Overview

In part one we discussed why we might feel the need to stretch and what we might gain by it. In part II we will look into more of the muscle anatomy and mechanisms behind muscle contraction and touch upon what we might lose. How can prolonged stretching or excessive stretching affect our bodies?

What’s your goal?

This should be the first and only legitimate question on your mind every day when you choose to perform a stretch (or anything for that matter). People tend to compete for the best flexibility among their friends or competitors or attempt to test the limits of the human body. If that’s your goal, you might want to ask yourself why the hell you’re actually doing it? Is it simply to say you are the most flexible and can lick your own backside? Or is there an actual physiological or athletic advantage?

Remember that we at The Athlete’s Forge are here to help athletes develop the skills and understanding to become the best they can be, so bear in mind that these articles may not hold much weight for those not interested in being more than a weekend warrior or staying physically fit for basic everyday tasks. We would still caution those here who fit that category, to take what you learn as a guideline for better health practices.

A large misconception, and very North American ideology, is that more is better. Every particular activity has its own unique purpose and set of skills. Remember that humans created these sports and they are not always necessarily natural in the way they approach conventional athleticism. We’re looking at you dance, yoga, gymnastics, and cheerleading. Each sport will have separate needs and designs. So if you HAVE to gain ridiculous levels of flexibility to compete in said activity, your only choice is to do it, but do it right (see the end of series).

Specialize

If you’re a runner, run. If you are a cheerleader, cheer and flip. If you play basketball, move around and shoot some balls (with the actual ball -- none of this shadow hoops nonsense). The main thing is that you warm-up and practice as you would participate. You wouldn’t warm up for wrestling the same way you would warm up for baseball. The way your body moves for each is distinct.

We’re not sure we’ve ever seen any of our elite-level cyclist buddies ever spend much time stretching, and that makes sense. Their range of motion is dictated by a predetermined crankset, and most muscle tightness that does occur does so in the lower back, shoulders, and calves which are usually reconciled by rest.

Track sprinters should focus on muscle and tendon “stiffness” to preserve high levels of force production. Distance runners on the other hand should focus on the economy of motion, as their range of motion is even more limited than most in their sport, and they have to keep moving for far longer periods of time. Wasted movement means a poor return on energy investment, which equals diminished competitive results.

If you happen to be a wrestler, you MAY find it advantageous to be more flexible when someone tries to put you in a hammerlock or some variant. You might be able to also argue that a lack of flexibility in your shoulder girdle could actually work to your benefit. The further your limbs get away from your body, the more leverage an opponent has on you and the weaker you are to resist because of the reduction in the length-tension relationship (ideal length of a muscle to produce maximal force).

For most, there isn’t a true benefit from stretching beyond our natural ability. Many children cannot touch their toes, and they are the most basic, natural versions of humans. They are the raw form of what we are supposed to be and what capabilities we possess. Some kids can touch their toes, though. But that shouldn’t be surprising as they are not fully developed, they are naturally more malleable, and there are always those who are more flexible than others by birthright.

Now, look at a few elite-level athletes who aren’t flexible. Eliud Kipchoge is one of the fastest men all-time in every distance from the 1500m through the marathon, of which he owns the world record (he’s broken it twice). He can’t touch his toes to save his life. Yet he can split an average of 4 minutes and 34 seconds per mile for 26.2 miles!

Several of our high-level sprinter and jumper compatriots were famously inflexible. A 7’5” high jumper, 17’ pole vaulter, and a 10.4 second 100m runner. Yet those of our friends who were heavy advocates of stretching, such as a few javelin throwers, sprinters, and hurdlers, tended to be hurt at least a third of every season due to hamstring, shoulder, or low back problems. Most of those who were hurt least often, and likewise couldn’t touch their toes or abduct their legs far, tended to avoid stretching altogether, which we always found interesting (and frustrating).

There are a good number of athletes who seem to fit the common stereotype for events though. We have had very flexible male hurdle athletes and teammates who could kick over their head and do the splits. People tend to gravitate to sports or other recreational activities that suit their given aptitudes. In particular, you will likely find men and women who participate in things like yoga, gymnastics, dance, or cheerleading who are naturally “bendy” as they excel in it. Often they don’t really know that all that flexibility is likely bad for them. They may suffer from joint stiffness or soreness or are prone to injury simply because they have natural hyper flexibility. These athletes may even have Ehlers Danlos Syndrome (EDS) or generalized joint hypermobility (GJH).

It’s about where you feel the stretch, not about how far you can go into it. We all like to tell ourselves that we are different and that we can’t do the same thing for everyone and expect the same results. Then why would we do the same for stretching? Do we ascend to godhood the moment we can touch our forehead to the ground or do a chair split? If it actually had a massive benefit to athletic performance, why are so many great athletes inflexible? Those who try to be more so, why are they often injured?

Real quickly, let’s understand how muscles are composed. We promise you’ll be happy you stuck around and we won’t bore you like a school lecture.

How Muscles Work

Muscles are made up of, like most things in your body, pieces within pieces. Muscle and tendon are structured like Russian nesting dolls (at least that’s how we like to think of it). At its most visible and recognizable point, you have the muscle belly. That’s essentially the “muscle” you all work out and focus on (ie, the bicep). The bicep, though, is a collective of many bundles of fascicles which are bundles of muscle fibers (cells), which are made up of a bundle of myofibrils. These myofibrils are a chain of contractile sections called sarcomeres, and this is where the magic happens.

Don’t worry about memorizing any of the things above, the picture below will help, and all we need to understand for these purposes is the sarcomere and how the muscle contracts!

Those myofibrils above constitute the sarcomeres. Linked together, side by side, like a long row of dominos. Click here to see what they look like at the microscopic level and how your muscles move by pulling the ends of each sarcomere closer together. No, seriously, click it, it’s a fantastic visual.

Kinda cool to watch, right?! Well, that’s nice and all, but where the hell does stretching come into play. Fair enough, let’s get to it.

If you look closely enough in the video, don’t the myosin heads that pull on the actin to make it all slide, remind you of boat oars rowing in the water, or hands on a tug o’ war rope? The more oars in the water, or more hands on the rope, the harder and more effectively you can move.

The same goes for your muscles. If not enough hands grab onto the rope, you can’t move as well, or as powerfully. This is where overstretching can cause issues. By stretching, you can cause the actin and myosin to separate enough from each other that only a small portion of hands can reach to grip the end of the rope! Figure 3 below is an overly simplified graphic to help understand.

When there are more myosin heads in contact with actin, you can pull harder. What should be learned is that you have a resting position and a fully contracted position. Between those two extremes lies your normal range of motion. In the resting position, your muscles have a slight overlap of actin and myosin filaments so that, when ready, there’s something to pull on. When fully contracted, there is no more real estate on the rope to pull and you would then start to have to overlap z-lines in the sarcomere (we’ll save that for another article).

The problem is when you try and stretch beyond your normal resting length. This is where tearing occurs in many instances. Regardless, if there are no myosin heads in reach of the actin “rope”, there’s nothing to pull on. Thankfully muscle fibers aren’t exactly uniform in length, so if a few hundred sarcomeres are out of whack, you can still contract the muscle itself, albeit weaker than normal.

We call this the length-tension relationship. As more heads pull on the actin, the tension increases as you might expect. As it reaches peak contraction, tension levels out and then fall off. As the two ends of the sarcomere (z-lines) get closer to each other at full contraction they begin to overlap and gain no additional tension. No more rope to pull.

That’s covers contracting a muscle, so it’s certainly not recommended for anyone performing speed or power movements where the need for strong contraction is necessary. The kinds of negative changes brought on by pulling your sarcomeres beyond ideal position can occur with static stretching.

If, for instance, you are about to go into the gym to do some heavy squatting, the worst thing you can do is perform long static stretches just prior. Why do I say this? Simply put, you not only put excess stress on the other soft tissues (such as your tendons and ligaments), you temporarily alter the resting range of your contractile muscle elements. This can cause joint instability because the tissues are more pliable and loose.

In doing so, it also creates a range your central nervous system is not used to at that moment, modifying the engram (stored motor pattern) you have set for the squat, and you potentially remove hands off that rope, so muscles don’t contract quite as hard. Imagine for a second you are going down into a squat and you’re more loose than normal. You would be capable of getting down lower into the squat.

I mentioned engrams. In short, over time, you repeatedly perform an exercise that becomes an ingrained or programmed movement pattern and requires very little to no thought. Think back to when you were a child. Putting a spoon to your mouth with food on it and successfully “landing the airplane in the hangar” was an extreme challenge.

After performing it thousands of times, you can simply push a quick mental button and it’s as easy as pie these days. When you alter that engram, even temporarily, you throw that natural movement out of whack enough to hinder the movement. It’s almost like you have to relearn the movement just a bit. Imagine you’re about to hit a baseball flying through the air, and just as you begin to swing, a bee flies in your face. You complete the swing but that predetermined path to the ball was changed and the movement was far from smooth. A little extreme, but I’m sure you get the point.

Now think of the squat. If your hips, calves, or hamstrings are more loose than normal, it can cause you to drop lower in your lift than you’re used to and might not be strong enough in that lower range to get up out of the hole. You may have to make sudden and strange movements elsewhere to get back up. There’s a risk of knee valgus, overpronation, leaning too far back or forward, overcompensating in your lower back, etc. Not good! You are just asking for injuries, especially at heavier weights.

Too much stretching could be hurting you

Aside from weakening the muscle and tendons (remember we are speaking on static stretching in particular), too much stretching can mess with proprioception, short-term. This is because, as with the squat example, your body isn’t quite honed into where your limbs are in space. You’ve gone outside its normal range and it doesn’t have that groove to ride in the same way.

Also, you can run into nerve and tendon impingements, as well as torn muscles when you go outside of your conventional range of motion. Hyperextension is a corresponding symptom of hyper flexibility. One easy area to pick on is the shoulder.

Swimmers, baseball pitchers, and jiu-jitsu fighters experience shoulder over-rotation and hyperextension more than most. By taking those joints through a larger span, purposefully, we allow for injury to ensue almost undoubtedly. Unnatural flexibility in this area creates a weakened and loose joint, but also a risk for shoulder dislocation and tendon impingement which can lead to tearing and subsequent inflammation. There’s the supraspinatus, infraspinatus, teres minor, and subscapularis that help support the shoulder during the rotation of the arm and keep it in the middle of the socket.

Notably, the supraspinatus and infraspinatus are most likely to be injured during hyperextension of the shoulder. If you are not in one of the above sports, or you are and are trying to be more flexible, STOP having people pull your arms back! Unless you have a particular muscle strength imbalance that’s causing you to round your back, for instance, you’re contributing to your own problems. Wouldn’t it be easier to work on strengthening those rotator cuff muscles, effectively giving your range back and adding power to your movements?

A lot of knee injuries in dancers are due to forceful turning out of their feet. By over-rotating at the knees and ankles, the fibula and tibia separate from the femur in a twisting motion, and the knee joint takes on the excessive strain. Surprisingly, dancers don’t have as many ACL injuries as other sports (women’s soccer, gymnastics, football) which may be due to repetitive jumping and seasoned proprioceptive abilities in that range of motion. That’s not to say that it doesn’t occur.

Many dancers and gymnasts choose the sport because they generally have naturally loose ligaments. They are also taught to lock out their knees in many instances which hyperextends the knee and puts undue pressure on the ACL in particular. This can also be a condition where the hamstrings require strengthening.

This is neither pretty, nor healthy, but it’s very common in dancers especially.

Another common hyperflexible sport is gymnastics. The most common injuries amongst this elite group are back, knee, and ankle sprains/strains, as well as foot fractures. Of these, the most notably relevant to our topic involve the back and knee. Gymnastics is a very dynamic and explosive sport in which injury is inevitable regardless of flexibility, but these two are of particular interest. A reason gymnastics remains a profitable mainstay on television is due to the immense beauty and athleticism on display. But a lot of its unique draw comes at a cost.

Hyperflexibility in the back...bad. We’re not sure if someone could argue positives for hypermobile spine in any other context than dance, gymnastics, or contortion. This is especially true in the rounded aspect of your thoracic spine. This area is meant to roll forward to allow for more flexion. You could do a simple lean backward right now with your hands on your hips and it should be no surprise that the portion that bends first and easiest is your lower lumbar, which curves in.

You don’t have to know much about anatomy to infer some things accurately. There are bony points (spinous processes) that stick out from the back of these bones that are fairly large and are angled downward a bit. When you flex your back far enough (not even that far really) they push against each other. As you can imagine, if done enough, you can cause some pretty significant damage.

Just as in dance (and swimming because you wouldn’t very effective without it) athletes are taught to plantarflex, or point their toes. There is no other reason but to extend the limb lines which looks pretty to onlookers. Imagine telling a running back to lead with their toe as they run, or a basketball player to work on their foot “pointe” to develop a better shot.

Well, there are athletes who are young, inexperienced, or transfer from sports like swimming, dance, or gymnastics who do this. Guess what? They very clearly have a problem when performing standard athletic movements like running and jumping don’t they? 

The only time we point our toes in sport is during a jump, but that is because of the summation of forces we require and full joint utilization for maximal displacement. It’s otherwise not efficient. Not only do we not twirl on our tippy toes, but we also don’t land on our toes. There’s very little to no supination to adapt to the ground when we land and there’s less surface area, making for a very long and weak joint. Boom rolled ankle.

What’s the next thing you do if you roll your ankle a lot? Get back up and go for another round, generally rolling it again until it’s overly flexible and unstable. These are the individuals (like me once upon a time) who trip over their feet and roll their ankles walking ALL the time.

We’ve discussed decreases in proprioception as well as overall short-term strength loss and loose joints. It might not even be that there is a problem in the particular area you are feeling discomfort or tension. In fact, quite a lot of the time we can’t reach standard ranges of motion or we feel pain due largely to a problem elsewhere in our body. So we might decide to stretch out our calves and lengthen the area for some temporary relief, but never realize that our lower back is actually the cause of everything below.

Remember that your body does a wonderful job of compensating to keep you upright and that can occur anywhere from your head all the way to your feet. Trouble ensues when you generally decide to overdo something and try to fix something that isn’t broken, to begin with.

Why Do I See A Benefit (increase) When I Stretch?

“Alright, I’ve sat through all of this and it sounds like you are telling me that muscles don’t stretch and it might not be a good idea to hold stretches. If that’s the case, riddle me this Batman, how is it we gain larger ranges of motion and we see an increase in performance by doing stretches?”

Increased range of motion

To address the first question, it’s because we are manipulating surrounding soft tissues that can stretch. Tendons, for example, attach muscles to bones and help not only pull the bone when the muscle contracts, but they absorb and store a ton of the force we put on our limbs helping to deter muscle tearing and rebound energy back. They are viscoelastic tissue that can be either rigid or softer depending on the rate at which it is pulled. You’ll hear people say that tendons can’t stretch. This is not the case and is a typical misconception. While they don’t stretch a lot, they certainly do stretch.

When you hold a stretch, the components of the muscle that slide (actin and myosin) will reach the maximum length and act like a taut rope that pulls on the tendon it’s attached to. The tendon, because it is under slow load, is more pliable and begins to lengthen ever so slightly. It takes them quite some time to return to their normal resting length. This is why you will gain range of motion, but will also notice that if you don’t continue to stretch every day in this manner, your range of motion will gradually fade back to where it was initially.

When things like your tendons stretch beyond normal ranges, you weaken them. Tendons aren’t meant to really lengthen much under normal circumstances. When they do, you also put your joints in a particularly precarious position. Without tension on the joints, they become more slack and liberated.

Take one look at a dancer. They are some of the most flexibly dynamic people around. Beautiful to watch, but also some of the most injury-prone individuals on the face of the planet. I know a few. Between the rolled ankles, dislocated or broken toes, sacroiliac joint dysfunction, hip labral tears, etc, it’s a wonder they aren’t all beat up and over it by their teenage years in many cases.

“By repeatedly pushing past "normal" range, you're getting micro-traumas, which can lead to more serious injury, such as joint dislocation, ligament strains, and tears, or tendon inflammation.”

It should be noted that there is science that states that we can increase our range of motion through hypertrophy (building muscle). When you think about building muscle, you will likely envision the muscle getting thicker. There is a good amount of research that points to us our ability to add more sarcomeres (sarcomerogenesis) to the ends of our myofibrils as well. More dominoes in the line.

This doesn’t mean you can stretch farther, but it would mean that you can damage the muscle enough to create an environment where it extends its own length thus allowing for a little more natural relaxation length….? How long this takes and how much stress (eccentric I would assume, but remember that muscles cannot hypertrophy in one direction? Eccentric puts the most stress on muscle) and how much length is to be gained, is unknown to me.

Perhaps this is why you see fewer and fewer injuries with people who have been doing this type of damage to their bodies for decades. Their bodies grew and adapted and the CNS is continually trained in the new ranges of motion so the speed and power are regained. Martial artists are a prime example. Might need to actually look into this.

Increased performance boost

As for why one might see a performance boost by stretching, we have to look at the big picture because it could be any number of things. For one, it’s heavily dependent on what the need of the athlete is and what their specific training goals are. If your goal is to be able to do a jump split, you’ll see an increase in performance by practicing your static ground splits.

If you are a hurdler who tends to put their leg up and bend over it to increase hamstring range of motion, you may see an increase in your ability to extend your lower leg out further when positioned above the hurdle, but that range does not equate to large increases in performance times unless you are a novice hurdler. For hurdlers specifically, full extension of your lead leg at the parabolic peak is not recommended. It’s usually an indication of a technical problem upon takeoff, and it’s slow. Is running straight-legged where you pull down toward the ground with your hamstrings faster, or driving your knee and foot down into the ground with your ass? Which one’s better for your hamstrings?

Also, we have to look at what other factors played a part in the boost in performance. Sometimes we forget the little things like sleep, food, other pre-competition preparation strategies, where you might be in regards to experience if you are coming off nagging injuries if you are on your period (hormone imbalances) if you’re in a peak part of your training schedule, other life stressors you had been going through before, new weight training and muscle work, you listened to a really good jam just before you went out, etc.

The list goes on, and while stretching may have been a new addition to your regime, it’s highly unlikely that it alone was the reason for your success. Of course, that is unless you were just stretching to be more flexible for your chosen activity.

It’s also very much about how and when you quantify or gather your results. It’s common knowledge that dynamic stretching is better (however potentially limited) immediately preceding an athletic performance than static stretching. If you were to choose to do static stretching but waited 45 minutes to compete, you may see an increase in performance over a similar test done with only 15 minutes of rest. While I can’t answer those things, it’s useful to think about.

Flexibility for flexibility’s sake is fine (if it makes you happy), but to the point of extending beyond normal resting ranges could be doing more to hamper all those gains.

Part III (Conclusion)

Phew! Sometimes you look back and go, “Damn, did I just read a book?” Not to worry, we wouldn’t make you work too hard at once, that’s why we break some of these deep dives into manageable bites.

In the final piece of this series, Part III, we will be addressing your central nervous system function in stretching and finally answer the questions surrounding how we should implement stretching into our sport-specific routines. Clearly stretching isn’t all bad, so doing it properly to benefit our overall health and athletic success is paramount to understand.

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