Would soccer be safer if young players were not allowed to head the ball?

According to a study of heading and concussions in youth soccer, the answer to that question is not the simple yes that many of us might have hoped.

Soccer parents naturally worry about head injuries to their kids. The resounding head-to-head collision between Alexandra Popp of Germany and Morgan Brian of the United States during the recent Women's World Cup sent shivers down viewers' spines.

Some doctors, parents and former professional players have begun to call for banning heading outright among boys and girls up to about age 14, and curtailing it at other levels of play.

But Dawn Comstock, an associate professor of public health at the University of Colorado in Denver and an expert on youth sports injuries, was skeptical, saying she and her colleagues could not find any large-scale studies examining the causes of concussions in youth soccer. So, for a study published last week in JAMA Pediatrics, she and her colleagues decided to investigate the issue themselves.

They began by turning to the National High School Sports-Related Injury Surveillance Study, a large online database administered by Comstock that collates reports from hundreds of certified athletic trainers nationwide.

The first finding that leapt from the data was that concussions related to soccer are clearly rising. But heading the ball was not the leading cause of the injuries.

Instead, the overwhelming majority of concussions resulted from player-to-player contact, especially among boys. Almost 70 percent of soccer-related concussions in boys occurred when players collided, the researchers found. Among girls, the portion was 51 percent.

Heading played a role in many concussions. But most of those injuries also involved player collisions, and it was the contact that typically caused the concussion, the researchers found, not the heading. Fewer than 17 percent of concussions in boys and 29 percent in girls resulted from direct impact with a soccer ball.

"What those numbers say to me is that banning heading" in youth soccer "would reduce the number of concussions," Comstock said, "but not nearly as much as people think that it would."

It would be "far more effective" she said, to teach young players better technique and sportsmanship, and to call fouls when they slam into one another.