NOCSAE-Driven Research Led to Breakthrough in Puzzling, Fatal Sports Injury

It is with pride that NOCSAE welcomes the start of each new lacrosse season. One of the impacts of NOCSAE-funded research has been to make the sport of lacrosse safer, and there’s an interesting story behind how this developed.

Mysterious deaths among young athletes 

We were already studying injuries caused by concussive hits before news stories brought it to the public’s attention that athletes were sometimes dying from what appeared to be a minor blow to the chest. These events were thought to be rare. But each death was not only a tragedy because it was a life lost — the circumstances of the fatalities were stunning. Often the case involved young athletes, with no underlying health conditions, who collapsed on the playing field. Most efforts to resuscitate were unsuccessful. 

The syndrome had a name, commotio cordis (CC), which means “disturbance of the heart,” but no one could explain why only some hits over the heart were fatal, nor why so many of the victims were adolescents. Adding to the mystery was that there was no physical damage to the heart. 

Joining forces, and a major discovery 

More incidences of CC began to be reported in the late 1990s after an article in the New England Journal of Medicine raised awareness of the phenomenon. Dr. Barry Maron, one of the article’s authors, would later take on an important role in NOCSAE’s efforts against CC. 

Meanwhile, NOCSAE-funded research efforts were making headway. Good stories have heroes, and Dr. Mark Link turned out to be one of the heroes of NOCSAE’s commotio cordis story. He is an expert in electrophysiology and specializes in abnormal heartbeat patterns. He was chosen to spearhead our research efforts because he had been making impressive progress on the problem in his lab at Tufts University. 

Dr. Link made a key discovery, answering the most puzzling question about CC. Why were some hits to the chest lethal even though most were not? He found that only hits striking at a critical moment in the cardiac electrical cycle cause CC arrythmia. Force transferred from a striking ball, through the chest wall to the heart, interrupts the heart’s cadence, sending it into a disorganized rhythm that fails to circulate blood through the body. Because of Link’s discovery, the world now knew how an ordinary-seeming ball strike can cause death. 

Turning point 

In 2000, NOCSAE received a call from a mother who had just lost her 14-year-old son to commotio cordis during his first high school lacrosse game. This tragedy became the inflection point, resulting in NOCSAE’s bringing to bear all its resources to attack CC. 

Beyond the lab, onto the playing field 

NOCSAE’s role in athlete safety is to write performance standards for athletic equipment. Sports equipment manufacturers design their products to perform to these standards. NOCSAE’s CC challenge was to develop a method for testing protective equipment against the conditions that cause this injury. There was still a lot of work to do. 

Dr. Nathan Dau’s work in the Sports and Ballistics Lab at Wayne State University for NOCSAE yielded an important leap toward developing such a standard. He created a biomechanical chest surrogate to model, and measure, the human response to ball impacts.  

In a series of further studies for NOCSAE, Dr. Link found that only perpendicular hits over the center of the heart cause CC. He also identified the injury prevention threshold, which is a measure of how much impact force is necessary before commotio cordis is triggered. This is a key metric to test equipment performance. It is one of the measures manufacturer’s need to develop prototypes. 

Almost the end of the story is that, based on the research we funded, the world’s first CC standard was approved by the NOCSAE Standards Committee. ND-200: Standard Test Method and Performance Specification Used in Evaluating the Performance Characteristics of Protectors for Commotio Cordis. NOCSAE also funded the establishment of a national registry to track CC cases, which was organized by Dr. Maron. As a result, it is now known that 15 – 25 athletes die from CC annually. 

This year youth, high school, and collegian lacrosse players will gear up in CC protectors manufactured to meet NOCSAE’s standard. The rest of the story is that these protectors must fit properly, according to manufacturer instructions. It’s also important for AEDs to be available on the field in case of emergencies. 

Annually, about 66% to 80% of CC cases occur in adolescents. It’s thought that this is because their chest walls are still somewhat pliable and more vulnerable to impacts near the heart. As we age, the chest becomes stiffer. Cases occur most frequently in sports with projectiles, such as baseball, softball, lacrosse, and hockey. Although, it can also occur from hits with a fist or foot, as in martial arts. 

The story of how NOCSAE developed the standard to lower CC risk spotlights our continued leadership in sports safety research.

What were the results of the study?
In the group of 5 to 9-year-olds, the researchers recorded 590 head impacts in 30 games.  In the group of 9 to 14-year-olds, researchers verified 805 head impacts. This difference in the number of impacts between groups is not statistically significant. In both age groups, most impacts were a result of head-to-head contact, and the next highest number were head-to-ground impacts.

The majority of impacts in both age groups had MPS values classified as low. While impacts in this category may not be linked to diagnosed concussions, they are important to note because they are linked to injuries that lead to changes in brain structures and cognitive impairments that may not have  symptoms.

More impacts in the moderate-range category occurred in the younger group than in the older group. Moderate-range MPS level impacts have been associated with concussions. This higher number of moderate-range impacts appears to be due to the relative inability of younger kids to control the the motion of their heads during an impact event. Further, because the added weight of a helmet adds to this problem, the researchers concluded that younger athletes may benefit from a smaller and lighter helmet.

In both age categories most of the head impacts occurred to running backs, followed by defensive line players, and then linebackers.  Impact events were similar for both age groups as well. Most impacts were a result of head-to-head followed in number by head-to-ground.

Laboratory reconstructions of the impacts showed that measurements of peak linear and rotational accelerations were both lower than the range used in testing helmets to the current football helmet standard. Because of this, researchers suggested lowering the pass/fail testing criteria for youth helmets to more accurately capture the magnitudes of impacts experienced by younger players on the field.

Ultimately the findings reported in this study helped support the development of a youth-specific helmet standard.

Where can I learn more about this study?
Read the full study: “Brain Trauma Exposure for American Tackle Football Players 5 to 9 and 9 to 14 Years of Age – PDF.”