Battered once more by injury, Lindsey Vonn begins what has become an all-too-familiar cycle of recovery and rehab.

The four-time overall World Cup champion broke her arm during a crash while training in Colorado. She said on Facebook the wipeout happened at Copper Mountain on Thursday and she had surgery that night in nearby Vail to fix the bone in her upper arm that was "severely fractured."

On her Twitter account, Vonn wrote: "I don't know why these things happen to me but I know I am a fighter and I refuse to let it bring me down! I will never give up!"

Late last February, Vonn sustained three significant breaks near her knee during a super-G crash in Andorra. She tried to ski through the pain — she was in contention for the World Cup overall title — only to end her season a few days later.

The 32-year-old Vonn has been steadily healing and was tentatively hoping to be back for the World Cup races in Lake Louise, Alberta, in early December.

Now, there's no timetable for her return to the start gate.

"While I am beyond frustrated by this latest setback, at least my knees are OK and I will return to the slopes as soon as possible, as I always do!" Vonn posted on Facebook.

ASSOCIATED PRESS