Alternating Leg Kicks
START: Stand in chest-deep water, and pull alternating knees to chest while treading water with your hands. Keep toes pointed down, and bring knee toward chest, not chest to knee.
MOVE: Extend leg straight out in front of your body. Return leg to start position, then perform with opposite leg for one repetition.
REPEAT: 3 sets of 8 repetitions
TIP: Maintain a tight core (abs and lower back) throughout the move. You can perform the move slowly for more strengthening benefits or increase speed for a cardio element.