Reverse Crunches: Lie on your back with your legs raised and bent at a 90-degree angle. Contract your abs to lift your hips off the floor, bringing your knees towards your chest.
Leg Raises: Lie flat on your back with your legs extended. Lift your legs off the ground while keeping them straight until they are perpendicular to the floor, then slowly lower them back down.
Bicycle Crunches: Lie on your back with your hands behind your head and legs lifted. Alternate bringing your right elbow towards your left knee while straightening your right leg, then switch to bring your left elbow towards your right knee.
Mountain Climbers: Get into a plank position with your hands directly under your shoulders. Drive one knee towards your chest, then quickly switch legs, alternating in a running motion.
Hanging Leg Raises: Hang from a pull-up bar with your arms extended. Raise your legs until they are parallel to the floor, then slowly lower them back down.
Scissor Kicks: Lie on your back with your hands under your glutes for support. Lift your legs off the ground slightly and alternate crossing one leg over the other in a scissor-like motion.
Plank Jacks: Begin in a plank position on your elbows. Jump both feet out wide, then back together while maintaining a strong plank position.
Russian Twists: Sit on the ground with your knees bent and feet lifted off the floor. Lean back slightly and rotate your torso to touch the ground on each side of your body with your hands.