Muscle Of The Month – Lateral Subsystem

Today’s blog is on the Lateral Subsystem group of muscles. These give stability to the frontal plane and the sacroiliac joint (SIJ), aiding balance and keeping the pelvis in alignment during single leg movements such as walking, running or climbing stairs.

The Lateral Subsystem comprises the following:

• Quadratus lumborum
• Gluteus medius
• Tensor fascia latae (TFL)
• Adductor complex

The origination and insertion of the Lateral Subsystem

Because it is a major muscle synergy, the Lateral Subsystem has various points of origination and insertion as follows:

• Quadratus lumborum – originates at the iliac crest of the pelvis, inserts at the 12th rib
• Gluteus medius – originates at the outer surface of the ilium, inserts at the greater trochanter of the femur
• Tensor fascia latae (TFL) – originates at the anteriour iliac crest and inserts at the iliotibial tract
• Adductor complex – originates at various parts of the spine and pelvis and inserts at points along the femur and tibia.

The action and basic functional movement of the Lateral Subsystem

The Lateral Subsystem is one of four muscle synergies that are used by the body during movement; the other three are:

The Deep Longitudinal Subsystem (see our previous blog)

The Posteriour Oblique Subsystem

The Anterior Oblique Subsystem

The action and basic functional movement are carried out in the frontal plane and include gluteal rotation, leg abduction and adduction, and stabilisation of the lumbar, pelvis and femur.

Problems associated with the Lateral Subsystem

These can include:

• Lower back pain, tightness or compression; muscle spasms
• Excessive pronation of the hip, knee or foot
• Hip, knee or ankle pain or injury
• Tightness and pain in the iliotibial band (Iliotibial Band Syndrome)
• Plantar fasciitis (see our blog on the Plantar Fascia)

If a personal trainer is working with a client who has excessive pronation of the hip, knee and/or feet, this may be due to dysfunction in the Lateral Subsystem.

Exercises to strengthen the Lateral Subsystem

The muscles in the Lateral Subsystem can be trained in groups, as a whole or in tandem with the other three muscle synergies. To work the Lateral Subsystem in particular, exercises should focus on single-leg movements and activity in the frontal plane, especially those that keep the pelvis level.

Fitness instructors and personal trainers could include any of the following in a programme of exercise for their clients:

• Lateral lunges and lunge to balance
• Frontal plane step ups and step ups to balance
• Frontal plane single-leg balance reach
• Single leg squat
• Squat with low row to lateral lunge
• Side step downs
• Single leg Passover weight exercise

Encouraging your client to develop a strong core will also help to support their Lateral Subsystem.