Core Stability -What? Why? & How? by Amy Dolan

Everyone who has set foot inside a gym in the last 5 years will have heard the term 'core stability' wafted about the place, but not many people really know what it is, why they should be doing it and what the best way to do it is. This article should clear all that up for you with an in depth look into the science behind core stability training.

Core Muscles
In the body there are 2 different types of skeletal muscles - mobilisers and stabilisers. Mobilisers are task-oriented muscles that act on demand to facilitate movement, in the abdominals these would be your rectus abdominis (6 pack) and external obliques (love handles!). The stabilisers support your posture and protect your lower back, in the abdominals the transversus abdominis (TVA) and the internal obliques act as the body's major stabilisers as they are the only muscles with attachments to both the lumbar spine and front of the trunk. These stabilising muscles (along with some others) are the deepest muscles of the trunk, the ones you can't really see or feel thus making it harder to successfully strengthen them. At beginners level, core stability training should focus on isolating these deep muscles, but in order to provide good, functional core stability under increased load, all the muscles of the trunk need to work together, so your training should progress to mirror this.

Why are core muscles important?
The human spine, without any muscles, can only withstand a load of 1-2kg before it buckles, thus it is the core muscles that provide the stability needed to resist the loads applied to the spine and pelvis during everyday life, sport and physical activity. The TVA, which is like a deep corset wrapping around your trunk, has been highlighted in many research studies as the key muscle involved in core stability, it has been shown to contract in preparation of limb movement (i.e. if you lift your arm your TVA will activate before the arm/shoulder muscles) to protect the spine and provide a stable base for limb movement. You could liken this to tube surfing (I know you've tried it!) if you tried to ride the tube standing on one leg you'd be sure to fall over, but take a nice wide stance at the right angle giving yourself a sturdy base and you're home and dry! Core stability training is essential for improved efficiency of movement, power, endurance, technique, performance and reduced risk of injury.

Why do core muscles become 'weak'?
Much of the strength/function of the core muscles is controlled by the neural system, messages are sent from the joints of the spine to the muscles about position and direction of movement, these messages need to be relayed quickly and accurately in order for adequate core stability to be maintained. When this neural system is malfunctioning, compensatory movement patterns occur which override the normal timing of muscle activation, allowing the stronger mobiliser muscles to take over. The more this occurs, the more the stabilising muscles will switch off and fail to do their job properly.

Spending long periods of time sitting with the spine in flexion (slouching) is the main reason so many people have weak core muscles these days, just by trying to sit upright with a 'neutral' position (gentle arch) in the lower back you will already be working your core more than you otherwise would.

Core muscles and low back pain (LBP)
In people with LBP the activation of TVA tends to be delayed thus the neuromuscular control of the lumbar spine is dysfunctional and the low back is not being supported effectively. This results in greater forces being applied to the discs, joints and ligaments of the low back resulting in pain, inflammation and in some cases serious injury. This leads to a bit of a vicious circle as inflammation in the area further interferes with the messages trying to get through to the core muscles inhibiting muscle activation. During these periods of pain and inflammation the mobilser muscles increase activity (muscle spasm) to protect the area, but you are left with faulty muscle recruitment patterns and stiffness. Specific core isolation training is required to break the cycle and get the neuromusclar system functioning correctly.

Is core stability training only important for those with LBP/bad posture?
NO, core stability training is beneficial for anybody and everybody who wants to prevent injury, maintain a healthy back, have their body functioning efficiently, and improve athletic performance. In elite swimmers for example, one study found a 10% increase in efficiency following a core stability training programme (Hines E, 1999); in cycling a strong core will help increase power output; and in runners good core stability will massively improve efficiency and help you preserve energy. If the core muscles are functioning well it leaves the mobilisers free to perform the powerful movements needed in sport rather than wasting energy trying to stabilise the trunk and hips, thus avoiding premature fatigue.

What is the best way to improve core stability?
Core stability training should be functional to your sport or daily activities and incorporate both isolation exercises of the core stabilisers (local muslces) and co-contraction of the local and global (mobiliser) muscles. However all core stability training programmes should begin with isolation exercises to improve your body awareness as to where your core muscles lie; and the ease at which you can engage them. Remember you are trying to break faulty muscle recruitment patterns so you need to 'teach' the core muscles to engage first, this can only be achieved when you become accomplished in isolating your core. Here's how:
These exercises can be done in any position (standing, lying, sitting) but we're going to start kneeling on all 4's

1. Kneel on all 4's with your hands directly under your shoulders and knees directly under your hips.
2. Tilt your pelvis under (tucking your bottom in) so that your low back rounds, then tilt it the other way (sticking your bottom out) so that your low back arches, you can do this several times to get used to the movement.
3. To find a 'neutral' position you need to work out where the mid point is between the two ranges of movement and then keep your pelvis still.
4. Check that when you are in the neutral position you have a very gentle curvature in your low back and the spine is not completely flat.
5. To engage your TVA (corset muscle), take a breath in to prepare, then as you exhale slowly pull your belly button in towards your spine but do not allow your pelvis to tilt or your back to flatten.
6. Breathe in and let your belly hang out again, repeat this 10 times, exhaling to flatten your tummy, breathing in to let it out. Engaging your core is really easy in this position as you're working against gravity you can get a really good sense of the 'hollowing method' we're looking for.
7. Then try exhaling to engage your core and keep it held in while you continue to breathe, try to avoid breathing into your belly and use the sides of your ribcage instead. Always watch out for the position your spine is sitting in, you will more than likely find it starts to flatten over time so try to keep that slight dip in the low back.

Once you've mastered this technique try applying it in everyday life, sitting at work, standing, when doing sport and physical activities, the more messages you send to your core muscles to engage the more they will automatically kick in without you even thinking about it.

To progress your core stability training you need to start adding load to the trunk and pelvis to challenge your core muscles to maintain stability, this should be progressive and always be done under control making sure that the local muscles are not giving up and letting the global muscles dominate. This type of training can be achieved with Pilates which has a great many other benefits such as increased flexibility, mobility and balance; or in the gym using swiss balls, body weight exercises and cables, which is great for sports specific core training.

Summary
The core muscles play a vital role in protecting your back, preventing injury and improving economy of movement. Specific core stability training will help balance out the negative effects of desk bound jobs, improve posture, biomechanics and athletic performance. Training should encorporate both local isolation exercises and more dynamic, activity/sports specific exercises for optimal results.


References

Hines E (1999) Fitness Swimming

Ransburg A V (2008), 'Why Core Training Works' Sports Injury Bulletin 79

Richardson C, Hoges P, Hides J (2004) Therapeutic Exercise for Lumbopelvic Stabilisation: Elsevier Health