How: Start in a plank position and drive your knees toward your chest as fast as possible while maintaining a flat back.
How: From a forearm plank, bring your right knee toward your right elbow, then switch. Goal: Combines static hold with active muscle contraction. How: Start in a plank position and drive
How: Lie flat and lift your shoulders and legs slightly off the ground, forming a "banana" shape. Keep your abs tucked in tight. How: Start in a plank position and drive
Don't just swing your legs; focus on "crunching" your ribs toward your pelvis. How: Start in a plank position and drive