Helmet Research at Virginia Tech

Note: This piece follows-up on my earlier overview of concussion research:  http://secondlevelfootball.wordpress.com/2012/05/04/football-and-brain-injury/

The Virginia Tech-Wake Forest Center for Injury Biomechanics (CIB) is one of the most impressive injury research institutions around.  While it’s best known for studies performed by the Virginia Tech branch on football helmets, the Center is a diverse operation.  The bulk of the VT head injury office’s floor-space is actually devoted to classified military research, mainly related to vehicle crashes and IED impacts.  The institute also studies the safety of civilian vehicles in crashes and the safety of children’s toys; the Wake Forest portion conducts a great deal of automotive work.

The CIB operates from within the VT-WF School of Biomedical Engineering and Sciences.  Running the school is Dr. Stefan Duma, who also happens to be the man responsible for kick-starting modern helmet research and making it a topic of public interest.  Duma has co-authored hundreds of papers on impact injuries; his work has lately included research on head impacts in baseball players, how organs are affected by crashes, and how vehicle-related impacts affect pregnant women.  Duma has also been the key force behind the rapid growth and rising prominence of biomedical engineering at VT.

Almost all of his head-safety projects (as well as those of the faculty, staff, and students beneath him) are funded either by the National Institutes of Health, which is a federal organization that awards research grants to promising health projects, or the Department of Defense.  The Center for Injury Biomechanics takes no money from the companies whose products are researched; even speaking fees are donated to youth football programs for the purpose of buying safer helmets.

Monitoring Player Impacts

Virginia Tech’s work in the field of helmet safety can be broken into two parts—lab experiments and fieldwork.  The fieldwork ramped-up shortly after Duma’s arrival in 2000.  Since there was little data on what happened on the college football field with regard to helmet impacts, that was where work needed to start.  The first major step was outfitting 38 Hokies with HITS, or Head Impact Telemetry System, which is an electronics suite manufactured by Simbex.

Helmet Impact Telemetry System; the piece at lower-left is the helmet sensor suite.  Image courtesy Simbex.

HITS includes both computerized impact-reporting devices consisting of helmet sensors and the sideline computers that monitor the helmet sensors.  The helmet sensors are simple accelerometers that measure linear and rotational impacts.  They’re housed in a flexible plastic strip that also contains a battery and WiFi transmitter.  The strip mounts inside a player’s helmet, where it fits between the side and crown cushions.

The collected data is wirelessly transmitted to a laptop computer on the sideline where it’s not only stored for later analysis, but also used for real-time monitoring of how hard (and where on their heads) players are getting hit.  You’ll see images and TV footage of the computer being carted around inside a formidable looking crate packed with black egg crate cushioning (included in the image above), and you’ll also see all of it–computers and carrying crate–contained within a clear, rainproof plastic housing that looks like it could double as protection for the Pope.  HITS also includes pagers that medical staff can wear to receive instant alerts on high-g impacts.

The entire VT team is being monitored by HITS, as are the teams for several other schools.  This means nearly every single hit experienced by thousands of players across the country has been pooled and analyzed.  The upshot is that undiagnosed concussions have been greatly reduced in teams using the equipment, perhaps to the point of being eliminated.

In my previous post I mentioned how a Tech player stayed on the field after receiving a concussion.  The player was Brandon Manning in 2003; despite the concussion, he not only stayed on the field but led the Hokies with 16 tackles in the game.  Since Manning stayed in the game, the concussion went unnoticed by trainers. Manning himself didn’t think enough of the hit to report it.

Thanks to HITS, Tech researchers/trainers are now notified immediately when any player’s head receives an impact acceleration at or near concussion-levels.  When this happens, the player is immediately pulled from the practice or game for an evaluation—the system is even fast enough to routinely have players pulled from the field between plays.  Its main limitation is signal problems encountered by players at the edges of the endzone.

Testing Helmets in the Lab

When enough impact data was collected, it was time to test helmets in the lab.  This required that many varieties of adult football helmets be subjected to controlled impact testing.  As the picture below shows, the process isn’t too different from using a crash test dummy in a car.  The testing device is called a drop tower, and consists of a dummy head fixed to a vertical frame, which itself is fixed to an impact platform.  Helmets (without facemasks) are fixed to the dummy head and dropped from various heights and with various parts of the helmet shell hitting the platform.

Drop tower prior to helmet-mounting; standing at right is Stefan Duma. Image courtesy Virginia Tech.

The ability of the helmets to dampen various blows is measured and applied to probability data collected from the thousands of actual impacts recorded in on-the-field testing.  This mix of helmet resilience and risk data is called STAR, or Summation of Tests for the Analysis of Risk.  Fittingly, the helmets are judged on a “star” scale, with 5-star helmets providing the most protection against severe acceleration, and helmets with fewer stars performing less-well as the stars are reduced.

The results of these tests are made publicly available at http://www.sbes.vt.edu/nid.  The first batch of results ran counter to the expectations of some, particularly in terms of helmet cost and intent.  First, higher cost didn’t necessarily correlate to greater impact reduction—several 4-star helmets cost less than a similarly priced helmet that was demonstrated to be the worst tested.  Second, as a few coaches at the Duma presentation I attended noted, several helmets marketed at skill positions showed better safety performance measures than some helmets marketed for use by players in the box.

Research Limitations

There are some limitations to what the CIB is doing with researching helmet safety and concussions.  Their goal is reducing high-risk head collisions either by improving helmet safety or reducing practices that lead to high-risk head collisions.  It’s important to realize that their work is informed by well-documented research on acute brain injuries.  While they’re certainly creating data that’ll be useful in measuring long-term health outcomes of concussions, we don’t have enough information to really understand the risk factors.  The CIB researchers also aren’t in the position of commenting on the long-term effect of sub-concussive impacts.  That’s the realm of epidemiologists and clinical neurologists, not biomechanics and engineering folks.  I think the smart money is that the CIB’s work is going to improve long-term outcomes for football players across the country, but that’s still far from proven.

More specifically, we have to understand that the end result of their work will not be a concussion-proof helmet.  Creating a helmet that would allow for the game to continue being played as-is while also being impervious to concussions is beyond our current technology.  The CIB’s helmet safety guidelines are creating helmets that are better at distributing impact energy, which will reduce head acceleration in properly tensed and positioned players.  Even the highest-rated helmet isn’t of much help in unexpected hits where there’s no muscular tension and skeletal alignment to resist impacts, or in angled hits that the human body has difficulty opposing.

Finally, the team is working on refining its testing methods.  They plan to further investigate the ability of helmets to reduce rotational forces, to test helmet differences at varying temperatures that might alter the properties of the helmet shell and cushion, and possibly to include tests with facemasks.  I doubt any of these refinements would significantly change STAR results–the variables have a measure of theoretical and statistical predictability–though more data is never a bad thing.

Looking Ahead

Because I thought it deserved its own space, I’ll talk about VT’s youth football research (and youth safety issues in general) in a later post.

What We Know (and Don’t Know) About Football and Brain Injury

With the recent deaths of Ray Easterling and Junior Seau, and the prominence of head-shots within the Saints bounty scandal, football-related brain injuries have returned to the news.  Unfortunately for the general public, these reports don’t contain much useful information on the injuries and their causes, diagnoses, and treatments.  Over the past few weeks, I’ve had the opportunity to listen  and speak to Dr. Stefan Duma of Virginia Tech and Dr. Jeffrey Barth of the University of Virginia, both of whom are leaders in the field of head injury research.  Duma leads the most sophisticated head injury research facility in the country, and also leads the program that monitors head impacts received by VT players during games and practices.  Barth is a member of the NFL Players Association Concussion Committee and co-wrote a study that first put concussions in the public spotlight back in the 80’s.

Comparison of healthy brain tissue to that of a football player and a boxer; slide courtesy J. Barth..

Though the media is focused on repeated blows to the head (and reasonably so), it’s important to note that a single concussion can be extremely harmful.   A concussion is an injury to the brain caused by sudden acceleration.  A common technical term for a concussion is “mild traumatic brain injury,” which highlights its potential seriousness.  Athletes in many sports often play through mild concussions; Dr. Duma showed one clip of a former Virginia Tech linebacker who suffered a concussion during a play, stayed on the field, and nearly started the next play lined-up at deep safety before a teammate redirected him back to the box.  This was in the early days of the program when guidelines were still being established; a player at VT (and other schools with helmet-safety programs) in this situation today wouldn’t return to the field.

Concussions can cause disorientation, nausea, head pain, light sensitivity, unconsciousness, insomnia, mood changes, and memory loss.  The acute effects of a concussion last on average between 5 and 10 days.  Longer-term symptoms generally clear within three months, though extreme examples can last for years.  Children generally take longer to recover.  The typical concussion occurs when the head experiences around 100 g-force of acceleration (or 100 times the acceleration of earth’s gravity).  As a comparison, an amateur boxer’s dominant-hand hook can create about 80 g of head acceleration.

An average player at Virginia Tech will have four incidents of  circa-100 g head acceleration every season.  Interestingly, out of the entire team only about four actual concussions are diagnosed annually, while the rest of VT athletics reports around 26 concussions during the same period.  This speaks to the variability of concussion susceptibility, and also to football players’ ability to tense their bodies in ways that dampen impact forces.  Additionally, Duma notes that his research has lead to VT and other schools to adopt safer helmets and reduce or eliminate drills that lead to excessive head impacts.  Barth noted that rather than follow his committee’s recommended practice guidelines (which would reduce helmeted practices by roughly three-fourths), the NFL ownership installed rules that halved helmeted practices.

Concussions occur because both the head and the brain are each flexibly tethered, and both can independently whip about on impact, causing the sudden acceleration and deceleration responsible for concussions.  We know this movement can actually rip apart the connective links of brain cells, though beyond that we’re less certain about what else happens within the brain during and after a concussion.  We do know that having one concussion increases your risk of having another by 3-to-6 times, though we aren’t sure if this means certain people are simply prone to concussions, or if having one concussion increases your sensitivity to future brain trauma.  This increased risk is especially important to know because having a second concussion (even a minor one) during the acute phase of a prior trauma can lead to serious complications.  The only proven form of concussion recovery is rest and time.

Getting more into the controversy of football and head injuries, we don’t know how to define or quantify the effects of repeated concussions or repeated sub-concussion blows to the head.  It seems that repeated blows can trigger chronic traumatic encephalopathy (CTE), which is a condition that causes both brain deterioration and the harmful accumulation of defective tau protein in the brain.  Symptoms of CTE include chronic and worsening dementia-like memory and cognition loss, as well as depression, aggression, loss of motor control, and disorientation/confusion.  The symptoms generally appear late in a player’s life, though tau deposits are now being found in the brains of middle-aged men, active NFL players, and even teenagers who’ve had multiple concussions.  Over a dozen former NFL/college players have been diagnosed, and if media reports are to be believed, Easterling and Seau both displayed behavioral symptoms consistent with CTE.  Compared to the entire league, this is still a very small sample, which makes it difficult to determine just how frequently CTE occurs.

At the moment, CTE can only be diagnosed by post-mortem examination of the brain.  The Boston Center for the Study of Traumatic Encephalopathy that’s frequently referenced in media reports is among the best known institutions performing these examinations, and has done so on the brains of several NFL players.  Dr. Barth notes that Siemens’ healthcare division claims to be 18 months away from deploying PET scan technology capable of detecting CTE in living patients; while PET equipment isn’t nearly as common in hospitals as MRI and CT equipment, it’s a step in the right direction.

Our limited understanding of the brain and impacts is very cloudy.  It may turn out that only a small, definable subset of the 5 million adults, teens, and children currently playing football will ever be at risk for severe and/or long-term brain injury.  Or it may turn out we’re experiencing a sport-related epidemic of lasting brain injury.  We just don’t know.  In this situation, knee-jerk fears can give rise to sham treatments and unwise practices, while apathy can dampen efforts to learn more and create healthier practices.  As Dr. Barth consistently reinforces, we need to be comfortable with the ambiguity of this subject while working towards resolving it.

Junior Seau (1969 – 2012)

While he was feared and admired among his peers like few others during his time in the league, the anecdote I remember when I think of Seau is actually about rehab. It was from a Sports Illustrated article, and it documented a rehab session for a hamstring injury. His trainer was putting him through a series of exercises–multiple sets of machine-based leg curls, which can be painful enough when you’re healthy–and he commented that he couldn’t believe just how intense Seau was in rehab. “The Tasmanian Devil” was fearsome and focused even when injured.

I know there are discussions his death will likely engender (and should engender, if the details hold-up), though that’s a topic for another time.

Don Faurot, Option Inventor

The roots of the Flexbone attacks seen in today’s Georgia Tech and Navy teams can be directly traced back to the work of Missouri University coach Don Faurot and his Split-T offense.  The same can be said for all Wishbone, Veer, and other option-heavy offenses.  Faurot’s biggest contributions were widening the T-formation and then “optioning” defensive players, which allowed for a fast, flanking attack.

Coach Faurot diagrams the option-pass play.

Faurot was a high school star in football, baseball, and basketball—no easy feat, and even more impressive considering he’d lost two fingers during a childhood farming mishap.  He had already been coaching college football almost twenty years when the idea of the option play struck him.  His inspiration was basketball, more specifically the defender’s dilemma during a two-on-one break.  A proper two-on-one essentially forces the defender into making a mistake.  Barring a screw-up by the players on the break, the defender has to leave someone open for an easy bucket.

Transferring this idea to football required an unusual approach: leaving a high-threat defender intentionally unblocked and then running right at him.  If the defender (usually a defensive end) went for the quarterback, the QB would toss the ball to a trailing running back.  If the defender went for the running back, the QB had a clear path upfield.  While the optioned defender was left in a bind, his teammates weren’t much better off, since the tight end on that side was free to block a linebacker or DB.

Split-T Option: The right-side defensive end is being optioned; the dotted line indicated the option toss if the end tackles the QB.

Faurot also had two plays that specifically complemented the option play.  First, Faurot had a basic fullback dive that went straight up the gut while the rest of the backs carried out an option fake.  The dive prevented the defense from loading-up the edges.  Second, if the deep defenders rushed the line of scrimmage without respecting the pass, Faurot could call an option-pass that looked nearly identical to the option play, but had the halfback throw downfield after taking the toss.  Finally, the option play faked the fullback dive and had its tightends fly downfield to block, so the three combined plays looked almost identical just after the snap.  That little fake dive ultimately evolved into part of today’s veer and triple pitch-option plays where the fullback can actually be a ball carrier.

MU's Option play in action; the QB has just tossed the ball (under the arrow) while being tackled by the defensive end.

While Faurot had tinkered with the Split-T during practices at Missouri, it didn’t become public until the absence of a good throwing QB forced him to employ it.  This was in 1941, and it nearly led him to an opening day victory over Paul Brown’s Ohio State squad.  Faurot’s teams frequently led the country in rushing and achieved several top-10 finishes that helped reinvigorate the entire MU athletic program.

Lombardi’s “Doo-Dad” and the History of the Zone Run Game

It’s tricky to say when a play or scheme was “invented,” partly because all football ideas stem from prior concepts, and partly because of how quickly information can be disseminated in the sport.  Between coaching changes, clinics, and gamefilm study, new ideas don’t stay secret for long.  With that said, I feel very comfortable stating that today’s inside/outside zone run tandem was first codified by Sam Wyche’s Cincinnati Bengals teams of the late 80’s and early 90’s, and almost as comfortable saying they invented the modern concept.  Famed OL coach Alex Gibbs gets lots of deserved credit for adding new elements and elevating its use to an art with his Super Bowl-winning Broncos teams, but most of what he preaches goes back to the Bengals of almost a quarter of a century ago.  The Bengals had so many unusual attributes—including heavy use of the no-huddle—that their zone runs didn’t get as much attention in the media.

I was actually taught the inside zone play by watching Bengals game film of Ickey Woods.  It was a thing of beauty seeing how zone schemes not only gave offenses a way to limit the effectiveness of blitzes, stunts, and slants, but actually turn these tactics against a defense.  Linemen were almost always put into positions to make great blocks in a much more effective manner than man-scheme combo blocks.  At the same time, the runningback’s movement and reads gave him the benefits of designed counters and option plays without the risks of cutting into a blitz or fumbling a pitch or mesh.

The key to modern zone runs is the use of controlled double-team blocks on defensive linemen that turn into single-man blocks depending on what the defense does.  The movement and intent of a playside tackle or end not only determines who picks up second-level linebackers and safeties, but also keys where running lanes are likely to develop.  Getting back to the idea of there being little new under the sun when it comes to football, we can trace this flexible double-team concept all the way back to Vince Lombardi’s coordinator and head coach positions with the New York Giants and Green Bay Packers, and we can probably assume he used it some at West Point or even earlier. (Of course, he may have gotten the technique from someone else.)

Depending on which of Lombardi’s playbooks you look at, this specialized double-team was called either a “doo-dad” or “do-dad” block, and was designed specifically to beat stunts and blitzes.  Doo-dads weren’t just for offensive linemen, but also for double-teams by a lineman and a runningback.  Just like today’s inside zone takes advantage of defenders overreacting to the outside zone run, Lombardi’s 36/37 Slant got defenders running to the sidelines, while his 30/31 hit them hard up the gut when they began overreacting to the outside run.  Doo-dad blocks were key to these plays.

In both plays, a back and a tackle use teamwork to defeat the playside linebacker and defensive end.  The diagram below shows the playside offensive tackle, fullback, and halfback roles in the play’s 36 Weakside variant, which is being run out of the Brown formation.  The defense is running a stunt where the defensive end slants weak while the backer loops around behind.  The play looks simple because the two offensive players are basically assigned an area to block.  The halfback and tackle are the blockers; halfbacks and fullbacks were largely interchangeable in the 60’s, and also not much smaller than typical linemen, so this arrangement isn’t unusual.

36 Weakside

Rather than having a fixed assignment, the halfback is responsible for blocking the outside defender, while the tackle blocks the inside man. Both blockers aim for the defensive end, with the tackle going for centerline and the back aiming for the outside hip.  If the defenders play straight-up, the result is nothing unusual: the tackle blocks the end across from him, and the halfback takes the linebacker.  If the defensive end slants weakside and the backer loops behind him, however, the two blockers keep their area assignments, which means the halfback is now responsible for the end and the tackle picks up the backer.  Whatever the defense does, the fullback watches the result and aims for the vacated area or, in Lombardi’s famous parlance, “runs to daylight.”  He can run off-tackle if defenders get bogged inside, split them down the middle, or cut inside if they over pursue to the intended hole.

The flexibility of this play allows for the best-positioned blocker to take on each defender at the hole.  Combined with the ball carrier’s read, Lombardi was espousing two of the major tenets of the modern zone ground game two decades before the Ickey Shuffle’s heyday.  It’s another sign of history repeating itself when we note that just as the Bengals’ zone plays were overshadowed by other facets of their offense, Lombardi’s doo-dad technique played second fiddle to his ubiquitous Packers’ Sweep play (which itself featured a guard/fullback doo-dad block.)