Our first topic that needs attention is “Stretching as a means to improve Flexibility.” It is still commonplace in both the healthcare community and fitness community to provide stretching methods to patients and clients alike. The question we must first ask ourselves is, “What are we trying to stretch?” Most practitioners or trainers would tell you that they are trying to stretch the muscle. In the context of muscle physiology, muscle length is determined by the number of cross bridges formed in all of the sarcomeres of a muscle. A sarcomere is the smallest unit of all of the components included that mechanically produces a muscle contraction. However, there is one missing piece.
A neuronal axon must be present and must innervate a muscle in order to effectively produce a contraction in all of that muscle’s sarcomeres. The combined collective parts, the muscle fiber with all of it’s sarcomeres, and the innervating axon are together known as a “motor unit.” So why all this talk of muscle contraction? Aren’t we trying to get a muscle to lengthen and not contract? It just so happens that the physiological process of contraction also happens to dictate the amount of length in a muscle. If a muscle’s length is determined by the number of cross bridges formed in all of the sarcomeres in a muscle, it must be true that the fewer cross bridges that are formed will then allow the muscle to lengthen. When we are stretching someone, we are not really stretching anything.
We are, however, changing the current settings of how many cross bridges are formed. The dilemma at hand is that the previous number of cross bridges that were set prior to the stretch were there for a reason. We will likely see a return to that set point after some time because we really didn’t affect the conditions that would allow for a lasting change to take place. Stay tuned for the next installment, “The Myth: Stretching to Improve Flexibility Part II.” We will dig a bit deeper into what you CAN do to promote longer lasting changes in muscle length to promote real improvements in flexibility as well as further elaboration on this mysterious topic.