The Core

Welcome to another insightful edition of Gold Coast Physiotherapy's blog. This month we wanted to dedicate our blog to the foundation for healthy movement in our bodies – the core. Often misunderstood and underestimated, the core plays a crucial role in every movement we make, from simple tasks like bending over to pick up a pen to more complex athletic endeavours like running or lifting weights. Understanding how to properly activate your core before any activity can not only improve performance but also prevent injuries. So, let’s take a look at what the core is, what it does, how to activate it and some of the key exercises we use to engage the core.

The Core: Your Body's Foundation

When we talk about the core, we're not talking about the six-pack abs you see on fitness magazines. The core is considered the dynamic yet harmonious activation of the deepest muscles surrounding our spines. We are referring to 3 key muscles, the diaphragm, the transverse abdominis, the pelvic floor muscles. These muscles work together to provide stability, support, and control for the spine and pelvis, allowing for efficient movement and force transmission throughout the body. In fact, when we have a healthy spine, these muscles switch on simultaneously and prior to movement, in preparation of the forces to come to support our spine. Early researchers found that in healthy populations the individual elements of the core spontaneously co-activate in advance of limb movement: transversus abdominis (Hodges and Richardson, 1996, 1997); the diaphragm (Hodges et al., 1997; Hodges and Gandevia, 2000), the pelvic floor (Hodges et al., 2007; Smith et al., 2007). Yet, in chronic low back pain and chronic pelvic girdle pain, the pre-activation response of all these muscles has been shown to be delayed and/or diminished during movement (Hungerford et al., 2003; O’Sullivan et al., 2002).

The Airbag Analogy

Think of your core muscles like an airbag in your car. Just as airbags provide support and protection in the event of a collision, your core muscles act as a natural "inner shock absorber," supporting and protecting your spine during movement. Our core does this by generating pressure. When our 3 core muscles contract, their direct line of pull is inward towards the centre of the abdomen. So, when they contract together, they create this pressure in the abdominal cavity which we call intra-abdominal pressure (IAP).

The diaphragm acts as the roof of the airbag while the pelvic floor muscles form the base, and the transverse abdominis wraps around the sides like the walls of the airbag. This pressure forms the strong and stable foundation for our spine. IAP is generated when the diaphragm descends creating a simultaneous reflex co-activation of the transversus abdominis and the pelvic floor muscles. This positive intra-abdominal pressure is an automatic, anticipatory or ‘pre- movement’ stabilizing response which acts like an inflated balloon providing internal ‘pneumatic support’ for the spine and pelvis. The pneumatic pressure pushes into the spine to straighten and decompress the spinal structures as well as improve tension of the supporting spinal tissues. This has been well documented in studies from the 1950’s onwards (Bartelink, (1957); Tesh et al. (1987); Hodges et al., (2001)).

Figure 1 - Core activation

The white arrows demonstrate the forces from the diaphragm, pelvic floor and transverse abdominus within the abdominal cavity in creating IAP. Whilst the orange arrows are demonstarting the affect on the spinal structures. An optimal intra-abdominal pressure which occurs with dynamic synchronicity of the core muscles (all done during movement/and breathing) has a corresponding affect on the spine is that of straightening, elongation and decompression. It is important to note that there is a fine balance to optimally contact the core not too much, not too little. See below sections for full explaination on how to optimally contact your core.

Injury and the Core

When we sustain a back injury / have back pain the strength and speed of contraction of the core muscles can be significantly reduced (Biały et al. 2019). Meaning that the more superficial muscles (rectus abdominus and obliques) are then able to exert more force on our unsupported / non-air bagged spine. Contrary to popular belief, chronic low back pain sufferers move their spines less (Mok et al., 2007) as they move with excess muscle tension and effort due to poor core muscle capacity to create IAP and therefore support the spine during movement (Key, 2013).

Activating Your Core: Key Cues

Now that we understand the importance of core activation, let's explore some key cues to help you engage these muscles effectively. These are the ones our therapist will commonly use:

Diaphragm:

"Breathe into your belly"

Simply focus on expanding your abdomen as you inhale deeply, allowing your diaphragm to descend and create space for your lungs to fill with air. You should feel some pressure build in your tummy. Then exhale slowly, allowing your belly to naturally relax. Practice this technique regularly for 3-5 minutes of slow and normal sized breathing to strengthen your diaphragm.

Pelvic Floor:

“Imagine stopping the flow of urine midstream” or “lifting an elevator up from the ground floor to the first floor”

This subtle lifting sensation engages your pelvic floor muscles, providing a solid foundation for core activation. Hold for 5 seconds and relax for 5 seconds is a good routine to practice for 1-2 minutes at a time.

Transverse Abdominus:

"Draw your belly button towards your spine" or “imagine you are wearing a waist belt, now draw the belt up towards your belly button and in towards your spine”

Imagine gently pulling your belly button inward towards your spine without holding your breath or tensing other muscles excessively. Practice holding for 5 seconds and relaxing for 5 seconds for 1-2 minutes at a time regularly to build the transversus muscles endurance.

To optimally activate our core begin with regularly activating these 3 muscles as individuals whilst laying down on your back. When you are confident you can contact them individually, begin practicing all 3 simultaneously to effectively engage your core. These 3 muscles working in harmony will effectively create intra-abdominal pressure and thereby support your spine. To optimally contact your core, have your hands wrapped around the narrowest part of your waist, thumbs at the back and fingers around front. Aim to create a smooth 30-40% effort of all three of the core muscles whilst diaphragm breathing into your abdominal cavity (see more on our previous blog The Power of Breath). You will know you are doing this right when you feel your fingers and thumbs expand away from the midline whilst feeling tension of the muscles under your fingers increase with your inhale. Feel a sense of elongation and ease in teh tension of your low-mid back is another sign you are doing it well. This is core breathing and is the optimal beathing pattern when we are doing most (not all) forms of physical activity.

Core Exercises for Back Pain

When we are dealing with back pain, it's essential to start with gentle yet effective exercises to activate and strengthen the core muscles. Here are three of our favourite exercises which we use commonly at Gold Coast Physiotherapy in the early stages of back pain recovery.

McGill's Crunch

Lie on your back with one knee bent and the other leg straight. Place your hands under the arch of your lower back for support. Gently lift your head and shoulders off the ground, focusing on engaging your core muscles while keeping your spine in a neutral position. Hold for 10 seconds, then lower back down with control. If you can tolerate do on both sides.

Side Plank

Lie on your side with your elbow directly beneath your shoulder and your legs stacked on top of each other. Lift your hips off the ground, creating a straight line from your head to your heels. Engage your core and hold for 20-30 seconds, then switch sides. Starting with a knees side plank first may be a good idea if you have significant and acute back pain.

Bird Dog

Start on your hands and knees with your wrists directly beneath your shoulders and your knees beneath your hips. Extend one arm forward and the opposite leg back while keeping your core engaged and your spine neutral. Hold for a few seconds, then return to the starting position and switch sides. Try to keep your back from moving during this exercise - feel your abdominals trying to help you achieve this.

Research has shown us that these exercises strongly activate the core muscles without significant forces on the spine compared to conventional core exercises. Incorporate these exercises into your daily routine to build a strong and resilient core and remember to focus on proper form and alignment to maximize effectiveness and prevent injury.

To Summarise

The core is the foundation of every movement we make, and learning how to activate and strengthen it properly is essential for optimal performance and injury prevention. By understanding the synergy between the diaphragm, pelvic floor, and transverse abdominis muscles and incorporating key cues and exercises into your routine, you can tap into the full potential of your core and take your fitness and function to the next level. So, take a deep breath, engage your core, and enjoy moving towards a stronger, healthier you!

References

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Hodges, P.W., & Richardson, C.A. (1997). Feedforward contraction of transversus abdominis is not influenced by direction of arm movement. Experimental Brain Research. 114 (2), 362- 370.

https://pubmed.ncbi.nlm.nih.gov/9166925/

Hodges, P.W., Butler, J.E., McKenzie, D.K., & Gandevia, S.C. (1997). Contraction of the human diaphragm during rapid postural adjustments. Journal of Physiology. 505(2), 539-548.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1160083/

Hodges, P.W., Heijnen, I., & Gandevia, S.C. (2001). Postural activity of the diaphragm is reduced in humans when respiratory demand increases. Journal of Physiology. 15, 999-1008.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2278995/

Hodges, P.W., Sapsford, R., Pengel, L.H.M., (2007). Postural and respiratory functions of the pelvic floor muscles. Neurourology and Urodynamics. 26 (3), 362e371. https://pubmed.ncbi.nlm.nih.gov/17304528/

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https://pubmed.ncbi.nlm.nih.gov/17139463/

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https://pubmed.ncbi.nlm.nih.gov/12865851/

O’Sullivan, P.B., Beales, D.J., Beetham, J.A., Cripps, J., Graf, F., Lin, I., Tucker, B., Avery, A., (2002). Altered motor control strategies in subjects with sacroiliac joint pain during active straight leg raise test. Spine 27 (1), E1eE8.

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Bialy, M., Adamczyk, W.M., Marczykowski, P., Rafał Majchrzak & Rafał Gnat (2019). Deformations of abdominal muscles under experimentally induced low back pain. European Spine Journal 28, 2444–2451.

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Hodges, P.W., Cresswell, A.G., Daggfeldt, K., Thorstensson, A., 2001b. In vivo measurement of the effect of intra-abdominal pressure on the human spine. Journal of Biomechanics. 34 (3), 347e353.

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Key J. (2013). ‘The core’: Understanding it and retraining its dysfunction. The Journal of Body Works and Movement Therapies. Volume 17. 541-559.

http://dx.doi.org/10.1016/j.jbmt.2013.03.012