Karen Johnston, a concussion specialist, called it a minor concussion after examining Lindros in Edmonton earlier this week.

He said that Dr. Karen Johnston, a concussion specialist, would have to clear him to play.

It is, as the concussion specialist Robert Cantu argues, with repetitive subconcussive trauma.

"There is a lot of risk involved," said Lindros, who was given clearance to play by Dr. James Kelly, a concussion specialist in Chicago.

It was his third light workout of the week; he received permission Tuesday from Dr. Karen Johnston, a concussion specialist, to begin exercising.

Richter, 36, returned to New York today after being tested in Montreal by Dr. Karen Johnston, a concussion specialist.

Although a concussion specialist cleared Lindros, he turned down $8.5 million from the Flyers and, as a restricted free agent, wants to play for Toronto.

He has gone through the parade of team doctors and concussion specialists, sitting out the entire playoffs while his brain tried to stabilize itself.

Sather was following the medical guidelines proposed by a panel of concussion specialists.

Doctors and other concussion specialists agree that a player must not return to play until symptoms are completely gone, both at rest and during exercise or exertion.