The freestyle is the classic stroke you learned as a kid: legs fluttering, one arm at a time coming overhead before cutting into the water. According to Latchford, the flutter kick is a crucial element of the stroke. "Letting your legs drag behind you slows you down and creates more work for your arms," she said. "The swimmer's toes should be pointed and their leg muscles engaged the entire time while swimming freestyle." This graceful stroke also challenges an athlete's core, back, and shoulders.