The idea that certain stabilizing muscles can be trained to automatically contract at the time of effort to protect the joints, has long been a tenet of the exercise sciences and practices and is passed on by personal trainers, Pilates instructors and many others working with people and exercise. In particular, the deep abdominal muscles are at the center of this instruction.
The Deep Abdominal Muscles
The deep abdominal muscles are called the transversus abdominis or TvA for short, and lie beneath the surface abdominals you know as the six-pack or the rectus abdominis -- the ones you train to get a nice washboard stomach.
The TvA has been targeted as a muscle group that has influence on the stability of the spine and thus has been promoted as important for back protection; and, the advice goes, that if you develop this muscle and train it to work subliminally for you, the spine will get protected from injury as you exercise. ‘Hollow out’ or ‘draw in’ the stomach by sucking in the transversus abdominis and this will set your torso up as a powerful unit able to withstand the rigor of weight lifting and other sports. Pilates in particular has a lot to say about the use of the TvA.
Origins of the Advice
It seems that the origin of the this information is a physiotherapy rehabilitation group at the University of Queensland, Australia (Richardson 1996). However, the advice seems to have been taken well beyond the original context, which was for the rehabilitation of back injury and pain.
What You Need to Know
I must admit that I have never practised or preached ‘drawing in’: it just did not seem useful or even practical to me. On the other hand, ‘bracing’ the stomach muscles ready for effort does seem intuitive. You only have to do a pullup or chinup on a bar to feel how these muscles automatically brace themselves for effort.
What bracing is. Most trainers agree that this procedure of bracing, as if for a feigned punch in the stomach, and not hollowing or drawing in, is a fundamental tool of the exercise trainer and a basic procedure from which every person involved in exercise or physical activity of any sort can benefit.
Strengthening this ‘core’ of muscle – at back and front of the torso – is paramount to performance and injury prevention. Let's not get confused here: it's important to understand the distinction between 'bracing' and 'drawing in' or 'hollowing'. Bracing is what we want you to do.
What bracing is not. Bracing is not holding the breath, pushing the stomach out or trying to push your belly button through your tailbone (coccyx). Get used to the bracing idea and you can do it almost anywhere, even running. Many endurance runners have poor core strength and abdominal posture because under fatigue they get very slack in the stomach area. Another group that can benefit from braced abdominals are office workers and people sitting at work or home most of the day.
Barr KP, Griggs M, Cadby T. Lumbar stabilization: core concepts and current literature, Part 1. Am J Phys Med Rehabil. 2005 Jun;84(6):473-80. Review.
Chiu, Loren ZF. Are Specific Spine Stabilization Exercises Necessary for Athletes? Strength and Conditioning Journal 29:1:15-17, 2007
Hodges PW, Richardson CA. Inefficient muscular stabilization of the lumbar spine associated with low back pain. A motor control evaluation of transversus abdominis. Spine. 1996 Nov 15;21(22):2640-50.