SAN FRANCISCO, June 8 (UPI) -- Too much time playing the Nintendo Wii video game system can give players an acute form of tennis elbow, a doctor in Barcelona, Spain, warns.

Dr. Julio Bonis of the Research Group in Biomedical Informatics has diagnosed acute "Wiiitis," a condition he discovered after a long session of Wii Sports tennis gave him a sore elbow.

Unlike real tennis or other sports, Wii encourages extended play because strength and endurance are not major factors, Bonis wrote in a letter to the New England Journal of Medicine. Wii lets one use a bat or a tennis racket by waving a light-weight controller.

 The risk of Wiiitis may be higher than that of "Nintendinitis," which refers to pain brought on by using a traditional Nintendo controller, Bonis said in a story reported Friday in the San Francisco Chronicle. Before there was Nintendinitis, there was Space Invader Wrist.

The key to avoiding Wiiitis is moderation, said Bonis, who recovered by taking Ibuprofen and turning off his Wii game.