What Are Subconcussive Head Impacts

Have you ever taken a close await at a football player's helmet? Surrounding the decals and logos, you'll commonly see scuffs and scratches that indicate where the player took a hit. Each one of these marks could also represent a subconcussive bear upon.

Near of you lot are probably post-obit the coverage of sport-related concussions – the traumatic brain injuries sustained on the "large" hits. Withal, there is growing concern that lower magnitude, more frequent subconcussive impacts could be the existent ticking time bomb that leads to serious long-term repercussions, including chronic traumatic encephalopathy (CTE).

The inquiry surrounding subconcussive hits is still in its infancy, though, which makes them a controversial category of caput trauma. Their exact meaning is however evolving, and we don't completely empathize the potential lasting effects.

Still, nosotros know enough to indicate subconcussive impacts have the potential to be dangerous and are something athletic trainers should exist aware of and attempt to preclude. By embracing available data and the strategies to reduce these hits to the head, athletic trainers tin can continue to be advocates for our athletes' brain health.

What are they?

A subconcussive striking is an impact that is below the threshold that would issue in a concussion. When i occurs, there is withal movement (or "slosh") of the brain, but it'south not severe enough to cause symptoms. At least, not immediately.

There is no definitive impact magnitude that would classify equally subconcussive (i.e., 10g, 20g or 50g) because each individual person'due south brain may react differently. An impact magnitude of 20g may not affect one athlete still cause a concussion in another. This makes studying head impact exposure and concussion inquiry very challenging.

As with concussions, football game is the epicenter for much of the word surrounding subconcussive impacts. Several studies have found that college football players may sustain 950 to 1,500 head impacts in a single season, and a high schoolhouse actor may face up upwardly to 1,100.

While information technology may be the wide receiver or the running dorsum that typically undergoes the "big hit," information technology is the linemen that sustain the nigh impacts per game, as well as the highest average number of impacts in a flavor. Granted, these hits to the head may have lower magnitudes, but the cumulative higher volume is the apropos cistron.

Although football game has been the focus of much of the research surrounding subconcussive impacts, they are not isolated to football. From heading the brawl in soccer to checking in hockey and lacrosse, whatsoever time in that location is contact or a collision, in that location is the risk for a subconcussive hitting. We need to think of this topic as a brain health consequence and not merely related to a single sport.

Potential dangers

The main concern surrounding subconcussive head impacts is the potential long-term neurological consequences. Nosotros know that long-term repetitive trauma results in degradation of other soft tissue (think of overuse injuries in baseball pitchers, for example), so information technology is intuitive that the brain may also feel damage from repeated trauma exposure.

Perhaps the well-nigh significant consequence being studied is the human relationship between subconcussive hits and CTE. Right at present, the best bachelor evidence suggests the cumulative nature of subconcussive impacts, not concussions, is the driving force behind CTE, and some of the athletes discovered with CTE never had a reported concussion.

» RELATED: A comprehensive arroyo to concussions

In addition to the connectedness to CTE, recent enquiry has identified several areas of potential repercussions to players who have been exposed to a greater number of head impacts. Memory, attention/focus, brain action, and oculomotor performance are all areas thought to be affected by subconcussive hits. Here's a breakup of some of the findings:

→ According to the Concussion Legacy Foundation (CLF), those athletes exposed to a greater number of impacts tend to perform worse on tasks designed to measure out retentivity and attention than athletes who've sustained fewer head impacts, and even show decreased brain activeness on functional magnetic resonance imaging. Other findings from the CLF noted that imaging studies using diffusion tensor imaging have shown structural damage to connections in the brain, which may make information technology harder for areas in the brain to communicate. The organization too believes there may be a link between repetitive head trauma and emotional and behavioral bug afterwards in life.

→ In a 2014 Journal of Neurotrauma written report, asymptomatic high school football players showed changes in both neurocognitive and neurophysiological changes over the class of a season. A follow-up written report institute those changes were correlated by the exposure to subconcussive impacts throughout the season. It is concerning that these participants demonstrated measurable change in neurocognitive function and brain physiology, still none were symptomatic, which would have promoted removal from activity.

→ The near-point convergence examination measures how well the optics focus and accommodate as a target is brought toward the field of study. A 2016 study in JAMA Ophthalmology examined collegiate football players and found that those athletes who sustained higher frequencies of head impacts had greater convergence insufficiency than teammates with fewer impacts. The differences returned to normal baseline value following iii weeks of residuum.

What ATs can do

As well staying current with the research, there are some practical steps athletic trainers tin can have to be proactive nearly subconcussive impacts. In that location are three proposed ways to reduce an athlete's exposure to them.

The first is to eliminate unnecessary contact. For football game in detail, this could exist accomplished by reducing the number of full-contact practice days. In 2017, the NCAA restricted do times and eliminated two-a-days in the hopes of reducing routine caput impacts, and many high school state athletic associations take taken similar steps.

A second way is to modify contact exposure. This could be by changing drills performed in practices, limiting the number of contact repetitions during each drill, and making certain technique is performed correctly during activities like football game tackling.

For case, a July 2018 article in Annals of Biomedical Engineering explained that making changes to certain college football drills could dramatically reduce the number of caput impacts players faced. The researchers said cutting the fourth dimension spent on the highest-adventure drills by simply a few minutes per practice could get rid of the equivalent of a years' worth of head impacts in players.

A tertiary fashion to limit subconcussive impacts is to actually delay athletes' exposure to them. An example of this would be substituting flag football for tackle football. A 2018 written report from the Aspen Plant's Sports and Social club Program recommends only that. It as well encourages athletes to delay the introduction of tackle football until the age of 14.

In other sports, The states Hockey banned body checking at the Peewee level in 2010, and researchers from the Mayo Clinic released recommendations in January 2019 to eliminate body checking in Bantam youth hockey leagues. In soccer, U.S. Soccer'southward 2016 Concussion Initiative banned heading for athletes 10 and under and restricted heading in practices for 11- to 13-year-sometime players.

In addition to impact-reduction efforts, measuring the magnitude, linear dispatch and rotational velocities of head impacts can exist beneficial. One way to practise this is through the use of accelerometers. These allow researchers to track and quantify the head impact exposures sustained past each athlete over the course of the session or season.

Whatsoever subconcussive touch on prevention or documentation efforts able-bodied trainers embark on will likely require getting coaches and parents on board. One way to get them to purchase-in is to suspension down the research – as information technology can exist overwhelming. I would recommend trying to present the data in as "lay-person" a fashion every bit possible and non with an alarmist intent.

A final discussion

Despite the studies we already have, longitudinal inquiry on the consequences of head touch on exposure is however being developed, and I predict more research in this expanse will be published over the next five years. This flurry of new evidence has the potential to overwhelm clinicians.

While athletic trainers need to proceed to cover new research as part of our evidence-based do, we should be disquisitional of enquiry well-nigh both concussions and subconcussive impacts. Critically assess the written report, the sample, and the methods.

For equally much as we are withal learning about subconcussive impacts, we know the potential is there for them to cause great issue in athletes. Athletic trainers should be informed about them, stay as proactive every bit possible to prevent them, and remain tuned into the long-term research on the consequences of caput touch exposure that will surely come out in the years to come.

Kim Barber Foss, MS, LAT, ATC, is an Able-bodied Trainer/Research Biomechanist at Cincinnati Children'southward Infirmary Medical Center, through which she provides outreach sports medicine intendance to Lockland (Ohio) High School. She is likewise an Assistant Professor in the Graduate School at Rocky Mountain University of Wellness Professions and an Offshoot Professor with Northern Kentucky Academy. Barber Foss serves on the Board of Directors of the National Operating Committee on the Standards of Athletic Equipment (NOCSAE) and serves on several local, country, and national committees. She received the 2018 Gatorade Secondary School Athletic Trainer of the Year Award and 2019 NATA Service Award and has participated in numerous studies on concussion and subconcussive impacts.