I am going to do Robert's sample leg program in the Shred It! book. After the bodyweight squats and front squats, he recommends hack squats. I've done these before so I am familiar with them, but when I perform them, my knees tend to waaaaay overshoot my toes when I'm in the downward position. Is this dangerous? Am I doing it wrong? If anyone can give me some insight, it would be appreciated. Thanks, K