What Happens When You Stretch?

• "This triggers the stretch reflex (also called the myotatic reflex) which attempts to resist the change in muscle length by causing the stretched muscle to contract." 
• I was intrigued by this quote, as it introduced to me the fact that when we stretch, there is an accompanying stretch reflex that prevents us from only relaxing and stretching the muscle. When I stretch, there is of course resistance from stretching all of the way, but I had always thought that it was because my muscles were not elastic enough or that I was not flexible enough, and not that my body was in fact resisting my efforts to stretch all the way. 
• " Some sources suggest that with extensive training, the stretch reflex of certain muscles can be controlled so that there is little or no reflex contraction in response to a sudden stretch." 
• I thought that this information was entirely interesting, because as I have danced before, I have met many people who are either naturally flexible or have stretched enough so that they can hold splits for an indefinite amount of time. These people have put the time in to stretch their body frequently, and thus are able to suffer little pain in a position that most would suffer from because their body has lessened the effect of the stretch reflex on their muscles. 
• " When an agonist contracts, in order to cause the desired motion, it usually forces the antagonists to relax. This phenomenon is called reciprocal inhibition because the antagonists are inhibited from contracting." 
• This quote relates to what we learned about muscles in class, as we also talked about the properties of the antagonist and agonist muscles in certain motions that we perform. When we stretch one muscle, the "opposite" muscle is contracting to make that muscle stretch. 

This reading was about the physiology of our muscles when we stretch, and how the muscle spindles and muscle fibers interact with each other(along with assisting structures) to help us stretch. When we stretch, the sarcomeres in our muscle fibers contracts and the muscle fiber is elongated as a result. Some of the fibers are responsible for the stretching, while some are simply going along for the ride", which as a result causes unaligned fibers to be put back where they belong. The fibers that help us stretch are divided into 2 types: extrafusal and intrafusal fibers. Extrafusal fibers contain myofibrils, while intrafusal fibers are divided into nuclear chain fibers and nuclear bag fibers, which are the static part of the stretch reflex(which resists the lengthening of muscle) and the dynamic components of the stretch reflex, respectively. Also, when the muscle changes in tension, the lengthening reaction is triggered after some time, relaxing the contracting muscle so that your muscle is not injured. Thus, the benefits of stretching can be shown as it makes the lengthening reaction lengthen your muscles, heal scarred tissue, and train the stretch receptors, which can be applied to my life today as I often stretch in color guard to train flexibility. It is useful to know what other benefits there may be to stretching periodically, beside the aspect of being able to dance better.