Sprains usually happen when a person falls, twists, or is hit in a way that forces the body out of its normal position. The most common type of sprain is a sprained ankle; about 25,000 people sprain an ankle every day. Think of a runner who goes over a curb and catches her foot, twisting the ankle; or a baseball player who slides into home plate and twists his knee. Strains happen when a person twists or pulls a muscle or a tendon. Athletes in contact sports, like football, hockey, and boxing, are at particularly high risk for strains. Frequent repetitive motions, like those used in tennis, rowing, and golf, can lead to strains of the hand and forearm.