The Dolphin Kick yoga exercise works your shoulders, abs and quads.
Bring your forearms down to the floor, and the elbows should be directly underneath the shoulders. You're gonna extend the legs straight, reach the heels back, and then drop the pelvis slightly. Maintain here, or if you want to take a challenge, bend the knees, and then straight. Bend, straight. And look forward, bend, straight. And one more time, bend, straight, and then release all the way down.