It may be surprising that I was in choir my entire middle school and high school life. I hated it, but it guess my parents wanted me to be "well-rounded."
My teacher, Mr. Klinzman, however did teach me the skill of belly breathing. Everyday we would start the first 5 minutes of class with our hands on our belly doing these, what I thought to be, ridiculous exercises of inhaling through our nose and forcefully exhaling out of our mouth. As we did this the goal was to fill our belly, not our chest. I guess this made us sing better.
This is called diaphragmatic breathing. It's " breathing that is done by contracting the diaphragm, a muscle located horizontally between the thoracic cavity and abdominal cavity. Air enters the lungs and the chest rises and the belly expands during this type of breathing."
Of course, as a kid, I thought this was just a stupid exercise I had to do that made no sense. But I started learning more about this technique even when I played basketball. I used it as way to calm my nervous system on the free throw line so I could relax and focus on my shot. I also used it for the same when I competed in Muay Thai kickboxing as a way to recover, relax and even strike.
So how can you use this to improve your core training?
Going through Mike Boyle's Complete Core Training program one of the things he emphasizes most is utilizing this breathing technique to recruit your inner core musculature. He say's he wants his athletes to think about breathing, "below the rib cage."
To do this you simply start on your back (see above) with your legs at 90 degrees on a bench or box and practice the technique of breathing in through your nose for 3 seconds and exhaling for 5. Watch that your belly is only filling up with air and not your chest.
Add this to your core training by inhaling and filling your belly before you start the exercise and exhaling forcefully as you execute the movement.
For example if you are doing a bridge, fill your belly with air at the bottom for 3 seconds and then exhale on the way up . This will improve the recruitment of the deep core musculature and quality of the exercise.
What he found is that instead of "drawing your belly button to your spine" or even using the bracing technique (bracing your core like you're going to be hit in the stomach) breathing correctly did the job of recruiting the deep core muscles to perform the exercises correctly.
Not that you have to exclude the techniques above, but correct breathing improves the quality of your core training and also helps you stay more conscious and engaged in what you are doing.
You can use this technique with almost any core exercise you do. Give it a try.