Answer: Full sit-ups are not the type of abdominal exercise I'd recommend. They can injure your back and aren't truly effective, because you use muscles other than the abdominals to do most of the work. Instead, try doing crunches. They're similar to sit-ups but you bring only your head, shoulders and upper back off the floor--and they specifically target your abdominal muscles.

To do a crunch, lie on your back on a mat with knees bent, feet hip-width apart and flat on the floor. Rest your hands behind your head. Tighten your stomach and lift your shoulder blades off the floor. Exhale as you lift up and hold for a count of two. Slowly lower down to the floor while inhaling. Do not pull your head up with your hands; leave your fingers resting lightly on your head. Repeat for a set of 20.

When doing crunches, try to maintain a pelvic tilt so that your abdominal muscles work harder. Also, be conscious of your abdominal muscles throughout the day. Tighten your abs (but don't hold your breath) when sitting and standing so you maintain good posture. Slouching and bad posture can stretch and weaken your abs.

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