Did you know that while the incidence of injuries in cheerleading is much lower than in the majority of high school sports, nearly a third of those injuries are concussions? The reason, Comstock explained, is a shocking lack of common sense and caution in monitoring an activity that isn’t automatically associated with violence.

“We’ve seen cheerleaders who’ve sustained concussions because they were practicing on the asphalt in the parking lot or on the cement sidewalk — or in the school cafeteria on a tiled floor,” said Comstock, adding that grass or mats would be infinitely more appropriate. “Why on earth would parents let that happen?”

Guskiewicz drew my attention to a study published just a few months ago in The American Journal of Sports Medicine that determined that among college athletes, concussions were most likely in wrestling, followed by men’s ice hockey and then women’s ice hockey. And women’s soccer and women’s basketball, in that order, were right behind football in terms of the danger of concussion.

Comstock, who supervises an ongoing national inventory of athletic injuries among high school students, said: “I have 22 sports in my surveillance system, and concussions have been reported in all but one of them. That includes swimming.” A distracted kid will swim head-on into the wall or into someone coming from the other direction. The sport without concussions, she said, was tennis.

BUT head injuries are just one peril, and not necessarily the chief one, even in football. There are many more deaths among football players of all ages from indirect trauma, including heatstroke and cardiac arrest, than from such direct trauma as head and spinal-cord injuries.

Douglas Casa, the chief executive officer of the Korey Stringer Institute at the University of Connecticut, said that from 2000 through 2009, which was the last full decade studied, such indirect-trauma deaths outnumbered direct-trauma deaths by 108 to 41.

Casa, who monitors and compiles that data, told me that he knows of 14 deaths among football players below the college level since July 1, which is about when practice for the fall season usually begins. Four were from cardiac arrest and two were from heatstroke.