5 Best Exercises for a Flat Tummy 

Women tend to be wider through the pelvis and have a longer waist. This can make it challenging to get flat, firm abs.

But visible abdominal muscles aren’t impossible — you might just need to commit to doing more than standard sit-ups. 

The best abdominal exercises for women target four muscle groups in your core:

• External abdominal obliques. These are the muscles in your sides that you can feel just beneath your arms, along your ribcage.

• Internal abdominal obliques. These are stabilizing muscles that lie underneath your external obliques.

• Transversus abdominus. These are the deepest muscles. They run horizontally around your midsection.

• Rectus abdominus. These muscles run from your sternum down to your pelvis. They help flex your spine as you walk. They’re also the most superficial muscles in your abdomen and the ones you see in “six-pack” abs.

To properly target and tone all four muscle groups, it’s important to perform a range of stabilization exercises. Training these core muscles will also stabilize your spine and pelvis to improve your posture and reduce or avoid back pain.

Unlike traditional crunches or sit-ups, stabilization exercises that target the core will work more muscles and burn more calories.

Plank Crawl Out 

1. Stand up tall with your feet together and your core engaged.

2. Bend at the hips and try to touch the floor. As soon as your fingertips hit the floor, walk your hands out until you reach a push-up position.

3. Crawl your way back up to the starting position by inching your hands backward and piking your hips up to the ceiling. When your feet are flat on the floor, bend at the hips again and lift yourself back up to the standing position.

Side Plank 

1. Begin on your left side, with your elbow directly below your shoulder and your forearm perpendicular to your body.

2. Stack your feet or place one in front of the other.

3. Contract your abs and lift your hips off the floor until your body makes a diagonal line from your shoulder to your feet.

4. Hold this position for 30 to 45 seconds.

5. Switch sides and repeat.

Reverse Crunch

1. Begin in a seated position, knees bent at 90-degree angles and feet flat.

2. Reach your arms forward, palms facing each other.

3. Exhale, pulling your belly button toward your spine.

4. Roll back onto your tailbone, curving your spine into a C shape.

5. Inhale and return to the starting position. Repeat, doing 15 more reverse crunches.

Boat Pose

1. Begin by sitting upright with your knees bent and feet flat on the floor.

2. Lean back, balancing on your sit bones and lift your legs off the floor.

3. Extend your arms out straight, palms up. Your body will form a V shape.

4. Hold for 30 seconds.

Alligator Drag

1. Begin in a plank position with your feet on a towel, bag, or Frisbee.

2. Walk forward, using your hands only and dragging your lower body along for 10 to 20 yards.

3. Keep your core and glutes tight as you move forward.

4. Rest for a minute and then alligator drag back to where you began.

5. Rest and repeat.

https://www.healthline.com/health/fitness-exercise/best-ab-exercises-women#9