Category Archives: Helmets

Barefoot running and cycling

An interesting analogy between barefoot running and cycling:

For years it has been ingrained in to folk that go hill-walking that it
is *essential* to wear “stout footwear with proper ankle support”, with
the latter taken to mean a high lacing cuff and the phrase really
meaning big, stiff hiking boots.

In more recent times folk have started to realise that this is a lot of
tosh, and in fact the literature on foot injuries tells you
counter-intuitive things about how and when feet get injured (like more
often in shoes than barefoot). Such people have started taking to the
hills in sandals and trainers, realising that the human foot isn’t an
evolutionary misfire but is perfectly capable of looking after itself as
long as the user engages in the ancient Zen mind-trick known as “looking
where they’re going”.

But you tell this to the boot die-hards, and they look at the scuffs on
their dreadnoughts and say they prefer intact toes to bloody puddings on
the end of their feet, and how their boots have saved them from terrible
injury etc. etc.

I used to preach the gospel of Big Boots too, but entering a Mountain
Marathon had a curative effect. All these people doing this regularly,
faster and over rougher terrain than I usually do, and hardly a pair of
boots in sight, perhaps they know something I’ve not been accepting?
c.f. cycling trip in Amsterdam and helmets…

This analogy is from by Peter Clinch, from Dundee, Scotland.

I love this part:

the ancient Zen mind-trick known as “looking where they’re going”

This highlights the difference in philosophy between the two groups.

  1. One takes responsibility for being cautious enough to avoid injuries.
  2. The other relies on technology to compensate for higher risk taking.

The belief in the “protection” using shoes is like the belief in the “protection” using helmets:

  • Both appear to “protect”, even though they can result in increased injuries.
  • Both seem so “obvious” than few people question them.
  • Both are harmful in ways that are counter-intuitive.
  • Both have their strong advocates who show a religious faith in them.
  • Both induce a false sense of safety, resulting in increasing risk taking.

In cycling, as the shoulders are much wider than the head, most falls do not result in the head touching the ground. Should it happen, the scalp makes the head slide, reducing friction and rotation. This reduces the risk of brain injury through rotational acceleration.

With a helmet, the larger volume of the head makes it more likely for the head to hit the ground. The polystyrene helmet tends to stick to the road and increases rotational acceleration. This increases the risk of brain injury.

Is this “protection”?

We can be fooled into accepting “protective” equipment that is not necessary, and even harmful. After the helmet law in Australia, the risk of injury tripled.

Helmet manufacturers know how to exploit our fears using scaremongering advertising. It takes effort to escape such insidious influence.

Next time somebody peddles “safety” equipment, ask

  • Does the risks warrant the equipment?
  • Could the “safety” equipment do more harm than good?
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The surprising impact of helmets on safety

Abstract

Contrary to popular belief, helmets main impact on safety has not been the protection they provide, but the increased in the risk of accident associated with them. Helmets protect, but not enough to compensate for the increased risk of accident.

Although the motivation for wearing a bicycle helmet is to reduce the risk of death & serious brain injury, the net result of imposing a helmet law has been to increase the risk of death & serious injury.

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Two types of injuries

Broadly speaking, there are two types of injuries relevant to bicycle helmets:

  1. Minor injuries like bruises and lacerations to the skull.
  2. Severe injuries like brain injury, skull fractured, or neck injury that can lead to disability.
Bicycle helmets provide cushion against minor head injuries.  On hitting a flat surface, the polystyrene compresses to attenuate the impact.  However, in a serious impact, helmets tend to “fail”, or break into pieces, providing little protection.  A polystyrene based helmet is not designed to protect in a serious accident:

“In cases of high impact, such as most crashes that involve a motor vehicle, the initial forces absorbed by a cycle helmet before breaking are only a small part of the total force and the protection provided by a helmet is likely to be minimal in this context. In cases where serious injury is likely, the impact energy potentials are commonly of a level that would overwhelm even Grand Prix motor racing helmets. Cycle helmets provide best protection in situations involving simple, low-speed falls with no other party involved. They are unlikely to offer adequate protection in life-threatening situations.

soft-shell-helmet
A soft-shell helmet is a piece of polystyrene covered by a layer of plastic less than 1mm thick.  It can protect in a minor accident.  However, it is not designed to protect in a serious accident.
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Helmets make little difference in a serious accident, as Dr Hooper reports:

“Looking at evidence, it does not matter if people are wearing a helmet or not, any serious accident on a bike is likely to kill them,”

Wearing a helmet can induce cyclists to take more risks, sometimes with serious consequences:

“the increased use of bike helmets may have had an unintended consequence: riders may feel an inflated sense of security and take more risks. …

The helmet he was wearing did not protect his neck; he was paralyzed from the neck down. …

”It didn’t cross my mind that this could happen,” said Philip, now 17. ”I definitely felt safe. I wouldn’t do something like that without a helmet.” ”

While helmets can reduce minor head injuries, they can also increase the risk of neck injury.  Contrary to popular belief, helmets are not designed to protect against severe brain injury, and may aggravate it some circumstances.

Yet most  helmet studies fail to distinguish between minor and sever injuries.  Minor and severe head injuries are lumped together into a category called “head injuries”. The much larger number of minor injuries masks the trend in severe injuries. An apparent reduction in minor head injuries can mask an increase in severe injuries.

What does the data tell us?

Relevant data that can shed some light on this issue comes from New South Wales (NSW), Australia. It includes minor injuries, separated as head injuries and non head-injuries, for child cyclists before and after the helmet law. It also includes data for death & serious injuries for child cyclists and pedestrians.

Before the helmet law, about 20% of cyclists wore helmets. After the helmet law, about 80% of cyclists wore helmets. To make sense of the data, it is worth keeping in mind two key factors affecting injuries:
  1. There were 40% fewer cyclists after the helmet law. The risk must be adjusted per cyclist.
  2. The helmet law was introduced at the same time as other road safety measures, like a crackdown on speeding and drink driving. Injuries declined significantly for pedestrians, who face a similar risk as cyclists, being hit by motorists. By adjusting for safety improvements observed with pedestrians, we can isolate the effect of external factors, so that we can better understand what can be genuinely attributed to helmets.

A detailed analysis of the data can be found here.  Additional injury data for pedestrians can be found here.  Here is a short summary of the analysis of the data:

  1. Compared to what would have been expected without the helmet law, the risk of non-head injury for cyclist almost doubled. This indicates that the risk of accident almost doubled. Explanations for the increase in accidents include risk compensation and safety in numbers.
  2. Compared to what would have been expected without the helmet law, the risk of death & serious injury increased by 57%. This indicates that helmets did protect against some serious injuries, but not enough to compensate for the rise in accidents.
  3. Compared to what would have been expected without the helmet law, the risk of head injuries for cyclists increased by 40%. This indicates the helmets were more effective at preventing minor injuries.

risk_of_injury_after_helmet_law

Compared to what would have been expected without the helmet law, the risk of accidents almost doubled, the risk of death & serious injury increased by 57%, and the risk of head injury increased by 40%.

The data indicates that bicycle helmets do protect, but not enough to compensate for the rise in accidents.

Accident avoidance vs protection

Although helmets do protect, they have not protected enough to compensate for the rise in accidents.  The net safety effect of imposing helmet has been to increase the risk of  injuries, both head-injuries and non-head injuries, and both minor and serious injuries.

However, the sharp increase in the risk of accident is the most significant impact of helmets on safety. Why wear a “safety device” that increases the risk of accident while failing to protect sufficiently to compensate for this increased risk of accident?

There is an odd discrepancy between the motivation for wearing bicycle helmets (to reduce the risk of death & chronic disability), and the actual result of the helmet law: a much higher risk of death & serious injury.

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The myth that bicycle helmets protect against brain injury

Abstract

Brain injury is caused by rotational acceleration.
Bicycle helmets are not designed to protect against it.
In some circumstances they can increase it, aggravating brain injury.
Wearing a helmet can make us feel safer. However feeling safe is different than being safe

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What surgeons say

This article reports from a surgeon who operates on cyclists:

“The ones with brain swelling, that’s diffuse axonal injury, and that’s bad news” …

the whole brain is shaken up, creating many little tears in its inner structure …

Such patients undergo personality change, can contract epilepsy and have difficulty controlling their anger. They might become unemployable. Depression is a common accompaniment to brain injury. Rosenfeld sees patients’ families shattered, too. “They’re never the same. It often leads to marriage disharmony and family breakdown.” …

Rosenfeld’s opinion is candid.  “I don’t know if [helmets] do much to protect the inner part of the brain,”

A neurosurgeon from the UK admits:

“I see lots of people in bike accidents and these flimsy little helmets don’t help.”

According to another Australian surgeon who operates on cyclists:

“The best evidence is that [a helmet] doesn’t make any difference to serious head injury when riding a bicycle …

initial research used to back the mandatory laws was “deeply flawed and criticised”. Some newer findings, he said, showed that these laws could increase the chance of serious injury. “

Sport cyclists are having doubts

Helmets are part of the sport cyclist uniform. Yet fatalities have doubled since mandatory helmets:

The helmet rule for professional cyclists was brought by the UCI in 2003 following the death of Andrei Kivlev during the Paris-Nice race.

Since then deaths of professional cyclists while racing have doubled, so where is the protection that helmets are supposed to give a rider?

Sport cyclists are having doubts, as reflected in a recent edition of Bicycling Magazine:

new research is finding that concussions could be as dangerous as splitting open your skull. And that brain bucket you own? It was never designed to prevent concussions.

Distinguishing between focal brain injury and diffuse brain injury

What’s going on? Why do people believe that bicycle helmets protect against brain injury while surgeons say they don’t? Much of the confusion comes from a lack of distinction between focal brain injury and diffuse brain injury.

An old popular belief is that brain injury is caused by a direct hit the head, like a head hitting a wall, causing linear acceleration. This is focal brain injury. Bicycle helmets are designed to reduce focal injury. The polystyrene reduces linear acceleration by compressing on impact.

Scientific research done in the 1970’s has revealed that the main cause of severe brain injury is not focal injury but diffuse axonal injury:

“The experiments gave special attention to direct comparison of the contributions of linear and angular acceleration because the widely accepted Head Injury Criterion for head injury is based on measurements of the former – see below. The essential role of angular acceleration in producing cerebral concussion was shown, the threshold being estimated as 2000-3000 rad/sec². Translation was also responsible for brain injuries, albeit only focal, and did not produce concussion.  …

Along with the support which research has provided for the new theory, it has discredited the notions of coup and contre-coup and of linear acceleration of the brain being a major factor in injury to it.”

Diffuse axonal injury, also called rotational injury, is caused by angular acceleration, for example when the head rotates quickly. The skull may be intact, but there can be severe internal brain damage. This is what the surgeon Dr.  Rosenfield was describing in the article mentioned above.

Some people believe helmets protect against brain injury. Not only is this not true, but the opposite is more likely to be the case:

“Protecting the brain from injury that results in death or chronic disablement provides the main motivation for wearing helmets. Their design has been driven by the development of synthetic polystyrene foams which can reduce the linear acceleration resulting from direct impact to the head, but scientific research shows that angular acceleration from oblique impulse is a more important cause of brain injury. Helmets are not tested for capacity to reduce it and, as Australian research first showed, they may increase it.

Even though helmets do not protect against brain injury, fear of chronic disability has been used to promote them. This has lead to an exaggerated opinion of the protection provided by helmets. A false sense of safety can lead to increase risk taking, as reported in the New York Times:

“the increased use of bike helmets may have had an unintended consequence: riders may feel an inflated sense of security and take more risks. …

The helmet he was wearing did not protect his neck; he was paralyzed from the neck down. …

I definitely felt safe. I wouldn’t do something like that without a helmet.” 

Research on bicycle helmets

Soft-shell helmets, the most common type of bicycle helmet, are helmets without a hard shell. They have a thin layer of plastic on top, less than 1 mm.

soft-shell-helmet A soft-shell helmet is a piece of polystyrene covered by a layer of plastic less than 1mm thick.

In 1987, an Australian government agency released research that highlighted deficiencies with bicycle helmets:

The substantial elastic deformation of the child head that can occur during impact can result in quite extensive diffuse brain damage. It is quite apparent that the liner material in children’s bicycle helmets is far too stiff …

rotational accelerations were found to be 30% higher than those found in similar tests using a full face polymer motorcycle helmet. More work needs to be done in this area as there would seem to be a deficiency in rotational acceleration attenuation that may be the result of insufficient shell stiffness

Helmets can increase brain injury, according to research done in Sweden:

“The non-shell helmet did in all trials grab the asphalt surface, which rotated the head together with
the helmet. The consequences were in addition to the rotating of the head, a heavily bent and compressed neck, transmitted on through the whole test dummy body after the impact.  …

This gives an average angular acceleration of 20800 rad/s² for rotating the head from 0 to 0.26 rad during the 5 ms. Löwenhielm proposes 4500 rad/s² to be the maximum angular acceleration that can be tolerated for a limited time period”

Soft-shell helmets amplified rotational acceleration to four times higher than the tolerable maximum.

On impact, the larger head volume amplifies rotational acceleration. 3cm increase in helmet circumference increases rotational acceleration by 150%:

“the 3000rad/s² to 8500rad/s² measured during abrasive and projection oblique tests with size 54cm (E) helmeted headforms. However, for the most severe cases using a size 57cm (J) headform, rotational acceleration was typically greater than 10,000rad/s² and increased to levels of 20,000rad/s², a level at which a 35% – 50% risk of serious AIS3+ injuries is anticipated.”

The difference between a helmeted and non-helmeted head is about 20cm.

The mechanics of bicycle helmets

Look at a bicycle helmet. It has been designed with comfort in mind. It is made of light weight material that grip the road on impact rather than glance off it (as is the case with motorcycle helmets).

Helmets increase the volume of the head. In the event of an accident, this increases the risk of the head hitting the road.

The increase in the volume of the head, coupled with the gripping of the road surface, means that when a head comes into contact with the ground at speed, the head or body is rotated, sometimes snapping the spinal cord. This can cause brain injury or permanent disability.

Post-crash studies found that most helmets show impacts to the side, where a bare head is protected by the shoulders.

helmet-head-size-2

Helmets increase volume of the head, increasing the chance of the head hitting the road in an accident.
The larger volume amplifies rotational acceleration, the main cause of brain injury.
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Is this just a theory?

Unfortunately it doesn’t seem like it.

doctor from New Zealand reports:

“cycle helmets were turning what would have been focal head injuries, perhaps with an associated skull fracture, into much more debilitating global head injuries”

In Canada, the length of stay in hospital increased increased following helmet laws, from 4.3 days to 6.9 days. The number of serious head injury admissions increased by 46%.

Helmeted riders are more than twice as likely to hit their head in an accident, with more impacts to the sides. A 1988 study reports that helmeted riders hit their heads seven times more often than un-helmeted riders.

In the US, a strong rise in helmet wearing was followed by an increase in head injuries:

“Bicycle helmets might not protect cyclists much at all.  And, in fact, in some cases, they might actually be more dangerous than going lidless. …

head injuries had increased even though the use of helmets had skyrocketed throughout the 1990s.  The risk of injury per cyclist had gone up by 51%. …

We don’t know what’s going on,” said one political appointee who should know.  Well, I’ll offer my idea.  People accepted the idea that helmets work, and then created studies to “prove” that they do. “

It is easy to take things for granted, and to assume that a device labeled a “helmet” can only protect, and cannot make things worse.

What about the studies that claim that helmets protect against 80% of brain injuries?

There have been many “studies” claiming that helmets protect against brain injuries. The most famous one was done by helmet lobbyists and funded by the helmet industry. This “study” had methodological errors. It was the basis for a US government claim that helmets reduce 85% of head injuries. The US government has since dropped this claim.

Many studies assume that helmets are effective and attempt to “prove” it. Such studies jump to a predetermined conclusion, with a disturbing lack of scientific discipline. Often the claims are contradicted by the study’s own data.

Governments who enacted helmet law have funded policy-driven studies defending their policy. Such “studies” use biased statistics, resulting misleading claims. Bill Curnow, a scientist from the CSIRO, wrote as a conclusion of a scientific article:

“Compulsion to wear a bicycle helmet is detrimental to public health in Australia but, to maintain the status quo, authorities have obfuscated evidence that shows this.”

In 2011, the New South Wales government funded a study trying to deny that helmets can aggravate brain injury. This risk exists for soft-shell helmets at high speed. The “study” set up unrealistic conditions at low speed, then magically generalized the results. This is deceitful as the unrealistic conditions are not representative of real life accidents.

The dilemma: minor skull injuries vs brain injury

Bicycle helmets are designed to protect cyclists if they fall on top of their heads at speeds below 20 km/h. They mitigate against minor skull injuries like bruises and lacerations. They are not tested for side impacts.

Is it worth to increase the risk of brain injury to mitigate minor skull injuries? An Australian cyclist challenged a helmet fine as helmets can increase brain injury. After reviewing evidence in a court of law, District Court Judge Roy Ellis concluded:

“”Having read all the material, I think I would fall down on your side of the ledger …

I frankly don’t think there is anything advantageous and there may well be a disadvantage in situations to have a helmet  and it seems to me that it’s one of those areas where it ought to be a matter of choice.”

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Misguided doctors or marketing agents?

Abstract

In the 1980′s, Bell, a helmet manufacturer, was keen to expand the market for bicycle helmets, its most profitable product. It approached the Snell foundation and offered funding for research on bicycle helmets. The Snell foundation chose avid helmet lobbyists to conduct this “research”.

The helmet lobbyists initial “research” claimed that helmets reduce 85% of head injuries. This claim is impossible due to inherent limitations of helmets. The authors had to re-work their data, and withdrew their claim.

The Snell foundation has kept funding these researchers. Boosted by the “research”, the market for bicycle helmets expanded. At $100 for a piece of polystyrene, the profits are huge. Helmets manufacturers have reinvested their profits into lobbying for helmet legislation. They sent executives all the way to Australia to lobby for a helmet law.

In 2013, the US government dropped its claim that helmets reduce 85% of head injuries. It first made the claim based on the research mentioned above, but then admitted that there was no credible basis for the claim.

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The misleading “research”

A 1989 study on bicycle helmets claimed:

“we found that riders with helmets had an 85 percent reduction in their risk of head injury”

How can helmets reduce 85% of head injuries considering they don’t cover the face where 70% of head injuries are?

bicycle_body_injuries

Injuries to the skull (the part of the body a helmet covers) constitute 10% of cycling injuries,
or 30% of what is usually classified as head injuries (including face injuries).
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How did they arrive at such impossible claims?
They compared a helmeted group who rode supervised in parks with an un-helmeted group who rode unsupervised on busy roads. The difference between the two groups was attributed to helmets. They failed to consider confounding factors, a common error in statistics.

The study compared helmeted cyclists in bicycle paths with un-helmeted cyclists on roads. It attributed the difference to helmets.

This flawed study was widely criticized. It failed to select a representative control group. It misused the odds-ratio. It lacked serious injuries. It failed to adjust the results by age group.

As summarised in this review:

“The study compares groups of cyclists who chose to wear helmets with those who did not. Many variables, such as the reasons for wearing a helmet and attitudes to risk, were not controlled for by the researchers and may have influenced the results.”

The 85% figure is meaningless. It does not correspond to physical protection provided by helmets. It is the authors own generous estimate misrepresented as the result of their “study”. Many researchers have tried to replicate its results, but have been unable to do so. The authors had to re-work their data, and withdrew the claim.

The data from the study indicates that helmet wearers were 7 times more likely to have accidents. The study ignored this.

Instead of claiming
“Helmets protect x% of head injuries”
A more objective assessment would be:
“Helmets appear to protect against some head injuries. However, they are also associated with more accidents.  It is not clear whether there is a net safety benefit.”

This study was influential. Few questioned it, as they were eager to believe its claims. Despite the authors withdrawing the claim, it is still quoted as if it was true.

This research became a model for further “research” replicating its flaws and bias. Such research tends to jump to a predetermined conclusion. Such studies exaggerate the protection provided by helmets while ignoring the increase in accidents. The sheer volume of this “research” has misled the medical community.

The vested interests behind this “research”

In 1956, a racing driver called Peter Snell died from head injuries despite wearing a Bell helmet. His death to the creation of the Snell foundation. Since, Bell has developed a close relationship with the Snell foundation.

In the 1970′s, Bell introduced polystyrene bicycle helmets. They were not adopted by mainstream cyclists. In the 1980′s, Bell started to market bicycle helmets more aggressively. They became the most profitable range of helmets. In the mid 1980′s, Bell suggested that the Snell foundation should commission research into bicycle helmets, and provided funding to do so.

Snell chose 3 researchers to do the study, including Dr. Frederick Rivara. Dr. Rivara was a bicycle helmet advocate and an active helmet lobbyist. This was an odd choice. Helmet research conducted by helmet lobbyists was likely to be biased.

Snell requested that the study was

“done to demonstrate the effectiveness of bicycle helmets in reducing head injury”.

Note the assumption of effectiveness upfront instead of asking an open-ended question. The bias also came from the Snell foundation.

Using sponsored “research” to promote helmets and lobby for legislation

Bell used the commissioned study in its advertising:

Bell advertising, using the “study” it sponsored to claim that helmets prevent 85% of head injuries

Scaremongering is a key tactic. Parents are an easy target, scared into buy a product to protect their child from an exaggerated danger.

Bell then used this commissioned research to lobby governments to promote helmets. Lobbyists funded by Bell started to lobby for mandatory legislation. The commercial benefits of such legislation was clear to the helmet industry.

Bell funded organisations like SafeKids. This was shrewd, as it made it look like there was popular demand for helmet legislation. This lobbying resulted in mandatory helmet laws for children in various US jurisdictions.

A vice-president from Bell flew to Australia to attend EVERY mandatory helmet law hearing.

The market for helmets almost doubled between 1993 and 1995. This lead to record profits for Bell bicycle helmet division. In 1995, the bicycle helmet market was worth about $200 million dollars. Large profits could be re-invested into further lobbying and funding of “studies”.

Funding more research

The Snell Foundation has kept funding these researchers. In 1996, they published a study claiming:

“Bicycle helmets, regardless of type, provide substantial protection against head injuries for cyclists of all ages involved in crashes, including crashes involving motor vehicles.”

There was a failure to disclose conflicts of interests:

“This research was supported by a grant from the Snell Memorial Foundation, to which the principal bicycle helmet manufacturers are contributors.”

The study attracted much criticism. The authors again failed to consider confounding factors. They made more implausible claims.

Close analysis of their data indicates that:

“The data show that, apparently, the protective effect of a helmet increases with increasing severity of injury. It is extremely difficult to accept such a result, and indeed, it is the opposite of what is seen in population level studies, which return the more sensible outcome of declining protection with increasing severity of injury. It must be the case that confounding factors systematically caused non-helmeted cyclists to be in more severe crashes”

These implausible claims did not cause the “researchers” to question their assumptions. Such lack of scientific discipline is disturbing.

The implausible Cochrane review

In 1999, the same researchers published a “review” of helmet studies in the Cochrane review, that claims

“helmet dramatically reduces the risk of head and facial injuries for bicyclists involved in a crash, even if it involves a motor vehicle”

This claim ignores the limitations of helmets.  Polystyrene helmets are designed for minor impacts. They do not cover the face.

Brian Walker,  a helmet testing expert from helmet-testing lab Head Protection Evaluations, reports:

“Cycle helmets are designed for falls without any other vehicle involved …

The tests that cycle helmets currently go through mean that they should offer similar protection to a pedestrian who trips and falls to the ground …

In today’s road traffic accidents, it’s not unlikely for a cycle helmet to be subjected to severity loads greater than it is designed to cope with.”

The study misleading claims were rebutted by an independent researcher:

“It is concluded that the review takes no account of scientific knowledge of types and mechanisms of brain injury

This biased review attracted much criticism, including the following:

“The review is not independent. Four of the seven papers selected for inclusion were the work of the reviewers themselves 

Only case-control studies were considered for inclusion, … studies of this type are acknowledged to be prone to bias …

The paradox presented by the failure of other types of studies to show any benefit from large increases in helmet use is left unstated and unaccounted for

The authors are dismissive of the possibility of risk compensation. However, it has subsequently been demonstrated that child cyclists often ride more riskily and suffer more crashes when wearing a cycle helmet (Mok et al, 2004).

No consideration is given to rotational injuries, which dominate the most serious injuries. Helmets … may increase the risk and/or severity of rotational injury.(BHRF, 1039).

Claims are accepted of efficacy for which no plausible mechanism exists (e.g. the prevention of mid-face injuries), … and which would not be possible even if helmets prevented all head injuries (e.g. an increase of 35% in cyclists wearing helmets leading to 66% fewer head injuries).

There is misleading interpretation of ‘odds ratio’ … This exaggerates the predicted benefit of helmets and masks the fact that studies of this type are not truly predictive, being essentially the authors’ estimate … The reviewed paper showing the least benefit from helmets is omitted from computation of odds ratio, thus again exaggerating benefit.”

One of the study included reported a higher accident rate and higher neck injuries for helmeted cyclists. This was ignored in the summary.

The review claimed that cyclists would need to increase their risk-taking four-fold to overcome the protection of helmets. This claim was refuted by an independent researcher.

From research to lobbying

The helmet lobbyists used their “research” to peddle their beliefs. For example, this article entitled “Bicycle helmets: it’s time to use them” claims:

“Further delays in promoting the use of helmets will be measured in the number of lives ruined by the devastating consequences of preventable brain injury.”

This ignores that helmets can increase brain injury.

Conclusion

This “research” contradicts the limitations of polystyrene helmets. It ignores whole-population studies, where a large rise in helmet wearing did not show any benefit. Yet it has been influential.

Manufacturing an artificial perception has delivered profits to the helmet industry. With a piece of polystyrene selling for $100, the profits are huge. No wonder Bell sponsors racing cyclists. Let the profits roll.

 Bell advertising in the Tour de France 2011

Update July 2013

In June 2013, the US government dropped its claim that helmets reduce 85% of head injuries. It first made the claim based on the research mentioned above, but then admitted that there was no credible basis for the claim.

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My helmet saved my life!

Abstract

After the helmet law, many cyclists insisted that their helmets had saved them.
Yet cycling injuries tripled.
Why? Because helmets increase the risk of accidents.
 

What the data tells us

Here are some stats on cycling death & serious injury for children in NSW, before and after the helmet law. Two years after the introduction of the helmet law, death and serious injuries decreased by 32%. Hooray! This proves that helmet saved lives! That is what many government commissioned studies have claimed.

Can this 32% decrease be fully attributed to helmets though? What if it was due to something else? Like what? Like a decrease in the number of cyclists. After the helmet law, the number of child cyclists in NSW decreased by 44%. The decrease in death & serious injuries was less than the reduction in cycling.

The helmet law was introduced at the same time as other road safety measures, like a crackdown on speeding and drink driving. This would have benefited cyclists and pedestrians. Pedestrians death and serious injuries decreased by 23% during this period.

The risk of death and serious injuries for cyclists, adjusted for the lower number of cyclists, increased by 21%.  For pedestrians it decreased by 21%.

It seems that the helmet law has made cycling more dangerous.

Hmm …..

Where are the cyclists saved by their helmets?  They cannot be found in the injury data. Many people claim a helmet saved their life. Yet the risk of death and serious injury has increased.

Why have helmets failed to reduce injuries?

One possible explanation is that the risk of accident tripled.

A false sense of safety can induce people to take more risks, leading to more accidents and more injuries. This is risk compensation, a well-known safety factor:

“the law of unintended consequences is extraordinarily applicable when talking about safety innovations. Sometimes things intended to make us safer may not make any improvement at all to our overall safety”

risk-compensation

Risk compensation is the tendency to take more risks when wearing safety equipment.
Lured by a false sense of safety, helmeted cyclists tend to have more accidents.
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Wearing a helmet can induce cyclists to take more risks, as reported in the New York Times:

the rate of head injuries per active cyclist has increased 51 percent just as bicycle helmets have become widespread. …

the increased use of bike helmets may have had an unintended consequence: riders may feel an inflated sense of security and take more risks. …

The helmet he was wearing did not protect his neck; he was paralyzed from the neck down. …

”It didn’t cross my mind that this could happen,” said Philip, now 17. ”
I definitely felt safe. I wouldn’t do something like that without a helmet.” ”

Risk compensation also affects motorists who tend to be less careful around helmeted cyclists. As reported in a study published by the University of Bath in the UK:

“Bicyclists who wear protective helmets are more likely to be struck by passing vehicles”

Both the behaviour of helmeted cyclists and surrounding motorists increase the risk of accidents.

 

There is a well-known phenomenon called safety in numbers. According to empirical data, reducing cycling by 44% increases the risk of accidents by 41%. Research published in the Injury Prevention journal concluded:

“the behavior of motorists controls the likelihood of collisions with people walking and bicycling.  It appears that motorists adjust their behavior in the presence of people walking and bicycling …

A motorist is less likely to collide with a person walking and bicycling if more people walk or bicycle. Policies that increase the numbers of people walking and bicycling appear to be an effective route to improving the safety of people walking and bicycling.”

safety_in_numbers_6

A key factor for cycling safety is the number of cyclists.  This is “safety in numbers”.
With fewer cyclists, cycling becomes more dangerous.
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What protection do helmets provide?

Despite the increase in accidents, helmets should have saved these people. Helmets saved some of them, as the 55% increase in the risk of death & serious injury is lower than the 93% increase in accidents. Yet overall the risk of death & serious injury increased.

Unfortunately polystyrene based helmets are not designed to protect in a serious accident:

“In cases of high impact, such as most crashes that involve a motor vehicle, the initial forces absorbed by a cycle helmet before breaking are only a small part of the total force and the protection provided by a helmet is likely to be minimal in this context. In cases where serious injury is likely, the impact energy potentials are commonly of a level that would overwhelm even Grand Prix motor racing helmets. Cycle helmets provide best protection in situations involving simple, low-speed falls with no other party involved. They are unlikely to offer adequate protection in life-threatening situations.

soft-shell-helmet

A soft-shell helmet is a piece of polystyrene covered by a layer of plastic less than 1mm thick.
It can protect in a minor accident.  However, it is not designed to protect in a serious accident.

 

Helmets make little difference in a serious accident, as Dr Hooper reports:

“Looking at evidence, it does not matter if people are wearing a helmet or not, any serious accident on a bike is likely to kill them,”

Suspending belief

On one hand, we have plenty of anecdotes from people who claim that a helmet saved their lives.
On the other hand, we have an increased risk of death and serious injury after the helmet law.
Both cannot be true at the same time.
Perhaps it would be more accurate to say that some people BELIEVE that a helmet saved them:

“The next time you see a broken helmet, suspend belief and do the most basic check – disregard the breakages and look to see if what’s left of the styrofoam has compressed. If it hasn’t, you can be reasonably sure that it hasn’t saved anyone’s life.

A helmet protects by absorbing the energy of the impact through compressing the polystyrene layer. If the polystyrene has not compressed, but has broken into pieces instead, it has failed. It may have prevented bruises & lacerations, but it didn’t do much to reduce the energy of the impact.

One can expect a severe head injury from cycling once every 8,000 years of average cycling.

It is natural to assume a helmet saved us. But that doesn’t mean it is true. We don’t know what would have happened without it. Cyclists, with and without helmets, get hit by cars; the survival rates are identical. Most bicycle accidents do not result in serious head injuries, with or without helmets. We tend to overlook this, and attribute a lack of head injury to the helmet:

“see the double-standard of finding it entirely logical when helmeted cyclists who survive collisions report that wearing a helmet saved their life. It is a powerful emotional argument, but logically, statistically, and scientifically, it is erroneous for the same reasons it would be erroneous to say that not wearing a helmet saved Gene Hackman’s life. If a cyclist wears a helmet and they emerge from a collision alive, that implies correlation, not causation.”

It is important to be realistic about helmets capabilities, and to base that assessment on facts rather than personal experiences, however traumatic they may be.

After being asked

“Can your helmet save your life?”,

a helmet manufacturer salesperson shrugged and laughed uncomfortably, before responding:

“Can it?” “Well, not save your life, no.”

This doesn’t mean that it is not possible that a helmet saved a cyclist life. It might have in some cases. However, few people consider that the lack of a helmet tends to make them ride more cautiously, and have fewer accidents. If they weren’t wearing a helmet, they may not have had a crash in which their life needed saving in the first place.

In many other instances, a helmet failed to save cyclists. Overall the risk of death & serious injury increased after the helmet law.

Before claiming that a helmet saved your life, ask:

  • How do I know what would have happen without a helmet?
  • Would I have ridden more cautiously without a helmet?
  • Is it reasonable to rely on a piece of polystyrene to save my life in a serious accident?
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Trying to deny that helmets can aggravate brain injury

Abstract

Several studies have reported that bicycle helmets can increase rotational acceleration. Rotational acceleration is the primary cause of brain injury.

The Australian government commissioned a study to defend its controversial helmet law. The study set up unrealistic conditions fostering low rotational acceleration. The study claims that helmets do not increase brain injury. This is deceitful. The study unrealistic conditions are not representative of real life accidents.

An interview with a study author revealed the study was not set up to address rotational acceleration. The author said:

“soft-shell helmets are for cosmetic purposes, not really for protection, …
current helmets do not appear to protect against brain injury.”

 

Look at a bicycle helmet. It has been designed with comfort in mind. It is made of light weight material that grip the road on impact rather than glance off it (as is the case with motorcycle helmets).

Helmets increase the volume of the head. In the event of an accident, this increases the risk of the head hitting the road.

The increase in the volume of the head, coupled with the gripping of the road surface, means that when a head comes into contact with the ground at speed, the head rotates quickly. This quick rotation is the main cause of brain injury.

What causes brain injury?

An old popular belief is that brain injury is caused by a direct hit the head, like a head hitting a wall, causing linear acceleration. This is focal brain injury. Bicycle helmets are designed to reduce focal injury. The polystyrene reduces linear acceleration by compressing on impact.

Scientific research done in the 1970′s has revealed that the main cause of severe brain injury is not focal injury but diffuse axonal injury:

“Protecting the brain from injury that results in death or chronic disablement provides the main motivation for wearing helmets. Their design has been driven by the development of synthetic polystyrene foams which can reduce the linear acceleration resulting from direct impact to the head, but scientific research shows that angular acceleration from oblique impulse is a more important cause of brain injury. Helmets are not tested for capacity to reduce it and, as Australian research first showed, they may increase it.

Rotational acceleration means the head turning quickly. This can create shearing inside the brain, tearing apart brain tissue. This is diffuse axonal injury. It can lead to permanent disability. This article reports from a surgeon who operates on cyclists:

” “The ones with brain swelling, that’s diffuse axonal injury, and that’s bad news” …

the whole brain is shaken up, creating many little tears in its inner structure …

Such patients undergo personality change, can contract epilepsy and have difficulty controlling their anger. They might become unemployable. Depression is a common accompaniment to brain injury. Rosenfeld sees patients’ families shattered, too. “They’re never the same. It often leads to marriage disharmony and family breakdown.” …

Rosenfeld’s opinion is candid.  “I don’t know if [helmets] do much to protect the inner part of the brain,” “

Helmets cannot protect against rotational injury but they can increase it, according to research done in Sweden:

“The non-shell helmet did in all trials grab the asphalt surface, which rotated the head together with
the helmet. The consequences were in addition to the rotating of the head, a heavily bent and compressed neck, transmitted on through the whole test dummy body after the impact.  …

This gives an average angular acceleration of 20800 rad/s² for rotating the head from 0 to 0.26 rad during the 5 ms. Löwenhielm proposes 4500 rad/s² to be the maximum angular acceleration that can be tolerated for a limited time period.”

Soft-shell helmets amplified rotational acceleration to four times higher than the tolerable maximum. Soft-shell helmets are helmets without a hard shell. They are the most common type of bicycle helmet.

On impact, the larger head volume amplifies rotational acceleration. 3cm increase in helmet circumference increases rotational acceleration by 150%:

“the 3000rad/s² to 8500rad/s² measured during abrasive and projection oblique tests with size 54cm (E) helmeted headforms. However, for the most severe cases using a size 57cm (J) headform, rotational acceleration was typically greater than 10,000rad/s² and increased to levels of 20,000rad/s², a level at which a 35% – 50% risk of serious AIS3+ injuries is anticipated.”

The difference between a helmeted and non-helmeted head is about 20cm.

In 1987, an Australian government agency released research that highlighted deficiencies with bicycle helmets:

The substantial elastic deformation of the child head that can occur during impact can result in quite extensive diffuse brain damage. It is quite apparent that the liner material in children’s bicycle helmets is far too stiff …

rotational accelerations were found to be 30% higher than those found in similar tests using a full face polymer motorcycle helmet. More work needs to be done in this area as there would seem to be a deficiency in rotational acceleration attenuation that may be the result of insufficient shell stiffness

doctor from New Zealand reports:

“cycle helmets were turning what would have been focal head injuries, perhaps with an associated skull fracture, into much more debilitating global head injuries”

In Canada, the length of stay in hospital increased increased following helmet laws, from 4.3 days to 6.9 days. The number of serious head injury admissions increased by 46%.

A strange “study”

The Australian government introduced a policy of mandatory helmets. Many people wrote to the government about brain injury from rotational acceleration. The bureaucrats claimed:

“A 2009 study by the University of NSW confirmed the effectiveness of a bicycle helmet in reducing angular acceleration and subsequent brain injury in crashes”.

This study was commissioned by the government. It was not published. After much insistence, a copy was obtained from a government agency. The abstract states that the study’s aim is to

investigate the ability of a bicycle helmet to reduce angular head acceleration“.

It seems to be a “study” with a pre-determined conclusion, like this one.

The study was set with unrealistic conditions, by

  1. Using a type of hard-shell helmet not representative of the most common type of helmet used
  2. Testing at unrealistically low speeds of 5 to 11 km/h
  3. Testing on a non-abrasive surface not representing standard road conditions
  4. Failing to test for oblique impacts (Oblique impacts generate high rotational acceleration)

Studies have reported high rotational acceleration with soft-shell helmets, at speeds above 30 km/h. This study fostered low rotational acceleration. 

The study used a helmet with a ABS shell, like the one on the right. Then it generalised its results to all bicycle helmets.

The study conclusion makes no mention of the unrealistically low speeds (5 km/h to 11 km/h). How can accident protection research only do tests a low speed? Speed is a major factor affecting impact severity. Testing only a low speeds is almost useless.

The study tested a low speeds like 5 km/h, even though the risks they are “studying” have been reported at higher speeds like 30 km/h.  The study then claimed that the risk doesn’t exist.

The conclusion fails to qualify the results by mentioning it was not using a realistic road surface. The flat surface used reduces the risk of the helmet sticking to the surface. Other studies have reported that helmets tend to stick to the road surface.

Despite the unrealistic conditions, the study claims are generalized without qualifications:

“At worst bicycle helmets do not appear to exacerbate head injury risks arising from angular acceleration.”

This is deceitful, as this claim is the result of the peculiar set up of the study. It cannot be generalised beyond the laboratory conditions.

Interview with an author of the study

CRAG has interviewed one of the study authors:

Why use hard-shell helmets?

“The helmets were supplied to us”

Why not use a soft-shell helmet, the most common type used today?

” the soft-shell helmet doesn’t do much – basically for cosmetic purposes – falls to pieces very easily – When touched can dent easily – Main function of soft shell helmets to ‘retain foam in semi-rigid format,’ not really for protection”

The tests were done at speed from 5 km/h to 11 km/h.  Why not higher speeds like 20 km/h?

“We had borrowed the RTA’s crash dummy and didn’t want to damage it”

Do you believe that the conditions used in the study are realistic of real-world conditions?

“No “

Is this study comprehensive enough to assert that helmets do not increase rotational acceleration?

the study does not address any oblique impact issues so therefore does not address potential increase in rotational acceleration of the brain

… current helmets on the market are limited in preventing rotational acceleration

… there is no rotational testing element in the helmet standard.”

In your opinion as an expert, do helmets do their job?

“As long as there is no oblique impact, yes

… But in an accident with any oblique impact, probably not

.. Current helmets do not appear to protect for brain injury such as concussion or haematoma

Ethical issues

Between 2006 & 2009, the University of NSW earned $248,000 from helmet “studies” such as this one.

This study is still not published, escaping independent scrutiny. Its purpose seems to be to defend a controversial government policy.

The government is expected to fund research to improve helmets, like it did in 1987 (before the helmet law). Commissioning research to mask deficiencies of a government policy is unethical.

The fundamental role of science is to serve the truth. It is NOT to serve the interests of the state.

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July 2013 update

The same team of researchers published a related study in 2013. It is called: “Bicycle helmets: head impact dynamics in helmeted and unhelmeted oblique impact tests“.

Like the “study” described above, this study sets up unrealistic conditions. Nothing can be concluded about real life accidents from unrealistic conditions.

Bureaucrats have peddled this study as “proof” that helmets reduce rotational acceleration.
Public money well spent?

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