Warm-ups are exercises done before sports to prepare muscles and joints to prevent injuries and improve performance. They include joint mobility movements, activation exercises like running and skipping, and games. Warm-ups increase body temperature, lung and muscle function, nerve transmission, and physical abilities. They also improve force levels and prevent injuries by increasing muscle elasticity and temperature. Exercises should move from feet to head and side to side across the court. Example activation exercises are running, heel walking, and jumping, while sample games described are tag and a catching game.