Former West Coast Eagle Chris Mainwaring's age and a punishing Sunday workout could have left him vulnerable to the potentially lethal effects of ecstasy and contributed to the seizure which preceded his death, medical experts said yesterday.

Australian Medical Association emergency medicine spokesman Dr David Mountain said the fact that Mainwaring was 41 and potentially either dehydrated or overhydrated following the workout meant there was higher potential for his ecstasy use to be harmful.

A St John Ambulance spokesman said Mainwaring was unconscious in a "post-seizure" state when paramedics found him at his Haining Avenue home in Cottesloe early yesterday morning.

Mainwaring, who on Sunday spent several hours exercising with fitness fanatic cricketer Justin Langer, was taken by ambulance to Sir Charles Gairdner Hospital, where he was pronounced dead.

Dr Mountain said seizures were often the result of low sodium levels caused by both poor hydration following exercise and ecstasy use.

"If sodium levels get very low then it can cause seizures, disorientation, coma. Sodium levels are known to drop when someone has been using ecstasy," he said.

"If he was still dehydrated or if he was overhydrated with the wrong fluids following his work-out, then his sodium levels would have been low. So that's an even more dangerous state to be in to then start indulging in a cocktail of amphetamine-related drugs like ecstasy."

Dr Mountain said all seizures were potentially lethal. "Obviously, if you fall during the seizure you can hit your head or sustain other fatal injuries," he said. "And if the seizures are prolonged and uncontrolled then they can cause major problems with the brain and metabolic disturbances. They can also cause problems with very high body temperatures and not getting enough oxygen to the brain."

National Drug Research Institute director Professor Steve Allsop said taking ecstasy was particularly risky for older people, who were more likely to have pre-existing health problems.

Mainwaring was yesterday described as "infectious" and "one of the great blokes you meet in footy" as West Coast tried to fathom the loss of one of their most decorated performers.

Mainwaring, a dual premiership player, was also selected last year on a wing in the Eagles' 20th anniversary team.

Eagles chief executive Trevor Nisbett paid tribute to the original Eagle who made his way down from Geraldton to initially play with East Fremantle."He had an infectious personality and will be sadly missed by everyone," Nisbett said. "He is one of the most popular blokes that have been involved at the club and just one of the great blokes you meet in footy.

"He was very close to a lot of our players and did some work with our kids so to not have him around is a huge loss. There are a lot of suggestions flying around at the moment, but we'll just wait and see what comes out of the port-mortem."

Langer was due to fight Chris Mainwaring on Thursday night in a kickboxing bout for a telethon on Channel Seven in Perth.

The former Test opener had been nervous about the fight for months. "I came home last night and said to [wife] Sue he was a lot heavier than me and would hit pretty hard," Langer said yesterday. "I was a bit nervous about it."

Langer only returned last week from a season of county cricket in England but immediately started sparring with the former Eagle in preparation for the charity fight.

The pair had trained together for the past three days and spent several hours together on Sunday when they sparred and recorded an interview with Seven.

"I was taking the mickey out of him for not being fit enough," Langer said. "He was taking the mickey out of me over being stronger and tougher."

Mainwaring was a behind-the-scenes participant trying to help Ben Cousins overcome his methamphetamine addiction and had the fallen Eagles star around to his house for dinner on more than one occasion on his return back to Australia.

He was an unofficial mentor and lent a sympathetic ear to the 29-year-old struggling to come to terms with how his life had changed dramatically since his public battle with drugs.