit faster than you were before. But then you might find yourself slowing down again. If so, stop where you are (do not reinforce poor kicking technique). Repeat peanut-butter-toe exercise, start kicking again. Repeat if necessary.

This is one of the hardest issues in swimming to tackle (besides breathing). Be patient with yourself, it might take a bit of time to conquer this. After all, on land we never walk around with straight knees and floppy ankles, it’s an inherently un-humanlike motion. So it’s something we have to teach ourselves to do.


Sara Cox Landolt said...

I had to read a post with popcorn in the title! But, this was timely and interesting, good read.

I can't wait to try the drill you describe. Thanks!

TriGirl 40 (okay - 41) said...

Love your swim posts and recommendations - and this is one of main remaining obstacles. I am going to try the drills you mentioned to get a better handle on what I am doing!