I always hate to be at all contradictory, but there are a few problems with this explanation about stretching.
1.) The idea that the Golgi Tendon Organs (GTOs) "prevent excessive strain" is from the old understandings of GTOs. They are not just protective from excessive stretch, but are directly involved with the stretch/contraction mechanisms in their entire spectrum of motion. It was discovered in the 1970s that the GTOs are far more sensitive than was originally thought, and actually measure the degree of contraction or stretch to a muscle from their zero point, and are directly involved in the entire range of their action/ relaxation. But medical research being what it is, it has taken a couple of decades for this fact to enter the educational track.
The implication for yogis here is that IF you maintain a VERY mild and low-intensity stretching action from the very beginning of your asana action, and let the GTOs do their thing before the muscle spindles (stretch reflexes) have time to activate, than you'll be using the natural, built-in-by-nature forces within your bodymind to begin the relaxation processes.
The yogic, meditative component here is to allow the self-sensitive mind to consciously restrain your initial, excessive ambition to get into the posture or asana too deeply, too quickly.
2.) The idea of actin-myosin bonds "breaking" gives, I believe, the wrong impression here. This is a subtle distinction, but that sounds too much like tearing or spraining or whatever. From a yogic point of view, the state of "being relaxed" is when the actin-myosin bonds are "non-activated," or in a Buddhist sense, "non-doing by non-activation." So, the ACT of relaxation is about "DE-activating" the bonding action of the actin-myosin fibers within the muscle cells.
So, the bonds don't "break" in the ordinary sense of the word, but the chemical bonds "de-activate" which is what allows the actin-myosin fibers to UN-overlap, sliding out from each other, which is THE essence of neuromuscular-fascial relaxation.
Yes, this distinction is subtle but, in my opinion, from a physiological point-of-view, this is THE most important understanding necessary to grasp what musculo-fascial relaxation is really all about.
3.) "Sarcomeres are also elastic." "... titin that gives it elasticity." I'll keep this short by saying that titin cannot express it's "elasticity" or "rubber band nature" unless the nerve charge to the actin-myosin fibers is turned off. The actin-myosin fibers themselves have the tensile strength of about half that of steel wire. They are, independently, almost totally resistant to "stretching" like rubber bands. It is only when you have learned, through yogic, meditative processes, to totally turn off the neuromuscular nerve charge (tonus) to the actin-myosin fibers that the titin elements of elasticity make any difference at all.
So, regardless of the "elasticity" of the titin fibers, sarcomeres cannot lengthen until you've learned to turn off the nerve charge (tonus) to your actin-myosin fibers. And muscle fibers will not lengthen without tearing until you've turned off the nerve charge to the actin-myosin fibers.
This means, bottom line, that so-called "elasticity" in the muscles (and fascia too) is almost, if not completely, irrelevant to being able to bend deeper into an asana.
4.) " ... elasticity of the connective tissue. It?s like a rubber band." No, it's not. This is an illusion. Every single research paper or anatomy/physiology book I've seen says that fascia -- especially the deep fascia of the muscle fibers -- has from 4 to 7 percent extensibility, MAXIMUM. In fact, it is this reality that gives the fascia/tendon unit one of its primary values. Ideally, the fascial/tendon unit efficiently transmits the force generated by the actin-myosin units to the bones. IF the fascia/tendon units were truly as extensible as a rubber band, we would lose massive amounts of muscular force as the fascial/tendon units stretched out. We'd move around like rag dolls instead.
Muscle and fascia being like rubber bands is one of the Great & Dangerous Myths of yoga and bodywork. It leads people to produce diagnoses and treatments that are NOT in accord with reality.
5.) The facial creep idea is probably more related to human being UN-learning their old muscular tension patterns. It might also be the fact that the human body will reduce the number of sarcomeres in a muscle if it falls into disuse. But the body will replace sarcomeres when the muscles comes back into more use. This is probably the single most un-researched or explored element of restoring flexibility I've run into. How long, and to what degree, does one need to be, in a "stretch" before the body starts replacing lost sarcomeres. I've seen next to nothing on this topic, unfortunately.
6.) The "Mind Component" is, as I said above, primarily about the mind learning to turn off the excess charge of tonus to the actin-myosin cells. That is the psycho-neuro-musculo-fascial NEXUS between mind and body. If we are working within what I call our minimum to moderate edges, rather than our maximum edges (where, unfortunately, most people tend to hang out) we'll get far better results because we are not pushing our tissues and nervous system too far, too deep, too fast.
7.) "Stretching fascia is the primary way to increase the range of motion of joints." I believe that, once people get over their excessive fascination for fascia (see comment below on Ida Rolf and Alfred Korzybski), and realize that facia and muscle fiber are totally and intimately related tissues with a very high division of labor (that being one of the most prevalent and important characteristics of being human), they will stop ignoring the facts about fascia, and realize that it is the NON-elasticity yet very high degree of flexibility (bend-ability, which does NOT mean they can lengthen much at all) of fascia that makes them so useful.
8.) Bouncing and Warming Up ... In my view, after 40 plus years of direct experience and extensive theoretical research, when it comes to "Yogic Warming Up," muscle temperature is nearly irrelevant. Properly Preparing the muscle is about reducing the initial psycho-neuro-muscular charge that is the first gate toward flexibility and fluid motion. So what's relevant is reducing the habitual nerve charge to the muscles is what is more important to everything else.
9.) As far as traditional texts and yoga postures go, I refer to you to Mark Singleton's book, Yoga Body, where he conclusively demonstrates that all but maybe 8 or so so-called yoga postures were actually from fitness and gymnastics in Europe in the late 1800s. The vast majority of yoga asana were not practiced AT ALL by any of the ancient yogis. Modern yoga asana practice is of very recent origin, and has no ancient lineage.
BottomLine: It is amazing to observe the so-called experts talk about how fascia is so resistant to stretching and lengthening on one hand, then, with no apparent awareness of their contradiction, talk about restoring its alleged "elasticity." Fascia is NOT elastic, beyond 4 to 7 percent.
It is the learned capacity of the thinking/feeling/meditative mind to sink its way down through the nerves to the actin-myosin cells that produces the relaxation of those actin-mysoin units, allowing them to relax and lengthen, that produce true, learned flexibility, rather than the far more common "forced flexibility" which is achieved, if at all, by willpower and NON-meditative, NON-yogic processes.
Elasticity can mean "bend-ability" or "length-ability." Fascia is highly bendable with high degree of strength, and very little length-ability. Muscle has a high degree of length-ability, but while it IS very bendable, it is VERY fragile in its bendable state. This is the beauty of the musculo-fascial unity. They have an exquisite and highly useful combination of both.
Ida Rolf was a student of Alfred Korzybski who had a lot to say about the fascial tissues and the part they played in many aspects of human life and health. Ida began saying everyone was talking about muscle, and not about fascia. That was probably true at the time. But now, everyone is talking about fascia, and not much about muscle. I hope to bring more people back to a balanced view of both tissues in harmonious relation to each other.