Concussions are receiving attention nationwide, but death from a blow to the head is exceedingly rare. In contrast, a young athlete dies from a cardiac incident once every three days in the United States, researchers say. In hot months like August, heat stroke often causes the death of a young athlete every other day on average.

“Concussion victims almost always get a second chance,” said Laura Friend, an attendee at the Washington summit whose 12-year-old daughter, Sarah, died of sudden cardiac arrest while swimming at a Texas community pool in 2004. “When your heart fails from something that could have been treated — which happens all the time — you don’t have another chance. As someone told me, sudden cardiac arrest is not rare; surviving it is.”

Heat stroke, also known as exertional heat illness, has been a focus of sports safety advocates because of simple, common-sense preventive measures, like introducing gradual levels of exercise at the beginning of a sports season in hot temperatures.

“When my son died, people treated it as a freak thing,” said Rhonda Fincher, whose 13-year-old son, Kendrick, died in 1995 from heat stroke sustained during a season-opening football practice in northwestern Arkansas. “The ignorance was unacceptable because, unfortunately, it is not infrequent. And we should all know that.

“No healthy child should be sent off to a routine practice and die from it.”

Leaders of youth sports acknowledge that concussions have long been overlooked and that the injury deserves a period of heightened awareness, especially because of the potential for long-term consequences. But as the focus of the February conference organized by the National Athletic Trainers’ Association suggests, there is a mounting worry that more hazardous health concerns are being disregarded because of the intense emphasis on brain injuries.

A sudden heart-related death is “so incredibly tragic and stunning that people aren’t comfortable putting it into the everyday conversation,” said Dr. Jonathan Drezner, the president of the American Medical Society for Sports Medicine.

“I do wish, to some extent, it was something people talked more about,” Drezner added, “because we are getting to a place where we could prevent many of these deaths.”

“The message we’re sending is that any time a concussion is suspected, even if you’re not sure, you should sit that player out until there has been an evaluation by a medical provider with concussion expertise,” said the guidelines’ lead author, Dr. Christopher Giza, an associate professor of pediatric neurology and neurosurgery at the David Geffen School of Medicine and the Mattel Children’s Hospital at the University of California, Los Angeles.

“We say:  ‘If in doubt, sit them out’.”

The researchers found, according to data they presented at a Radiological Society of North America meeting last month, that the players who had headed the ball more than about 1,100 times in the previous 12 months showed significant loss of white matter in parts of their brains involved with memory, attention and the processing of visual information, compared with players who had headed the ball fewer times. (White matter is the brain’s communication wiring, the axons and other structures that relay messages between neurons.)

This pattern of white matter loss is “similar to those seen in traumatic brain injury,” like after a serious concussion, the researchers reported, even though only one of these players reported having ever experienced a concussion.

The players who had headed the ball about 1,100 times or more in the past year were also substantially worse at recalling lists of words read to them, forgetting or fumbling the words far more often than players who had headed the ball less often.

“Based on these results, it does look like there is a potential for significant effects on the brain from frequent heading,” says Dr. Michael L. Lipton, associate director of the Gruss Magnetic Resonance Research Center at Einstein and senior author of the study.