The Best Circuit-Training Workouts
Works: core, chest, arms.
(A) Get in high plank position, with your hands under your shoulders and your body straight from head to heels.
(B) Lift your hips and shift your body back into a pike shape by pressing your hands into the floor. Return to the starting position and repeat.
Make it easier: Lower your knees to the floor in plank position (then lift them when you lift your hips).
Make it harder: Add a push-up to the pike position. Bend your elbows and lower your head toward the floor, keeping your hips in the air.