Core Stabilizers aka "The Powerhouse" and "Abdominal Wrap"

In general, people are either too rigid (lots of strength with little mobility) or too bendy (lots of mobility with little strength).

Core stability is delicate a balance of strength and mobility — the balance of strong but flexible core muscles: found not just in the front of the body, but the back and wrapping around torso.

In Yoga the “Abdominal Wrap” muscles include

• Transversus Abdominis
• Internal Obliques
• External Obliques
• Serratus Anterior
• Lower Trapezius
• Latissimus Dorsi

And in Pilates the “Powerhouse” muscles

• Transversus Abdominis
• Internal Obliques
• External Obliques
• Rectus Abdominus
• Erector Spinae
• Multifidius and Rotators

I prefer to merge the two and call them simply Core Stabilizers.

Transversus Abdominis (TVA)

The innermost muscle of the abdomen. It connects posteriorly (in the back) at the thoracolumbar fascia and anteriorly (in the front) at the lower ribs and at the pelvis. The muscle is essentially horizontal. The important thing to know is that when you contract your transversus abdominis, it’s like tightening a girdle, squeezing or cinching the core of your body. Hence its nickname as the “corset muscle”. An easy way to find this muscle is to wrap your hands on your side and cough. Training the TVA is what will give you a flattened belly, not the Rectus Abdominis (the six pack muscles).

Internal Obliques

These muscles attach at the lower ribs, iliac crest, and at the pubis. The fibers run essentially up-forward to down-back. They work in conjunction with the transversus abdominus compressing into the core of the body. They bilaterally flex the spine, and in conjunction with the external obliques on the opposite side, they unilaterally rotate the vertebral column.

External Obliques

The external obliques attach to the outer surface of the ribs where its fibers interweave with the Serratus Anterior and Latissimus Dorsi. The average direction of the muscle fibers is perpendicular to those of the internal obliques: up-back to down-forward. These muscles bilaterally flex the vertebral column anteriorly (forward), and in conjunction with the internal obliques on the opposite side, they unilaterally rotate the vertebral column.

Rectus Abdominis

The most superficial (closest to the surface) abdominal muscle. Contraction of this muscle will flex the spine anteriorly (forward). But it also assists the other three abdominal muscles in compression of the abdomen. Because of its visibility (6-pack muscle) most mistakenly try to train this muscle and ignore the deeper muscles.

Serratus Anterior

Originates at the top 8 or so ribs and inserts along the inside of the shouderblades. Its often called the “boxer’s muscle” since it’s responsible for pulling the shoulderblade forward and around the ribcage (protraction) when throwing a punch. We feel it when doing the “cat” position from cat/cow or when pressing the floor away in the plank position. It is important in shoulderblade stabilization.

Lower Trapezius

The Trapezius is a very large, superficial, and multidirectional muscle that has three regions. In relation to core stabilization, we’re only concerned with the lower region that depresses the shoulderblade (pulls them down the back towards the hips). A key function in backbends and inversions.

Latissimus Dorsi

The larger, flat, dorso-lateral muscle on the trunk, partly covered by the trapezius. The latissimus dorsi are responsible for extension, adduction, and internal rotation of the shoulder joint. Typical exercises to strengthen your Lats are Pull-downs or Pull-ups, However, in relation to core stabilization, we are mostly concerned with its synergistic role in extension and lateral flexion of the lumbar spine. This is the muscle that brings the chest up and forward between the arms in Urdhva Mukha Svanasana (upward-facing dog).

Erector Spinae

Muscles that run the length of the spine. They vary in size and structure along the vertebral column: narrow and pointed near the sacrum, thick in the lumbar region, then separating into three columns and thinning until they insert the ribs and vertebrae. The Erector Spinae is responsible for bilaterally extending the vertebral column.

Transversopinalis: Multifidus and Rotators

The multifidus is a very thin muscle. Deep in the spine, it spans three joint segments, and works to stabilize the joints at each segmental level. The rotator spinae are found beneath the multifidus in the thoracic (upper back) region and are involved in postural control. Together they are small, deep muscles that connect vertebrae from the neck to the lower back. They extend the vertebral column and initiate rotation of the spine.

As you move through your next Yoga or Pilates practice, take a moment in each pose or exercise and consider which muscles you’re using. Then consider which muscles you ~should~ be using. They are not always the same.

Namaste.