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Stretching the Truth: Part III

Thomas L Teter Jr, DC

So far in our conversation, we have discussed the main reasons why people stretch, and the different forms of stretching that are common in fitness. To move the dialogue forward, we must discover what what if anything stretching may or may not be good for.

One could inherently say stretching is neither good nor bad, but I would say that it is not good for the reasons that most people are suggesting when justifying its use. Undoubtedly some specific stretching techniques are good for specific purposes, but are quite different from the stretching goals that most people have in mind. My main concern is not that stretching is useless, but rather that people are stretching aimlessly, and ineffectively, to the exclusion of evidence based alternatives such as a proper warm up or specific active mobilizations.

I would suggest as a general sense, that stretching may be generically useful in the sense that it is stimulating. It enhances your body awareness, and creates a specific physiological stress that creates a neurological response in the brain. But when used as a therapeutic exercise ritual, done with the attempt to structurally lengthen tissue, it has a lousy effort to reward ration. I can even be down right dangerous if applied at the wrong joint with the wrong amount of force.

When stretching, people routinely report that it feels good, and that is also can reduce muscle soreness. If most people were stretching with the intent only to feel good, but understood that they were not making any real physiological changes to tissue, then most clinicians would have no problem with its use as part of an overall fitness routine. However, most who stretch have been educated that they are actually attempting to lengthen muscular tissue, which is physiologically impossible without massive amounts of tissue trauma, and long term detriment. Another main problem we see with stretching is the time factor associated with creating any real change in the tissue. Several authors have suggested that a period of 20 minutes or more is necessary for a stretch to be effective in increasing range of motion when a low intensity prolonged mechanical stretch is used. Im not sure about most fitness enthusiasts, but I would dare to say most don’t have the time to do a 20 to 40 minutes stretching routine as part of their daily fitness.

Another significant but difficult topic about stretching that rarely gets discussed is muscles are mechanically impossible to stretch. The structural components of muscle tissue is non-elastic, meaning it cannot return to its normal state after deformation. So not only would it take 20 minutes or longer of sustained mechanical pressure to begin to deform muscle tissue even if you could, but it would not be able to return to its normal resting state after you did if we were truly creating mechanical changes through the application of physiological stress. Another justification for the use of stretching centers around yoga. Most yoga participants swear by the benefits they receive from their ongoing yoga classes. I am not saying that yoga is not beneficial, but rather that the benefits on receives is not due to a lengthening of tissue.

In my mind, the main benefits one receives from yoga, and the associated increases in range of motion, are due through sustained isometric muscle contractions around end range joint positions. We know that when a muscle contracts isometrically with low force, it forces the brain to create a neurological response that causes increases in ranges of motion. This response can be due to the muscle stimulation being enough to cause increased efficiency during contraction, or it could also be due to a neurological phenomenon known as post activation potentiation. Post activation potentiation states that when a muscle contracts with sufficient force, that any following contraction will cause increased force output of the target tissue, and thus increasing joint range of motion. This may be why we see yoga enthusiasts who see changes in range of motion within their yoga sessions. Again, I think there is great benefit to participation in yoga, but maybe just not for the reasons most are suggesting.

Another suggestion made by those who stretch is that stretching can align fibers in tendons. In reality, muscle and tendon are distinct tissues, but blend together seamlessly. Much of what we see is a muscle is just and extension of tendinous tissue, and vice versa. It is impossible to draw a line between where the tendon stops, and the muscle begins. If stretching does not help muscle, it most likely is not going to do anything for tendons either. Tendons are quite static compared to other tissues. Where as muscles contract, tendons only transmit the force from the muscle contraction to bone to move a joint. If you could make a structural change in tendons through stretching, it would probably take months of regular and consistent stresses to the tendon. If one were to attempt to make changes to tendinous fibers, it would be the equivalent to the tearing away of a rope before it breaks.

As you can see, there are many things that stretching can do to the body. It is suggested to feel good, and in certain circumstances can increase range of motion, or even improve muscle function around a specific joint position. However, it is important to note that stretching cannot and does not lengthen muscle or tendinous tissue. If this is the goal when one attempts to stretch, then there will be an extreme amount of wasted time and effort on a goal that can never be attained. Next month is part four of this series, we will discuss when and how to incorporate proper methods to increase mobility as part of your fitness routine.

To read the rest of this article series:

Stretching the Truth

Stretching the Truth: Part II