Squat question: shifting pelvis

[Adam Wood]

Rip,

My girlfriend has recently started doing a strength workout once per week to improve her CrossFit performance (squat/press/deadlift alternating with squat/bench/power clean).

When she squats, her pelvis shifts to her left side as she comes out of the bottom and comes back in line on the way up. Towards the end of a set it sometimes moves in a complete clockwise circle.

I've tried cueing tightness, knees out, driving hips up, etc. but none of those seem to correct it. She does not do it when she air squats. She is very flexible and also has a very mild scoliosis of the thoracic spine, not sure if either of those are contributing to this. I'm hesitant to increase the weight until we can get her pelvis stabilized.

I've included two videos of 55x5 that demonstrate this problem. Any ideas on how to fix this would be much appreciated. Thanks.

[youtube]RA23zbm_pEs[/youtube]

[youtube]rSNWUaSyUpA[/youtube]

[Mark Rippetoe]

The problem is that she's just not very strong right now. Her right knee is badly controlled at the bottom of the squat (such that there is, she's a little high visible in the side angle video), and if you cue her knees-out most of this should go away. But even if you don't she'll get more stable as her squat goes up and her hip external rotators get better at controlling her femurs at the bottom.