Friday, 29 May 2020

Core stability

What comes to mind when you think about core stability? For many, it conjures up strength and being able to hold the plank forever, and certainly strength is a useful aspect of core stability that provides endurance. However, it is helpful to consider function: what does core stability give us, why would we want it?  

I would like you to consider core stability as responsive and adaptive. Many muscles and other connective tissues work together with our nervous system to absorb forces, recover and adapt, so that we can maintain our trunk where we need it to be; providing a connection between our head, arms and legs. Like a spring, this works with movement, dampening forces rather than just blocking. 

The core muscles are found in our trunk and provide the connection between our legs and arms. When I hit a tennis ball, reach for a saucepan or use a fork to stir the compost pile, I am powering from the feet and legs as well as the shoulders and a steady, responsive trunk provides a stable and adaptive platform to transmit that power. You can feel this connection for yourself when you do push ups against a wall. If you let your trunk collapse, you lose both power and control. However, if we concentrate on bracing the trunk we lose an important aspect of core stability: the ability to note and respond rapidly to challenges such as a push or pull.  

Stability is adaptive and responsive. If you think about everyday life, would it be helpful to walk about braced, as if your body is a suit of armour? How would it affect your ability to react to someone throwing a ball at you, or if you slipped on mud? The trunk is most resilient to challenges when it uses a range of mechanisms. At the foundation of core stability are the local stabilisers: postural muscles such as the diaphragm, the transversus abdominus and the multifidus. These work continuously to stabilise the joint that they cross: before, during and after an action that other muscles such as global stabilisers and prime movers are providing the power for. Through nervous system training, these local muscles activate before we even need them, anticipating the perturbation that is about to happen. This is why we need to practice activities until we can focus on what we want to achieve rather than micromanaging how we are going to do the movement. Our core stability kicks in without us even having to think about it – although if we see a huge impact coming our way we may consciously brace a bit more. This is fine if we release again afterwards, but if we are always consciously holding ourselves the global muscles that are activated can override the local stabilisers and we lose the fine control that those local muscles provide. Rather than thinking on/off, it is helpful to think of the core muscles continuously monitoring the situation (via the nervous system) at low effort and making small adjustments. 

People with back pain are often concerned with improving their core stability. Investigations have found that they are often protectively activating muscles to protect their spine, which is a natural reaction. This corset like activation has the effect of limiting movement which has the counterproductive effect of putting more stress on a limited area instead of sharing the load by involving more of the body in the movement. You can try this out for yourself by comparing reaching your arm up for something first with your back and abdomen tensed up; then with your torso relaxed feel the ground with your feet and let the movement come from there. Your foot provides neuromuscular feedback that helps the core muscles to engage and react appropriately to stabilise you, your torso is able to lengthen and the effort is shared. Now repeat tensing/relaxing but this time seeing how it affects turning your torso; it should feel much easier when you keep relaxed and allow the movement to initiate from your feet and feel that connection through the body. 

Pain, even anticipated, and injury can cause the postural muscles to switch off, and to remain switched off even once you have recovered. In these cases, it is beneficial to explore movement in a safe, relaxed way that helps the neuromuscular system to engage again and to let go of the protective tension. Again, think of the postural stability muscles as springs, that bring you back to where you need to be. If the feedback system is not performing optimally, then there will be a loss in anticipation, adaption and recovery – in other words, stability - that will be further exacerbated by protective tensing. 

Developing resilient core stability involves vestibular, visual and sensory feedback as well as that from the muscle spindles and joints. Often the best way to train this is through varied challenges, as we want to be able to maintain stability through a variety of situations that are often unpredictable. The correct level of challenge will depend on your starting point, but examples could include: keeping your balance sitting on a swiss ball or standing on a wobble board whilst catching and throwing a ball; keeping your balance on both or one leg: with your eyes shut, or whilst moving your arms around, or maybe whilst performing lunges, or whilst someone pulls you gently in different directions using a band around your waist. You can explore different ways of engaging with the activity and see what feels most efficient and easy; notice what is happening with your body and what it is feeling. You will be generating feedback that will improve your anticipation and response, and hence your stability resilience. You will be helping the local postural muscles to activate so that you get smooth control and support; without those, no matter how strong you get the movement will lack that solid foundation and precision. If you are doing core muscle exercises such as the kneeling superman, please do ensure that you are not tensing and overusing your back muscles - as before, if you can feel two mountain ridges appearing either side of your spine that has itself disappeared into the valley, you are overusing your back. Instead, think of lengthening through the body, pressing out through the crown of your head (your face should be looking down so that your neck is aligned with your spine) and the heel of your foot; continue that lengthening sensation through your leg and arm as they extend away from each other in alignment with your spine. Some videos will instruct you to tense your gluts and abdominals before moving; maybe experiment with doing this, then release and experiment with the strategies I have discussed above and explore how it feels. 

Part of moving well is developing a range of options that your body, including nervous system, can choose from. Selecting only strength limits our potential. We need responsiveness, adaptability, endurance and robustness. 

You can read more about this, including useful exercises to explore, on the JEMS blog page:
For instance, the post on (not) all about the gluts; golf swing, skiing and dancing the tango; posts about the foot - all so useful even if you never play golf, ski or go dancing!

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