Muscle spindle cells are located in the bodies of muscles and are usually wrapped around sensory nerve fiber endings in muscle fibers. The muscle spindle cells' main purpose is to monitor when a muscle is either at rest or being stretched. Muscle spindle cells may even measure the length and speed of the change in a muscle. "Responding to small displacements & after-effects spindle output to a given amount of stretch is not always constant series of rapid stretches, the response to a slow test stretch depends on the length at which muscle was held after stretches ex. If muscle is elongated for several seconds then returned to initial length, the response is smaller with longer latency when given test stretch compared to when the muscle is returned to its initial length after series of stretches - more slack in sensory region." (HHP, 2004) The human body uses these muscle spindle cells in a type of balancing act. If a person were to lean left than the muscles on one side of the body would contract while the muscles on the other...

The message from both sides of the body in turn would be sent through the spinal cord to the brain and therefore the body is able to maintain an erect posture. Through massage, the muscle spindle cells would be quite active as the constant stimuli from a massage would contract and stretch muscles.
In conclusion, this report described how massage can be used to affect changes in both the Golgi Tendon Organs and Muscle spindle cells. Since massage has been used as a therapeutic technique there has been little scientific proof of the effects on muscle relaxation. Over time, mankind has begun to get a grasp on the complexities of the body. Massage is a form of muscle manipulation that would affect the Golgi Tendon Organs and Muscle spindle cells through constant muscle contraction and strectching.

References

HHP. (n.d.). Proprioceptors In Muscles, Joints And Skin. Retrieved October 24, 2004, at http://www.hhp.uh.edu/clayne/73404text.html

Anatomy