A leading Australian sports cardiologists says there is no conclusive evidence well-trained athletes like ironman champion Dean Mercer are more likely to suffer sudden cardiac death.

Associate Professor Andre La Gerche, head of Sports Cardiology at Baker Heart and Diabetes Institute, says people in their middle age should not be discouraged from exercising.

"The people at actual risk of having a heart attack are the people doing very little exercise," he said. To suggest those in their 50s out training for a triathlon or marathon are tempting sudden death is "absolutely ludicrous".

The Melbourne-based cardiologist says he is speaking out after receiving numerous calls from colleagues and clients concerned about the reports that circulated following the sudden death of Mercer at age 47.

"There was an interview with a cardiologist on the Gold Coast who I think extrapolated quite wildly when not all the facts are available," he said. "Some of the information that was spread was really quite inaccurate.

"To assert that his death might have been contributed to or maybe even was due to the exercise he'd done is absolutely wild and baseless," Professor La Gerche told AAP.

While some animal studies have suggested really extreme exercise might cause some problems, there "really is no strong evidence at all that endurance exercise is linked to an increased risk of cardiac arrest".

"There's also some evidence that endurance exercise is associated with some heart rhythm problems but not sudden death."

In fact, he says, the evidence shows endurance athletes actually live longer.

"The Tour De France cyclists have been studied, Olympians in the '30s and '40s have been studied, there is even one study that suggests gold medallists live longer than silver medallists and bronze medallists," he said.

"This idea that Dean Mercer, who was a highly accomplished athlete, in some ways has contributed to his death is really not based on fact and I believe sends very much the wrong message."

There is only benefit associated with regular exercise, he says.

"Everyone agrees that up to two-and-a-half, three hours of exercise a week has incremental benefits," Prof La Gerche said.

"My message is to encourage exercise in any amount but treat exercise with respect, get into it gradually and consistently."