“Draw your belly button to your spine” is a universally accepted cue for abdominal hollowing that perhaps you have heard before. In fact, it has become so popular that abdominal hollowing is one of the #1 exercises to be prescribed by a therapist for low back pain. You’ll see the cue used in yoga classes, pilates, personal trainers, you name it. What if I told you that it was one of the worst things you can do for spinal stability?
So how did something that is so poor for spinal stability get so popular? To start at the beginning, in 1999, a study was produced by a group of Australian researchers (http://www.ncbi.nlm.nih.gov/pubmed/10489000) that showed that healthy folks would produce a contraction of their transversus abdominis (TrA) before any movement occurred. Conversely, people with low back pain had a delayed contraction of their transversus abdominis. According to this research, a hypothesis was drawn that the delayed contraction of the transversus abdominis was the reason for the low back pain. As a result, an exercise where the transversus abdominis could be isolated and trained was developed and this was the start of abdominal hollowing.
However, if the researchers had taken a look at the other abdominal muscles, they would have quickly found out that ALL the muscles have a delayed contraction not just the transversus abdominis (http://www.ncbi.nlm.nih.gov/pubmed/19501348). In fact, drawing the abdominis in actually creates instability in the core (http://www.ncbi.nlm.nih.gov/pubmed/15797580). While it appeared at first glance that researchers had found the missing link to low back pain, it now appears from the research that this was an ill-advised conclusion. Those who are still in favor of abdominal hollowing are simply misguided.
So how should you train the core? If someone was about to punch you in the stomach, what would you do? Correct me if I’m wrong but you would brace your core for the impact. And, according to Dr. Stuart McGill, a leading spine biomechanics researcher, this is how we should train our cores. The term is called abdominal bracing. Abdominal bracing encompasses all the muscles of core stability, not just a select few. It is by far and away the most functional way to train your core.
The Big Picture
I like to think of the core like the guide wires on the mast of a ship. You want 360 degrees of stability around that mast with a wide base to hold it up. If you perform abdominal hollowing, you’ll end up with 1 or 2 really strong guide wires on the same side of the mast and weak wires around the rest of the mast leading to a decrease in stability. However, if you train your core by bracing it, you encompass all the structures and build strong guide wires 360 degrees around that mast. I’m no sailor but if it was my ship, I’d opt for the second scenario. It is long past the time for a paradigm shift, people need to stop getting it wrong and creating instability instead of stability.
-Dr. Brian Damhoff