Tombstone Kick With your back to edge of pool, hold kickboard with both hands so that its vertical (rounded edge up) and half of it is below surface of water. Push off wall with feet, holding kickboard in tombstone position, and kick as hard as you can toward opposite side of pool. Continue for 1 minute. MAKE IT HARDER: Hold kickboard horizontally and completely submerged.

Tombstone Kick With your back to edge of pool, hold kickboard with both hands so that its vertical (rounded edge up) and half of it is below surface of water. Push off wall with feet, holding kickboard in tombstone position, and kick as hard as you can toward opposite side of pool. Continue for 1 minute. MAKE IT HARDER: Hold kickboard horizontally and completely submerged.

Original article and pictures take https://fitnessmagazine.com site