One of the quickest and most effective ways to strengthen your leg muscles is by using a kickboard. This lightweight and versatile training tool is mainly used during practice or for warm up during a meet. Developing proper kick technique is essential in learning how to swim. By highlighting the leg muscles and immobilizing the upper body, your lower body is targeted to become stronger and more efficient in the water. Kickboards come in all sizes, shapes and are usually made of durable foam for a sturdy, yet soft feeling on your upper body.