Pellegrini, 20, was swimming at the Italian short-course championships in Genoa when she began hyperventilating during the 800-meter event, but after tests appears to be fine, ANSA, the Italian news agency, reported Monday.

"It went well, we did all the tests and they were all negative," Pellegrini told reporters. "It was only an attack of hyperventilation, it could have happened to anyone."

Pellegrini, who became Italy's darling after winning a gold medal in the 200-meter freestyle in Beijing, said she became frightened because she had never hyperventilated before, and as a precautionary measure would wear a heartbeat monitor for 24 hours, ANSA reported.

She was set to begin training for the European swimming championships Tuesday.