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Working As A Unit – The Body’s Subsystems

When we experience pain, injury or stiffness we instinctively focus on that particular area or body part. The way we treat ourselves or manage this complaint then takes the same specific focus, targeting the painful or restricted area. This may help reduce any of the local trauma and be temporarily relieving. However, in order to fix any underlying dysfunctions that may be contributing to any pain, or stiffness we sometimes need to approach the body a series of “chains” or systems. These systems work together to allow efficient movement, and aren’t just independent muscles.

The Body’s Subsystems…

Five of the main subsystem identified in the health and fitness world are the Anterior Oblique Subsystem (AOS), Posterior Oblique Subsystem (POS), Lateral Subsystem (LS), Deep Longitudinal Subsystem (DLS), and the Intrinsic Stabilisation Subsystem (ISS). Each system offers a different function but they all need to be working effectively together to ensure the body is stable and moving properly. This then helps prevent injury or dysfunction.

Should any of the subsystems be not be functioning optimally it will have a debilitating effect on movement efficiency, joint function, and cause potential alterations in posture. If we can understand the function of these subsystems, and how they can affect our posture and movements then we may be able to rectify any dysfunctions, improve our posture, and maintain pain free function. This blog post will therefore discuss each of the five subsystems and provide an overview to help recognise common dysfunctions so we can address these systems in our daily training.

Anterior Oblique Subsystem…

The AOS consists of the External Obliques, Abdominal Fascia, and opposite side Adductors (National Association of Sports Medicine). Additional muscles have been considered part of this subsystem such as the Internal Obliques, and Rectus Abdominis (Brookbush Institute).

This subsystem stabilises the anterior or front chain and trunk during functional movements such as walking. It also helps transfer force between the lower and body, specifically integrating pushing and twisting movements. This system helps reduce any excessive or forceful rotation or extension through the trunk, anterior pelvic tilt or sacroiliac joint (SIJ) motion within the Lumbo-Pelvic Hip Complex (LPHC). The muscles of this subsystem achieve its function by actively lengthening or eccentrically contracting.

Common Dysfunctions…

This system can commonly be either overactive or underactive, which can contribute and present as a dysfunction in certain areas of the body.

…Overactivity of AOS…

The AOS can be overactive and can cause a dysfunction in the upper body. This may present as certain adaptations during an overhead squat assessment. Specific things to look for are and excessive forward lean of the torso, scapula winging, excessive internal rotation of the shoulder, increased curve of the upper back (thoracic kyphosis). It is common for an over-active AOS to be paired with and underactive POS which will be discussed later.

If these adaptations arise and you think your obliques, and adductors being overworked then you can approach this by reducing any core flexion exercises in your program i.e. crunches, and release shortened, tight structures associated with the dysfunction such as the pecs, and obviously adductors and obliques. You will also want to increase the activity of the POS which will be discussed later.

…Underactivity of AOS…

An underactive AOS can contribute to a dysfunction in the LPHC. This dysfunction will display an anterior pelvic tilt, and an excessive curve in the lumbar spine (lumbar lordosis) as a result of excessive extension coupled with no resistance or stabilisation from the AOS. This again is often paired with an underactive POS.
You can approach this underactivity of the AOS and pelvic tilt etc. by loosening the tight structures, usually the hip flexors and the erector spinae muscles in the lower back. You should also then activate the AOS by including the following into your program.

1. Cable Chop Patterns – to activate the AOS, squeeze glutes, legs stabilise and AOS resists the extension and rotation of the cables as you chop from high to low.

2. Ball Catch-Twist-Throw – sit on a yoga ball, have a partner throw you a medicine ball, catch the ball whilst maintaining stable, twist to one side then twist back throwing the ball back. Repeat on the other side.

3. Standing Cable Chest Press – this increases the workload for the anterior trunk and legs. Stand with cables behind so you have to resist their pull. Then perform your chest press keeping the trunk stable.

4. Step Up to Press – Step up, raise trailing leg knee to 90° (forcing single leg balance and stability), then press the arms without the trunk folding and becoming unstable.
• Progression 1: drop to one band resisting the rotation pull of the band. Hold band in opposite hand to lead step up leg. Look for a good reach and avoid leaning back and turning out with the band.
• Progression 2: start side on, lead leg nearest step. This starts you in a turned out position forcing AOS to activate to turn the body into the step up, press and stabilise.

Posterior Oblique Subsystem…

The POS consists of the Gluteus Maximus, the opposite Latissimus Dorsi, and the Thoraco-Lumbar Fascia. The Gluteus Medius has also been considered as part of the POS by Brookbush Institutes.

The role of the POS is to stabilise the posterior “chain” (Lumbar Spine and SIJ). It transfers forces between the lower and upper body, and in particular combines pulling and turning out movements as well as decelerating whole body turning in or face down (pronation). It also helps control spine flexion and rotation, and hip flexion, adduction and internal rotation.

This subsystem runs from the Glute Max diagonally across the SIJ into lumbar fascia and into the opposite Latissimus Dorsi. The POS plays a big part in asymmetric movements such as walking with one side decelerating and one side accelerating thus requiring high levels of stabilisation.

Common Dysfunctions…

…Underactivity of POS…

The POS is almost always underactive and often in combination with either an overactive or underactive AOS. This can then contribute to dysfunctions in the upper body or the LPHC as mentioned.
To approach an underactive POS we obviously need to activate the muscles of this subsystem (Glutes and Lat Dorsi). This can be done using the following examples.

1. Glute Bridge Progressions – focusing on a good squeeze of the glutes.

2. Cable Squat to Row – squat holding cable out in front, under tension, as you stand tall, stabilise the trunk and row the bands in. Resist the pull of the band and avoid forward lean or sway.
• Progression 1: progress to single arm row, maintaining stable trunk position minimalizing twist of the trunk.

3. Step Up to Row – This is similar to the AOS step up to press, but the press is substituted with a cable row. But again focus on keeping trunk stable.
• Progression 1: progress to single arm row, maintaining stable trunk position minimalizing twist of the trunk.

Deep Longitudinal Subsystem…

The structures of the DLS are the Sacrotuberous Ligament in the hip, the Biceps Femoris (one of the hamstrings), Tibialis Anterior, and Peroneals. Other muscles have been suggested as part of this subsystem such as the Erector Spinae, and Piriformis (Brookbush Institute).

The job of this subsystem is to stabilise the Lumbosacral Joint Complex as well as the Medial Arch of the foot. It also controls the lower leg and foot during walking. It helps decelerate the lower leg during the swing phase of walking. It also controls foot position when striking the floor during walking by controlling lifting of the toes (dorsiflexion) and controlling the tilt of the ankle (inversion-eversion).

It also helps with proprioceptive communication (sensory feedback) of forces between the foot, knee and hip complex during high intensity activities. Therefore it helps ensure good positioning, balance and alignment of the lower body joints thus preventing injury. However, if this system isn’t functioning optimally this may not be the case.

Common Dysfunction…

This system is almost always overactive meaning Biceps Femoris and Erector Spinae to become dominant. Individuals may then present with low back pain, hip pain and an alteration in functional movements such as squatting, running or jumping etc. This alteration is linked to an excessive pronation (rolling flat) of the foot during activities. The ability to dorsiflex (raise the foot) is also inefficient and places excessive force on the structures of the foot. You may also notice an inward buckling of the knees, thus putting the ankle, knee and hip out of alignment during movement.

As with all the other subsystem we approach this by releasing the tight structures of the overactive DLS such as the biceps femoris, erectors spinae, peroneals, and often the piriformis. This can be done by seeking manual therapy, foam rolling techniques or active stretching work. Isolated hamstring exercises should be avoided as this will further activate the already overactive structures.

POS activation exercises as described above should be added to help support this subsystem and reduce the responsibility place on the DLS. To activate the POS you should basically include any leg work (squats, step ups, lunges) with pulling movements (row).

Lateral Subsystem…

This LS consists of the Gluteus Medius, Adductors, and opposite Quadratus Lumborum. Other muscles are considered to be involved such as the Gluteus Minimus, and Tensor Fascia Latae (Brookbush Institue).

The role of the LS is to stabilise the LPHC in side to side movements, it also transferring forces between the lower and upper body. It plays a significant part in single-leg movements, ensuring optimal alignment of the hip, pelvis, SIJ, and lumbar spine during both double and single leg stance.

Common Dysfunctions…

This can be underactive on one side but the opposite side will compensate and become overactive. This can cause dysfunction in the SIJ, and lower leg function. You will notice a drop of the pelvis to the side of under-activity when standing on one leg. The standing thigh will also adduct, as well as some side flexion of the trunk. This will affect the alignment of the leg during single stance exercises and cause unnecessary forces will be placed on the structures of these joints.

Like the majority of dysfunctions in the other subsystems an underactivity of this system often pairs with an underactive POS and overactive DLS.

As discussed before tightness of the overactive muscles should be released. The common shortened muscles are the quadratus lumborum, and adductors. However muscles such as the gluteus medius can be underactive, and therefore the approach should be release the QL and adductors but activate the gluteus medius.

You can then include POS exercise as described earlier as well as single leg exercises with shoulder exercises such as:

1. Step up to single leg stabilisation then curl and press (keeping hips level and core engaged, avoiding side bend).

Also include glute medius activation:
2. Clams

3. Side Plank – but avoid dynamic side bending exercises.

Intrinsic Stabilisation Subsystem…

The ISS consists of the Tranversus Abdominis, Multifidus, Pelvic Floor, Diaphragm, and the Thoracolumbar Fascia. The Brookbush Institute considers the Internal Obliques as part of this system too.

Its role is to increase abdominal pressure, increase the stiffness of the spinal segments and SIJ, and stabilise the LPHC. The pressure created by pushes back on the vertebrae reducing any forward moevement that may be caused by excessive spine extension or over-activity of the QL, Latissimus Dorsi or Erector Spinae.

The Multifidi provide feedback to the central nervous system allowing continuous alteration of movement and postural, this helps with spinal alignment and stability during activity.

Common Dysfunctions…

Like the POS this subsystem is almost always underactive which leaves us prone to disc herniation (slipped disc), sprains and strains of the spine, as well as LPHC and SIJ dysfunction. It will also affect posture, and stability of the trunk, spine and core during activity. Its ability to withstand sudden position or postural changes, or impacts to the body, this leaves us at risk of injury.

To approach this system the muscles need activating. They are only small muscle groups so there isn’t a huge amount of movement but the following exercises can be introduced to any warm up before training.

1. Draw belly button to the floor in lying position, this can be done by “squeezing the anus” (transversus abdominis activation)

2. Kneeling “superman” exercises – ensure the transversus abdominis is activated throughout.

3. Explosive Moutain Climbers – do these explosively keeping trunk straight and stiff.

Overview of Subsystems and Dysfunctions…

Below is a table of which systems are usually underactive or overactive in certain dysfunctions. Along with the discussion above this may help you approach how to deal with any issues you have and what to include and take out of your training.

Upper Body DysfunctionUnderactiveUnderactiveOveractiveOveractive
LPHC DysfunctionUnderactiveUnderactiveUnderactiveOveractive
SIJ DysfunctionUnderactiveUnderactiveUnderactive on affected side
Overactive on opposite side
Underactive on affected side
Overactive on opposite side
Lower Leg DysfunctionUnderactiveUnderactiveOveractive

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