Heading in youth soccer: what the science says

Recently, the United States Soccer Federation (USSF) released a report advising the elimination of heading in soccer for kids under the age of 10. And recommends that full-contact heading not be allowed till athletes get to 16 years of age.

Now, while everyone is on board with the idea that player safety is very important, particularly that of children and young adults, there has been much debate over whether the guidelines would benefit athletes and soccer in the long-term.

Let me start by saying that I believe that concussions in soccer are a serious, serious, serious, serious, serious, serious, serious concern. Is that serious enough? I believe that concussions are currently being managed incorrectly by the Football Associations and FIFA. And that things need to change rapidly so that our soccer players can live a healthy life after they retire. However, today, we will be focusing on the topic of concussions in youth soccer players.

While one can have a myriad of personal opinions on this topic, and certainly, I do, too (I'll discuss those later), the majority of this post will look at what the scientific literature says re: Heading in youth soccer. I understand that many do not have access to the articles I'm citing here, so I will link to the abstract (which is available to all), and if you are interested in a particular article, tweet at me, and I'll send it to you.

1. Can heading the ball lead to concussions in high school players?

Yes. It isn't the most common form of concussive injury in youth soccer players, but, it is certainly possible (Cornstock et al, 2015 ). However, what this study does not look at  is HOW those ball-to-head related concussions were procured. That is a key caveat to this study.

There is another study that suggests that zero concussions were produced by heading the ball correctly, and all were a result of the ball striking an unprepared player at close distance (Boden, 1998) .

2. Can heading the ball lead to concussions in youth soccer players?

Doesn't seem like it. Here's a key excerpt from a book chapter  ---

"Dr. Kirkendall . . . calculated the impact of a soccer ball on the head of youths of various sizes, based on the likely speed of the ball, and concluded that the force of impact is well below the force that is thought to be necessary to cause a concussion in heading a soccer ball." --- Dr. Donald Kirkendall, Causes of head injuries in soccer .

Even in U14's soccer, there is likely not enough ball velocity to cause concussion (Hanlon and Bir, 2012) .

A meta-analysis (looking at various studies between athletes 10-24) suggested heading the ball was unlikely to cause injuries (Pickett et al., 2005).

Essentially, those kids do not kick the ball hard enough to cause the G-forces (acceleration forces) to result in concussive injuries.

3. What about subconcussive injuries from heading?

In order to answer this, a quick primer on subconcussive injuries: It is an emerging area of research that suggests that repeated impact to the brain can result in brain damage, even though concussion hasn't occurred. The problem with studying subconcussive injuries is - how do you tell if someone has one? Neuroscience tackles this in a couple of ways. Firstly, we have identified certain biomarkers (biological red flags) to suggest if someone is exhibiting hallmarks of disease. The second technique is to look at behavioral tests that suggest whether someone is cognitively impaired. The assumption being, in both cases, if subconcussive injuries have occurred, there will be a biological (biomarker) and/or behavioral (neurocognitive) change.

Coming back to the original question. Most literature suggests that heading the ball does NOT lead to changes in biomarkers/neurocognition. These can be found here --- Kontos et al. (2011), Stephens et al. (2005), Kaminski et al. (2007), Broglio et al. (2004), Guskiewicz et al. (2002) and others.

But, this study, does suggest that a cognitive change may occur - Zhang et al. (2013) . I have to state a caveat - this Zhang study is poor. The effect size (how different the soccer-playing and non-soccer-playing groups were from each other) is very small. For my science friends - they set a non-one sided gaussian t-test alpha of 0.1, which is an immediate red flag. For my non-science friends - I think the effect they observe is not worth believing.

4. Okay, that's a lot of words. What's the gist?

Currently, a preponderance of the literature does not support the idea that heading the ball leads to subconcussive injuries in youth (kids - high school) soccer players.

5. Is that a definitive no then?

Not quite. You see, the work surround subconcussive injuries is nascent. And, as such, has caveats. For example, some of the behavioral tests and biomarker tests need further validation. Therefore, it is theoretically possible that subconcussive injuries ARE occurring, but our tests aren't well enough designed to detect them... just yet.

6. What about the report of the kid who almost died after heading the ball?

That's a real report. That happened a few years ago, and no one has contradicted the young man's claim that his subdural hematoma (potentially fatal bleed in the brain) was the result of a single header (Lutfi et al., 2009). My concern is that the report says he headed the goalkick with the "front" of his head. I am not sure if this means with his forehead (which would be the correct way to head the ball), or with the top of the head (incorrect, and unfortunately seen in young soccer players who haven't practiced heading).

7. What about player to player contact?

Yes, this often is the culprit for concussions. Most of the articles I've linked to above suggests the same. These injuries can be a result of two players going for a header, or accidental contact with one player's knee, while the other is on the ground, etc. There are a myriad of ways that player to player contact can result in head injury and concussion.

Head to head injury is a serious concern

Okay, now we are going away from the realm of scientific literature into my own opinion (using the literature I've read as a basis, of course)

8. So, what's the solution?

In my opinion, there should be a serious punishment for serious player to player contact. In the last 3-4 years, the concept of "out of control" tackling has come into play.

You see, while I was growing up, the definition of a good tackle was "getting the ball". If a player got the ball before he made contact with the player, it was deemed a good tackle - regardless of whether this involved excessive force or injury to the opposing player. However, now, even if a player wins the ball, if he comes in with excessive force, tackles from behind or uses two-feet, the referee usually punishes the tackler with a red card (FIFA, law 12) . Why? Because all of those conditions are optimal for causing injury.

Similarly, excessive force, using elbows, out of control contact with an opposing player's head (knee-head, for example) should be deemed dangerous play, and therefore a red card. This would result in players being careful of so-called 50-50 balls, and wary of using their elbows as leverage.

9. But, what about heading itself?

I respect people's opinion who think "well, removing heading in youth players won't hurt". But, in my opinion, having young kids learn how to head the ball early would lead to developing the appropriate neck muscles needed (Gutierrez et al., 2014) to prevent head injury in the future. If heading the ball isn't being introduced to them until they are 14, this may lead to an INCREASE in the number of concussions. Because, by the time they're 14, they are kicking the ball much harder, and have yet to learn the basics of heading.

Incorrect way to head the ball. (Image via http://hubpages.com/sports/Soccer-Head-Injuries-in-Children-Brain-Damage-from-Heading)

10. To summarize:

1. Preponderance of scientific literature does not support the idea that heading can lead to concussions or subconcussive injuries in soccer players.
2. More work needs to be done.
3. In order to minimize concussion, new rules regarding player contact need to be made.

Day 2 of SFN - Crashing helmets on Stampede Sunday

Stampede Sunday, as I like to call it, was as packed as it is each year. 

There was lots of cool science to talk about and cool scientists to talk about it with. Here with the highlights ---

1. Hendrix (DD56) – Her aim was to raise awareness for her local “brain awareness day”. She was able to do by promoting via social media and designing flyers. She also talked about having visited Capitol Hill and talking to policy-makers about the changing funding climate. Basically, Ms. Hendrix is an advocate for both neuroscience and neuroscientists. We need more people like her. Follow her @RDHendrix.

2. Brager (DD38) – a fellow blogger, her poster showed that cryotherapy increases both the amount as well as the quality of sleep in athletes. Sleep remains an underappreciated area of neuroscience and I saw some other cool work looking at sleep disruption in rodent models. Brager’s work was particularly fascinating because it was in athletes; something many of us ex-athletes can appreciate. Basically - those ice baths are really, really important for recovery. And, if possible, a cryo chambers is even better. 

3. Whitesall (D31) – Working at the Allen Institute, Ms. Whitesall’s work looked at Default Mode Network (DMN) in the mouse brain. In recent years, the idea of the Default Mode – essentially, the baseline of your brain activity – has become apparent. It makes for both interesting science, as well as interesting science fiction. Whitesall’s work hypothesizes that the brain regions comprising the DMN may be one of the first to perturbed in Alzhiemer’s Disease. She will test whether this is true in an AD transgenic mouse line.

4. Kawarabayashi – Looking at tg mice models, they found that PrPc, Abeta mono and dimers, Fyn, NMDA, GSK3beta and pTau all localized in lipid rafts! This ties in both the possible involvement of lipid rafts in AD, as well as seemed to support the amyloid hypothesis.

5. Graham (C87) – Western diet in APP/PS1 mice increases A-beta load and TREM2 activation. TREM2 is the new baby in the AD field, and there will be a lot of work on it. And, as for western diet, STOP BEING SUCH FATTIES, YOU GUYS. And, by you, i mean, me.

6. Brkic (C86) – Omega-3-Fatty Acids have beneficial effects on brain of AD mice – by reducing amyloid plaque burden. There was recently a longitudinal study that determined that fish oil showed no benefit for cognition in AD patients. Brkic informed me that she thought that study was done with patients who has advanced AD, and therefore, an amelioration of symptoms would have been lost in the noise of progressed neurodegeneration. I agree with her. Most AD therapies should be looking at helping decelerate the pathology in mild cognitive impairment patients, in my opinion.

7. Colello (C91) – This was my favorite poster of the day. Their group decided to address the issue of the g-forces experienced by helmet to helmet collisions in football players. They posit doing so by placing repulsive magnets in the helmet of players. This would lead to the generation of a repulsive force that would reduce the g-forces. Their proof of concept suggests that they are able to reduce g-forces (measured by accelerometers) in a rig where they are essentially crashing two helmets together. This is fascinating work! And, a perfect example of how invention often come from people who cross disciplines.

Lunch

All the places close by were closed! Stampede Sunday is the worst. I ate a sandwich from a grocery store. It was awful.

Afternoon sesh

I spent the entire time presenting the boss-man's poster.

What were your highlights from today? My poster is tomorrow (Afternoon session, D25). Stop by and say hi!

Day 1 - Soccer in the morning, Neuroscience all afternoon

I started the day early, in order to attend a couple of networking sessions and to watch soccer, in peace, on my laptop. Luckily, the team I support - Manchester United - won comfortably, which ensured that I was in an amicable mood all day.

While watching United play, I met Dr. Ferchmin, who informed me that he has been attending SFN conferences since the mid-70s. And, that's pretty neat. He must have watched, first-hand, some of the breakthrough work, particularly in the mid-90s - when neuroscience hit it's first boom.


Morning session
The official "kickoff" ceremony for SFN this year was a lecture by Judge Jed (his name is suspiciously similar to Judge Dredd)

Judge Jed? Dredd? Jredd?

Judge Jed Rakoff discussed the relevance and somewhat uncomfortable relationship between neuroscience and the judiciary. He cited the history of eugenics, Freudian idealogies, lobotomies, etc. to underline the necessity for a skeptical look at what neuroscience tells us.

Personally, I believe that Judge Rakoff may have conflated some history that is more relevant to psychology than it is to neuroscience, but his overall point is still valid. Science is not a perfect machine. Things that we consider to be true today, may be experimentally precluded in 5 years. However, the necessity to commit to neuroscience - as a self-correcting discipline - is essential. And, I think Judge Rakoff did a commendable job of reiterating that fact. Especially, since he was sitting in a room of neuroscientists - who would not have been pleased to hear him tear down their life's work!

Lunch

Overpriced, overrated.

Afternoon session
I was excited to run in to my friends from the On Your Mind podcast on the way to the poster session. Kathryn and Liam are two Canadian neuroscientists who started this podcast about 2 years ago. The podcast starts with a discussion about current topics in neuroscience, and ends with a discussion of an interesting neuroscience paper. They often have great guests who bring their own interests to the table, thereby increasing the list of topics covered. I highly recommend you check them out.

In between limping through poster sessions, I found the following posters worth highlighting (I apologize if I misspelled any of your names; my handwriting is horrible) ---

1. Teneka Jean-Louis (#B90) - Prostaglandins impair APP glycosylation. The Post-translational modification of APP, in my opinion, is an area of research that requires much more understanding. As, many of you are aware, APP is the protein from which A-beta is excised.

2. Caverly (#B93?) - While they did not manage to address their primary hypothesis, they found that buffering A-beta does improve memory in Alzheimer's transgenic mice. ONE FOR THE AMYLOID HYPOTHESIS!

3. Bachsetter (#B109) - Microglia in human AD brain are very different - in terms of morphology and biomarkers. This is important because we often tend to treat microglia as one homogeneous population. And, their group shows that they are not.

4. Harach (#C27) - This was my favorite poster of the day! They suggest that our gut microbiota may play a role in generating AD pathology. They are not sure of the mechanism, but, they believe that it is related to inflammation.

5. Moore (#D12) - They found that athletes with a history of concussion exhibited alterations in EEG signature. While this is not surprising, they found that these abnormalities extended longer than the recommended "Grace period" for athletes. Therefore, it's possible that when we tell athletes that they need to take 2 weeks off after a concussion, that may NOT be long enough.

6. Kitko (DP02) - Using quantum dots as a way to improve in vivo visualization. I'll admit, I didn't quite understand the details of this, but it definitely looked cool! One for the biophysicists.

7. Moses (G27) - Addicts who performed well on a memory task, seemed to have a better ability to abstain from drug relapse. A bit paradoxical to me - I always assumed that memory triggers would be a key reason behind drug relapse, and therefore, a reduction in memory recall would be beneficial to treating addiction. Goes to show - our intuition isn't always correct, and mine wasn't in this case.



What did YOU enjoy today? Let me know if you'd like for me to stop by your poster/symposia tomorrow. Enjoy your Saturday in Chicago!