Rather, most cardiac arrests may happen in adult men playing recreational sports, the study found.
The findings come in the wake of several sudden deaths on the playing field, such as Michigan high school basketball player Wes Leonard, who collapsed earlier this year when his heart stopped just moments after he'd sunk a game-winning basket.
In the new study, researchers documented 820 cases of sports-related cardiac arrest over five years. That works out to only four or five deaths per million per year, although the true rate may be higher, they say.
"We cannot transmit the message that sport participation is dangerous for health," study author Dr Eloi Marijon, from the Paris Cardiovascular Research Center said. Rather, the findings point to the importance of prompt cardiopulmonary resuscitation, the French team says.
Cardiac arrest data
The new data came from a combination of ambulance reports of sudden cardiac arrest in exercisers and media releases on those emergencies. From 2005 to 2010, the researchers tracked all sport-related cardiac arrests in adolescents and adults living in 60 of 96 districts in France.
Out of 820 cardiac arrests - with 93% witnessed - 50 occurred in younger competitive athletes age 10 to 35. On average, they still suffered cardiac arrests at a higher rate than the population in general – about 10 per million per year.
But more than 90% of all cardiac arrests happened during recreational sports, most often biking or running, the researchers reported online in Circulation. The majority were in otherwise healthy men between age 35 and 65.
Less than a third of cardiac arrest victims received CPR – but when they did, their odds of surviving more than tripled.
In total, 253 people in the study made it to the hospital alive, and 128 ultimately survived.
According to the research team, bystander CPR and initial use of cardiac defibrillation were the strongest independent predictors for survival to hospital discharge (odds ratios 3.73 and 3.71, respectively; p<0.0001 for both).
Sports-related sudden death quite common
The French researchers observe that "sports-related sudden death in the general population is considerably more common than previously suspected," but add that studies that look beyond competitive athletes have been limited.
Dr Kim Harmon, a sports medicine physician at the University of Washington in Seattle who reviewed the findings, said there's no reason to think the findings would be very different in the US or other countries.
"The types of heart (conditions) that cause this in different populations might be a little different, but the problem is the same," she said.
"I think that this study really highlights... that early defibrillation and CPR is important."
(Reuters Health, Genevra Pittman, August 2011)