Best Bodyweight Exercises for a Strong Core
Vertical Leg Crunch
Lie flat on the floor with lower back pressed to the ground. Place hands behind head. Extend legs straight up, crossed at the ankles with a slight bend in the knee. Contract abdominal muscles by lifting torso toward knees. Make sure to keep chin off your chest with each contraction. Exhale as you contract upward; inhale as you return to the starting position.