Masso-kinesitherapy
The search for the perfect body is becoming more and more obsessive in our society. We are looking for an advantageous silhouette, of course, but more and more disillusioned with the relevance of an ideal weight, the quest for particular muscular qualities is gaining popularity.
Often, we look for the endurance to run a marathon, or the muscular strength to lift impressive loads. Far fewer people train to develop the flexibility of their body.
Yet, there are many benefits to seeking an increase in the flexibility of the body: a better comfort in one's body, a greater ease in performing daily movements, a prevention of certain injuries, etc...
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One of the biggest problems that hinders people in their progress in flexibility is that they don't know how and when to stretch.
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So let's dive into the subject of types of stretching and their particularities.
The Monosynaptic Stretch Reflex
Before we divide up the stretching methods, we need to understand in depth a specific neuromuscular phenomenon: the monosynaptic stretch reflex.
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In your muscle there are nerve sensors. Located in the muscle belly and in the tendon fibers, they measure the variation in tension and stretch in the muscle.
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In other words, if the length or tension on the muscle changes too quickly, these sensors will trigger and send a nerve signal. This signal travels quickly to the spinal cord and there, if the signal is deemed important enough, a new neuron will send a message to the muscle to contract (often to protect the muscle from tearing).
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This reflex, although very simple, is the main concept around which the different stretching modalities work.
Static/Passive Stretching
The majority of stretches that are performed fall into the family of static stretches. These are characterized by the adoption of a pose that stretches one or more targeted muscles for a prolonged period of time, increasing the amplitude at the rate allowed by the relaxation of the body.
In static stretching, although elongation and tension in the muscle are high, there is not a large variation in both variables, and therefore, no signal triggering a monosynaptic stretch reflex. For static stretching to be effective, the position must be held long enough to allow the muscle fibers to relax completely, a minimum of 30 or 45 seconds according to sources.
Static stretching produces the best results when performed on a warmed-up muscle. This way, the flexibility of the tissues is more likely to allow the fibers to lengthen.
This is probably where the myth that it is better to stretch after physical activity comes from. In fact, it is true that this is a good time to stretch, but it is just as good to stretch after a hot bath or a day outside in the heat.
Avoid static stretching before physical activity, however, as stretching the muscles more than usual will disrupt the stretch reflex during the activity that follows. This can result in decreased performance and even an increased risk of injury, especially when large forces are involved (1) .
Dynamic/active stretching
Before an activity, while passive stretching is not recommended, dynamic stretching is encouraged.
Dynamic stretching is characterized by a wide range of motion, alternately lengthening and shortening the targeted muscles. These stretches often reproduce movements and actions repeated during the practice of the given sport in a sub-maximal amplitude. They have the peculiarity of requiring more muscular work to create the movement, which creates a warming up of the anatomical segments, but also a great variation of our two neuromuscular variables named two sections ago (that is, tension and muscular lengthening).
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This has the effect of stimulating and gently awakening the monosynaptic stretch reflex in the regions that will be solicited during the physical activity.
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Dynamic stretching can be thought of as a check of the body's mechanisms before performance. It is therefore obvious that they should be performed before physical activities, often as an integral part of the warm-up routine. That said, when it comes to increasing joint or muscle range of motion, the gains from passive stretching are definitely more substantial.
Other modalities
There are several other stretching modalities that I will not cover extensively here, but I feel it is important to mention to keep in mind the extent to which stretching techniques have evolved.
There is a stretching modality called ballistic stretching (2) which is similar to passive stretching, but with small pushes at the end of the range of motion. Another popular technique is the neuro-proprioceptive facilitation stretch (3).
Chances are that your therapist will recommend stretching. Most of the time, the goal is to relax a tight muscle.
As you may have guessed, in this case, it will be a static stretch.
It is also possible that a dynamic stretch may be suggested, especially after an injury that may have caused stiffness in a joint that was used during your preferred physical activity.
The objective is often to simply prolong and enhance the effects of relaxation and softening produced during the treatment.
Conclusion
You are now armed with a greater understanding of stretching, its physiology, its specific modalities and when it is applicable. As explained in the previous paragraph, there are many more nuances to modern stretching than this, but you know enough to be functional. I wish you success in your quest for flexibility and apologize in advance for all the times in the future that you see someone stretching the wrong way and feel the uncontrollable urge to go correct them!
By Izaak Lavarenne, Physical Therapist