Both stretching and releasing a muscle can improve your flexibility but have different methods of accomplishing this. The quick difference is that when you stretch a muscle, you are lengthening it and when you release a muscle you are spreading it apart. Examples of lengthening stretches include holding a calf stretch against the wall. Stretching usually does not require any additional equipment. Releasing a muscle requires you to spread out that muscle using some sort of device like a foam roller or a yoga ball. If you want to warm up before a tennis match or an aerobics class then traditional stretching is all that is needed. But, if you have very tight muscles because of old injuries or being sedentary most of the day like sitting at a desk, then releasing the muscle is a better choice. This is because injured muscle heals by scarring down. Scarred tissue requires direct pressure to break up the scar. Typical stretching is not localized to an exact location so stretching a scar is inefficient. The BackStrap® holds three different sizes and firmnesses of Therapy Balls to release large an small muscle scars at any point within the muscle and tendon.