Sydney defender Dane Rampe has suffered a broken arm after falling over while running around Centennial Parklands with his teammates on Monday morning.

Swans coach John Longmire confirmed the injury news in a press conference on Monday, stating that Rampe attempted to jump over a chain before landing on his arm and breaking it.

"At the moment it looks like a five-week injury," Longmire said.

"I couldn't believe it to be honest, to fall on it trying to jump the chain then falling on the concrete 20 metres from the front door.

"He has a crack just below his elbow and at this stage I have been told it is a minimum of five weeks.

"I went through the game with him an hour beforehand and so obviously it is very disappointing."

Rampe played for Sydney against Port Adelaide in round one over the weekend, collecting nine disposals and four marks.