extended, toes pointed, and hands tucked underneath glutes to support lower back. Lift both legs off the floor a few inches and alternately kick legs up and down.
(rest for 10 seconds)
Plank
Lie facedown on the floor with feet together and forearms on the ground. Draw abs in and tighten glutes.
Then, lift entire body off the ground until it forms a straight line from head to toe, resting on forearms and toes. Hold. Slowly return body to the ground, keeping chin tucked and back flat.
(rest for 10 seconds)
Helicopters
Lie faceup with knees bent and feet flat on the floor, arms extended out to sides, palms down. Contract core, take a deep breath in, and draw knees into chest.
Exhale, pressing lower back into floor as you extend feet toward the ceiling. (Upper torso and lower body will form a 90-degree angle with feet pressed together.)
Keep core contracted, flex toes toward the floor, and begin circling legs clockwise, keeping legs fully extended and hips resting firmly on the floor.
You can create more of a challenge by flipping palms up to face the ceiling. This will decrease stability while increasing core activity.