Zero in on Transverse Abdominis exercises that work . . . . and cut out the dross in your exercise regime
Transverse abdominis (TrA) forms the deepest layer of the abdominal musculature with the obliques (internal and external) forming the middle layer and rectus abdominis the most superficial. TrA wraps around the abdomen horizontally, predominantly below navel level. Rectus runs vertically up the abdomen either side of the mid-line and is the least efficient abdominal muscles, with a bowstring action on contraction that bends the upper body forward. The highly-prized indentations of the six-pack are in this muscle.
Some very 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, since 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 Pilates classes.
The role of Transverse abdominis is to control the mobility of the lumbar spinal segments. 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!
The idea that strengthening TrA in itself was therapeutic led to exercise regimes designed to specifically isolate this muscle. Despite the ill-effects of this (see below) it was always a strange and somewhat naïve mission, since it is simply not possible to work a single muscle in isolation. It is also not possible to focus on strengthening one muscle in a highly complex working system thereby hoping to improve its timing and highly complex co-ordinated behaviour.
Transverse abdominis fibres wrap around the belly horizontally and are most effective at drawing in the lower abdomen
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 upper abdominal wall ~ just as much for low load activities (picking up a sock) as for high (picking up a bucket of water). This may give you a sought after six-pack but at the expense of bowing the upper body forward into a perpetual stoop and creating more sustained compression of the spinal base.
Excessive bracing of TrA in isolation also over-compresses the lumbar spinal segments, as per its job description, and often increases pain from the lower back. The un-natural premeditation also engenders a lack of spontaneity and fluency in back movement ~ too much thinking about it and what you should be switching on before moving ~ making the back more bound up and painfully rigid as time goes by.
Excessive core stability training and attempting to isolate transverse abdominis also increases bearing down abdominal pressures that weaken the pelvic floor (and it is estimated that 40% of elite female athletes suffer stress incontinence for this reason). Excessive abdominal workouts (typically up to 400 sit-ups or crunches in a session) are also implicated in the rising incidence of breathing difficulties and related problems, such as sleep apnoea and panic attacks. It is thought to be the consequence of excessive abdominal muscle tone disabling the lowering excursion of the diaphragm into the abdomen to get a clear breath.
Transversus abdominis fibres inserting into a diagonal lattice
either side of the spine compresses the spinal segments
To help rid a lower back of pain it needs better support from your lower abdominals, not the deepest. Any lower abs exercises should incorporate all three layers of abdominal musculature at the one time, without trying to single any one out. The emphasis should be on strengthening the abdominal wall below navel level. Apart from helping to off-load the lumbar spine, strengthening the lower abdominals helps recruit the pelvic floor muscles which are often over-looked in spinal strengthening regimes.
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 very unnatural and bears little relation to normal everyday activity.
Professor Lederman puts it a little more succinctly:
‘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.’
It may be that Transversus abdominis is weak in the first instance because it has switched off as an automatic pain-relieving mechanism. This is not an elective, cerebrally pre-meditated action. It is a simple 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 inhibit.
The best formal lower abs exercise is ‘reverse curl-ups’. But in terms of recruiting TrA functionally, all you need to do is pull in your tummy hard 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.
For any physiotherapists reading this and interested in doing my Masterclasses (now available on webinar for the Theory component (see here) you will see that ‘The Pitfalls of Core Stability Training’ is Lecture 18 in Stage 4.
We all need to have a strongly effective abdominal wall - and pelvic floor - to support the lumbar spine and make bending safe.
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** Urquhart et al.