Muscles Don't Stretch
Updated: Sep 7, 2020
You’ve heard me say it before, and I will say it again. Stop wasting your time with stretching.
Stretching has been a massive part of the industry for so many decades. So many people follow daily routines in an attempt to improve their functionality, attempt to rehabilitate from injury (I’m not even going to go there - a stretch given to a rehab patient is just darn right ludicrous). It is in the history of health and fitness, and so many people will be emotionally attached to stretching. Im not trying to gun down your practices, I’m simply trying to educate so you can from your own opinion.
There are so many scientifically backed reasons stretching is not ideal, can be harmful, and essentially wastes your time. Im going to just quickly run over the reasons why it will not be beneficial for increased muscular flexibility, performance and long term range of motion improvements.
Disclaimer: Understanding this article will require basic understanding to micro-anatomy, the role of passive tissue and muscle and joint function.
1 Force production post passive stretch reduces.
the myofilaments (contractile units of skeletal muscle tissue) are detached at at a fast rate (ripped apart/damaged). The force production is impaired for some time after due to the rate and level of displacement.
“Stretch Induced Strength Loss” a study showed significant difference in acceleration (p < 0.0167), maximal-velocity sprint time (p < 0.0167), and overall sprint time (p < 0.0167) between the stretch and no-stretch conditions. Static stretching before sprinting resulted in slower times in all three performance variables.
2 There is less nervous control where we see maximal end range stretching/loading, as there is little to no cross-bridging, thus, passive structures take more of the load that have less innovation.
The nervous system controls all, and if we are trying to cause muscular adaptation via passive stretching where we enter excessive ranges that are more controlled by passive structures, we can’t optimally potentiate and ultimately cant ‘remember’ the increase in length and will be unable to transfer this into sporting activities and force production. With less ability to produce muscular contraction in severe end ranges, there is less of a need for action potentials, less mechanical efficiency, more of a reliance on our passive structures and consequently our ability to negotiate with the nervous system is impaired and neuromuscular adaptation not very likely.
What we feel during a stretch is an uncomfortable, unnecessary feeling that is produced by pulling a structure to its end range. 99% of the time, as I will come to later, it is the dysfunction of the contractile elements within muscle tissue that makes us feel ‘tight’.
Passive structures, namely tendons and ligaments, as well as other passive units, have a finite length and ability to increase passive stiffness. There are copies amounts of injuries due to taking certain passive structures to lengths that we are bot able to tolerate. This is called the ultimate yield point, where if structure deformation reaches and exceeds this position, macrofailure may occur and we would experience ruptures and avulsion fractures, not to mention all the incidences microfailure we would see before this ultimate point, that would have implications to overall joint structure and function. Essentially these structures after deformation are in no rush to return to their pre-deformed dimensions, increasing their laxity and reducing their ability to help with joint integrity. Firstly, ask yourself how this would help in sporting performance. Secondly ask yourself how this would improve your range of motion and flexibility? Also ask yourself why you think pulling passive structures to their ‘stretch’ limit is beneficial?
The length tension graph (including the contribution of passive tissues) tells us the relationship between the length of a muscle, the the amount of tension it can produce. We can quickly see that passive stretching will become somewhat useless after breaking down the graph.
RUBBER BANDS STRETCH, MUSCLES DON’T. A lovely quote from Jaques Taylor (neuroscientist). Muscles (sarcomeres if we are getting geeky) don’t have the ability to ‘stretch’. They do have the ability to lengthen, but not stretch. Passive structures, ligaments, fasciae, blood vessels, nerves, the elastic protein titin and tendons to some degree, will have an elastic component to them, and they will stretch. But what’s the benefit there? There will be no muscular adaptation, connective tissues will be nearing the end of their elastic limit, which increases the risk of injury, reducing the tensile strength of these components for some time after (dependant on the rate and extent of tissue deformation)
The contractile units of muscle tissue within the sarcomeres 9/10 times will be causing the ‘tightness’ firstly because they haven’t been adequately trained in such positions and because of this, the nervous system will be using nocioceptors and protective mechanisms not to allow the tissue any further - it’s unknown territory. The ONLY answer is to manipulate the nervous system. And that is certainly not achieved by pulling a limb until you feel a ‘stretch’
Some people, personal trainers or coaches will either accept this, and start a journey to understand and apply this science. Others will read this and disregard it as they don’t understand it, they will keep stretching, and keep prescribing stretches as a tool to improve ‘flexibility’. When people say ‘learn the basics’ or ‘the foundations of exercise’ this is what we as exercise professionals need to know. The ‘basics’ are far from basics. ‘Simple’ exercises are far from simple. The ‘foundations’ of exercise are massively misinterpreted by the masses.