What is the Anatomy of Transverse Abdominis?

Transverse abdominis (TrA) forms the deepest layer of the abdominal musculature, the obliques (internal and external) the middle and rectus abdominis the most superficial layer. TrA is the most efficiently activated by drawing in action of the bellybutton. 

TrA wraps around the abdomen horizontally, predominantly below navel level. The obliques cross over the front of the belly like an 'X' in two large diagonal sheets, whereas rectus runs vertically either side of the mid-line. Rectus abdominis is the least efficient abdominal muscle, with a bowstring action on contraction that bends the upper body forward. The highly-prized six-pack contours are in this muscle.

What is the Role of Transversus Abdominis?

The job of TrA is to increase intra-abdominal pressure and control the mobility of the lumbar spinal segments. In a feedforward mechanism it switches on a fraction before any elective movement to stabilise the stack of lumbar segments. It does this primarily via verteberal compression, which stops the segments jostling about.

It was assumed therefore that strengthening the core muscles would make a spine more stable and less painful, even though very few patients with low back pain show symptoms of 'instability'. Indeed their problems are the converse. Their lumbar spines are too stiff! 

Transversus Abdominis Action is Delayed when Your back Is Bad

Some good research at Queensland University* demonstrated 'weakness and delayed action' of TrA in people with lower back pain. However, this research has led to confusion in its application in the therapeutic world because it was automatically assumed the converse would be true: that strengthening TrA (the core) would make the lower back pain go away. This led to a flourishing industry of core work and Pilates classes. 

The Pitfalls of Excessive Core Strengthening Are...

Professor Eyal Lederman in his paper ‘The Myth of Core Stability’ tells us: ‘The division of the trunk into core and global muscle system is a reductionist fantasy, which serves only to promote the core stability (industry)’. 

Excessive abdominals workouts result in an over cinched-in abdominal wall. This may give you a sought after six-pack, but at the expense of spinal compression and bowing the upper body forward into a perpetual stoop. 

Excessive bracing of TrA over-compresses the lumbar spinal segments and can increase pain from a lower back. Pre-meditating your every move by deliberately 'switching on' also makes the back more bound up and painfully rigid as time goes by. 

Attempting to isolate transverse abdominis also increases bearing down on the pelvic floor. This is a potent cause of stress incontinence so common with elite athletes. Workouts of up to 400 sit-ups or crunches in a session are also implicated breathing problems (asthma, sleep apnoea and panic attacks) by the cinched-in upper abdomen disabling the downward excursion of the diaphragm.

Excessive Transverse Abdominis Strengthening Can Increase Back Pain

A lot of the core stability classes involve repetitive non-functional exercises such as kneeling on all fours and lifting the arms and legs without allowing the trunk to move. This type of formal exercising is unnatural and unfunctional and bears little relation to normal everyday activity.

Professor Lederman puts it better:

‘It is believed that low velocity exercise performed laying or kneeling on all fours would help normalise motor control which would include timing dysfunction (of TrA).This kind of training is unlikely to help reset timing differences. It is like aspiring to play the piano faster by exercising with finger weights, or doing slow push ups. To overcome the timing problem the proponents of core stability came up with a solution - teach everyone to continuously contract the TrA or to tense/brace the core muscle. By continuously contracting it would overcome the need to worry about onset timing.’

Watch how to strengthen transverse abdominis and multifidus with Sarah's famous Roman Chair exercise.

You can download it now 

Transverse Abdominis May Be Switched Off As a 'Reflex'

When your back is painful Transversus abdominis may switch off as an automatic pain-relieving mechanism. This is not an elective, cerebrally pre-meditated action; it is a simple brain reflex to spare the lumbar segments excessive compression – and thus to reduce pain emanating from a painful spinal link.  It is indeed fantasy to think that vigorously exercising a muscle can over-ride its instinct to reflexively relieve pain.

The Best Core Strengthening Exercises Are 'Reverse Curl Ups'

The best formal lower abs exercise is ‘reverse curl-ups’. All you need to think about is pulling in your tummy below navel level like a greyhound whenever you go to bend over ~ whether it be your toothbrush or multiple bags of shopping. Of course, it goes without saying this will not work if you don’t draw up your pelvic floor at the same time. It’s no use pulling your lower tummy in if you leave the lowest flank of the abdominal cavity out of the equation. It will be like the floor of a laden cardboard collapsing out when it is lifted.

We all need to have a strongly effective abdominal wall - and pelvic floor - to support the lumbar spine and make bending safe.

Read more in-depth information about The Best Abs Exercises for lower backs, to be sure you're on the right track.

It seems a shame to be doing harm when you're exercising with the best intent. You need to know why.

Read here about The Worst Abs Exercises, and why. Too many fitness regimes include the three cardinal sins (abs exercises I mean).

When you have a bad back, it's important to get the exercises just right. Here is a detailed rundown of the three (just 3!) important and highly effective lower abs strengthening exercises. Read more about 'The Best Exercises for the Lower Abs'

Refs:

* Hodges & Richardson

** Urquhart et al.