Since 2012 the NFL has been running simulations to test helmets, which manufacturers submit to on a voluntary basis. Researchers on contract with the NFL mount the helmet to a dummy head (outfitted with an accelerometer to measure head movement at impact) and then strike it with a helmet-shaped dome at various speeds and locations, simulating helmet-to-helmet impacts. The problem: That’s all they test.
This testing condition is what disqualified wide receiver Antonio Brown’s desired helmet for 2019; the ensuing saga was national sports news. What wasn’t reported is that the NFL’s helmet testing and ranking system does not take into account helmet-to-ground and helmet-to-body impacts—scenarios that in the 2015 to 2017 NFL seasons accounted for 46 percent and 18 percent of concussions, respectively. Safety testing that ignores two-thirds of scenarios that cause injuries the equipment is designed to protect athletes from is suspect at best. By analogy, for a long time, corner impacts were not tested to rank car safety. As a result, drivers were being killed because cars were not engineered to protect from these impacts. What happened? Lab-based testing of corner impacts led to new rankings, and car manufacturers responded with new engineering.
Adnan Hirad is a MD/PhD candidate at the Medical Scientist Training Program at the University of Rochester. He completed his PhD thesis on neuroimaging and biomechanics of concussion and subconcussion in football. Brad Mahon is an associate professor of psychology at Carnegie Mellon University, and scientific director of the Program for Translational Brain Mapping at the University of Rochester Medical Center. He established the Open Brain Project to support open science initiatives that advance understanding of how the brain recovers from injury.
One might argue that testing only 36 percent of impact scenarios could be sufficient if they were representative of all scenarios. Above all, testing must assess how helmets reduce linear and rotational forces to the brain. But we know that head-to-ground hits can cause higher levels of rotational acceleration, especially when they represent a “combined impact” scenario: a player is hit on the shoulder, say, causing a whiplash effect with rotational acceleration to the head, and then when the player hits the ground with increased momentum, that second contact imparts a force in the opposite direction. Studies show that combined impact carries higher rotational loading compared with isolated hits. Why is this important? Because the science is clear: Rotational loading on the brain is the principal driver of both clinically significant injury (i.e., concussion or mTBI) and clinically silent injury (subconcussive hits).
So it’s not surprising that the NFL’s helmet testing and ranking has had no discernable impact on the incidence of concussions (to say nothing of the incidence of clinically silent injury, which hasn’t been measured at all). Over the seven years the ranking has been in place, the number of concussions has fluctuated slightly but essentially remained the same, with an average of 244 cases per season. There are 256 games in an NFL season. (Some of the reported concussions are sustained during practice.)
The implications go far beyond the NFL: The NCAA and Pop Warner don’t have their own ranking and testing systems. Therefore, helmet manufacturers are designing technology to perform well under the NFL’s testing conditions, and the NFL rankings drive the helmet technology available for the NCAA and youth helmets, perpetuating inefficiencies across the industry. Studies find that youth and varsity helmets perform about the same under the current testing conditions, and that youth helmets are only about 5 percent lighter than varsity helmets. A helmet that adds weight to the head of a youth football player risks exacerbating the issue; the helmet does not protect against rotational acceleration, and now a weight has been added to the player’s head, potentially causing greater rotational loading on brain tissues.
The deeper issue is that the NFL chooses to simply rank available technologies, rather than set minimal performance standards for reduction in rotational and linear acceleration. This has encouraged a culture of lethargic and inadequate application of scientific findings to helmet safety. Helmet technology has stagnated as a result. Much like when helmets were first introduced to the game, current helmets in widespread use are optimized to reduce linear acceleration and fractures of the skull, with no major innovations for reducing the rotational forces that cause injury (both clinically significant and clinically silent injury).
While improvements in helmet technologies can never eliminate concussion risk, much can be done to improve their performance to reduce the twisting head kinematics that are known to lead to concussion. Moreover, reducing overall forces and shear waves transmitted to the brain under most impact conditions can potentially reduce high magnitude subconcussive hits, and that is certainly in the best interest of the NFL as it continues to grapple with CTE and other long-term neurodegenerative diseases in former players.
The NFL has no credibility today to pick fights over helmet performance. The league, which earned some $16 billion last year, has the resources and the ability to modify these tests so that the ranking system can have face validity, and there is still time to implement these changes for the 2020 season. Standard-setting, evidence-based regulation often leads to innovations that save lives. Consider the seat belt.
social experiment by Livio Acerbo #greengroundit #wired https://www.wired.com/story/the-nfls-helmet-tests-are-brainless