What Happens When You Stretch?

For homework, I read an article called "What Happens When You Stretch."

When a muscle is stretched, it is the sarcomere (basic unit of contraction in a muscle fiber) that stretches first. Then, after all the sarcomeres in a muscle are fully stretched, the connective tissue around the muscle start to stretch also. Fibers in the connective tissue line up along the force of tension, realigning any disorganized fibers -- I have heard something along these lines before, and it's nice to have than information confirmed. Stretching affects many different parts of the muscles from  intrafusal muscle fibers (those that contain myofibrils) to extrafusal muscle fibers (muscle spindles) to
proprioceptors (mechanoreceptros, or nerve endings from the muscular system). All these different parts of a muscle -- and different parts of those parts -- interact to create the stretch reflex, which tries to resist the muscle lengthening, and the lengthening reflex, which occurs when the stretching passes a certain point and stops the stretched muscle from contracting. The article also talks about how stretching can be made more effective by contracting the opposites and relaxing the synergists of the muscle being stretched. This explains why when we do certain stretches in certain ways, for example keeping our leg straight when we stretch our quads.

I chose 3 phrases that I felt held the most meaning:

• "[Stretching] helps to realign any disorganized fibers in the direction of the tension. This realignment is what helps to rehabilitate scarred tissue."
• I remember hearing about this a long time ago, but never really found out if it was true until now. I also find it interesting that stretching can help rehabilitate scarred tissue -- does that mean people with damaged muscles can do stretches to help them heal?
• "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."
• It's interesting to me that reflexes can be trained out of somebody. I have heard of certain responses being conditioned into people, but I didn't know you could condition an innate response out of someone. However, this also sounds a bit dangerous, since the reflex of a muscle to contract is there to stop the muscle from overstretching and becoming damaged, and removing it seems like a bad idea (nature has gone through all this trouble to make sure it's there in the first place, so it's probably quite important).
• "[Y]ou can get a more effective stretch by inducing the antagonists to relax during the stretch due to the contraction of the agonists. You also want to relax any muscles used as synergists by the muscle you are trying to stretch."
• This explains why we do certain stretches certain ways, and why coaches and PE teachers are so adamant that you follow their directions in stretches. It also explains why a stretch done properly "feels better" than one that is not done well.