The Deep Longitudinal Subsystem (DLS) is one of the four major muscle synergies in the human body that work together to provide stability and control movement. Here are the key points about the Deep Longitudinal Subsystem:
Composition
The DLS is comprised of:
- Erector spinae muscles
- Thoracolumbar fascia
- Sacrotuberous ligament
- Biceps femoris muscle
- Fibularis (peroneal) muscles
- Multifidus muscles
Some sources also include the anterior tibialis and contralateral erector spinae as part of this system.
Function
The primary functions of the Deep Longitudinal Subsystem include:
- Controlling ground reaction forces during gait motions.
- Providing longitudinal force transmission from the foot and ankle to the trunk and back down.
- Stabilizing the body from the ground up, including the tibiofibular joints, hip joints, sacroiliac joints, and spine.
- Assisting in lifting from a forward bent position and lumbar hyperextension.
- Eccentrically decelerating spine flexion, hip flexion, and ankle inversion.
Role in Movement
The DLS plays a crucial role in:
- Walking, running, and other gait-related activities
- Forward bending, especially when knees are near full extension
- Lumbar extension
- Absorbing and transferring energy from the ground up through the body during movement[5]
Importance in Stability and Performance
The Deep Longitudinal Subsystem is vital for:
- Core and hip stability
- Efficient force transfer between the lower and upper body
- Maintaining proper alignment and function of the sacroiliac joint
- Contributing to overall back health and prevention of lower back pain
Understanding and properly training the Deep Longitudinal Subsystem can be beneficial for improving overall movement quality, reducing the risk of injury, and enhancing athletic performance.
