Self-myofascial release (SMR) on a foam roller is possible thanks to the principle known as autogenic inhibition. The Golgi Tendon Organ is responsible for this. The GTO is a mechanoreceptor found at the muscle-tendon junction; it’s highly sensitive to changes in tension in the muscle.
When tension increases to the point of high risk of injury (i.e. tendon rupture), the GTO stimulates muscle spindles to relax the muscle in question. This reflex relaxation is autogenic inhibition. The GTO isn’t only useful in protecting us from injuries, but it also plays a role in making proprioceptive neuromuscular facilitation (PNF) stretching techniques highly effective.
The muscle contraction that precedes the passive stretch stimulates the GTO, which in turn causes relaxation that facilitates this passive stretch and allows for greater range of motion. With foam rolling, you can simulate this muscle tension, thus causing the GTO to relax the muscle. Essentially, you get many of the benefits of stretching and then some.
Traditional stretching techniques simply cause transient increases in muscle length (assuming that we don’t exceed the “point of no return” on the stress-strain curve, which will lead to unwanted deformities). SMR on the foam roller, on the other hand, offers these benefits and breakdown of soft tissue adhesions and scar tissue. Think of the foam roller as an iron taking the creases out of a shirt. It is taking all the knots and imperfections out of your muscles.
SMR on the foam roller offers an effective, inexpensive, and convenient way to both reduce adhesion and scar tissue accumulation and eliminate what’s already present on a daily basis. Just note that like stretching, foam rolling doesn’t yield marked improvements overnight; you’ll need to be diligent and stick with it, although some instant benefits will be noticed.
So enough talk about what it does and why it is good for you. Here is a great video demonstrating five effective exercises you can do on a foam roller. I would recommend slowing down the movement compared to this video. The slower you roll the muscle the better.