I have been giving a lot of thought about how to approach the subject of the science behind stretching and flexibility. There is a whole wealth of information readily available on the subject of stretching and flexibility but it can be way too saturated and weighed down at times with information that athletes and coaches don’t really need to know about. At the end of the day all you guys want to know is how to get more flexible as quickly as possible!
As mentioned in a previous article static, active and dynamic forms of flexibility are all elements which are important to a Taekwondo athlete. A great example of this is the dollyo chagi or turning kick where the muscles of the supporting leg are stretched statically whilst the muscles of the kicking leg are rotated dynamically and actively held. The whole goal is to increase the Range Of Motion (ROM) within the body – to kick people in head!
So what exactly happens when we stretch?
Again there is a lot of information about this out there but a lot of articles and texts contain too much scientific information about “Huxley’s sliding filament theory”, “macro/micro structural muscle processes” and “central nervous system anatomy”.
Now as a coach it is important to have at least a basic knowledge of these processes to appreciate the mechanics of physiological actions but you don’t need to be a professor in sport science to understand whether or not the training methods you are using are effective or not.
If you really want to delve deeper into the world of Taekwondo Stretching one of the best texts to read is ‘Science of Flexibility’ by Michael J. Alter which is an excellent source of the most up to date research in the field and is regarded by many in the academic world as the ‘bible’ of flexibility studies.
To understand how muscles are stretched we need to know how a muscle is made up.
At a very basic level muscles are made up of two parts: the muscle belly and the tendon. The muscle belly is made up of muscle fibres. There are two kinds of muscle fibres: intrafusal muscle fibres and extrafusal muscle fibres. Extrafusil fibres are the ones that contain myofibrils. Intrafusal fibres are also called muscle spindles and lie parallel to the extrafusal fibres. The tendon is made of collagen fibres and is the section of the muscle which attaches it to the bone.
Proprioceptors are special sensory receptors located within muscles, joints and tendons which are sensitive to pressure and tension and relay information to the central nervous system (CNS) via sensory and motor neurons.
As mentioned already, intrafusal muscle fibres or muscle spindles are proprioceptors which provide information about muscle length. Golgi tendon organs (GTO) are proprioceptors which are located within the tendon and are activated when muscle tension increases.
During a rapid stretching movement (i.e. ballistic/‘bouncing’) the sensory neuron is activated by the muscle spindles and sent to the CNS which in turn activates a motor neuron. The motor neuron then activates the extrafusal muscle fibres which in turn contract stopping a stretching action. This is known as the Stretch Reflex.
When a muscle actively contracts (i.e. it’s tensed) the GTO is stimulated in turn causing a relaxation of the contracted muscle. This is the underlying principle behind Proprioceptive Neuromuscular Facilitation where the muscle is contracted then relaxed and passively stretched. This is known as the Lengthening Reaction.
Relaxation can also occur in the muscle opposing the muscle experiencing the tension. This is known as Reciprocal Inhibition where you contract one muscle to relax another.
To conclude, by having an understanding of how the muscles react to stretching you can stretch more effectively. By isolating the activation of the stretch reflex and by understanding how to activate the Golgi Tendon Organ will allow greater relaxation of the muscle to be stretched.
I hope this has helped to give a better idea behind the very basic science of how a muscle is stretched. Greater understanding of this will allow you to be more effective in your training. Future articles and videos will cover techniques that use these processes to greater increase your ROM (ie kicking them in the head!).
Let me know what you think of this article in the comments box below. And as always, let me know any Taekwondo Stetching or Flexibility questions you have, and I’ll answer them for you. 🙂