In as many 80 percent of those cases, there are absolutely no symptoms to warn that the cardiac arrest might occur.
Without urgent treatment, including Cardiac Pulmonary Resuscitation and the use of a defibrillator, applied within minutes of the heart stopping, death is certain.
Even with prompt treatment, only 11 percent of these athletes survive. Sudden cardiac arrest is the leading cause of death among young athletes.
But at least quick treatment gives them a chance to make it.
The National Athletic Trainers' Association is out with new guidelines to help high schools and colleges deal with such emergencies. The guidelines are published in the Spring 2007 issue of the Journal of Athletic Training.
The association says high schools and colleges haven't placed enough importance on planning to deal with the collapse of a young athlete on the field or court, and the guidelines seek to change that.
On The Early Show Thursday, Russ Mitchell spoke with the lead author of the new guidelines, Dr. Jonathan Drezner, an associate professor of family medicine at the University of Washington.
He said the guidelines are actually a call to action, because defibrillators still aren't universal at schools. More than 90 percent of universities have the devices, but only somewhere between a quarter and half of high schools have them.
And even if a school, especially a high school, owns one, that doesn't mean it's handy and people know where it is and how to use it.
So, say the guidelines and Drezner, anyplace where emergency medical services treatment isn't assured within five minutes, schools are urged to come up with an emergency plan including:
While all athletes should have a thorough physical before competing in sports, defects that might cause sudden cardiac arrest may not be detectable, Drezner says. Most episodes of sudden cardiac arrest come with absolutely no forewarning. That's why a school emergency plan is so important.
And it's a good idea for parents to ask their child's school and athletic conference whether they actually have a plan, and if so:
If not, there may be no violation of any law, but it could be worth parents' while to lobby the school to make sure a plan is in place.
These guidelines aren't meant as an alarm bell, rather, a framework to spur discussion.
Even though most episodes of sudden cardiac arrest occur completely without warning, occasionally, warning signs may appear, Drezner points out. If they do, the athlete should absolutely stop activity at once, since continued exertion can trigger an episode. The signs include lightheadedness, a very rapid heart rate, chest pain, and fainting.
He added that, while meant for schools that stage athletic events, the guidelines aren't just aimed at sudden cardiac arrest in athletes. Anyone, from spectators to faculty and ordinary people on campus, can experience sudden cardiac arrest and need immediate help. The safeguards a school sets up for athletes apply to these other people too.
Training people to do the resuscitation properly isn't hard, and doesn't take that long to learn. Drezner tells of sixth graders being able to start resuscitation measures only 23 seconds later than trained pros, as long as they have a sense of what to do. Basically, anyone can learn to use a defibrillator, and that knowledge can be lifesaving.
Incidentally, the terms "trainer" and "athletic trainer" aren't interchangeable. For the purposes of dealing with sudden cardiac arrest, only "athletic trainer" applies. A "trainer" is considered a person who helps a person exercise at a gym or health club. An "athletic trainer" treats athletic injuries, including heart emergencies.