Good lower ab exercises you can do at home or the gym.

Knee-Up

Good Lower Ab Exercises

Execution

1. Sit on the edge of a flat bench, legs hanging down with knees slightly bent, and grip the bench behind you.

2. Raise your knees up toward your chest, keeping your legs together.

3. Lower your legs back down until your heels almost touch the floor.

Muscles Involved

Primary: Rectus abdominis.

Secondary: Obliques, hip flexors (iliosoas, rectus femoris).

Range of motion:

Raise your knees up until your thighs almost touch your abdomen. As you lower your legs down, stop before your heels make contact with the floor to keep tension on the muscles. 

Hanging Leg Lifts

Good Lower Ab Exercises

Target Muscles: Lower Abs 

Equipment: Bar

Instructions: Grab a chin up bar with an overhand grip and hang with you knees slightly bent. Use the muscles of your lower abs to pull your hips up as you curl them toward your chest. Lift your knees as close to your chest as possible, rounding your lower back at the top. Pause and feel the contraction in the your lower-abdominal muscles. Then return to the starting position. 

Reverse Crunch

Good Lower Ab Exercises

Reverse Crunch

Exercise Data
Main Muscle Worked: Abdominals
Other Muscles Worked: None
Equipment: BodyOnly
Mechanics Type: Isolation

V-Leg Raise

Good Lower Ab Exercises

Muscles trained:  Abdominals, hip flexors

Sit crossways on a flat bench with your legs slightly bent and your hands just outside your hips. Lean back, and without changing the amount of bend in your knees, use your abs and hip flexors to bring your torso and legs as close together as possible. Hold the highest point for as second lower, and return back to the starting position.

Leg Pull-In

Good Lower Ab Exercises

Leg Pull-In

Exercise Data
Main Muscle Worked: Abdominals
Other Muscles Worked: None
Equipment: BodyOnly
Mechanics Type: Compound