From Little League to college football to
the World Cup, sports is a huge industry.
We play on neighborhood teams as kids, root
for our favorite professional athletes, and
buy millions of dollars’ worth of branded
merchandise each year.
But even if you don’t personally care what
the next big sportsball thing is,
you’ve probably heard about what’s
happening with head injuries
causing dementia in football players.
When I say “football,”
I mostly mean American football,
because that’s what most of the news
and research has been about.
But it’s not just the NFL that has the problem.
We’re learning that concussions from soccer,
aka football for most of the world,
can lead to dementia, too.
And there are serious injuries that
come with all kinds of other sports
that have only recently been taken seriously.
We know that physical activity is super important
for staying healthy, so it’s pretty great
that our society values athletic achievement.
But sports-related injuries are expensive,
painful, and can have lifelong effects,
some of which we’re only just discovering now.
Some researchers are starting to
think that for some sports,
the risk of injury could outweigh
the benefits of playing.
But giving up on sports or completely
changing the way games are played
isn’t really a practical solution.
Football isn’t just gonna disappear, and
most people wouldn’t want it to.
So researchers, coaches, and doctors
have two main priorities:
learning as much about the effects
of sports injuries as we can,
and finding ways to protect players without
completely changing how the game works.
When it comes to risky sports, American football
has been the big one in the research so far.
It’s a high-contact sport where players
are prone to all kinds of injuries.
But even though there have been professional
leagues since 1892, it’s only in the last
25 years that doctors have really begun to
examine what’s happening to players’ heads.
And they’re becoming increasingly concerned
about the relationship between head injuries
and a neurodegenerative disease called chronic
traumatic encephalopathy, or CTE.
It’s chronic because it’s long-term, traumatic
because it comes from physical trauma,
and encephalopathy just means “brain disease.”
But as brain diseases go, it’s a bad one.
Symptoms range from confusion and disorientation
to memory loss, speech disorders,
impulsive behavior, depression, and suicidality.
Essentially, it’s a form of dementia, but
it shows up much earlier than most other types,
usually when the person is in their 40s or 50s.
And it seems to be caused
by repetitive head injuries.
The thing is, head injuries happen
all the time in football.
A major part of the sport literally involves
slamming people to the ground.
And, as we know from our
good friend Isaac Newton’s first law,
things in motion want to stay in motion.
So when the motion of your head is suddenly stopped,
like when it slams against another player’s
knee as you dive for a fumbled ball,
the inertia of your brain keeps it moving
forward … until it hits your skull.
You have some fluid in there to cushion your
brain against normal jostling,
but it can only do so much protecting.
If a hit is hard enough, the brain literally
rattles around inside the skull,
which can bang up, stretch,
and even break brain cells,
interrupting their normal blood flow
and chemical signaling.
That’s what we call a concussion,
and it can take a month for the brain
to get things back in order afterward.
Now, it’s not like anyone thought head injuries
were good for people.
But the effects were believed
to be somewhat short-term.
Then retiring NFL players started
describing something else:
lasting disabilities from head injuries
they’d received on the field.
Growing concerns led the NFL to create the
Mild Traumatic Brain Injury Committee in 1994.
Its main goal was to make sure that players
were immediately assessed
and treated for possible concussions.
That was a start, but the NFL still
argued that the so-called
“concussion issue” was being
overblown by the media.
Then, in 2002, a doctor discovered CTE in
the brain of a football player who’d died.
People were skeptical at first, including
But over time, researchers discovered more
and more cases of football players with CTE.
At first, they thought it was just concussions
that were the problem.
But we now know that any kind of repetitive
head injury can cause CTE.
And evidence suggests that it’s really common
in NFL players.
For example, a 2017 study looked at
the brains of 111 former NFL players
and found that 110 of them,
99%! had evidence of CTE.
Since the brains were donated, the sample
was super biased towards players with suspected
CTE or similar brain damage, but that’s
still about a tenth of all NFL players who
died since the study began in 2008.
So at the very least, about a tenth of NFL
players end up with CTE.
At most, close to 100% of them do.
Researchers think CTE happens because players
receive so many hard hits that their neurons
don’t get the chance to recover after an
injury before the next trauma.
So cells become irreversibly damaged, or even
die, making the brain atrophy and shrink.
It can take years or even decades
for CTE to fully manifest,
but there’s no way to detect it early on,
when interventions could be most helpful.
Doctors diagnose CTE by looking for what are
known as hyperphosphorylated tau proteins,
which also show up in other degenerative conditions
like Alzheimer’s disease.
And you can’t just open up someone’s brain
to examine their proteins while they’re alive,
so they can only diagnose it postmortem.
Normally, tau proteins help stabilize the
structural proteins within cells.
But hyperphosphorylation changes their molecular
structure in a way that makes them tangle up
and get in the way of normal cell functioning,
eventually killing cells.
Kill enough brain cells, and the person ends
up with dementia.
In the past decade, the NFL has changed some
rules to prevent at least some concussions,
and it has a whole set of
requirements players have to meet
before they can start playing again
if they do get one.
But concussions still happen all of the time,
and the guidelines don’t help with
other hard hits to the head.
Meanwhile, the increased awareness
of the condition has led to
doctors noticing it in other sports, too.
CTE has been seen in
mixed martial arts fighters, hockey players,
soccer and rugby, and even
in professional wrestlers!
And most recently, researchers have found
evidence for it in kids.
A 2018 study in the journal Brain examined, well,
the brains of eight teenage athletes with
histories of concussions that died young.
And the researchers found that one in four
had those distinctive tau proteins,
the signs of degenerative damage.
The others had signs of inflammation
and damaged brain cells;
the kinds of things believed to lead to CTE.
So it’s possible that the beginning stages
of CTE can start really early on,
from just a few hits to the head.
You might think it would be easier for younger
athletes to go for sports with less
like cheerleading or gymnastics.
But they can carry significant injury risks,
In the US, cheerleading is second only to
football in the amount of money spent
on student athlete insurance claims.
From 1990 to 2002, over 200,000 kids were
treated in hospitals for cheerleading injuries.
And a study from 2009-2014 found that the
most common cheerleading injuries,
about a third of them, were,
you guessed it: concussions.
Cheerleading is dangerous enough that the American Association of Cheerleading Coaches and
Administrators developed a whole set of
rules meant to protect athletes back in 1984.
But even with oversight,
sports can cause lasting injuries
when athletes are pressured to start young.
Take gymnastics, for example.
Since being small has a ton of advantages
when it comes to the physics of twists and flips,
gymnasts tend to specialize in the
sport when they’re very young.
Specialization means more training,
for longer periods,
with more targeted kinds of exercises and goals.
It also increases an athlete’s risk of both
sudden onset injuries, like sprained ankles,
and overuse injuries, like tendonitis,
where the tissue connecting bones
and muscles gets irritated or inflamed.
Landing hard on thin mats over and over again
can also cause stress fractures in your legs,
as well as injuries in your wrists, knees,
back, and ankles.
While getting a sprain or tendonitis once
might not seem like that big of a deal,
research has found that more than 40%
of people with these kinds of injuries
develop chronic conditions like
osteoarthritis down the line.
That’s a painful degeneration of the cartilage
cushion between joints.
They can also lead to osteoporosis, fragile
bone tissue that’s prone to breaking.
And because yes, there are more problems,
there’s research suggesting younger athletes
have more spinal abnormalities from
repeated stress on their growing bones,
making them at higher risk
for chronic pain as adults.
That’s a lot of potential health problems.
And it’s not like specialization and overly-intense
training are limited to gymnasts.
Kids as young as 8 and 9 can need surgery
for damaged elbow
ligaments from pitching too much
while playing baseball.
And some overuse injuries are so common that
they’re named after the sports that cause them,
like swimmer’s shoulder or runner’s
There’s no easy solution to any of this.
But the good news is, all this knowledge
about sports injuries is starting to
change how we approach physical activities.
Injuries that might have slipped under the
radar in the past are now being noticed and
treated sooner, before they become irreversible.
And research into the long-term
consequences of injuries,
like what’s been done on head trauma and CTE,
is helping develop better training
guidelines that protect athletes.
For kids, for example, the American Academy
of Pediatrics’ official recommendations
say that they should train for fun and social
interaction, not for intense contests.
Then, competitiveness can
ramp up as they get older
because their bodies can
handle more once they’re more mature.
Which, okay, these guidelines are meant for
pediatricians, not parents.
But what doctors tell parents and coaches
can change the way we approach this stuff.
The AAP also recommends playing a bunch of
different sports instead of focusing on just
one, because that reduces the injury risks
that come with specialization.
And research suggests that early
specialization isn’t necessary
for athletic success later in life, anyways,
so there’s not really any reason to do it.
But what about adults, especially when it
comes to CTE?
Well, it helps that we’re developing better
tools of the trade.
Sports engineers are using the latest research
to build better sports equipment,
like safer helmets.
But even the best equipment isn’t going
to prevent all injuries.
So the other part of the solution is to try
to make the sports themselves safer.
Some organizations have already changed some rules,
like in 2010 when the NFL started forbidding
certain kinds of hits to the head and neck.
But there are definitely more changes that
could be made to reduce injuries,
like developing better techniques,
safer tackling methods, for example.
Having more severe punishments
for players who do things that are
deliberately dangerous would probably help too.
Still, there’s no perfect or easy way to
If there’s anything we’ve learned from
the last decade’s worth of research on sports
injuries, though, it’s how much we don’t
And with more research into the ways these injuries happen,
hopefully we’ll also find out
more ways to prevent them.
Because yeah, sports are great, and we’re
gonna keep playing them.
But nobody one wants people hurting themselves.
Thanks for watching this episode of SciShow!
SciShow is produced by Complexly, a group
of people with a shared thirst for knowledge.
You might already be familiar with some of
our other channels, like Crash Course.
And if you liked this video, you might want
to check out our show Healthcare Triage, where
Dr. Aaron Carroll gives you the rundown on
all things medical science,
from the opioid crisis to the truth about cancer risk.
Just head over to youtube.com/healthcaretriage
to learn more.