Last week Dophin Quarterback Tua Tagovailoa was thrown to the ground and suffered a concussion and clear neurologic event on national television. Quarterbacks are somewhere near the middle of the pack when it comes to concussions by position. A new study looks at concussions among the Nittany Lions.
Force = Mass * Acceleration
A quick moment of physics. The force experienced by your head when hitting an object is related to how fast your head is accelerating and how massive the object is applying that acceleration. More rapid acceleration and more mass result in a greater force, so all things being equal, being sent to the ground by a 300-lb offensive tackle is worse when they are fully up to speed than when they just come off the line.
This is important because the two main ways to classify position in football are based on those forces, at least to some degree. One classification divides players into those in “speed” positions and those who are not.  The second classification considers “strain” a measure of force and frequency of contact; creating Profile 1, 2, and 3. 
Both of these classifications are biomechanical. In this latest study, researchers sought to correlate these biomechanical stresses with biological markers, four blood tests associated with traumatic brain injury. They included:
- Glial fibrillary acidic protein (GFAP) - a protein associated with glial cells – the support cells providing physical and metabolic support to our neurons
- Ubiquitin C-terminal hydrolase-L1 (UCH-L1) – a protein involved in neuron metabolism
- Tau – while most infamous in its association with Alzheimer's, this is a protein in the axon of a nerve cell involved in assembly and transport.
- Neurofilament light chain polypeptide (NF-L) – a structural support protein of the axon.
The researchers measured these biomarkers in collegiate athletes over two seasons of Division 1 NCAA football before and after the season, correlating their findings with the two position classifications. There were 52 participants with a mean age of 21, each with an average of 11 years of football experience; mean height 75 inches and weight 265 pounds. 40% had experienced a concussion previously. The non-speed players were significantly heavier.
Five players had concussions during the seasons, and no differences were detected based on the two biomechanical classification schemes. This should not be surprising given the small number of participants involved.
- GFAP and NF-L increased, UCH-L1 decreased, and Tau was unchanged for all players over the season. Biomarkers were no different in those who did or did not experience a concussion.
- GFAP and NF-L were more increased in speed vs. non-speed players. Similar increases were seen when the players were classified by profile, with Profile 1 players having the most significant increases.
It's all about momentum.
Levels of Tau and NF-L, measures of axonal injury, are higher in speed players who “build considerable momentum prior to tackling or being tackled.” Those far heavier non-speed players make contact before momentum becomes an issue. There are many other factors to be considered. First, as a caveat, these biomarkers may hang around for months. The disparities in biomarker levels were already present in the pre-season studies. Second, we have little information on where head contact occurs, location matters. The cervical spine is particularly vulnerable.
The bottom line for your budding football players or concerned parents. Speed or Profile 1 players are the most at risk.
An article on Medium summarized the data from the NFL through 2018 and ended with some advice to those wishing to avoid concussions.
“If you want to minimize the chances for a concussion, you should play on the defensive side of the ball. If you play offense look for the defense equivalent.
If you’re a wide receiver, play safety or cornerback.
If you’re a center, play nose tackle.
If you’re a tight end, play defensive end.”
Football is a contact sport, and the injuries that capture our attention, like those of Tua Tagovailoa, are just the tip of the iceberg. By the way, for those smirking about soccer being safer, it is, but not as much as you might think. In 2018, football was associated with nearly 52,000 ER visits for head injuries, and soccer was 27,000. For comparison, golf was responsible for 6,300 ER visits for head injuries, although many would argue that golf is not a sport. Still, playing hockey, undeniably a contact sport, was responsible for 7,600.
 “speed (quarterbacks, running backs, halfbacks, fullbacks, wide receivers, tight ends, defensive backs, safety, and linebackers) versus non-speed (offensive and defensive linemen).”
 “Profile 1” (low frequency/high strain magnitudes positions including quarterbacks, wide receivers, and defensive backs), “Profile 2” (mid-range impact frequency and strain positions including linebackers, running backs, and tight ends), and “Profile 3” (high frequency/low strains positions including defensive and offensive linemen.”
Source: Effect of Player Position on Serum Biomarkers during Participation in a Season of Collegiate Football Journal of Neurotrauma DOI: 10.1089/neu.2022.0083
What Football Positions Are Most Prone To Concussions? By Phil Andrews on Medium