Youth Sports and Brain Safety: Which sports carry the greatest risk for the brain?

Our understanding of the consequences of brain trauma in sports, both concussive and repetitive "subconcussive" trauma, has grown immensely over the last two decades. With that has come growing concern from parents about the safety of their children playing sports.

Sports have so many benefits for children in a variety of areas, including physical and mental health, academics, and social life. Youth sports are a great venue for learning life skills, such as grit, determination, discipline, persistence, and teamwork. Every child should have the opportunity to reap the benefits of playing sports.

But which sports are the safest for a child's developing brain? And how can we make high-risk sports safer?

Concussion Risk

First and foremost, it is important to say that no sport or activity is without risk. Accidents happen, and concussions can happen in any sport or other activities in life. Yet, some sports come with a higher concussion risk than others due to the nature of the sport itself.

In the United States, football is consistently the sport with the highest overall number and rate of concussions. This is true across all levels of play. Each season, around one in twenty youth players under age 14 sustain a concussion each season. Nearly 100,000 youth and 80,000 high school football players sustain a concussion each year.

Other sports carry relatively high concussion risks. Though hockey is often second to football among common sports in the United States, rates have declined over the last decade as a result of a ban on checking in the boy’s game before age thirteen. Soccer falls just behind hockey in most studies, but it is the sport with the highest rate of concussions for females at all levels. Concussion rates in lacrosse, wrestling, and competitive cheerleading are also concerning. Rugby is popular internationally and a growing sport in the in the United States, and it carries a concussion risk similar to football.

A few studies have found higher concussion rates in girls’ soccer or hockey than football, but those are in the minority. The vast majority of concussion epidemiology studies show football has the highest concussion rate. But ultimately, those details don't matter. One sport carrying dangers for the brain doesn’t somehow make another sport safe. All of these sports carry a higher concussion risk, and we should be taking steps to improve brain safety in all of them.

Repetitive "Subconcussive" Impacts

A growing body of research shows that repetitive brain trauma causes changes in the brain over the course of a season and career, regardless of whether or not those impacts result in concussion symptoms. These impacts are sometimes called “subconcussive.” Chronic traumatic encephalopathy (CTE) has been diagnosed in individuals with no known history of concussions but who were exposed to repetitive subconcussive impacts through sports or other exposures. (Though it is important to note that many concussions go undiagnosed, and it is possible, if not likely, that some of those individuals sustained concussions that were never reported.)

Which sports carry the greatest risk for repetitive impacts? I have a chapter of my book dedicated to head impact exposure in sports. Here’s a brief summary to address this question:

Research using accelerometers placed in helmets, mouth guards, patches, or headgear have given us valuable insight into the number and force of impacts athletes sustain in their sport. Football carries the highest average risk for repetitive brain trauma in athletes in the United States. The average high school and college football player experiences hundreds of impacts over the course of a season. In fact, it is common for some athletes studied to have sustained over 1000 impacts, with a few incurring over 2000 impacts in just one season. At the high school level, it is more common for athletes to play both offense and defense, greatly increasing impact exposure. Linemen tend to have higher overall impact numbers, while wide receivers and defensive backs tend to experience higher-magnitude impacts.

You might think that smaller, slower youth athletes can’t hit that much or that hard, but that isn’t true. Youth football players ages 9 to 14 average 200-300 impacts per season, with several experiencing hundreds more. Even the youngest players average over 100 impacts per season. This is despite the fact that the average youth season involves far fewer practices and games than the college or high school season. These impacts are of similar magnitudes to those experienced by the older players, despite their smaller size. This may be because a child’s head grows quickly, making it disproportionately larger than the rest of their body. Like a bobblehead doll, their smaller, weaker necks have a difficult time stabilizing their head, and the weight of a helmet makes this effect even worse.

Though less than football players on average, hockey players can also experience hundreds of impacts each season, including many high-force impacts. Studies of soccer impacts suggest that hits are less frequent overall compared to hockey and football, but they can still exceed 100 in a season. These studies may also be deceiving, given how common it is for soccer players to play year-round and in multiple leagues at the same time. There is limited research on other sports like rugby and lacrosse, especially at the youth level, but early evidence suggests that they tend to expose athletes to impacts at similar levels as football and hockey.

Which sports are safe for the brain?

There are many non-contact or limited contact sports that don’t involve repetitive impacts and carry lower concussion risks. Concussions can still happen in any sport, including basketball, softball, baseball, or volleyball, but the repetitive subconcussive impacts aren’t part of those sports.

For contact sports, the numbers I just presented are concerning, but that doesn’t mean we should be eliminating or avoiding sports like football, hockey, soccer, and rugby altogether. Instead, there are ways to enjoy these sports without the repetitive impacts and high concussion risk. Alternative versions of these sports, or versions with specific rules for the youth level, can be great ways to get kids involved in sports without the greater risk to their brain.

Hockey has banned checking prior to age 13, and concussion rates, as well as overall injuries, have dropped since. Soccer delayed the introduction of heading until age 11, and limited it until age 13. While age 11 may still be early to introduce heading, the delay is a step in the right direction. As I described in an earlier blog post, flag football players experience substantially fewer impacts than tackle football players, while still learning about the game and developing football skills. Other non-tackle forms of football, such as TackleBar and Flex Football, can also be great, safer options.

If athletes do start to play the full contact form of these sports, head impact exposure can still be greatly reduced by substantially limiting or completely eliminating checking, heading, or tackling in practice. For example, many elite high school and college teams have chosen to eliminate tackling from most or all practices. The athletes can still successfully tackle in games without practicing on each other, and the athletes tends to stay healthier overall throughout the season. Coaches make the choices about drills and tackling in practice, and they also create the culture of safety, or lack thereof, on the team. Some coaches value brain safety, concussion reporting, and minimizing contact over a season. Other coaches create a culture that discourages athletes from reporting concussions and valuing their health. When rules or laws limit contact practice time, some coaches simply pack as much contact into the limited time as possible, exposing their players to just as many if not more impacts as they experienced prior to the law. Parents and athletes should feel comfortable with the culture around safety created by the coaching staff before joining a team.  

Given the rapid brain development happening in a child’s brain and evidence for potential disruption of these processes, avoiding the full-contact form of high-contact sports before high school is ideal. Though some coaches and leagues may promote “new” and “safer” techniques, the data isn’t there to show these techniques make a meaningful difference in brain safety for youth players. Not only does delaying the introduction of the source of repetitive impacts allow more time for brain development, but it also reduces the overall number of impacts experienced by athletes over their lifetime, which has been linked to long-term cognitive, mood, and behavioral difficulties and the development of CTE. While the risk is not zero, current evidence suggest that only playing a few years of high school football, especially when contact is minimized at the high school level, leaves athletes at low risk of developing CTE.

Brain safety in sports isn't an all-or-nothing issue. With strong measures to eliminate impacts at youth levels, even traditionally high-risk sports can be played in a low-risk way, giving more opportunities for kids to thrive in sports with minimal likelihood of short- and long-term consequences for their brain.

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.

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.