Monday, September 19, 2016

Bike Helmets Cannot Prevent Brain Injuries

Perhaps the most deceptive misconception that bicycle helmet manufacturers and proponents like to see in the media and from public (even if they avoid making the statement themselves) is that bicycle helmets prevent brain injuries. Those who profit from helmet sales and those who genuinely believe they are saving lives by pushing bike helmets often prompt these lies by emphasizing that helmets “can” prevent “head injuries.” Note that a cut to the scalp is a head injury. Brain injuries are different, though most readers don’t make the distinction.

Many supposedly scientific studies readily skew data to force their intended outcome of showing bike helmets do protect brains, but each of these have been debunked, usually finding that deaths were from other causes and data sets were lopsided. But many people simply want to believe that helmets prevent brain damage, even though no such device on the outside of the head can prevent the brain from impacting the inside of the skull. Our brains are suspended in fluid. Upon impact, whether the skull is protected or not, the brain will hit the skull. Simple physics.

Unfortunately, we must look to other activities where helmets have been tried in order to find sincere efforts to question their use or at least effectiveness. Here in the U.S., the National Football League (NFL) has been forced by injured players and their families to admit that no helmet can stop concussions. Instead, they are finally engaging a concussion protocol that takes players out of the game after a blow to their helmeted head.

The article linked in the above paragraph about the NFL notes that there could conceivably be a helmet that lessened brain injury but the design would require 15 inches (38 centimeters) of foam wrapping the entire head. Another potential design could mimic single-use motorcycle helmets – full head, heavy shell – and even their manufactures admit they cannot prevent brain injury. We can safely assume that most cyclists will not want to wear such a helmet, especially since the risk of a cyclist banging their head is no more likely than that of pedestrian’s and far less likely than those is cars.

The latest sport to ditch helmets is boxing. This interests me because I have recently taken up the sport and love it. I learned last week from our coach that we need to focus our punches on our opponent’s head. And yet, the Olympics banned headgear for male boxers this year citing an increase in concussions since headgear was made mandatory. They show that boxers began leading with their head more, similar to studies that show an increase in risky behavior by helmeted cyclists. I also wonder if the increased diameter of the boxers’ heads increased potential for contact, much like a bike helmet increases the chance of a cyclists’ head hitting the ground or the object they collide with.

Let’s hope that bicycle helmet manufacturers and proponents will soon follow American football and Olympic boxing in admitting that their product cannot prevent brain injuries. It’s time for more honesty on this topic!

24 comments:

  1. Bicycle helmets have saved me from serious head injuries twice and I personally will not ride without one. Likewise on a motorcycle!!

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    1. Wear one if you please - no one would even think of trying to stop you from doing so - but there is no way on Earth that you can measure what damage may or may not have occurred if you had not been wearing one at the time of your two incidents.

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    2. You may think that, but have no way to actually prove it. I know you will point to your two incidents as proof, but I could just as easily point to the time I was hit by a car while not wearing a helmet and say that not wearing one saved my life. At the end of the day there is little evidence that helmets actually save lives.

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    3. How do you KNOW they "saved" you?? Did you repeat the impact without the bicycle helmet?

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    4. I have experienced the benefits of a helmet using the bicycle, when a nut wheel bolt of a truck, which went to the side of me, left the wheel and hit the back of my helmet getting embedded in his carbon fiber. Doctors agreed that despite the head injury, if I was not with the helmet would be dead with a nut inside my head.

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    5. Josereimunde, that's an exciting story. I'm sure there are similar stories about backpacks stopping flying objects from piercing hearts and other vital organs. But none of us would even think of shouting at people in the street to ask where their backpack is or demanding laws requiring backpacks.

      If you wear your helmet to stop flying objects, great (actually, hard hats are even better suited for this). If you wear your helmet to prevent cuts and bruises, great. But don't expect your bike helmet to prevent brain injuries.

      And for goodness sake, don't undermine bicycle advocacy by pushing bike helmets as if bicycling is more dangerous than walking (which it is not) and as if bike helmets will protect cyclists in a severe crash (which they cannot).

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    6. Bicycling IS potentially more dangerous. It is just physics. You fall from usually higher position and at ususally much higher speed. Not mentioning reaction times at cetera...

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    7. Actually, statistics show that bicycling is not more dangerous than walking, including head injuries. And car occupants are far more likely to suffer head injuries. Find just a few of the data charts here: http://www.onestreet.org/resources-for-increasing-bicycling/136-bicycle-helmets

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  2. Thanks Henry. Please continue to distinguish your personal impression of comfort and safety while wearing a helmet from the public messages and often mandatory laws passed using misleading information, which is more the focus of this blog. If you feel more comfortable wearing a helmet while riding, by all means do so. But make sure to learn and understand the limited protection your helmet offers.

    You might also be interested in this post: http://www.bikehelmetblog.com/2015/08/my-bike-helmet-saved-my-life.html

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  3. Sue: I had a crash that split the helmet interior foam in five or six places. Went to ER. Lost about three days and pieces of weeks from the hard drive. Had an impact with Mother Earth. Did the helmet prevent the concussion? NO. Did the helmet lessen the severity of the injury. Most probably. There have been other impacts that the helmet mitigated the severity. I am a believer. I always ride with a helmet. Have for years. Have two. A POC brand for the cooler seasons and a better vented helmet for hot weather.

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  4. I like the way you put this, Tom. You're wearing your helmet knowing it won't protect your brain, but that it could prevent some skull injuries. Do read that other post "My Bike Helmet Saved My Life!" linked in my previous comment or to the right for some more details, though. There are injuries caused by helmets, so in some crashes, you'd be better without one.

    Most importantly, once folks understand how limited the protection is that helmets offer and that there is even some danger, they are less likely to push helmets and, even worse, stop happy cyclists and demand where their helmet is. That never happens to car occupants, though they suffer far, far more head and brain injuries than cyclists.

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    1. There are some cases that safety belts in the car can hurt you. It is about balancing the risks.

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  5. Its all these funny storys of people being saved by their helmet. Without a helmet, would you even have hit your head? What you wrote on boxing is interesting: you stop protecting your head, maye even start leading out with your head. Maybe this is a factor for cycling as well, because how the hell does at least every other helmeted person tell me they hit their head and were saved.

    A friend of mine fell off his bike not wearing a helmet and hit the sidewalk edge with his back head. His skull split in two. Since it happened in the Italian countryside it took hours until he got transported to a proper clinic.

    The surgeon later told him that he had never seen a patient with this severe brain injury survive, and it was a result of his broken skull releasing the pressure of the brain swelling. Had he worn a helmet and not broken the skull, he would be dead certainly. I am by no means saying a helmet is completely counterproductive against certain injuries, but in this case it would have been lethal.

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    1. Thanks! These are great points. In fact, this point about non-helmeted riders not hitting their head is one of the main reasons I jumped into this effort to counter misleading bike helmet promotions and laws.

      In the 1980s I worked as a San Francisco bike messenger. For seven winters I rode ten hours a day as hard and fast as I could without a helmet. I hit the pavement hard almost every day - collisions, wet bricks, tracks, avoiding something, keeping that darn lower pedal down on high-speed turns off hills - and I NEVER hit my head!

      As soon as I heard this point from my colleagues fighting bike helmet lies, I was hooked. They explained that even as babies we learn to raise our heads as we fall. But when you add the weight and thickness of a helmet, it forces your head to hit the ground or object. Other lies, deceptive messages, and omitted information are just as disturbing, but this one hit a personal chord with me.

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    2. Hey, don't let the extremes prevail! I'd prefer medical trepanation over sidewalk one anyway.

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  6. My brother was an amateur boxer in the days before headguards, he said that headguards made for more headshots contacting because it was a bigger target, punches that had glancing blows that caught the headguard affected you in so much as twisting your head but without would either have missed altogether or glanced with little impression. he also mentioned lessened visibility/comfort. Also that fighters would go in more all guns blazing with a different style when they started wearing them, basically taking more risks.
    That the boxing world looked at the concussion levels and decided to remove them for some levels of boxing (it should be all IMHO) and put up with more cuts as opposed to more concussions is pretty telling.
    Additionally, my main sport was rugby, no helmets, tough as hell and yet compared to gridiron nothing like the concussions/head injuries. Why, because you are taught how to tackle with your head very much out of the way from when you are barely out of nappies (they teach kids as young as 6/7 to play rugby), because hitting the head even accidentally has ALWAYS been a penalty, since 150 years of the sport. More severe head shots get penalties of players being banned for weeks and fined.
    Personally I've ridden on road for 34 years and never wore a helmet, I've ridden at high speed, I've ridden off road, I've had some offs too but knowing your limitations, learning how to ride, what to avoid, knowing what your bike can and can't do is far far more important than wearing an ineffective 'safety' device.
    I think those in competition should be banned from wearing them, maybe they might actually ride with more respect for each other and for the prevailing conditions and actually crash less. The pro riders of today certainly on the road crash far more frequently than their non helmetted forbears but suffer far more incidents and injuries, it's not difficult to understand why tbh.

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  7. The link behind "studies that show an increase in risky behavior by helmeted cyclists" says the opposite of what you are refering!?
    Seems quite misguiding!

    https://en.wikipedia.org/wiki/Risk_compensation#Bicycle_helmets

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    1. Sorry. Good catch. I read too quickly and thought it included this study: http://pss.sagepub.com/content/early/2016/01/05/0956797615620784.abstract

      I still like the Wikipedia link because it includes many facets of risk compensation.

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  8. Hi I'm generally in 100% agreement with your views on bicycle so called "helmets" but I think you chose the wrong animation above to illustrate brain injuries. If you've read W. J. Curnow's excellent paper "Bicycle helmets: A Scientific Evaluation" he explains quite nicely how the formerly held view of the mechanism for brain injury, namely coup and contre-coup (shown in the animation) first proposed by the Italian researcher Morgagni in 1766 does not accurately model the forces that typically cause injury to the brain. Coup and contre-coup was the prevailing theory explaining brain injuries until the middle of the last century (and is still held by some today)until Cairns & Holbourn's work with motorcycle crash injuries sustained by soldiers during the second world war showed that in the vast majority of cases brain injuries are caused by rotational forces acting on the brain and not linear ones.

    I don't think this is irrelevant because bicycle so called "helmets" can in fact help mitigate linear forces to some minor extent but because of their additional size and other factors of their design they can, and have, increase rotational forces applied to the brain increasing the likelihood in most cases a person will suffer a brain injury should they experience an impact while wearing a bicycle helmet.

    Otherwise keep up the great work.


    Here's one link to Bill Curnow's paper titled Bicycle helmets: A Scientific Evaluation;

    https://books.google.ca/books?id=IlRychZFYwQC&pg=PA139&lpg=PA139&dq=bicycle+helmets+a+scientific+evaluation&source=bl&ots=9s_rixhSg9&sig=8dZrfjFni5gOYLDkgphYWi000T0&hl=en&sa=X&redir_esc=y#v=onepage&q=bicycle%20helmets%20a%20scientific%20evaluation&f=false

    and here's another short article interviewing Charles Tator a leading Canadian neurosurgeon wherein he talks about bicycle helmets and rotational brain injuries also know as Diffuse Axonal Injuries.

    http://www.cbc.ca/news/health/bike-helmets-should-address-concussion-risk-scientists-say-1.1367454


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    1. Thanks Alex. I agree that the graphic is rather basic. I chose it, though, because most people believe that bike helmets prevent brain injury. While it doesn't show the exact motion of the brain within the skull during a crash, it shows that the brain moves and hits the inside of the skull. Most people don't know that.

      I'm glad you have pointed out the further concern of rotational brain injuries, which bike helmets can actually accentuate or even cause when no brain injury would have occurred if the cyclist had not been wearing a helmet.

      Both of these points are generally unknown by those who purchase bike helmets and, most disturbing, by those who promote bike helmets.

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  9. Again I agree with you entirely and I'll read the Curnow paper again this weekend but as I understood it the brain does not strike the inside of the skull (coup and contre-coup) in most instances. As was explained to me our cerebral spinal fluid and our brain matter which is very fluid like are of approximately equal densities and as every good engineer knows fluids are incompressible. As the brain can neither compress nor displace said fluid it would take extreme forces to deform or fracture the skull for the brain to strike bone, forces way way beyond the structural strength of bike helmets. Nature has designed a wonderfully protective case for our brains except when rotational forces come into place, in that case the brain moves laterally pulling at the brain stem and other tissues due to inertial drag as the head spins around it. Bike helmets, unless they are very strong, round, smooth and frictionless tend to make injuries worse than they would have been if an unhelmeted head skipped along the contact surface. It's far better to tear the scalp and hair (is you still have it) than to torsion the head.

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    1. Be careful with correcting this language too much, though. The effect, rather than whether or not brain matter touches bone, is the concern. Read up on concussions, too, especially what the NFL and other sports leagues are discovering. No helmet can stop the force to the brain that occurs within the skull in a collision.

      Also, I have to note that nature actually didn't do such a great job with human heads. Now, if we were talking woodpeckers, that's a different story. Their tongue actually wraps around their brain as they bang on trees! Kinda doubt the helmet manufactures can copy that :).

      Let's also move away from helmets at all. As you note, many crashes would have better results without helmets. But also, bicycling has very few head injuries, about the same as pedestrians. There's no reason to push these pieces of foam anyway, and especially when we realize how ineffective and even harmful they are during a rare crash.

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  10. In the end, why can't we just let the rider decide?

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    1. Exactly. However, we need to ensure that factual information about bike helmets is readily available to everyone who is making that choice. Too many people are wearing these helmets believing they will protect their brains in a crash and not knowing that their helmets could actually contribute to a brain injury if they do crash.

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