If you just arrived at this article, be sure to also check out our second installment of this series where we look at muscle anatomy, the mechanisms behind muscle contraction, and how stretching can affect your ability to perform optimally.

What is your central nervous system?

Something that is often overlooked is your central nervous system (CNS). This puppy runs it all. It is composed of your brain and spinal cord. All of your nerves and signals pass through here at some point. When something is stretched too far, or too fast, your CNS is immediately alerted to make sure to fire a muscle to loosen up or contract.

When you touch something hot, your CNS fires to move your arm away. When you want to wink at the cute girl/guy at the gym, your CNS sends the signals to the appropriate muscles to do so and creep ‘em out. Just what you were going for.

Let’s look at something as simple as a stretch and demonstrate why your CNS is super important to your day-to-day flexibility and why you might feel like you are getting more range of motion, but likely aren’t “stretching” anything at all. 

Put your leg up on a chair and quickly bend over it until you feel yourself bounce up against some resistance. How far did you get? Now take your other leg and do the same thing but this time slowly bend over it and don’t push. How far did you go on that leg? I would guess you went further with the second leg. If that’s not good enough for you, do both tests on the same leg.

Why did that happen? Your body is made up of so many cool mechanisms and safeguards and one of them is extremely important to keeping us bipedal humans from hurting ourselves and also walking balanced upright. The one I’m speaking of here is called the monosynaptic reflex, or the stretch reflex.

If a muscle is pulled on too fast or too far, your body will immediately, and subconsciously fire that muscle group to keep it from getting damaged by overstretching. Your body does this a lot. If something stretches too much, it will contract it to keep it within safe ranges. If it contracts too much, it may sense this and send a signal to relax it.

We’ve all been to the doctor’s office where they pull out that funny little rubber triangle hammer and hit us on the knee. Ever wonder what the heck they are doing? Are you supposed to kick them in the face? Should you not move at all??

They are testing your stretch reflex and determining if there is any neuronal damage or malfunction in your body’s messaging response system. It just so happens that the patellar tendon on your knee is one of the largest and easiest to test. When they smack that hammer on your tendon, your tendon pulls on the quads which get stretched really fast. Under the right circumstances, your quads should contract which pulls your lower leg up in a kicking motion.

It might be subtle, because the hit doesn’t need to be large, but that’s the idea! Pretty cool right?

This is due to a few little organisms in your body called muscle spindles and Golgi tendon organs (GTO). We don’t need to go into each right now but their job is to detect the rate of stretch and amount of stretch in your muscles and tendons in real-time and send signals to your CNS to fire an appropriate response to keep you from hurting yourself. 

By the way, if the doc hits your patellar tendon and your legs fire but doesn’t stop firing, as in it continues to jump or spasm after the initial hit, that’s a sign of a problem. This is called clonus and it’s a sign of a possible upper motor neuron lesion.

How your CNS aids your “flexibility”

When you go down into your stretch, your CNS will automatically monitor the movement, determine if the range is safe, and then let you proceed. If you go too fast or too far, it will stop you in your tracks, as you may have experienced upon your first attempt above. If you can convince your CNS that you aren’t doing anything crazy, it will release some of the tension and allow for your muscle fibers to relax a bit more. In other words, it tends to like to keep a little slack in the rope.

So when you decide to start stretching, initially you are asking the CNS to give you a bit more of the slack, so you will see an improvement. Warming up can be a good way of doing this. Taking yourself through those ranges in a gentle manner can help the CNS determine if you’re being safe and grease the groove.

You can convince it to let you have more by doing a few different things that involve autogenic and reciprocal inhibition, which we will get into once we go over the types of stretches you can do.

Stretching for Injury Prevention

Humans are biomechanically precarious. What I mean by this is that when we walk upright on two legs, we are in a constant falling and catching scenario. We are never very well balanced, especially as we go into single-leg support, and we are significantly taller than that base of support. Quadrupedal animals like dogs, cats, cows, moose, etc, always have a minimum of two legs on the ground when running.

When walking, they have three legs in constant contact with the ground, and the bulk of their weight is concentrated in the lowermost areas to the ground. This leads to superior balance, which in turn, leads to almost no instance of injury especially from muscle strains.

Since we aren’t as fortunate in this area as we may have once been before choosing to walk upright, we have to live with what evolutionary predispositions we now own. The common edict has been to stretch to avoid injury. Unfortunately, clinical studies have been largely inconclusive on whether this prescription is at all worthwhile and valuable.

Studies from the American Journal of Sports Medicine on preventative routines in soldier populations, to Sports Medicine’s numerous stretching studies of young athletes, to university research and the British Journal of Sports Medicine, have continually demonstrated little to no statistical differences between injury rates in those who stretch versus those who don’t.

Most of these studies are in young athletic populations which are relevant to our purposes, but it must be stated that there are plenty of data on potential successes for older populations for more obvious reasons. As we age, our tissues become stiffer and we move significantly less. With less movement and a much higher risk for injury due to lack of range of motion, a daily gentle stretching and movement routine could be ideal.

Stretching for recovery or rehabilitation

Surgery, pulled muscles, lactic acid, delayed onset muscle syndrome. All of these are either prime candidates for stretching or lackluster scapegoats. 

Everything we’ve discussed thus far has been in an attempt to persuade you away from OVER stretching. Here, we shall advocate “stretching” and its benefits under appropriate measures. 

The first two examples above are great use cases for stretching. Tissue remodeling is imperative during the healing process as it helps to regenerate and reform damaged muscles. Through light stretching or more dynamic range of motion drills, we allow the tissue to remodel itself in the necessary direction of pull. This is because, while the human body is great at many things, it’s not very good at efficiently rebuilding.

It often lays down scar tissue and fibers in more of a crosshatched, jumbled, “spaghetti bowl” mess as I like to call it. So by doing gentle traction exercises, we’re able to communicate how we want it to be reconstructed in a way.

Lactic acid buildup after a particularly strenuous workout is familiar to just about any athlete and it’s a literal pain in the ass sometimes. The best way to get rid of that burn is two-fold. First, you must breathe. The main reason you get such high levels of acidity in your muscles in the first place is that you can’t take in enough oxygen to offset the hydrogen you’re accumulating (more on this in other articles). So stopping and taking in more air help reduce the burning.

For our purposes, the second part is more relevant, and that is movement. Just by jogging around or light stretching after a workout, you can help to deter or counteract the burning. This is because stretching helps to loosen the muscles and release the lactate built up at the site while re-establishing a full range of motion.

When you build up that concentration of lactate, you pump the muscle full of waste product which might make you look like a swoll beast but it keeps your muscle’s range of motion limited. Because of this, stretching can, and generally does help to ensure less long-term soreness and why it’s typically recommended after more intense workouts.

Other forms of stretching

While we have been giving static stretching a good hounding, and rightfully so, it should be known that there are several other types of stretching. Some have more known effectiveness in particular areas, while others are more harmful and should never be used.

Dynamic stretching is one form that has been constantly preferred by many athletes and sports professionals over the last couple of decades and is decidedly better as a pre-workout method. Its use is shown to help improve range of motion while increasing nerve conduction speed and enzymatic cycling by elevating core body temperature.

It does this in a way that is contrary to static stretching which does not excite the system for movement but rather coaxes it into relaxation. Therefore, dynamic stretching is more commonly used for warmups where you may want to do something fast and powerful, whereas a static stretching session is best utilized as a cool down or a warmup on workout days less intense or billed as a recovery.

Proprioceptive Neuromuscular Facilitation, or PNF, is another option and it takes advantage of the autogenic and reciprocal inhibition protocols inside your body. More on this below, but think of PNF as a way of stretching using your body’s own protective mechanisms to induce greater relaxation. It’s less about pushing and holding until your soft tissues start to deform like static stretching and more about tricking your body into giving you more available slack in the rope as we discussed in the prior segments of this series.

It should also be mentioned that other forms or subcategories of stretching exist, but types of stretching may need a shorter article on their own to better understand without taking away from the purposes of this article. Static stretching, dynamic stretching, and PNF stretching are three of the most common, most used, and most effective means of stretching, so that should suffice.

How Should We Stretch?

A case for autogenic and reciprocal inhibition

Stretching has its place in your everyday routine, especially if you exercise regularly. But how you perform the stretch, which you choose to utilize, and how much will vary depending on your individual case.  What is most important is understanding why you are stretching and, again, what the end goal is. If your only goal is to become more flexible, you’re doing it for the wrong reasons and you need to understand that you will be actively putting your health at risk.

If you choose to participate in activities that promote hyper flexibility such as gymnastics, yoga, dance, or martial arts, you cannot get around this. It is an inherent component to each.

We spoke just a moment ago about PNF stretching and how it uses autogenic and reciprocal inhibition. Now it’s time we tell you what the hell those actually are because I believe that these are two methods of stretching that are not only more fun to use but more effective at bringing about athletic success. They help, of course, with range of motion but also maintaining peak tissue health.

Simply put, autogenic inhibition is when you cause a muscle to relax due to an increase in tension. Reciprocal inhibition is muscle relaxation on one side of a joint due to contraction on the other side. In the real world, this translates to the following:

You lie on your back with your leg in the air while a partner grabs that leg and gets in a position about to push back on your leg like a typical hamstring stretch. The key difference here is that instead of passively letting them push your leg back toward your face, you resist their push with a push of your own. Mind you, you shouldn’t be trying to see who can push hardest, but you should feel the tension in the hamstring. That tension can only be held for about 20-30 seconds before your hamstring wants to relax naturally. This is autogenic inhibition. This is a safety mechanism.

Ever tried to hold a heavyweight in your arms for an extended amount of time? Bet you can’t do it for too long before your arms start to slowly lower the weight. You can keep the tension for a while but eventually, in order to keep you from tearing muscles, your body relaxes the muscle being worked. Strain as you may, you will give in…

Now to visualize reciprocal inhibition, you need only imagine the same situation with a slight twist. Instead of your partner trying to push your leg back against your resistance, they take you to where your muscle’s range of motion naturally stops. As they stabilize your knee and hold that position, you contract your quad as hard as you can and hold it for 10 seconds.

Remember that if one muscle is contracting, the antagonist MUST relax or there will be no movement. Your quad contracting will signal your hamstring to relax, thus allowing the leg to then be pushed back a little further and the process repeated.

So stretching is good then, right?

Yes! …and no. If you’ve learned anything from the two other articles, we try to emphasize a partisan push to steer away from overstretching in particular. Stretching in its own right is a fantastic tool for athleticism and for recovery when used correctly.

Stretching, in general, is great for everyday living and health, and for athletes, it’s a tool to help develop a bit more functional force production. BUT its particular use is not nearly as fruitful as other tools in our toolbox, such as weight training.

Usain Bolt is the fastest man in recorded history. If he stretched like a gymnast, he’d be a loose and often discombobulated mess if he tried to break another world record sprint. He’d likely spend more time recouping from injury than he would be burning up the track, or at the very least, he wouldn’t be finding the same kind of success that garner finals races or podiums. This is partially because he’s extraordinarily strong and requires a lot of his tissues to apply force.

Speed and power dictate taught, steel ropes for muscles and tendons. Some have likened it to wanting a tight suspension and I can concur. With the little amount of time he has to hit the ground with as much force as possible and get off, any energy leaks would cost him medaling especially at an elite level where mere hundredths of seconds mean everything. A softer suspension makes for a smoother ride, but rarely in any sport are we trying to attain soft joints. We want that high-efficiency kinetic transfer of energy so we can move better.

Let’s not forget we cater specifically to those wanting to be the best athletes they can be at an elite level. So why practice something we already know is not beneficial to our everyday warrior athletes when it would do nothing but hurt our chances of making it to the ultimate level?

As we’ve mentioned before, tendons don’t like prolonged stretching or compression. When you spend time stretching too much or through an abnormal range of motion, you create a situation in which a tendon can be compressed against a nearby bone or it loses its elasticity by you holding your stretches. You can imagine this is not the best for you for a number of reasons, and as an athlete can diminish speed and power. This is one reason we advocate against static stretches in a warmup before explosive activities especially.

If you are a competitive athlete, and if you’re reading this I would assume you likely are, I would focus more on dynamic stretches or eccentric loading exercises for strength and normal range of motion maintenance for your particular event. If you have a decade to train and build an extended, abnormal range of motion along with strength through that ROM (martial arts masters, dancers, cheer, yoga) then perhaps you can do whatever the hell you want. But there’s a more inherent risk involved, and most athletes aren’t big fans of working hard just to sit out every season...

Conclusion

Again, this series pertains to high-level athletes in particular and focuses on how particular types of stretching can affect performance and overall health. We push for an immediate departure from overstretching and limited use of static stretching for rest and recovery, with an emphasis on more acceptable and beneficial forms of range of motion training for a majority of sports-related activities.

If you are a moderately active weekend warrior, or you’re a younger individual whose main focus is basic yoga, some of these concepts won’t apply to you as well. There’s some research that shows no difference between injury risk, for example, in those who stretch and those who don’t stretch in a non-competitive dynamic and/or contact activities.

By stretching too much, we can actually reduce the alpha-gamma co-activation mechanism in our muscles, over extended periods of time. That is to say, by overstretching, we can lose sensitivity to elicit stretch reflexes and signaling to our muscles. Imagine kicking something on the ground as you walk and not being able to sense the stretch as well and just falling on your face rather than a slight stumble and catch. Because they are overstretched and therefore less sensitive to sensing it, you are less sensitive to pain which can hinder your own natural abilities for detecting problems sooner.

You don’t have to look hard at all to find counter studies on the effectiveness of stretching or the inability of stretching to do anything. What we should take from all of this is that we are still very much up in the air, but there’s far more research lending evidence to negative effects on human performance than the opposition. 

Quick review:

• It’s really simple. If it feels like too much, it’s too much. 

• No static stretching before working out.

• Eccentric stretches are arguably the best.

• Perform regular warm-ups through standard ranges of motion, no further than your fully relaxed range.

• Don’t compete for flexibility.

• Instead of focusing on stretching a short or tight muscle group, choose to work out its antagonist group more to begin bringing its ranges back to normal. More often you work one side more and have a weak opposing muscle that cannot resist the pull of the other side.

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