Within our muscles are spindles that measure changes in muscle length, and each of these spindles has about 10 sensory receptors in the surrounding fascia. There are two different types of these myofascial mechanoreceptors, which measure the mechanical load on our muscles and fascia and each responds to different types of stretching and movement.
Fascia in Long Holds:
The Golgi tendon organs are receptors that measure the load on muscle fibers. They are responsive to muscle contraction and also allow muscle tissue to yield when you hold long, deep stretches. One way to stimulate these receptors in yoga is through strong, held positions (like warrior 1 & 2), where muscles are engaged in a lengthened position. The benefit of this type of work is a decrease in muscle tonus so that our muscles feel more relaxed afterward. We’ve all experienced how much easier it is to melt into stretches at the end of a yoga practice after standing poses, compared with how it feels at the beginning.
Fascia in Flow:
The most numerous of the receptors are the small interstitial nerve endings, which respond to varied triggers including load, pressure, shear forces, and rapid movement. These receptors respond to varied, fluid, graceful movements, like Vinyasa flow (for example, Sun A & Sun B flow sequences). The benefit of this type of work is increased blood flow and the expanding and contraction action of the periosteum, a vascular connective tissue that surrounds the bones.