The way athletes sail across the water while swimming backstroke makes it seem so simple, but the stroke actually requires a lot of technique. First, a swimmer must keep their head up and back at all times. Then, "similar to freestyle, backstroke requires the swimmer to rotate their body and pull one arm at a time over their head," Latchford told POPSUGAR. "Backstroke kicks are also similar to freestyle, just on the back." Great backstrokers have amazing shoulder flexibility and core strength.