You're holding your knees too tight. It knots up the muscles.
7 seconds sound clip from the They Shoot Horses, Don't They? movie soundboard.
You can hear this line at 00:30:47 in the Blu-ray version of the movie.
Quote context
[...]
- We're not supposed to stay in one spot for too long.
- I understand. You go along. But don't give up, 'cause you're going to win. I know you are.
- You can't leave the floor. I gotta eliminate you.
- They'll never know what they missed.
- Why didn't you tell me it was gonna be this tough?
- You're holding your knees too tight. It knots up the muscles.
- Sixty-five. I figured it out. That's how old she is. God, I hope I never live to be that old.
- That's not the way it happened. It wasn't like that.
- We were very close in a way. I was her friend.
- Yowsah, yowsah! Watch your feet, folks. It's all part of the show.
[...]