Muscle Of The Month – The Deep Longitudinal Subsystem

The Deep Longitudinal Subsystem is one of four common muscle synergies used by the body during exercise and other movement.

Stretching down the back and legs, it’s a combination of muscle groups, membranes and ligaments, including the erector spinae, thoracolumbar fascia, sacrotuberous ligament, bicep femoris.

The origination and insertion of the Deep Longitudinal Subsystem

As a major muscle synergy, the Deep Longitudinal Subsystem has several points of origination and insertion.

The uppermost part is the erector spinae, which comprises three muscles: the illiocostalis, the longissimus and the spinalis. These originate and insert at various points between base of the skull and the cervical transverse processes.

Other muscles in the system originate and insert at various points in the back, hips and legs.  

The action and basic functional movement of the Deep Longitudinal Subsystem

The Deep Longitudinal Subsystem works alongside three other muscle synergies:

The Lateral Subsystem

The Posteriour Oblique Subsystem

The Anterior Oblique Subsystem

Personal trainers and other fitness professionals should be aware of how these four systems work together as one unit during exercise, each having its part to play.

The muscles and ligaments in the Deep Longitudinal Subsystem group transfer kinetic energy up the legs and above the pelvis, allowing you to walk, jog and run. They also help you bend forwards, squat and lunge, as well as carry out other contralateral movements in the sagittal plane, which divides the left and the right side of the body from the back to the front.  

The Deep Longitudinal Subsystem helps to stabilise the sacroiliac joint (SIJ), which is found between the sacrum and the pelvis. Support in this area is important to avoid back pain. It also acts to stabilise the whole of the back, core and hips.

Problems associated with the Deep Longitudinal Subsystem

Because it covers such a large area of the body, there are many issues that can arise through problems with the Deep Longitudinal Subsystem. These range from joint pain and restricted movement in the neck, back, hips and legs to lack of stability in the core.

As so many people suffer from back pain, it’s worth remembering the importance of this system in supporting and allowing movement in the back. In particular, those who spend a lot of time seated at a desk might encounter problems when they then use their legs during sporting activities or at the gym, in particular when squatting or deadlifting. This can be eased by using a foam roller after being seated and before a work out.

Exercises to strengthen the Deep Longitudinal Subsystem

Exercise that activates the whole group of muscles in the Deep Longitudinal Subsystem can help strengthen its component parts. These include:

• Squats
• Bent leg deadlifts
• Alternating forward lunges
• Anterior lunges with reach at knee height
• Alternating power step-ups
• Hip hinges with overhead lift
• Bridge and curl

Static stretches for the back muscles, hip flexors and hamstrings are also helpful.