Four-year-olds have the coordination and balance of adults and demonstrate their skills by descending stairs without the handrail, standing on one foot, and pumping themselves on swings. They run, hop, and climb easily and confidently, and now have the muscular strength to turn somersaults or execute a standing broad jump.
Shelov, S. P. (Editor-in-Chief). (2004.) Caring for Your Baby and Young Child: Birth to Age 5. The American Association of Pediatrics. Revised edition. New York: Bantam Books.