Muscle Madness: designing the Pilates body
The deepest muscle of the "powerhouse", the Transverse Abdominus, doesn't function alone in creating the Pilates scoop". Superficial to the TA is the pair of Internal Oblique Muscles that form an inverted "V" shape at the front of our torso. They assist in the forceful exhale that compresses the abdominals and increases spine and pelvic stability. Their oblique (diagonal) fibers also provide lateral flexion and rotation of the spine toward the same side. In other words, the right internal obliques assist in lateral flexion and rotation to the right side.
ANATOMY OF INTERNAL OBLIQUES
As you can see from the illustrations, the internal obliques have a similar corset-like appearance to the TA. They even share some of the same attachments such as origins at the anterior iliac crest, inguinal ligament and lumbar fascia. But rather than running horizontally like the TA, the internal obliques run superiomedially (on an upward diagonal toward the midline) and insert on the inferior borders of ribs 10-12 and the linea alba (the fibrous ridge that runs vertically through the rectus abdominus).
INTERNAL OBLIQUES IN PILATES
Here's an example of Cheryl's left internal obliques performing same side rotation during twist-reach on the Short Box.
Here's an example of Shari Berkowitz's left internal obliques contracting eccentrically (lengthening of the muscle even though the muscle is contracting), as she lengthens her torso over the ladder barrel during side sit-ups.
Here's an example of Shari's left internal obliques contracting concentrically. They work to pull her left ribs proximal to her left hip in lateral flexion in side sit-ups.
Rock Your Powerhouse!