Synchronized swimming is a low-injury competitive aquatic sport for all ages. It requires flexibility, kinesthetic awareness, and aerobic conditioning, with the ability to function anaerobically as well. Few acute injuries occur during participation in the sport, but overuse injuries are becoming more common as synchronized swimmers participate in longer, more strenuous workout programs. Most common among these injuries are knee pain associated with the eggbeater kick and shoulder pain associated with sculling. Synchronized swimmers are also prone to otitis externa ("swimmer's ear") and chemical conjunctivitis. Stress-related symptoms are common.