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Impact Sensors: Frequently Asked Questions


Until very recently, impact sensors - accelerometers measuring the forces which, when transmitted to the brain, cause sports-related concussions - were only used by scientists in conducting research.

The last several years, however, have seen a growing number of companies introduce to the consumer market the first generation of impact sensors intended for real time monitoring of impacts to the heads of athletes in actual games and practices. 

As is often the case with new technology-based products, the sensors in initial use at some colleges, and by a small but growing number of high schools around the country - including the football program at Newcastle High School in Oklahoma featured in the new PBS documentary, "The Smartest Team: Making High School Football Safer," - are still relatively expensive, and they are just now being tested extensively under real world conditions.

Brain Sentry impact sensor on Newcastle High School football helmetAs a result, only time will tell whether they will fulfill the promise that many in the concussion community see them as having, although I, for one, think they will eventually revolutionize the way in which athletes are identified for remove-from-play screening on the sports sideline, among other uses.

Since I began writing several years ago about the use of impact sensors as a technological "end around" the problem of chronic underreporting of concussions - and especially since "The Smartest Team" began being broadcast widely  on PBS stations around the country - I have been getting a lot of questions about them.

Fortunately, as result of my first-hand experience, working closely the past two football seasons with sensor manufacturers and the Newcastle football program, and from covering the concussion beat, along with a team of  experts and staff journalists, for the past thirteen years, I believe MomsTEAM and I are in a unique position to explain just what impact sensors are all about.

To help parents, coaches, athletic directors, booster clubs, and sports program administrators understand what this cutting-edge technology does - and, just as importantly, what it doesn't do, here are answers to the questions MomsTEAM is most frequently asked about impact sensors:

Question: What are impact sensors?

Answer: Impact sensors are small, highly sophisticated electronic devices designed to measure and, in many cases, record in real time the number and force of impacts athletes sustain during games or practices. Most sensor systems send impact data wirelessly via Blue Tooth connection to a dedicated monitor, iPhone, iPad or laptop on the sports sideline. In some products, the sensor triggers an audible or visual alarm to alert sideline personnel to a high impact hit.  

Question: What are impact sensors designed to do?

Answer: While impact sensors take a number of different forms (ie. installed inside or on the outside of a player's helmet, embedded in a mouth guard, helmet chin strap, skull cap, head band, or ear bud, for instance), all are essentially designed to do the same thing: alert coaches, athletic trainers, team doctors, other sideline personnel and/or parents about high-risk single and multiple head impacts in order to improve the rate at which concussions are identified.  Some also record data on impacts to a player that day, that week, that season, and over the course of their career.

Question: Why is identification of concussion so important?

Answer: Early identification is critical because if sideline personnel suspect that an athlete has sustained a concussion or an even more serious brain injury, they can immediately remove them the game, eliminating the risk of further injury.  If a concussed athlete is quickly removed from a game or practice and not allowed to return that day, and not until cleared by a health care professional with concussion expertise, most will recover without incident fairly quickly.

If, however, a concussion or even more serious brain injury goes undetected and an athlete is allowed to continue playing, studies suggest that recovery from concussion, when the concussion is ultimately detected and diagnosed, is likely to take longer. In addition, delayed identification increases the risk of long-term problems such as early dementia, depression, more rapid aging of the brain, or of the devastating degenerative neurological condition known as chronic traumatic encephalopathy or CTE (although medical science has not come close to quantifying that risk). In extremely rare instances, a player who continues to play with concussion symptoms can suffer catastrophic injury or death from second impact syndrome, a form of diffuse cerebral swelling. It is thus critically important that athletes with concussion be identified and removed from play as quickly as possible.  

Question: Don't athletes know when they have suffered concussions and routinely remove themselves from the game so they can be checked out by medical staff?

Answer: Unfortunately, no. Studies published over the past ten years have consistently found that concussions are significantly under-reported by athletes, with at least half, and perhaps many more, going unreported. One 2013 study, for instance, found that high school athletes only reported 1 in 7 impacts they classified as "dings" or "bell-ringers," many of which are likely concussions.



Impact Sensors Missing Link: Sub-Concussive Events

Hi Brooke,

Good job on an in depth article exploring the role of impact sensors.

However, before the coming tidal wave of the next big thing in youth sports protection, impact sensors, we need to not overlook one of the most important factors in concussive injury - Sub-Concussive events.

Impact sensors need to be calibrated below the theoretical impact threshold for a concussive event. If the objective is simply to identify a likely concussive event, then the point is being missed, while the real, underlying threat goes largely unaddressed.

The proverbial straw that breaks the camel's back is the thinking to apply here.

Sub-concussive events are what sensors need to be reacting to. So far, the research points to sub-concussive events that create the causes for a future concussive event in sports, whether it be moments, hours, days or weeks. As with many sports related injuries, multiple sub-concussive events adds to the cumulative trauma that diminishes the athletes capacity to produce, endure and recover. Many athletes with diagnosed concussions are not the result of a single large magnitude event, but rather the result of multiple, small sub-concussive events.

This dynamic has been studied extensively in boxing. It is much less common for a boxer to be knocked out with a single blow. Most that are concussed and/or rendered unconscious are the result of repeated, cumulative trauma: sub-concussive events.

Within the given capacity of each athlete, the repeated cycle of impact and inflammation, without enough time to recover eventually leads to a concussive event.

Use of Sensors in Tracking Subconcussive Blows

You raise a good point, Chris, and one worth exploring. Do you have citations to peer reviewed research to supports your point about the straw breaking the camel's back in terms of the accumulation of sub-concussive blows eventually leading to a concussive event or at least a measurable decline in neurocognitive function? The Purdue study of high school players suggests that there is a cumulative effect/dose response, but some of Broglio's studies at the University of Michigan (will have to dig them out), as I recall, didn't find that.  I think your theory, that, given inadequate time to recover between impacts, a player will eventually sustain a concussive event, has logical and intuitive appeal, but I'm just not sure the science is to the point of proving that. 

However, I do agree with you that one use of impact sensors, not discussed in the current iteration of this article, is to help coaches and other personnel identify athletes who are sustaining a high number of high force impacts, especially to the top front of their helmets, who are likely sustaining such a high number of impacts because of poor technique.  I recently came across a 2011 Frontline interview with Tom Talavage, the lead author in the Purdue study, talking about this potential use of sensors, and Kevin Guskiewicz at UNC, just yesterday, in an article on SI.com, talked about how sensor data is used by football coaches to "modify behavior: If a player is observed repeatedly sustaining larger impacts to the crown of his head, for instance, coaches will work with him on adjusting his technique."  If, as you say, and as the science seems to be pointing towards finding, the cumulative effect of repeated subconcussive impacts is brain trauma, and, above a certain threshhold and over time, may increase the risk of long-term neurodegenerative diseases such as CTE, PD, AD, MCI and ALS, then the sensors could not only help, eventually, to help determine what that threshold is, but track hits so that a player, when he or she approached the threshold, could be tested to determine whether their neurocognitive function was being adversely affected, either in the short term (as the Purdue researchers found) or in the long term. 

Lindsay Barton

Senior Editor


Helmet Sensors

Hi Brooke!
Excellent article with great timing after the PBS special "League of Denial."
As a former high school and college football player, helmets were improved for
the protection of the head but were quickly coached to be used as a weapon.
Some have said to go back to the old leather helmet without a face guard which to me is
extreme. The problem we face in sports is that with borderline concussions that occur in the heat of competition, coaches cannot resist the temptation to put players back in who will help determine the outcome of the game. The Impact Sensors are just one positive step to help study the potential brain injuries. More studies and awareness have to continue. The other challenge is that the amount of money being made in college and pro football will sometimes blur the long term issues. In youth football just as with the issue of "pitch counts" for youth baseball pitchers in multiple leagues, it is up to the parents to be more proactive and protective of their kids. Leaving the responsibility to the coach who is competitive and puts winning over everything else is the biggest mistake parents can make.

Coach Marty Schupak
President, Youth Sports Club Inc.| www.youthsportsclub.com
Follow Me on Twitter @CoachSchupak
Follow My Blog http://blog.youthsportsclub.com/

Parents need to put safety above winning, even if coaches won't

Thank you for your comments, Marty. They are spot on. Coaches need to be part of the concussion solution, not continue to be part of the concussion problem by putting winning ahead of player safety. The important role that parents play was highlighted by one of the mothers in our documentary "The Smartest Team" (a/k/a the "other" PBS concussion documentary) in which Kerali Davis, the mom who asked Brooke to come to Newcastle to help the football implement a concusison risk management program, talks about the role of parents in trying to change what the new IOC/NRC report on concussions in youth sports calls the "culture of resistance": 

"The boys, they don't want their moms going up there and talking to the coaches, cause they think that there's gonna be an adverse reaction to the way they're treated, it's gonna make it worse. And my son's even said, ‘Mom, don't say anything to the coach, you'll just make it worse.' That has to start with the coaches. They've got to stop portraying the image that if your mom has a concern I'm gonna take it out on you, or you're weak because you've sent your parents to talk to me. Those coaches are parents too, and maybe they don't understand quite yet, and maybe they completely understand, but they have to find that fine line between being a coach and, you know, accommodating concerned parents. Kids are kids, they don't know how concerned they should be. We do know, they're our children. We want to take care of them."