One of the unexpected side-effects of the Covid-19 pandemic was what the BBC called ‘the great bicycle boom of 2020’.
As people across the world were forced into solo exercise, cycle retailers experienced a dramatic increase in sales while many lapsed riders dug out their old bike from the back of the garage, pumped up the tires and took to the road or trail.
An inevitable consequence of this upsurge in activity on two wheels, as well as in other activities, has been an increase in accidents and injuries. It has also exposed a critical but so far unconsidered ‘protective gap’. While helmets offer strong protection against the rare, catastrophic high-energy impacts that can lead to skull fractures and severe concussions, they do not protect against the low- to mid-energy impacts that happen far more often in everyday action sports.
Now, impact protection specialist D3O has come up with a solution to fill this ‘protective gap’. As this article explains, D3O has formulated a patented material which offers optimal protection against the effects of these frequent, lower-energy impacts.
A study conducted by the Department of Oral and Maxillofacial Surgery at the Royal Free London NHS Foundation Trust found that 22 of the 322 patients who attended with facial emergencies during the four-month study period had suffered cycling-related accidents, and that eight of those 22 had incurred a minor head injury or traumatic brain injury (TBI). These statistics don’t include the much higher – and equally worrying – count of ‘invisible’ head injuries, for which riders don’t end up in hospital but instead silently suffer from mild traumatic brain injuries (mTBIs) like concussions and sub-concussions.
Such mTBIs aren’t the result of horrifying crashes, car collisions or riders falling off cliffs; they happen during routine low- to mid-speed falls: a rider going over their handlebars, falling sideways when clipped into their pedals or even hitting a sturdy branch. Such lower velocity crashes still generate a significant impact energy – defined as the total work done when two objects collide – estimated around 30 to 50 joules. In layman’s terms, that’s the same as a three-kilogram brick dropped from a height of one meter, or an adult human head, weighing around five kilograms, hitting a solid object at a jogging speed of just over 12 kilometers per hour. Not quite as ‘low energy’ as one would think.
In a poll of 22,000 mountain bike riders carried out by Pinkbike, a leading community website, 42 per cent reported that they crashed at least once a week, with more than 10 per cent crashing almost every time they rode or more than once per ride. Less than 1 per cent claimed never to crash.
The same applies to other action sports. In winter sports, impacts with hazards such as rocks, rails, trees and other participants are frequent, with most head injuries classed as minor. For example, snowboarding head injuries mostly occur because of falls on mild to moderate slopes among beginner to intermediate-level participants. Likewise in skateboarding, where bumps are common but only five percent of total head injuries are classed as severe, according to 2020 statistics cited by skateboardsafety.org. Similar everyday impacts can also be found in motorsports, such as when a rider misjudges a corner or jump, slips on gravel or wobbles over when stationary. The list goes on…
If riders don’t end up in hospital and only experience minor head injuries like concussions during low- to mid-energy impact events, why should participants feel the need to protect against them?
The scientific community’s position on head injuries has evolved dramatically since the first helmets were designed and the first CE and ASTM standards brought to life. While preventing skull fractures was the one and only priority a few decades ago, researchers have now demonstrated the short- and long-term effects of mild traumatic brain injuries.
Just one fall, one collision with another rider, at a low to mid-velocity, can cause individuals to experience memory loss, debilitating headaches, issues concentrating, nausea, balance problems or dizziness.
"Just one fall, one collision with another rider, at a low to mid-velocity, can cause individuals to experience memory loss, debilitating headaches, issues concentrating, nausea, balance problems or dizziness."
These risks are further heightened among the young, whose developing brains are particularly vulnerable to injury from repeated low- to mid-energy impacts. A paper published in the Journal of Neurosurgery: Pediatrics, reported: ‘The youth data set showed higher brain tissue strain responses for lower energy and impact velocities than measured in adults, suggesting that youths are at higher risk of concussive injury at lower event severities.’
Unlike for skull fractures, establishing a minimum biomechanical threshold for traumatic brain injury has been one of the most elusive concepts, frustrating biomechanists and neuroscience researchers alike. An impact that does not lead to a concussion in one person may have far more damaging effects in another. This is what Virginia Tech researchers call the ‘sliding scale of injury probability’. No two individuals are physically the same, even more so when it comes to the brain.
For some high-profile impact sports – including American football, hockey, rugby and soccer – concussion prevention has now taken the spotlight with doctors, clubs and participants urging helmet manufacturers to look beyond skull fractures and address the less obvious yet far more frequent and insidious mTBIs. Even though this trend is encouraging and displays a greater understanding of the importance of multi-energy impact protection, it's yet to reach other popular action sports such as mountain biking, skiing or skateboarding.
Numerous action sports helmet standards – CE, CPSC, ASTM and Snell Foundation to name the main ones – have been established over the last few decades to make sure products placed on the market by manufacturers are fit for purpose and meet basic safety requirements. How do these standards fare in addressing the frequent real-life impacts found in action sports and mTBIs discussed earlier? Unfortunately, poorly. Such standards haven’t evolved at all over the last few decades, despite the theoretical and practical evidence provided by the international science and sports communities.
In fact, current test methods used to establish these standards only replicate single, high-energy, ‘worst case scenario’ impacts. In the case of European CE standards and those developed by the international organization ASTM, the impact energies average 100 joules – far from the impacts at 30 to 50 joules experienced on a frequent basis by riders across disciplines.
Likewise, the head acceleration thresholds that determine whether a helmet is safe enough for the mass market – defined some decades ago to prevent skull fractures – can go as high as 250G. Even a third of this acceleration may be sufficient to cause a concussion. It’s evident that both the impact velocities and the pass/fail thresholds are not aligned with real-life impacts and the safety needs of ordinary helmet wearers. This is what D3O calls the ‘protective gap’.
"It’s evident that both the impact velocities and the pass/fail thresholds are not aligned with real-life impacts and the safety needs of ordinary helmet wearers."
Standards need clear pass/fail criteria, whereas concussions and sub-concussions are too complex to fit the typical black or white framework that standards committees find in skull fractures. Getting all countries, all industrial players, and all scientists to agree on a single standardized test method to tackle mTBI seems to be a dream unlikely to come true in the foreseeable future.
In the meantime, helmet manufacturers have no choice but to design products and select materials that will enable their products to meet the established standards.
Because CE and ASTM standards require single impact, high energy protection, most helmets on the market today are made of expanded polystyrene (EPS). This cheap, widely available material dissipates high amounts of energy by breaking under impact, thereby offering outstanding one-time protection against the kind of collision that could lead to a skull fracture or the most severe concussions. EPS is considered ‘sacrificial’ – in other words, an EPS helmet should no longer be regarded as offering protection after impact and should be discarded.
However, such helmets fail to attenuate the much more frequent low- to mid-energy impacts experienced in everyday action sports, such as falling sideways or backwards, or simply misjudging a corner. Indeed, EPS may be ideal for high-velocity impacts but is too stiff for lower energies where a softer cushioning material is needed. So not only do standards fail to address mTBIs, they also lead manufacturers to use materials with properties that go in the opposite direction to what concussion prevention requires.
‘Bike helmets protect against skull fractures, not concussion,’ says the Weill Cornell Medicine Concussion and Brain Injury Clinic in New York. To use a motoring analogy, the helmets provide the airbag – but not the seat belt.
According to the authors of a paper, ‘Modeling and Optimization of Airbag Helmets for Preventing Head Injuries in Bicycling’: ‘Studies have shown that although wearing the EPS helmet decreases the risk of severe head injury by approximately 75 per cent, the reduction in mild traumatic brain injury rates is statistically insignificant.’
"Studies have shown that although wearing the EPS helmet decreases the risk of severe head injury by approximately 75 per cent, the reduction in mild traumatic brain injury rates is statistically insignificant."
A report by the American College of Sports Medicine observes this same ‘protection gap’ in helmets for snow sports: ‘Ski helmets are currently designed and evaluated for impact energies much higher than those met during skiing falls, snowboarding falls and collisions between users, which account for more than 70 per cent of recorded TBI. This might partly explain why the effect of the helmet in reducing mild TBI was non-significant or low in recent epidemiological studies.’
Just like cars, helmets need complementary safety systems to protect from frequent low- to mid-energy impacts (seat belts), in addition to – and not instead of – high energy impact safety features (air bags).
How, then, to address the disparity between the test methods driving standards and the real-life impacts that fall below the standard velocity used in testing?
A new solution from D3O addresses this issue by protecting against the more common low- to mid-energy impacts. This is achieved with a simple upgrade that part-substitutes a helmet’s existing comfort liner for a layer of D3O® AMP™ – an Advanced Multi-energy Protection system that deploys the same world-leading D3O® shock absorption technology already protecting elite and everyday riders from head to toe, on bike and on snow.
Not only has the patented D3O® material been carefully formulated to offer optimal protection from lower-energy impacts, but it is also ‘rate sensitive’ – meaning D3O® AMP™ will react to the intensity of the impact, stiffening just enough when it needs to but remaining soft and comfortable the rest of the time.
The remainder of the helmet remains unchanged, meaning brands can simply retrofit products already on the market. D3O® AMP™ is also compatible with complementary rotational safety systems such as the Multi-directional Impact Protection System (MIPS) found in many helmets. Multi-energy impact protection doesn’t compete with rotational acceleration prevention; both contribute to a safer helmet and reduction in risk of mTBIs. Furthermore, retrofitting a helmet with D3O® AMP™ brings no increase in thickness or compromise on comfort.
“Over time we have built a deep and multi-faceted understanding of protection, from impact types and the biomechanics of impacts to the medical consequences of those impacts, along with recognition of the limitations of a standards-based approach,” explains Oliver Sunnucks, D3O’s Senior Product Design Engineer.
“D3O is widely regarded as a market leader in the team sports and defense sectors, and our work has revealed a ‘protection gap’ in helmets for individual action sports – the gap that D3O® AMP™ fills. This solution improves performance against varying impact energies. It makes a helmet safer by providing improved protection against a wider range of everyday crash scenarios rather than the single extreme crash tested against for a standard.”
The need to recognize this ‘protection gap’ is acknowledged in the authoritative Virginia Tech Summation of Tests for the Evaluation of Risk (STAR) rating system, which now tests bicycle helmets at two different impact velocities.
The response in some quarters to D3O® AMP™ has been to suggest that this new system is seeking to replace EPS in a helmet. On the contrary – EPS is excellent at what it does, it is not a problem that needs fixing. But what about impacts at lower speeds? How can you make a helmet more versatile, so it protects against everyday impacts as well as the very occasional high-energy crash?
Put simply, the D3O® AMP™ System absorbs low- to mid-speed impacts so the wearer’s head doesn’t have to.