Shilpa Shetty highlights the benefits of flutter kicks for core strength, muscle endurance, and balance, and recommends using a tennis ball.

Dressed in sleek black athleisure, Shilpa Shetty demonstrated flutter kicks while lying on her back.

Core training has always been part of military PT and fitness testing. From crunches to sit-ups, flutter kicks, leg tucks and plank poses, the U.S. military uses many exercises to test core strength.