London - Manchester United legend Roy Keane has responded to growing fears about the damage done by concussions in sport by telling stars to 'play chess' if they are worried about getting hurt.
Keane now serves as assistant to Republic of Ireland manager Martin O'Neill and his country can no longer call on Kevin Doyle after the striker retired last week because of concussion issues.
The family of former West Bromwich Albion striker Jeff Astle have launched a foundation to campaign for better protection for modern players after his death at the age of 59 from a degenerative brain disease, which has been attributed to repeated heading of the ball.
Concussion is also an increasing concern in rugby union and American football.
"I'm sure there is (a need for more research), that's ongoing. But if you're worried about the physical side of any sport, you're wary of it, then play chess," Keane said on Tuesday.
"It's part of the game, whether it be hurling, football, American football, the rugby lads, it's part of the game.
"When you cross that line, there is an element of risk involved. I don't think it would make a difference to the players playing now. When you cross that line, there's a chance that you might get a knock. They're the risks you take."
Keane is sympathic to Doyle's predicament, but the former Republic midfielder insists all injuries are an occupational hazard for professional athletes.
"If he's had concussions over the years and he feels he's suffering from them, then obviously he feels that's right for him," Keane said.
"But it's part of the game - players picking up injuries and getting knocks. He's a centre-forward, he's going to be running the channels with centre-halves - it's what you'd expect.
"There's risk involved in everything, particularly sport. It's a physical game. I think Kevin's picked the right time to say, 'Enough's enough'. We wish him well, of course."