Practice the basic components of abdominal bracing before your attempt to combine this practice with any other specific exercises. While standing in a comfortable position or lying down, initiate the movement by taking a large breath, using your diaphragm to pull air into your stomach. This breath should cause your stomach to expand, but your chest should not move much, if at all. Hold the breath and "brace" your abdominal muscles by contracting them as though you were going to get punched in the stomach. These are the essential requirements of abdominal bracing. Repeat this drill for several days to ingrain the movement pattern in your muscles
Perform a bridge to practice combining abdominal bracing with a simple exercise. Get down on the ground on your forearms and toes, with your body supported in midair in a relatively straight line. Employ the principles of abdominal bracing to tighten and stabilize your core muscles, which will keep your posture rigid. Hold this position for as long as you are able. To breathe while keeping your core tight, breathe slowly and smoothly, using the "belly breathing" technique described in step one to keep your abs braced throughout. Repeat two or three sets of 30- to 60-second holds.
Perform squats for a weighted abdominal bracing exercise. Place a barbell across your upper back, holding it in place with your hands, or hold a pair of dumbbells in your hands at your side. Initiate the movement by taking a deep breath and bracing your abdominal muscles, then sitting back as though you were descending into a chair. Stop and reverse the movement when your legs are completely parallel to the ground, exhaling on the way up--but without releasing the tension in your abdominal muscles. Repeat for three or four sets of six to eight repetitions.