I bought a foam massage roller yesterday. I had heard about these some time ago, and have had people recommend them to me as a runner and since I hurt my knee. Daughter Carrie mentioned getting to try one out where she works out the other night, so I investigated.
Their purpose is to relieve muscle aches, decrease muscle tightness and relieve stress on the joints. They are also used in physical therapy to improve healing time. It's basically like getting a deep tissue massage where they rub out the toxins in your muscles. And, as an added bonus, for most exercises it works out your core muscles as well.
They are 6" in diameter and come in various colors, densities, and lengths. I bought this 24" Gold's Gym roller even though it is pink because it was only $18 (at Walmart). You can find them at most stores that sell sporting goods equipment or online.
I have to say, the first time I used this (last night) it just about killed me. I only used it on my legs, but I was sweating and in pain the whole time. It literally wore me out. My muscles were pretty tight. Mostly my calves and the sides of my thighs. I have to think this should help with my knee pain.
Here are four basic exercises for men: http://www.menshealth.co.uk/fitness/sports-injuries/4-foam-roller-exercises
Here is some advice on what exactly foam rolling does for you: http://www.menshealth.com/best-life/foam-rolling