New Study CDC Compares Head Impacts in Youth Tackle Football and Youth Flag Football

A new study from the CDC found that tackle football players sustain substantially more head impacts and are at greater risk of sustaining high-magnitude head impacts compared to flag football players. For most people, these findings aren’t surprising. Flag football is a non-contact version of the sport, so it makes sense that there would be fewer head impacts. Yet, this is only the second study to directly compare the difference in impacts between flag and tackle football. Like the first, this study provides data to back up what was already believed to be true, and it has important implications for safety in youth football.

What the Study Found

CDC researcher Dana Waltzman and colleagues measured head impacts in 477 tackle football players and 47 flag football players ages 6- to 14-years-old over one regular season. Tackle football players sustained a median of 378 impacts during the season, while the flag football players sustained a median of just 8 impacts.

The flag players did, on average, participate in fewer practices than tackle players, though the number of games were similar. The researchers account for this by comparing the impacts per athletic exposure, essentially measuring the average number of hits the players incur every time they step on the field for a game or practice. On average, the tackle football players sustained 9 impacts per athletic exposure compared to just 0.63 for flag players. That means tackle football players averaged 15 times more impacts per athletic exposure than flag football players.

The magnitude of impact was also higher in the tackle football players. The average linear acceleration, or the strength of head acceleration in one direction, was slightly lower in flag (16.8 g) than tackle (18.2 g) players. However, the tackle football players were 23 times more likely to sustain a high magnitude impact of 40g or higher.

I often hear people say that youth players don’t hit that much or that hard compared to the older players. Unfortunately, the results of this study (and others like it) show that isn’t really true. Sure, they’re smaller and slower, but youth tackle football players still experience hundreds of impacts over a season at magnitudes similar to that of their high school and college counterparts. Many players in this study sustained impacts over 40g, with the highest-magnitude impact measuring in at 80.7 g. The strongest impact sustained by a flag football player was 55.2 g. One youth tackle player in this study sustained 1170 impacts in one season. That is high even for high school and college players, who average between 300-775 impacts per season. The most impacts sustained over the season by a flag player in this study was just 43.

Why is this important?

When it comes to brain trauma in sports, concussions are only part of the story. The repetitive brain trauma that occurs on every play with routine tackles and blocks has an effect on the brain, even when the impacts don’t result in concussion symptoms. These hits are often called subconcussive impacts. Studies have shown alterations in brain structure and function over the course of one season of football in youth, high school, and college athletes who did not sustain a concussion. Repetitive impacts over time have also been linked to later-life cognitive, behavioral, and mood difficulties and the development of the neurodegenerative disease chronic traumatic encephalopathy (CTE). The more impacts sustained over a lifetime, the greater the risk for developing these later-life consequences.

Repetitive impacts during youth, while the brain is rapidly developing, may have additional consequences. The brain undergoes critical developmental processes in childhood and early adolescence, and there is evidence to suggest that sustaining repetitive impacts during that time can alter or disrupt these processes (more on this in an upcoming blog). Though the effects of this disruption may not be apparent in early or even middle adulthood, it may lead to accelerated aging or an earlier age of onset of symptoms in those who go on to develop a neurodegenerative disease such as CTE or Alzheimer’s disease.

What does this mean for youth athletes?

The best way to protect the brain is to avoid impacts altogether, and this study clearly shows that playing flag football leads to far fewer impacts than tackle football. Of course, we will never eliminate every single impact, or every single concussion for that matter. Accidental collisions will happen. Kids will fall. Players will collide while jumping to catch a pass. That is a natural and acceptable risk of sport in general.

But tackles are not accidents. They are an inherent part of the game that are known to lead to repetitive brain trauma. Playing a non-tackle form of the game until high school will substantially reduce the amount of repetitive brain trauma sustained by athletes over their careers, reducing their likelihood of having long-term cognitive or behavioral consequences or developing CTE. It will also give their brain more time to mature without disruption.

There has been a lot of emphasis in recent years on teaching proper tackling technique. This study examined youth tackle football in the fall of 2017, well after most youth leagues implemented tackling restrictions in practice and adopted “new” (though not really new) tackling techniques intended to reduce impacts and improve safety in the sport. In fact, the study authors stated that the tackle football players were originally divided into groups to study two different tackling techniques and the use of robotic dummies for tackling practice, but there were not differences between the groups using these techniques. As a result, they chose to group them all together in this study to compare tackle to flag football. That is consistent with other studies that showing minimal effects of different tackling techniques in youth football. While better technique may have some benefit, especially at older ages when athletes have better body control, the only way to avoid repetitive brain trauma is to avoid impacts.

I want to be very clear that I am all for kids playing sports. We shouldn’t be eliminating tackle football without substituting a non-contact version of the game. And it isn’t about eliminating football, just the tackling aspect of the game at younger ages. Much of the sport remains the same, with the key difference being how the play ends. Youth players can learn a lot about the game and develop football skills and athleticism without tackling. Unfortunately, many communities have limited if any flag football options, leaving athletes and their parents to choose between playing tackle football or not playing at all. Additionally, rules need to be enforced in flag football to ensure it doesn’t just become tackle without padding.

There is no downside to playing flag football before high school. Many arguments have been made for why kids need to tackle young, and none of them hold water. I have a whole section of my book dedicated to busting these myths, but here are a few examples: You don’t have to hit young to earn a scholarship or become a superstar. Many great players, including Tom Brady, didn’t start playing tackle football until high school. Waiting to start tackling until an older age does not increase the risk of injury when the athlete does start tackling. Participation numbers won’t suffer if kids aren’t tackling. In fact, after USA Hockey eliminated checking before age 13, participation in the sport skyrocketed. And there is no evidence that children will fall behind or high school teams won’t be successful if their feeder programs don’t tackle.

Flag football is a great way to promote physical activity and all of the wonderful benefits of sports without a high number of repetitive impacts and brain trauma. Ultimately, we should be doing everything we can to promote sport participation while also protecting children’s developing brains.

Can a new blood test diagnose a concussion?

The FDA recently gave clearance for a new rapid blood test for mild traumatic brain injuries, or concussions. In media articles this new test has been touted as “game changing” for evaluating concussions. But can the test really diagnose a concussion on the sidelines? I have had a few questions about it, so I want to explain what this new test really means for concussions in athletes.

The new test, from Abbot Laboratories, measures specific proteins in the blood that can be elevated in traumatic brain injuries. Right now, the primary use of this test is in the emergency room to determine whether or not a patient should get a CT scan. This is important because every CT scan exposes the patient to radiation, which can increase the risk of developing cancer. Damage to the brain occurs with a concussion, but traditional medical imaging doesn’t show that damage or any bleeding in the brain in the vast majority of cases. We don’t want to subject patients to radiation when the scan is likely to yield no meaningful findings that would affect patient care. Of course, there are rare occasions where bleeding is present, and the consequences of missing it can be dire.

That’s where this test comes in. The patient undergoes a simple blood draw. A hand-held machine will then process the plasma in the blood, looking for specific proteins that would raise concern. The results are ready in less than 15 minutes. If the protein levels in the blood are normal, the patient likely does not have a brain bleed, and there is no need for a CT scan. As a bonus, it will save patients time waiting in the ER, and a blood test costs substantially less money than a CT scan.

What does this mean for concussions in athletes? At this point, not much. The test is only approved for individuals ages 18 or older. There is some evidence that the protein levels in the blood may be different in children following concussions or other traumatic injury compared to adults. The developing brain is undergoing a variety of processes and changes, and it doesn’t always react the same way as the adult brain to environmental factors, such as a head impact. At the youth and high school level, it would be difficult to do a blood draw on the sideline. The test also requires the plasma to be separated from the blood before being tested in the handheld machine, which requires special equipment. As a result, this test is really only useful in the hospital (and potentially clinic) setting to rule out the need for a CT scan. It isn’t a tool that could be used to diagnose a sports-related concussion on the sideline.

It’s also important to know that we have a lot to learn about these blood biomarkers in the brain when it comes to diagnosing concussions in sports. At this point, having normal levels of these proteins in the blood does not necessarily mean a patient doesn’t have a concussion. They simply may not have enough damage to the brain to cause substantially increased levels of these proteins in the blood. Research has shown that these markers tend to be particularly high in patients who lost consciousness or have post-traumatic amnesia, but only about ten percent of concussions result in a loss of consciousness, and amnesia is not a common symptom either. It is critical that clinicians consider the entire clinical picture, including the patients symptoms and other potential signs of a concussion.

Despite these current limitations, there is great promise for a sideline concussion blood test in the future. Right now we have to rely primarily on the patient disclosing their symptoms, and many athletes hide their concussion symptoms in order to stay in the game. Research is investigating the proteins examined in this test as well as other proteins in the blood that might indicate that an athlete has a concussion. It is very likely that athletic trainers and team doctors will someday be able to use a finger-prick blood test with a handheld sideline device to diagnose a concussion in minutes, or even seconds. Other research is looking into saliva tests to diagnose concussions.

This biomarker research could lead to advancements beyond simply diagnosing concussions. Studies have shown that blood protein levels shortly after the injury may predict who will have a prolonged recovery. Another challenging aspect of concussion management is knowing when the athlete is ready to return to play. Like diagnosing a concussion, readiness to return to play is typically determined based on the athlete’s symptoms. An athlete could claim their symptoms have resolved before they really have so they can return to play as soon as possible. Certain proteins in the blood may remain elevated as the brain is healing, and following the levels of these proteins over the days or weeks following the concussion could give us insight as to when the brain has healed and it is safe for the athlete to return to play.

This new test is a step in the right direction, and it has the potential to have great benefit in the emergency room. While the science has come a long way, it just hasn’t hit the finish line yet. We have more work to do before we can use this type of test becomes a regular part of a sideline concussion evaluation.

Is rugby-style tackling effective in reducing the number and force of hits in football players?

A new study presented at the American Academy of Neurology Sports Concussion Conference yesterday found that the frequency and force of impacts was lower with rugby-style tackling compared to football tackling. At first glance, this like a great thing, given that rugby-style, heads-up, lead with the shoulder tackling is being taught more commonly in football today. But what do the findings of this research really mean for the safety of heads-up tackling in American football? Not much.

The study compared hits happening in athletes playing rugby to hits happening in athletes playing football. This is an important point that isn’t made clear in the reporting on the study. Rugby and football have similarities, but they are different games.

Rugby players don’t wear helmets or pads, so the big collisions hurt more than they do in a fully-padded football player. They also can’t use their helmet as a weapon, since they aren’t wearing one. For these reasons, some people have suggested that safety in football would be improved if the athletes didn’t wear this protective equipment.

The findings of this study do support the idea that rugby-style tackling without helmets and padding while playing rugby results in fewer hits and hits of a lower force than tackling while playing football.

The study does not, however, say anything about the effect of using heads-up tackling in football. Researchers would need to examine the hits in football players taught traditional tackling techniques compared to football players taught the rugby-style tackling technique in order to determine if the rugby-style tackling actually making a meaningful difference in football head impacts. It’s possible that the padded and helmeted football players still hit hard, even if they are using this “safer” technique.

One other issue of concern is the use of mouth guard impact sensors used to measure the number and force of the impacts in this study. Though the technology has improved, the accuracy of these types of sensors have been questioned in the past. According to the study, the rugby players had an average impact of 21g (linear acceleration, or acceleration in one, straight-line direction, measured as g-force). The football players experienced impacts with an average of 63g. This is way higher than findings from most other studies of head impacts in football, where the average tends to be between 19-25g. It seems odd that the average force of impact in football players is so high in this study.

While teaching rugby-style tackling in football is likely an improvement on the status quo, we don’t yet know if it results in meaningful differences in head impacts in the sport. Other research presented at the AAN Sport Concussion Conference showed that teaching tackling without helmets in practice led to a decrease in head impacts in games early in the season. However, by the end of the season the football players experienced the same number of head impacts in games as those who practiced with helmets.

Although the findings of this study on tackling techniques are intriguing, we need more research to understand whether or not rugby-style tackling has a positive effect on the number and force of impacts in American football, and, ultimately, the safety of the game.

Your Brain Doesn't Know What Hits It: Repeated Brain Trauma in Performers

Did you know that chronic traumatic encephalopathy (CTE) has been diagnosed in a clown repeatedly shot out of a cannon?

Though CTE is more widely known as a disease that can affect contact sport athletes who experience repeated hits to the head, this unique CTE case was published In 1996. Williams and Tannenberg described evidence of the disease in the brain of a 33-year-old former circus clown. He was achondroplastic dwarf with a history of alcohol abuse. The performer experienced repeated brain trauma for years as he was repeatedly shot out of a circus cannon and through his participation in “dwarf-throwing” events (yes, it is as bad as it sounds).

The issue of repeated brain injuries in stunt performers was brought to light again in a recent article out of British Columbia. In a survey by the Union of British Columbia Performers, 44% of respondents reported suffering one or more concussions in their career, with 14% suffering 3 or more concussions. On top of these injuries, routine falls with controlled landings, as are often performed repeatedly in rehearsals and filming, can cause similar forces on their brain to those experienced by American football players.

Yet, most performers, like athletes, don’t report their injuries. Understandably, many are concerned that they will lose their job if they are unable to perform their stunts due to a concussion. The cumulative effect of these repeated hits and mismanagement of concussions can lead to long-term consequences for stunt performers.

Ultimately, your brain can’t tell the difference between a collision in football, heading a soccer ball, your head hitting the pavement with a helmet on, or the landing after being shot out of a cannon. It just knows it is being jostled, stretched, and traumatized as it’s thrown around within the skull. Your brain doesn’t know what hits it.