Complex sentence: The risk of an ankle sprain is greatest during activities that involve explosive side-to-side motion, such as tennis or basketball, but you can also sprain your ankle during normal daily activities such as stepping off a curb or slipping on ice.
Split into simpler sentences: The risk of an ankle sprain is greatest during activities that involve explosive side-to-side motion, such as tennis or basketball. Sprained ankles can also occur during normal daily activities such as stepping off a curb or slipping on ice.