Trunk Training


If you think of a tree (our body) and its branches (our limbs), in order for the branches to withstand mother nature and all her elements (everyday tasks, sporting movements, walking/running etc.), the tree trunk needs to remain stable. In this instance, a ‘bulletproof core’ is required, as is required by the human body when performing and executing everyday tasks and sporting movements such as; walking, lifting objects, running, weightlifting movements etc. But, what is the core? Where is it located? and how do we improve the stability of our core to reduce the risk of injury and provide the foundations to express force when executing subsequent movement tasks or sport specific movements .

The remainder of this blog will expand on and address the topic of core stability, drawing on its importance during movement tasks, concluding with appropriate exercises and strategies to address any core issues you or your athletes may be experiencing. My aim is to provide a systematic breakdown of the roles and responsibilities of the relevant structures within the body when it comes to core stability, and how underlying issues can be rectified through sound planning/programmeming. Additionally, throughout I’ll briefly discuss other modalities that can be used or implemented into a holistic programme aimed at either improving sport performance, reducing injury risk or simply unlocking ones athletic potential.

Core Stability and its Importance

The core is located more or less in the centre of the body and comprises of the structures that surround the spine, that create a corset-like stabilisation effect on the trunk and spine . These structures include the lumbar spine, the muscles of the abdominal wall; located on the front (anterior) and the sides (lateral), the back extensors and quadratus lumborum. Also included are the multijoint muscles, namely, the latissimus dorsi and psoas that pass through the core, linking it to the shoulders, arms, pelvis and legs. Lastly, due to their anatomical and biomechanical synergy with the pelvis, the gluteal muscle group can also be considered in this group, as they play an integral role in maintaining hip position during movement (Image 1) . Each and every one of the aforementioned muscles/muscle groups along with others must work in synergy to enhance the stability of the spine during movement to prevent injury while maximising the opportunity to express forces through various athletic positions and movements (sprinting, jumping, weightlifting, changing direction etc) as well as everyday tasks.

Now that we’ve painted a picture in regards to the core; its location and relevant anatomy. It’s important to discuss its function as the musculature of the core work differently to the musculature of the limbs in the sense that the core muscles often co-contract, stiffening the torso such that all muscles become synergists. It is the stiffness part that is important for maintaining postural integrity during movement. To give you some examples, If we take the back squat; we need to produce stiffness around the spine to protect it from the compressive and shear forces experienced during the execution of movement. If we fail to do so, we will not only leak forces and become weak in certain positions, but, it could lead to detriments in performance and increase the risk of sustaining an acute injury or developing more degenerative type injuries overtime .

Furthermore, if we take sprinting as another example, the body functions as a linked system whereby distal movement through the extremities requires proximal stiffness and subsequent force production . The majority of the force required during sprinting comes from a powerful hip extension, upon the foot making contact with the ground right up to the point in which the foot leaves the ground again. The proximal stiffness and force produced during this hip extension travels distally through the lower extremities into the ground which results in the horizontal or forward propulsion of the body . It is integral that during this movement there is enough stiffness created around the core and hips to create the stability for force production through the hip extension, but, also to reduce the risk of sustaining injuries to the surrounding structures. Moreover, an inability to maximise force production or maintain a stable position may not solely be down to an inability to create stiffness through the core, but inefficiencies elsewhere…

Pelvic tilt

One common inefficiency found in individuals, is the inability to maintain a neutral hip position which could be due to pelvic tilt; described as “the orientation of the pelvis in respect to the thighbone and the rest of the body” (Image 2). This inability to maintain a neutral hip position during movement can lead to poor movement patterns and subsequent lower back pain and/or disorders overtime . As a practitioner, pelvic tilt is an important area that must be understood and considered when addressing the topic of neutral hip position and core stability, and can be broken down into three categories;

Anterior pelvic tilt: When the front of the pelvis drops in relation to the back of the pelvis

Posterior pelvic tilt: The opposite, when the front of the pelvis rises and the back of the pelvis drops

Lateral pelvic tilt: Tilting either right or left. left pelvic tilt is when the right side of the pelvis is elevated higher than the left and vice versa.

If you’re someone, or work with an individual who possesses one of the above, you may experience discomfort or pain through movement particularly in the lower back, or find it difficult to get into certain positions, let alone express forces through these positions. This could be a result of other underlying issues that could be addressed through the implementation of additional modalities such as; the integration of corrective exercises, foam rolling, mobility exercises and/or addressing movement patterns, all prior to or in conjunction with appropriate core stability/strengthening exercises that have clear and purposeful progressions/regressions (Image 3).

With all this in mind, at this stage I feel it’s prudent to highlight the importance of adopting a holistic approach to your programmeming and exercise prescription. At the end of the day, if all you have is a hammer, then everything will begin to look like a nail, and with limited tools, a single-minded approach, you could be limiting yours or your athletes potential, and exposing yourself or others to an environment that could result in injury and subsequent detriments in performance. This brief summary leads nicely into the final section of this blog; practical application and addressing potential underlying issues.

Practical Application

It is important now, to take a step back and identify any underlying issues that could be causing either you or your athlete pain during movement, limited range of movement or the inability to maintain a neutral hip position during specific movements . As advised in the literature, a ‘staged process’ should be adopted; 1. Implementation of corrective and therapeutic exercises 2. Engraining appropriate movement patterns 3. Building whole-body and joint stability (hips, lumbar and the core region in particular when referring to the topic of this blog) 4. Increasing work capacity (“Sometimes Less is More” blog) 5. Develop strength qualities through various ranges (isometric, eccentric and concentric contractions) 6. Finally, develop speed, power and agility through more sport-specific movements . But, with the focus of this blog being around core stability, I will use this final section to discuss and explore the ‘McGill Big 3’ and how it can be implemented into a training programme or specific session as part of a warm up, or corrective/supplementary batch of exercises, to help you or your athlete address underlying issues or simply unlock yours your athletes athletic potential.

Before we dive into the McGill Big 3, it is now clear that you or your athlete should be using or integrating relevant mobility and/or corrective exercises aimed at addressing any underlying issues you may be experiencing. Reason being; if you were to only perform core stability/strengthening exercises and are not resolving any significant mobility restrictions in the joints above or below the lumbar spine for example, the stiffness you do create will always be short-lived, not to mention that strength without control, endurance and perfect form increases risk of injury or re-injury . The McGill big 3 have been quantified and selected for their ability to ensure sufficient spine stability and optimal motor patterns; they spare the spine of many injury mechanisms and are designed to build stability and muscular endurance. Spine stability requires that the musculature be co-contracted for substantial durations but at relatively low levels of contraction (isometric in nature, whereby, force is produced with no movement over a joint or joints) . The nature of the McGill Big 3 align with this requirement, and are an excellent choice for addressing weak links in stability, while placing minimal forces on the spine . Lastly, it’s important to note that there is no one universal movement that equally stresses all of the muscles that surround the spine, hence the utilisation of all three exercises in the McGill big 3 efficiently works all the relevant musculature .

The Big Three

Curl – Up

This first exercise targets the musculature of the abdominal wall, located on the front (anterior) and the sides (lateral) of the body. The primary function of this muscle group is anti-extension, whereby they actively resist extension through the spine;

Lie on your back with one knee bent (inside of foot parallel to the opposite knee).

Head on the floor, with both hands underneath the lower back (to ensure a neutral slightly arched position is present).

“Chest to the sky” – bring your head and chest towards the sky and pause for ten seconds, the aim is to perform this movement without any movement in the lower back.

It’s important to note here that a common error seen during this movement is individuals trying to perform a ‘crunch’ movement. This causes the lower back to round and excessive forces will be experienced through that region, therefore, practitioners need to be extra vigilant when incorporating this exercise into their training plans for their respective athletes.

Side Plank

After addressing the anterior core muscles, the side plank is used to target the lateral muscles; the internal/external obliques and the quadratus lumborum, whose function is anti-flexion, whereby they actively resist side flexion or bending of the spine;

Lay on your side, with your legs knees bent and your upper body supported through your elbow, placing your free hand on your opposite chest or shoulder.

Raise your hips so that only the bottom knee and arm are supporting your body.

Keep your body/ in a straight line, and try to prevent your hips from dropping.


When compared to the other two exercises, the bird-dog has a little more movement in regard to its extremities, however the aim of maintaining a neutral hip position and a stable core during movement is still ever present. This exercise targets the muscles of the posterior chain namely the back extensors whose function is anti-flexion, whereby they actively resist flexion through the spine – quite the opposite of the anti-extensors used during the curl-up.

Assume an ‘all four’s’ position, with the spine in a neutral position (slight arch, not completely flat).

Without allowing any movement to occur in the lower back, extend one leg back through the hip while.

As you extend one leg, simultaneously extend the opposite arm out in front of you, until both extremities are fully extended and hold.

Finally, in regards to rep schemes for the big 3, Dr. McGill advocates for using a descending pyramid rep scheme with 10-second isometric holds, in order to enhance stability without fatiguing and over- working the body. E.g. five reps, then three and so on (each with a 8-10 second hold). With 20-30 seconds rest between each set – As this rep schemes becomes easier, it is advised to increase the number of repetitions rather than the duration of the isometric holds, in order to build endurance . If you’re new to training or your athlete has a young training age, the big 3 are an excellent addition to a session, whereas, with more advanced lifters or athletes the use of the big 3 at the latter stages of a warm up are equally as advantageous .


In summary, the core musculature and its function in maintaining neutral spine alignment, optimal trunk position (eliminating pelvic tilt), and the transfer of loads along the kinetic chain (everyday tasks and sport-specific movements) are integral and shouldn’t be overlooked. The integration of the relevant core stability exercises (McGill big 3) within a holistic programme, are proven to be advantageous, however, they have their place among other modalities (mobility, corrective exercises, muscular endurance etc.) that should be integrated where suited based on yours or your individual needs. Like all training, foundations need to be laid and everyone needs to ‘earn the right’ before progression is introduced.

Remember; “If your only tool is a hammer, everything will begin to look like a nail”. Richard Walters

Written by

Richard Walters


1. Bliven, K. C. H., Anderson, B. E. (2013) Core Stability Training for Injury Prevention. Sport Health 5(6): 514-522.

2. Horschig, A 2018, The Mcgill Big 3 for Core Stability, viewed 19 July 2020, <>

3. Panjabi, M.M. (1992) The Stabilising System of the Spine. Part II. Neutral Zone and Instability Hypothesis. Journal of Spinal Discord. 5: 390-396

4. McGill, S.M. (2010) Core Training: Evidence Translating to Better Performance and Injury Prevention. Strength and Conditioning Journal 32(3): 33-46

5. McGill, S.M. (2009) Ultimate Back Fitness and Performance (4th ed). Waterloo, Canada: Backfitpro Inc. pp. 84-86

6. McGill, S.M. (2009) Ultimate Back Fitness and Performance (4th ed). Waterloo, Canada: Backfitpro Inc. pp. 112-113, 188-197

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