People who suffer a cardiac arrest during exercise are three times more likely to survive than couch potatoes, reveals study.
It found almost half of victims who were exercising at the time they had a cardiac arrest survived, compared with 15 per cent of those who were not.
They said that it may be because exercising victims were generally fitter than the rest - but also indicated that survival rates could be aided by the fact that those who collapsed during exercise generally did so in a public place, meaning they got help quicker, the Daily Mail reported.
The study looked at data on all cardiac arrests, which took place outside hospital in the Amsterdam area from 2006 to 2009.
6 per cent of the total happened during or within one hour of doing exercise.
The exercise was mostly cycling, playing tennis, working out at the gym and swimming, with all but seven victims aged over 35.
Survival rates for exercisers were 45 per cent compared with 15 per cent of those having a cardiac arrest that was not exercise-related.
"Although physical activity is the best way to promote cardiovascular health, exercise can trigger an acute cardiac event leading to death," said lead researcher Dr Arend Mosterd, of the Meander Medical Centre, Amersfoort, in the Netherlands.
"Sport is not a big risk for cardiac arrest - it's an uncommon thing to happen but when it does it attracts a great deal of publicity.
"Good physical health is a factor in the good survival of victims of exercise-related cardiac arrest, but they are more likely to suffer the arrest in public, leading to bystander resuscitation, often with the use of an automated external defibrillator.
"Taking this into account exercise contributes to a better outcome," he stated.
Dr Mosterd presented his findings at the European Cardiology Congress in Munich.