The excellent book: The Tyranny of Words speaks about the fact that words are not the thing they reference. The map is not the territory. Words simply reference the thing. With objects this is fairly straightforward, but with abstract concepts it creates some problems. If you are having a conversation about love, or communism, or art; it is impossible to have meaningful discourse unless the participants have the same concept when using the same referent. Put simply, if you speak to someone about “democracy”, the chances that you are having a conversation about the exact same thing are fairly low. Imagine if you misunderstood a conversation about bicycles to be about cars. You might think your dialogical partner a maniac for talking about the cup-holders, seat-warmers, and windscreen wipers his bike has. This example may sound silly, but it is a concept I experience frequently when talking about specific terms within movement.
When people say: “exercise is good for you” it all depends on the context. Depending on the goal your choice of exercise may be utterly pointless. There are even many situations where exercise can be destructive. This is the same for diet. It is foolishly reductive to consider “exercise” or “dieting” to be “good” things. Much of what I speak about on social media is misinterpreted due to assumptions of meaning based on incomplete contextual understanding of the referent. I have found myself in discussions and disagreements that are not productive and I can see that it is because the opposing standpoint is not actually discussing the same concept as me. I’m trying to explain bicycles aren’t ideal to be used on the motorway. Meanwhile, the opposition is pointing out in disbelief that it has been done for decades, is why the bike was invented, and is extremely safe; all the while I can see the intended referent being the car. The occasion where this is most prevalent in real life is, unsurprisingly, when I talk about stretching. And the referent I wish to define in this piece specifically: flexibility.
What is flexibility?
To make my own assumptions: I believe that most people consider “flexibility” to mean someone’s ability to move into different positions. For example, to perform a toe touch I need to have “flexible” hamstrings. To squat I need “flexible” calves. When I feel stiff, I have lost “flexibility”.
The old model of muscles being pulleys is outdated. We know that live human beings who rely on tensegrity and are 99% water per molecule, behave differently than a dead body when they move. Our entire model of human movement is based on pulling cadavers around, rather than observing the obvious differences in living systems, and following the principles of motion which we all obey. Instead, we should think of muscle as squeezers that contribute to positional expansion or compression. This means that movement is less about a pulley providing slack, than whether or not there is space into which to expand. The key point here is that a muscle’s ability to lengthen does not contribute significantly to the body’s ability to change position. Almost every movement you would perform on a daily basis involves very little excursion from normal length for the muscles involved. Only very specifically chosen movements really take the muscles to end ranges of motion, and even in those extreme cases (doing the splits for example), it requires extreme joint laxity to reduce pressure that allows the expansion to take place.
How do we actually create movement?
To give a common example of this model in action: it is extremely common to see someone who is unable to hit depth in a squat movement, but who is completely clear when testing for ankle, knee, and hip flexibility in isolated tests. If the individual tissues have enough length, what then causes the restriction when putting the movement together? The answer is rooted in the compression/expansion model where they simply run out of space to continue compressing themselves. For example, consider the task of singing “Happy Birthday”. The first thing you must do is inhale. Expansion. If you try to sing “Happy Birthday” after a full exhale you won’t get the job done. You might get an isolated note out, but you aren’t singing a tune. Compressed people are trying to sing after an exhale. They have no space left to continue compressing to continue creating motion.
Someone who is compressed is either stuck in an exhaled position, or to initiate movement they rely on compressive strategies that reduce their remaining space too rapidly. As an example to try: stand up straight and lean forward into your toes like a Michael Jackson dance move. Then try to squat. Shifting your weight forwards is a compressive strategy. It puts force into the ground. You won’t squat as far down as easily. Some will say the restricted ankle range in this position is to blame but this is demonstrably false. If you take someone will full expansive capabilities, you will see that they can squat with their knees well behind their toes. Dorsiflexion is not the limiting factor. If you put a wedge under someone’s heels and have them lean forwards so that their ankles are at 90 degrees, they will squat less far than leant backwards in flats.
The evidence is also seen in the corrective. People either lack the space to move into, or the tolerance to compress further. You can perform drills that restore expansive or compressive capacities that require barely any movement, and not even at full range, and you can see dramatic results. Clients are often amazed when a single drill of internal rotation creating pressure through the hip results in them performing a long-lost skill of sitting in a squat. But it isn’t magic- it is simply operating within the correct model of movement. If you have the wrong model, you create the wrong solutions. The Earth might appear flat on a day-to-day basis when you’re simply walking around; but if you use that model to plan your plane voyage you will get to the wrong place.
Another common example of this model in action is with chin ups. It is common to see very strong people unable to pull chest to bar. The issue isn’t strength. And the position is not that is difficult to assume with no movement gradient or tension. But suddenly when they are moving their bodyweight, and are forced to apply a compressive strategy to do so; they run out of space. If you can’t continue to internally rotate, you cannot continue to move. Imagine singing happy birthday through a restricted breathing apparatus. The force required spends your exhalation capacity early, and you can’t continue.
Do I need to be flexible to be mobile?
So, when I talk about being highly flexible, I think about contortionism. I think about muscles operating at the extremes of their length. However, this is not representative of typical movement. Even when it feels like you range of motion is limited by tissue length, it rarely is the case. It makes sense that normal movement wouldn’t operate in this way because end range of motion is where you have the least force potential and where you carry the highest risk of injury. It is a position with the fewest options for subsequent movement and you shouldn’t be there long or often. So, when I say: flexibility is not an important quality to train or develop – I don’t mean that it is unimportant to be able to move into extravagant ranges of motion. I fully support the notion that someone should be easily able to touch their toes, sit in a deep squat, execute a head-kick, throw a javelin, perform a perfect breaststroke, etc. I merely argue that flexibility is the not the primary feature that allows these tasks to be performed.
A further reason for confusion is that there are plenty of occasions where pursuing flexibility DOES allow the movements listed above when they were not accessible previously. However, I would argue that it is not the ideal route to that goal. If we ignore the role of the skeleton, and the relative motions which must take place to accommodate certain physical tasks, then we likely won’t develop those abilities in our training. If we put so much slack into the system that we can subvert this requirement, and move without the relative motion of joints, then we are causing problems which are hard to solve.
Could flexibility be hurting my movement!?
When people cannot squat and they believe their dorsiflexion is at fault, they stretch their calves. This tensions the back of the lower leg but also the plantar fascia underneath the sole of the foot. This tension under the foot will actively prevent the foot flattening as it must do during functional pronation to create the space for the shin bone to move into. You have made it harder for the shin to translate forward. If you continue to stretch you may end up putting so much slack into the region that you can achieve massive dorsiflexion ranges, but you likely be doing so without proper pronation.
Another example is a straight leg raise. Most people assume this is purely a test of hamstring flexibility. In fact, in healthy movement there are many contributing components. You need rotation of the femur, rotation of the innominate bones, nutation of the sacrum. If someone lacks these pelvic articulations, they often get stuck with their foot barely off the floor. To blame the hamstrings is ridiculous; especially when a one degree bend in the knee (which reduces the propagation of IR into the pelvis) allows them to bring the leg up perpendicular to the ground further. If the movement was solely due to flexibility, then one degree of slack should mean one degree of increase range. If we only focus on the role of muscle, we can indeed make the hamstrings so stretch tolerant that they can do 100% of the job. I have seen this approach over and over again result in pelvic and lower back pain. It makes more sense to optimise each moving component so that the task is distributed across multiple areas. It is extremely common to highly flexible people who have poor relative motion within joints. The tricky thing is identifying this because sometimes the laxity means they can display good results in common table tests; but when you add load or constraints or controls to the movement the range disappears.
So, if flexibility is still responsible some degree of movement, then why do I ignore it as a trainable quality? My answer to this is that I have almost never anyone who has lost so much flexibility that it becomes the limiting factor in functional movement tasks. On the other hand, I rarely see anyone who has no restriction in relative motion (in fact the more trained they are the worse it often becomes!). I believe that to have the flexibility to fulfil its quota is extremely straightforward and can be obtained and maintained with the most meagre movement practice. Regular short walks I feel are likely enough for many individuals. I hope that this explanation has given enough context behind my referent of flexibility to prompt more constructive discourse. I will reiterate that I am not against the idea of being able to move the body significantly away from a resting baseline position, I am against the method of creating so much slack through an intentionally tensioned system that we can neglect other features of functional mobility.
The final point I wish to make is that if you are aware of the long-term consequences of excessive slack through joints and connective tissue, and you perform activities which require supra-functional ranges of motion such as doing the splits for gymnastics, then it is likely that you may need to stretch. I have seen a growing number of institutions moving away from stretching as their process for gaining extreme mobility; but as those ranges are not something I condone or teach; I cannot speak to the efficacy of non-static-stretching protocols in this regard. However, it is my strongest recommendation that if you are performing regular exercise, and your motivation is to be healthy, or to improve your athletic performance, stretching is not necessary, and will likely be detrimental to your progress. If you feel that for your health or performance, you need to be able increase your range of motion- there are other more likely culprits holding you back than the extensibility of muscle tissue.