It's a moment football fans relish: A running back breaks through the line and heads up the field for a big play. A defender streaks toward the ball carrier, intent on stopping his forward progress as quickly as possible. The spectacularly violent collision that follows brings the cheering crowd to its feet. That hit—and the dozens more like it in any given game—have helped make American football enormously popular worldwide.

Such electrifying plays have also placed the sport in a great quandary because the concussive forces at work, particularly when helmets collide, put players at risk for traumatic brain injury. Head injuries are nothing new to football—the sport has been grappling with its brutal nature since its inception nearly 150 years ago. Now research is connecting several high-profile former players' repeated gridiron head impacts with the emergence of chronic traumatic encephalopathy (CTE), a neurodegenerative disorder characterized by atrophied, abnormal brain tissue.

The proposed link between football head injuries and CTE in former players has put the National Football League (NFL) on the defensive. The NFL has identified poor tackling technique as the main culprit in players' brain injuries, reasoning that this aspect of the game explains why concussions have persisted despite improvements to helmets and rules banning helmet-to-helmet collisions.

Acknowledging that pro and college players are too far along in their careers to make major adjustments to their style of play, the league teamed up with Indianapolis-based national youth organization USA Football to convince coaches, parents and young players to buy into a new approach called Heads Up Football, which was introduced in 2012.

Heads Up's centerpiece is a campaign to teach young players to tackle without using their heads as battering rams. In principle, the defender makes contact with his opponent using the front of his shoulders and his chest, just above the numbers on his jersey. Instead of lowering his helmet into the ball carrier, the defender's head should travel up and away from his opponent's helmet.

The technique's effectiveness for both taking down opponents and preventing concussions is debatable, particularly when players are moving at full speed. What is not debatable is work that shows that hits to the top of the helmet create the greatest risks for head and spinal injuries. Steven Broglio, director of the University of Michigan's NeuroSport Research Laboratory, has for years studied the forces exerted on high school players' helmets using Head Impact Telemetry System (HITS) technology. HITS consists of several battery-powered sensors in the helmet's padding that record every impact's location, magnitude, duration and direction.

Broglio's data indicate that blows to the top of the helmet have an average acceleration equivalent to about 35 g, whereas those to the facemask average less than 25 g. Concussions typically occur beginning in the 90-g range; nonetheless, research suggests that subconcussive blows also can cause damage. “If you're not hitting with the top of the helmet, you're reducing concussion risks,” he says. “Whether [Heads Up tackling] can be carried out on the field in real time, no one's shown those data, but I can't disagree with the theory behind it.”

Heads Up might diminish the number of head injuries to some degree. Yet it is no guarantee against brain trauma, which can happen anytime a person is involved in a collision, says Robert Cantu, co-director of the Boston University Center for the Study of Traumatic Encephalopathy. A better idea would be limiting contact in practice or even prohibiting tackle football for kids younger than 14, he adds.

Even if Heads Up's tackling initiative is just a start, the broader program promises to educate coaches, young players and their families about concussion risks and consequences, says Donald Marion, a senior clinical consultant at the Defense and Veterans Brain Injury Center in Silver Spring, Md. Marion studies the impact of concussions on both athletes and military personnel. Even as researchers investigate the causes of CTE, “it's becoming increasingly clear that multiple concussions can be a problem, especially if they're not reported or if the [player] is not appropriately diagnosed and treated,” he says.

Contact sports such as football will never be truly safe, nor is scrubbing them of all risk anyone's intention. Still, the collateral damage is evident—at press time 71 NFL players had sustained concussions this season, with 160 suffering similar injuries the previous season. With the Heads Up campaign, both professional and youth football leagues are finally acknowledging players' vulnerability to head injuries. The question is whether new approaches to tackling and heightened awareness of concussions are enough to prevent future generations of players from suffering the same neurodegenerative conditions that plague many of their retired gridiron heroes.