Foam rolling may not be the most comfortable way to release a tense knot in your muscles, but it is effective. The foam roll is the primary tool used for a technique referred to as myofascial release. This technique is very similar to deep tissue massage -- in fact, the name myofascial release, really is just another way to say self-massage. Start with a soft roller and work your way up to the harder ones over time.
Standard Hamstring Stretch
The standard hamstring stretch on a foam roll is done by placing the foam roll on the floor and sitting on top of it with your hamstrings resting on the roll. Your feet should be straight out in front of you, and your back straight. This position will place some tension on the hamstring as it is in a stretched position already. Slowly roll up and down on the roll until you feel any tender spots and remain on them until the pain dissipates by at least 50 percent; then move on to the next spot and repeat the process.
Single Leg Hamstring Strech
Rolling both hamstrings at the same time may not work for someone who is familiar with using a foam roll. If you need a deeper penetration into the muscle, place one leg on the roll with the other leg crossed over, to put some additional weight on the hamstring. The leg being rolled should be straight and the back should remain straight as well. As with the double leg roll, move up and down slowly until you find a tender spot, and remain on it until the pain subsides. Repeat the process for the other leg.
Internal And External Rotation
Many times the sides of the hamstrings can get tight and sore as well. To roll the sides of the hamstrings effectively, you should position yourself in the single leg roll, so that you can emphasize the weight placed on the sides of the hamstrings. Instead of rolling straight up and down, turn your leg over so that the arch of your foot is pointed towards the ground. Now that you are on the inside of the hamstring, roll up and down till you find a tender spot and hold it. When you have completed the inside hamstring, turn the leg so that the foot is pointed out, then roll out the tender spots here. Repeat the process on the opposite leg.