Melanie Oudin came to prominence when she reached the quarterfinals of the 2009 U.S. Open.
Melanie Oudin came to prominence when she reached the quarterfinals of the 2009 U.S. Open.
Dennis Grombkowski/Getty Images

Surprise 2009 U.S. Open quarterfinalist Melanie Oudin (oo-DAN) says she has a muscle-damaging condition that may be caused by intense exertion.

Oudin has written on her Twitter feed that her ''off season is a little paused at the moment'' because of the ailment, called rhabdomyolysis (rab-doe-my-OL-uh-sis), and she is ''doing everything possible for a speedy'' recovery.

Her agent, Sam Duvall, confirms to The Associated Press on Monday that Oudin sent the tweets.

Oudin, who turned 22 in September, is ranked 129th. At 17, she pulled off a series of upsets, including against Maria Sharapova, to reach the U.S. Open's final eight.

Heavy exertion can cause muscle cells to leak enzymes and protein into the blood. Symptoms of rhabdomyolysis can include muscle pain and severe cases can lead to kidney damage.

Copyright 2014 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

SI Apps
We've Got Apps Too
Get expert analysis, unrivaled access, and the award-winning storytelling only SI can provide - from Peter King, Tom Verducci, Lee Jenkins, Seth Davis, and more - delivered straight to you, along with up-to-the-minute news and live scores.