NO MORE KNEE PAIN FOR THIS ROLLER DERBY QUEEN... I play roller derby and I hurt my knee. I lost complete range of motion. I noticed twinges and pains in my knees and hips that I just thought I had to deal with but now they’re completely gone with Flexcin. After about three weeks or so I really got a lot of my range of motion back and after six weeks I could completely squat down with no pain at all.