Good core exercises for women include the ball roll out and Pilates beginner "100." According to ABC News, doing these moves five to 10 times, two or three times a week is a better core workout than hundreds of crunches.
A woman performs the ball rollout by kneeling behind a big exercise ball with her palms on the ball and arms straight. The woman slowly rolls the ball forward and away from her, stretching as she goes and going as far as possible while still maintaining balance. This exercise works the woman's core while reducing the risk of back injury because of the minimal hip involvement.
A woman performs the Pilates beginner "100" by lying on her back with knees and feet together and then lifting bent legs off of the floor, aligning them over her hips. Next, she stretches her arms out at her side a few inches above the floor, palms down, and then brings her belly button towards her spine. Next, she exhales deeply and lifts her chin to her chest. While keeping arms rigid and core tight, she then vigorously pumps her arms up and down by a few inches, inhaling deep breaths through her nose for five pumps and exhaling for five pumps until she has completed 100 pumps. This exercise is effective because it activates the waist's oblique side muscles.