JAMES LEE was a super-fit time trial cyclist. When he suddenly found he couldn't keep the pace with other competitors, he had no idea what was wrong.

He was not out of breath and he felt no pain.

He said: "It was just as though someone had flicked a switch off. I could only just manage to turn the pedals to get back to the finish line."

Over the next few months Mr Lee, 45, of Alne, North Yorkshire, looked at every aspect of his training regime, to try to find why this had happened to him.

But he had more of these episodes and started noticing a bumping sensation in his chest while resting.

He said: "My GP couldn't detect anything wrong and a heart specialist told me that I was very fit and could resume training and racing."

But his performances continued to worsen and he suffered near-blackouts at work.

After more tests, he was put on beta-blockers, but still had no firm diagnosis. Cue yet more tests, which diagnosed cardiomyopathy, a condition that affects 1 in 500 people and can cause heart cells to die and be replaced by fatty and scar tissue.

Mr Lee, who is married to Debbie and has three sons, has not been able to cycle competitively since.

He has told his story to raise awareness of the condition, as part of Cardiomyopathy week, which runs from September 20 to 26.

He said: "It's very important that more people are aware of cardiomyopathy, its symptoms and its implications.

"Cardiomyopathy is not rare and is the biggest medical cause of sudden death in the under 35s.

"There are good treatments for it. With proper care, most sufferers can lead a long and full life. The condition is often inherited.

"If someone in the family has it, it is important that close family members have heart checks so they can be diagnosed early.

"My sons are receiving regular heart checks, which so far show they are unaffected."

Mr Lee is a member of the Cardiomyopathy Association, which provides information and support to affected families and funds specialist nurses at UK hospitals.

For more information, call freephone 0800-0181-024 or visit cardiomyopathy.org