Category Archives: head protection

Head protection Dr. John Lloyd has served attorneys nationwide for 25+ years in biomechanics, human factors, helmet testing and motorcycle accident expert

Researchers Discover Objective Indicator of Concussion

Opportunity to Protect Professional and Youth Sports Players from Traumatic Brain Injuries

sport concussion and sport accident reconstruction expert Dr. John Lloyd
Sport concussion researchers teamed up with football players at a Florida high school. Ten players were equipped with Riddell Revolution Speed helmets, with the embedded Simbex HITS encoders, which were worn throughout the 2011/2 football season. The HITS system recorded the severity and location of all head impacts during both football practice sessions and games.

To measure the physiological effects of acute and cumulative head impacts, players agreed to wear a wireless EEG system, which was housed on the back of the shoulder pads. In addition, heart rate variability, respiration rate as well as linear and angular motion was recorded using a Tricorder developed by ReThink Medical.

During the 2011/2- football season, several concussive level impacts were recorded. Two players were removed from the field due to suspected sport concussion / mTBI, one of whom was wearing the complete data acquisition system, including HITS encoders, Nicolet EEG and ReThink Tricorder at the time of impact and for approximately 30 minutes post-impact. For the first time we have the opportunity to investigate physiological responses and brain activity changes in response to a concussive level head impact.

sport concussion and sport accident reconstruction expert John Lloyd PhDAnalysis of one player’s self-reported concussive impact clearly shows decreased Gamma band activity and increased Theta band activity in the frontal cortex of the brain immediately following significant head impact. This suggests that the player had reduced cognitive performance and was perhaps in a ‘drowsy’ state for about 10 minutes following impact. During this time, the player may have been dazed and confused and certainly less effective on the field. But more importantly, his ability to protect himself from a second, potentially harmful impact was greatly compromised.

The findings of our study clearly indicate compromised brain activity as a result of head impact, which appears to be correlated with the magnitude of the impact.

EEG graph showing sport concussion by expert witness Dr. John Lloyd

Normalized Power Trend Analysis. Normalized Theta (Left) and Gamma (Right) Power (log of % power within band) of a football player, who experienced a concussion following a moderately forceful head impact (Red line), show phasic modulations in power throughout the practice. Fluctuations in power rarely exceed 25% of the total average power for the recording session in Theta and Gamma frequencies. Yet, immediately following a violent hit (Red line), gamma power begins to decline rapidly and exceeds an arbitrary criterion of ±50% change from average power (peaking at 90 min.). Indeed gamma power remained within 20% of the mean for most of the duration of practice, exceeding this degree of change for over 10 minutes after the impact and two other brief episodes (around 20 min. and 50 min. for less than five minutes; Note, the first and last five minutes were ignored due to the temporal filtering artifact at both edges). Whereas, a peak in theta power coincided with the greatest change in gamma power, the degree of change from the mean normalized power never exceeded 10%. This preliminary data suggests that our algorithms provide (1) the sensitivity to detect significant change in brain activity following a concussive event, and (2) specificity in detecting which frequency band (i.e., gamma) provides the most meaningful brain signal for detecting concussion / brain trauma

Our future goals for the upcoming football season include a new micro-EEG recorder, which is in development, that will allow unobtrusive measurement of several players simultaneously during both football practice and games.

Ultimately, it is our hope that this technology will be widely available to both professional and youth teams so that medical staff can monitor the brain health of players in real-time so that injured participants can be objectively identified, effectively protected and successfully treated.

New Helmet Technology Reduces Brain Injuries

Dr. John Lloyd, Research Director of Brains, Inc. announced today that football head injuries and concussions can be reduced up to 50 percent with their new helmet technology.

New Helmet Technology Reduces Brain Injuries - football helmet prototype by Dr. John Lloyd | expert

football helmet prototype

Tampa, FL – John Lloyd PhD, Research Director of Brains, Inc. announced their latest breakthrough in football helmet safety today. The unique new helmet technology promises to provide up to 50 percent more protection against football head injuries and concussions. The helmet technology has wide application and can be used in every kind of helmet from baby helmets to military helmets, and for all athletes at risk of concussion and head injuries such as football players, cyclists, skiers, snowboarders, skateboarders, hockey players, baseball players, lacrosse players, boxers, soccer players, equestrian / horse-riding sports, such as polo and horse racing, as well as motorcycle and race car drivers.

Recent medical research documents found that concussions and cumulative head impacts can lead to lifelong neurological consequences such as chronic traumatic encephalopathy, a degenerative brain disease known as CTE and early Alzheimer’s.

The U.S. Centers for Disease Control and Prevention, estimates 1.6 – 3.8 million sport-related brain injuries annually in the United States. Of these 300,000 are attributed to youth football players, some of whom die from their injuries every year – a tragedy difficult for their mothers and families to recover from. The severity of the issue touching both the nation’s youth and professional athletes has led to thousands of lawsuits and Congressional Hearings. Growing concern has spread to the White House where President Obama recently spoke at the Healthy Kids and Safe Sports Concussion Summit.

The BRAINS research team, led by renowned brain injury expert, Dr. John Lloyd, has worked for years on their project to help make sports safer. A controversial subject, some opponents have stated that concussion prevention is impossible. Dedicated to saving lives and preserving brain health, Dr. Lloyd and team persevered with their work leading to this new innovation. “Our results show that forces associated with concussion and brain injury are reduced more than 50% compared to similar testing with a leading football helmet,” said Dr. John Lloyd, Research Director. Results of our prototype helmet technology compared to the Riddell Revolution Speed varsity helmet are presented below: New Helmet Technology Reduces Brain Injury - football helmet prototype based on Riddell Revolution Speed “The patent-pending matrix of non-Newtonian materials will not only benefit football, but can be utilized in all sports helmets as well as military, motorcycle and even baby helmets to improve protection and dramatically reduce the risk of brain injuries,” reported Dr. Lloyd. The materials are inexpensive, and produce a helmet that is considerably lighter and more comfortable than a traditional helmet.   Two additional applications of this new safety technology include medical flooring especially in hospitals and nursing homes or child play areas , as well as vehicle interiors.

Testing Methods: A modification to the NOCSAE standard test apparatus has been developed and validated for impact testing of protective headwear to include measurement of both linear and angular kinematics . This apparatus consists of a twin wire fall test system equipped with a drop arm that incorporates a 50th percentile Hybrid III head and neck assembly from HumaneticsATD. The aluminum flyarm runs on Teflon sleeves through parallel braided stainless steel wires, which are attached to mounting points in the building structure and anchored into the concrete foundation. The anvil onto which the head drop systems impacts consists of a 350mm x 350mm steel based plate. Both the Riddell Revolution Speed varsity football helmet and prototype helmet were dropped from a height 2.0 meters onto a flat steel anvil, in accordance with ASTM standards, generating an impact velocity of 6.2 m/s (13.9 mph). The following slow motion videos show testing on an unhelmeted head and prototype using this apparatus

 

 


Instrumentation: A triaxial accelerometer from PCB Piezotronics (Depew, NY) and three DTS-ARS Pro 18k angular rate sensors (Diversified Technical Systems, Seal Beach, CA) affixed to a triaxial block were installed at the center of mass of the Hybrid III head form (HumaneticsATD, Plymouth, MI). Data from the accelerometer and angular rate sensors were acquired using National Instruments (Austin, TX) compact DAQ hardware.

Analysis: In accordance with SAE J211, data from the analog sensors were acquired at 10,000 Hz, per channel, using LabView (National Instruments, Austin, TX), then filtered in Matlab (The Mathworks, Natick, MA) using a phaseless 4th order Butterworth filter with a cut off frequency of 1650Hz. Angular acceleration measures were derived from the angular velocity data based on a 5-point least squares quartic equation.

About Lloyd Industries, Inc.

Lloyd Industries, Inc., located in San Antonio, Florida, is a research and development company focused on the biomechanics of brain injuries. The company was founded in 2004 by John D. Lloyd Bio, Ph.D., CPE, CBIS, Board Certified Ergonomist and Certified Brain Injury Specialist. He has also provided expert witness services nationwide for over 20 years in the fields of biomechanics, ergonomics and human factors, specializing in the biomechanics of brain injury, including sport and motorcycle helmet cases, slips and falls, motor vehicle accidents and pediatric head trauma. Lloyd Industries is open to licensing with manufacturers to bring this much-needed technology to market for the protection of sports participants and athletes of all ages. For additional information call 813-624-8986.

Motorcycle Helmet Standards

Motorcycle helmets were originally developed in the early 20th century and, like most helmets, are modeled after military helmets, the purpose of which is to protect against penetrating head injury. The modern motorcycle helmet, with a hard outer shell and rigid expanded polystyrene (EPS) liner was actually introduced over 60 years ago. The outer shell serves as a second skull, dispersing the impact force over a wider surface area, while the inner shell compresses in an attempt to reduce translational forces. A mechanism to mitigate tangential forces is absent. Since the liner fills the entire inner surface of the shell, tangential forces cannot be absorbed and are transmitted directly to the head and brain. Motorcycle helmet standards focus on reducing the effect of linear impact forces by dropping them from a given height onto an anvil and measuring the resultant peak linear acceleration.

Motorcycle Helmet Standards

In motorcycle helmet testing, the risk of impact loading injuries, such as skull fractures, can be determined by measuring linear accelerations experienced by a surrogate head form in response to impact. Whereas risk of impulse or inertial loading injuries, such as concussion, axonal injury and subdural hematoma can be quantified by measuring impact-related angular accelerations at the center of mass of a test head form.

Unfortunately, the evolution of motorcycle helmet design is not driven by advances in scientific knowledge, but rather by the need to meet applicable testing standards. In the United States, standards include the federal motor vehicle safety standard (FMVSS) #218, commonly known as the DOT motorcycle helmet testing standards, and Snell M2015, while ECE 22.05 and BSI 6658 were adopted in European countries. Test procedures involve dropping a helmeted head form onto various steel anvils at impact velocities ranging from only 5.0 to 7.75 m/s (11-17 mph). Pass/fail is based on the ability of the helmet to provide protection against forces associated with linear acceleration in response to impact.

John Lloyd expert witness motorcycle helmet standardsCurrent motorcycle helmet testing standards do not incorporate measures of angular acceleration and therefore fail to assess whether helmets offer protection against catastrophic brain injuries. The omission of this critical measure is reflected epidemiologically in the disproportion of closed head injuries in fatal motorcycle accidents.

Helmets – The Ultimate Protection?

Motorcycle helmet and accident reconstruction expert Dr. John LloydThe common belief among riders is that a motorcycle helmet protects the whole head, including the brain. However testing standards in Europe (ECE 22.05) and the US (DOT & Snell), which involve dropping helmeted headforms from heights of 2-3 meters onto a steel plate, only evaluate a motorcycle helmet in terms of its ability to protect against blunt force trauma, such as skull fractures and penetrating head injuries. The mechanism underlying diffuse brain injuries, such as concussions and brain hemorrhages is distinctly different, but is not assessed by current motorcycle helmet testing standards.

Imagine a bowl of jelly, where the bowl represents the skull and the jelly represents the brain. The bowl (skull) serves to protect the jelly (brain) from impact by dispersing forces over a larger surface area. If the bowl were impacted such that the force passes through the center of the jelly, the jelly moves very little. This is called linear force. Whereas, if you rotate the bowl of jelly between your hands you will see that the jelly moves quite a lot, especially towards its center. This is called a rotational force.

In reality, most motorcycle helmet impacts will produce both linear and rotational forces. In the case of head and brain injury, linear forces are responsible for injuries such as bruises and fractures. Whereas rotational forces cause the nerves and blood vessels in the brain to stretch and tear, leading to concussions, injury to the nerve fibers (axonal trauma) and brain bleeding (hematomas).

The human head is designed to protect the brain against typical impacts associated with daily living, such as normal bumps and falls. The skull can be thought of as a helmet to the brain by resisting penetrating injury to the brain. While the scalp glides over the skull to decrease rotational forces, thereby reducing the risk and severity of diffuse brain injuries. However, the forces associated with motorcycle collisions far exceed that which the human skull and scalp was intended to protect. Hence in motorcycling the use of a helmet to reduce the risk of such injuries is typically mandated.

Helmets are designed with 3 principal components – the outer shell, the inner liner and a comfort layer. The shell is typically made of polycarbonate plastics or fiberglass and serves two purposes; to minimize the likelihood that a sharp object might penetrate the head, and to dissipate the impact over a larger surface area. The inner liner is made from EPS foam (polystyrene) and serves to absorb the impact forces. The comfort layer does nothing more than provide comfort between the head and the polystyrene liner. Unfortunately, the polystyrene liner has limited effectiveness at reducing the rotational forces – those responsible for diffuse brain injuries – below safe levels.

A cooperative study was undertaken in Europe in the late 1990s to examine motorcycle accidents and their causes. Based on data from 4,700 helmeted motorcyclist deaths, the study found head injuries accounted for three-quarters of all fatalities. More than 60 percent of which were brain injuries caused by rotational forces, while only 30 percent of fatal head injuries were due to linear forces. This extensive study proves that motorcycle helmets are inadequate in providing necessary protection against diffuse brain injuries.

One might propose that protection against diffuse brain injury ought to deserve a higher priority. After all, the skull will likely heal from trauma, but the brain may not.

The challenge with protective headgear, including motorcycle, military and sports helmets is that, due to the characteristics of the liner materials, the head is directly coupled to the helmet. That is, the head and helmet are effectively joined and move as one. Therefore upon impact, any rotational forces generated on the helmet are transmitted directly to the brain. In fact, due to the size of helmets rotational forces can actually be amplified. The solution lies in de-coupling the head from the helmet, much the way that the scalp is de-coupled from the skull, so that the helmet can have some degree of rotation independent of the head. In this way, the rotational forces are dampened before they are transmitted to the brain, thereby lessening the risk and severity of brain injury.

BRAINS, Inc., of which Dr. Lloyd is the Research Director, is developing a new generation of motorcycle helmets, utilizing a patented composite of shear-thickening non-Newtonian materials. Due to their nature, these advanced materials respond differently to linear and rotational forces, thereby allowing the helmet some independent rotational motion, effectively de-coupling the helmet from the head. This technology was demonstrated at NI Week (http://youtu.be/T591x950oRI) and shows great promise for protection against both blunt force trauma and traumatic brain injuries.

Given the choice of a helmet that protected against skull fracture and one which also provides protection against brain injury, which would you choose?

For more information, please contact John@DrBiomechanics.com

 

Biography:

Dr. John Lloyd holds a PhD in Ergonomics from Loughborough University and is a Brain Injury Specialist. He is an expert in the field of brain injury biomechanics.

As a motorcycle enthusiast, John has clocked more than 250,000 miles and completed numerous training programs. Dr. Lloyd has served as a biomechanics expert on a variety of motorcycle accident cases.

How Well Do Football Helmets Protect Against Concussion and Brain Injury?

Football helmet research presented by John Lloyd, PhD – BRAINS, Inc. & Frank Conidi, MD – Florida Center for Headache and Sports Neurology at the 66th Annual Meeting of the American Academy of Neurology, 2014

YouTube link to video on Biomechanics of Football Helmets

Sports related concussion is the most widely publicized neurological disorder, with football accounting for the highest incidence across all sports. There is a silent epidemic of these invisible injuries across players of all ages from youth through professional, resulting in a 3-fold increase in ER visits among high school players from 2000-2010. It is estimated that a quarter of a million of these injuries each year have long-term consequences. A single moderate to severe brain injury can leave one at risk for early onset dementia, while repeated mild concussions may have the same effects (Giza).

The football helmet became mandatory in the 1930’s to provide protection against catastrophic head injuries. Over the past eighty years there have been significant modifications in football helmet design. Yet despite advances in technology there is still little evidence that helmets offer significant protection against concussion and traumatic brain injury (Giza). hile the widely utilized Simbex HITS system and the Virginia Tech STAR rating system attempt to measure helmet performance, neither offer a direct measure of concussion or brain injury risk.

Methods

According to Holbourn, risk of focal head injury, such as skull fracture and brain contusion, can be expressed in terms of linear acceleration, while the risk of concussion, axonal injury and diffuse brain injury is associated with angular/rotational acceleration. The standard NOCSAE / ASTM helmet tests only measure forces associated with linear acceleration and therefore fail to account for risk of brain injury.

Goldsmith Leatherhead football helmet - sports accident reconstruction expert John Lloyd

A modified test apparatus, incorporating a Hybrid III crash test dummy head and neck, has been validated by Caccese and Lloyd. This method induces a rotational inertia on impact, thereby facilitating measurement of risk of focal head and diffuse brain injuries.

We purchased 60 football helmets, including three samples each of 20 different models.  All helmets were dropped five times from a height of 2.0 meters onto a steel plate, generating an impact velocity of 13.9 mph.

Football Helmet Results

Our findings show that football helmets vary widely in terms of their performance to protect against focal head injury and concussion / diffuse brain injury. All tested football helmets, including the 1930s leatherhead meet the minimum performance criteria of 275G as set by the ASTM F717 standard. However, this standard does not account for duration of impact, which is a critical factor. Moreover, ASTM F717 does nothing to set helmets performance standards in terms of protection against concussion and brain injury.

football helmet testing and analysis Dr. John Lloyd sports accident reconstruction expertBy design, helmets reduce impact force by increasing the impact duration. But, as demonstrated by Depreitere (blue) and Lowenhielm (red) increasing impact duration actually lowers the brain injury threshold.
Head injury risk was calculated with respect to the140g threshold for 7msec impact documented by Ono, wwhile brain injury risk was calculated based on Ommaya’s1700 rad/s^2 tolerance limit for moderate AIS2 brain injury, which concurs with Rowan and Duma’s top 25% of sub-concussive impacts.

Results are presented below, where % reduction of head injury risk is shown in red and % reduction of concussion/mTBI is presented in blue.

Bars above the x-axis indicate that the helmet performs better than the documented threshold, while those below the x-axis did not meet our performance thresholds.

Football helmet results by sports accident reconstruction expert Dr. John Lloyd

It is noted, interestingly, that the 1930s Goldsmith leatherhead helmet actually outperformed several contemporary football helmets in terms of protecting against concussion and brain injury, including the Adams a2000 Pro, the Rawlings Quantum and the Riddell 360.

Based on our research, the top 3 varsity helmets are: Xenith X1, Schutt Air XP Pro, and Rawlings Quantum Plus, respectively. The top 10 helmets are presented below, based on their protection against traumatic focal head injuries and diffuse brain injuries:

Football helmet top 10 results from testing and analysis by sports accident reconstruction expert John Lloyd PhD

Conclusions

None of the football helmets on the market today offer what most would consider adequate protection against concussions and traumatic brain injuries. A shift in thinking towards lighter high-tech materials for helmets, teaching proper hitting and tackling techniques, pre and in-season isometric and isokinetic cervical strengthening programs, and continued concussion awareness and education are the best means of protecting athletes of all levels from the consequences of concussion and traumatic brain injury.

Future Research

It is hypothesized that oblique impacts present even longer impact durations, which may explain why such seemingly innocuous impacts cause increased incidence of concussion.

Embracing the findings from testing of the 1930s Goldsmith leatherhead,  a new generation of soft football helmets is proposed, utilizing today’s advanced non-Newtonian materials, which we anticipate might outperform contemporary helmets in terms of protection against both traumatic head and brain injuries.

References

1. Caccese V, Lloyd J, F et al (2014). An Impact Test Apparatus for Protective Head Wear Testing Using a Hybrid III Head-Neck Assembly. Experimental Techniques.
2. Depreitere, B. et al. (2006). Mechanics of acute subdural hematomas resulting from bridging vein rupture, J Neurosurg, 104; 950–956.
3. Holbourn, A.C.H. (1943). Mechanics of Head Injuries. The Lancet p438-441
4. Giza CC, Kutcher JS, Ashwal S, et al. (2013) Evidence based guideline update: Evaluation and management of concussion in sports. Report of the Guideline Development Subcommittee of the American Academy of Neurology. Epub March 18.
5. Lowenhielm, P. (1974). Strain Tolerance of the Vv. Cerebri sup. (. Z. Reehtsmedizin 75, 131-144
6. Ommaya A. (1985). Biomechanics of Head Injury – Experimental Aspects. In Nahum A M & Melvin J (Eds). The Biomechanics of Trauma. 
7. Ono K. (1998) Human head impact tolerance. In Yoganandan (Ed). Frontiers in Head and Neck Trauma: Clinical and Biomechanical. IOS Press, Amsterdam. Appleton-Century-Crofts publishers, Norwalk, CT.
8. Rowan S. & Duma S. (2013). Brain Injury Prediction: Assessing the Combined Probability of Concussion Using Linear and Rotational Head Acceleration. Annals of Biomedical Eng. 41, (5): 873–882

Brain Injury in Sports

Dr. Lloyd’s research article “Brain Injury in Sports”, co-authored with Dr. Frank Conidi has been published in the Journal of Neurosurgery.

Please email me at DrJohnLloyd@Tampabay.RR.com  if you would like to receive a full copy of the published article.

Abstract

BACKGROUND
Helmets are used for sports, military, and transportation to protect against impact forces and associated injuries. The common belief among end users is that the helmet protects the whole head, including the brain. However, current consensus among biomechanists and sports neurologists indicates that helmets do not provide significant protection against concussion and brain injuries. In this paper the authors present existing scientific evidence on the mechanisms underlying traumatic head and brain injuries, along with a biomechanical evaluation of 21 current and retired football helmets.

METHODS
The National Operating Committee on Standards for Athletic Equipment (NOCSAE) standard test apparatus was modified and validated for impact testing of protective headwear to include the measurement of both linear and angular kinematics. From a drop height of 2.0 m onto a flat steel anvil, each football helmet was impacted 5 times in the occipital area.

Brain Injury in Sports - apparatus

RESULTS
Skull fracture risk was determined for each of the current varsity football helmets by calculating the percentage reduction in linear acceleration relative to a 140-g skull fracture threshold. Risk of subdural hematoma was determined by calculating the percentage reduction in angular acceleration relative to the bridging vein failure threshold, computed as a function of impact duration. Ranking the helmets according to their performance under these criteria, the authors determined that the Schutt Vengeance performed the best overall.

Brain Injury in Sports - results

CONCLUSIONS
The study findings demonstrated that not all football helmets provide equal or adequate protection against either focal head injuries or traumatic brain injuries. In fact, some of the most popular helmets on the field ranked among the worst. While protection is improving, none of the current or retired varsity football helmets can provide absolute protection against brain injuries, including concussions and subdural hematomas. To maximize protection against head and brain injuries for football players of all ages, the authors propose thresholds for all sports helmets based on a peak linear acceleration no greater than 90 g and a peak angular acceleration not exceeding 1700 rad/sec2.

 

Please call Dr. Lloyd at 813-624-8986 or email  DrJohnLloyd@Tampabay.RR.com if you would like to receive a full copy of the published article “Brain Injury in Sports”

Concussion starting Will Smith portrays Dr. Bennett Omalu who challenges the NFL with discovery of Chronic Traumatic Encephalopathy caused by repeated blows to the head in football

In December a movie titled “Concussion”, staring Will Smith will be released in theaters, chronicling the work and bravery of Dr. Bennett Omalu, who first discovered Chronic Traumatic Encephalopathy (CTE) as the consequence of repeated blows to the brain in football and attempts by the National Football League (NFL) to deny any causal link.