Core Muscles I: Transversus Abdominis

Extreme stomach crunch

Over the coming weeks we’ll be presenting a series of short articles on the core muscles, looking at why they are important, how they function and why Pilates is so effective at training them to work properly.

To start the series, let’s consider the transversus abdominis, arguably the most significant of the core muscles…


Transversus abdominis (often referred to as the TVA or trans abs) is the deepest of the abdominal muscles and wraps around the abdomen between the lower ribs and the top of the pelvis.  See image below.  You can click on it to make it larger…

transversus abdominis


The TVA works like a corset. When it contracts, the waist narrows slightly and the lower abdomen flattens. The function of the transversus abdominis is to stabilize the lower back and pelvis before movement of the arms and/or legs occurs. This function is critical if wear and tear (degeneration) of the joints in your lumbar spine and pelvis is to be prevented. When healthy, this muscle anticipates motion, e.g. the TVA involuntarily contracts during lifting, stabilizing the spine and pelvis by creating a kind of corset or hoop of tension around the mid-section of the trunk. It is estimated that the contraction of the TVA and other core muscles reduces the vertical pressure on the inter-vertebral discs by as much as 40%. Failure to engage the TVA during heavy lifting is dangerous and can cause injury to the spine.

Because of the anticipatory action of a healthy functioning TVA, we can use “intention” or imagery with specific Pilates exercises to retrain its function. This is a vital part of core training since you cannot strengthen a muscle that your nervous system/brain isn’t properly connecting to.


Mid or lower back pain, abdominal injury or surgery and/or excessive lengthening due to pregnancy can cause a delay or absence in the anticipatory contraction of the trans abs. If this muscle contraction delay or absence is not corrected, dysfunction will remain even after any pain has subsided.

Pilates to Train the Trans Abs

First we need to learn to isolate the TVA in order to train it to contract. Research shows the better you are at isolating this muscle, the faster it will integrate into functional day-to-day tasks. In class we use specific Pilates exercises lying on the side or on the back in neutral pelvis to help us find the TVA and activate it properly without other muscles contracting at the same time. Clues that this is happening include the pelvis tipping backwards, the belly bulging outwards or the breath being held.

The second step is to strengthen or teach the trans abs to co-contract with the other core muscles (each of which we’ll look at in more detail over the coming weeks). In class we do this using a number of Pilates exercises in sitting, in crooked side-lying, four point table top and supine lying with the lower back in the neutral position.

The final step is to remember to use the trans abs during regular activities. Each time you get out of a chair, lift something, bend over or reach forwards, the trans abs along with the other muscles of the core should be working with and for you. The goal of Pilates is to train your body to do this, to help the brain remember to use the core muscles as you go about your daily activities.

The next article in the Core Muscles series will look at the rectus abdominis or six-pack muscle, as depicted in the image below of Aidan Turner from the drama serial, And Then There Were None…thank you, BBC, you made our Christmas!

Aidan Turner, towel scene, And Then There Were None

Leave a Reply