It's always like that. It's just like that because when u stand your putting all your weight on your feet towards you claves. But as soon as u dit down there all Jiguly, I think that's how you spell it ohh well.
Okay so it's a weird exercise but it works so well. You stand, bend like your sitting in a chair almost. Then, put your arms out and hold them together like a fist. In this position, bounce while using your upper legs. You can go as fast as you want and it will work very well. Do this for at least 3 minutes a day or when you are bored and in a month you will see awesome results. Hope this helps you :)