Virginia Tech and Wake Forest researchers Ray W. Daniel, Steven Rowson, and Stefan M. Duma have published a new research article on impact telemetry on youth football players. The abstract is as follows;
The head impact exposure for athletes involved in football at the college and high school levels has been well documented; however, the head impact exposure of the youth population involved with football has yet to be investigated, despite its dramatically larger population. The objective of this study was to investigate the head impact exposure in youth football. Impacts were monitored using a custom 12 accelerometer array equipped inside the helmets of seven players aged 7–8 years old during each game and practice for an entire season. A total of 748 impacts were collected from the 7 participating players during the season, with an average of 107 impacts per player. Linear accelerations ranged from 10 to 100 g, and the rotational accelerations ranged from 52 to 7694 rad/s2. The majority of the high level impacts occurred during practices, with 29 of the 38 impacts above 40 g occurring in practices. Although less frequent, youth football can produce high head accelerations in the range of concussion causing impacts measured in adults. In order to minimize these most severe head impacts, youth football practices should be modified to eliminate high impact drills that do not replicate the game situations.
There are some very interesting findings in the abstract alone that need to be noted:
- Age of the participants (7-8 years old)
- 107 impacts per player
- Top end of observed G forces
- 76% of the high-end impacts were at PRACTICE
- Possible validation of both the ‘Hit Count‘ and ‘Delayed Participation in Tackle Football‘
The article appears in the Annals of Biomedical Engineering and as Stefan Duma wrote to me;
Our paper containing the youth football head impact data has been published and is now available for download from the Annals of Biomedical Engineering. We paid the copyright fee to Springer so that the paper can be downloaded and shared for free by anyone.
Here is the LINK. The study does have limitations the most obvious being the sample size, but interestingly enough extrapolating said data across youth football conservatively creates many issues. The study concludes with urging further research and education in this matter;
In conclusion, this study is the first to report the head impact biomechanics associated with youth football. Valuable insight to the head impact exposure in youth football has been presented. While youth football players impact their heads less frequently than high school and college players, and have impact distributions more heavily weighted toward low magnitude impacts; high magnitude impacts still occur. Interestingly, the majority of these high magnitude impacts occur during practice. Restructuring youth football practices may be an effective method of reducing the head impact exposure in youth football. These data are the basis of educated decisions about future changes to youth football and have applications toward determining guidelines for youth-specific helmet design.
It may not be feasible in terms of money, but again this emphasizes the need for proper medical professional oversight, ATHLETIC TRAINERS.
Thank you for posting this important study! My thoughts are that due to resource limitations, youth football games and practices should only be allowed with very restrictive requirements in place; including, but not limited to: no more than one contact practice per week, need to focus on technique and rules of game rather than hitting hard, and the removal of any player who sustains a hard hit (send home with CDC tear off sheet).
I haven’t read the study yet, but am curious to see how many full contact practices and games the boys participated in, and how much of each practice was spent in tackle drills. My son’s group had 3 full contact practices per week and up to two games on Saturday (I suspect impacts were greater than 100 g … a number of boys weighed over 100 pounds, they were 8 & 9 year olds).
SLI’s facebook page has a link to a story ESPN did on the youth impact study. Pop Warner may limit the amount of time spent on tackle drills. Unfortunately, I believe many feeder programs using school facilities don’t belong to either Pop Warner or USA Football.
It seems that they need to take as many of the collisions out of practice as possible. Further rule adaptations seems another way they can help get traumatic brain injuries out of the game.
One of the most important factors is training all of the coaches and parents on recognizing a concussion. Kids aren’t always the most honest when it comes to incriminating themselves as to having to sit on the bench of a week or two. Coaches and parents need to be aware of changes in players and not afraid to sit them out when suspecting a concussion.
Thanks for posting this. If youth prgrams cannot afford ATs, maybe some ATs can volunteer their services pro bono like attorneys do?
I would do it, except for the ugly liability issue… Even good intentions could be hammered by overzealous people…
We already can not place an ATC at all high school games. Thinking that we could at the lower levels of contact football is unrealistic. Given that, and the fact that contact at this level serves no purpose (ie: does not lead to better high school or college players), the solution is to eliminate contact below high school. These children need to be taught the basic concepts of the game and having fun (ie: have the ball in their hands). Having young players slam into eachother on every play serves no purpose, is harmful, and is not fun for them.
I read somewhere when a football player (I am assuming this article if I can remember was about the NFL Concussions)takes a hit to the head, the speeds can range between 17-215 mph and that translated into a g force of 98 g’s(or 98 times the force of gravity).
My 1st of 2 question is
1) With respect to rotational acceleration of the neck, in this article there refer rad/sec2. Could someone translate that into layparents language so non scientists who donot do this research can understand what this type of rotational force means?
2) Also did they know about the Number of concussion reports and what the linear/rotational acceleration were when any of these youths were concussed?
Sorry that was 17-25 mph not 17-215 mph
I should of proof read what I wrote
Force = mass multiplied by acceleration
Acceleration is the rate of change of velocity
gravity = 9.8m/s-2
So when one investigates linear force or anterior/posterior F=the mass of object (player’s mass expressed in kilograms) x the player’s acceleration. If two objects are hitting one another the force will be determined by the vector sums of the players and whether the blow is inelastic (hit and stop) or elestic (bounce off one another).
In the case of measuring rotational acceleration one needs measure the rate of change in velocity in a circle. If one looks at a circle, a radian is a segment of a circumferance of a circle that equals the measure of the radius. So radians per s-2 is the acceleration in a circle. Therefore force can be measured based on mass and acceleration that is defined as torque. Think of it as turning force. This is important as twisting the nerves and brain tissues. In fact, rotational forces may be more important than liner force.
While Joe gives a good definition of the physics, not sure if it explains to the layperson why rotational forces are so important.
Even if it’s not the same exact forces, I usually use this example. Take a lump of dough. If you press straight down with a flat hand it squishes, but stays together. If you move your hand horizontal the dough will roll along (again staying together). Now if you press down and move horizontal at the same time the dough will not only be squished flat, but stretched sideways and sometimes will tear.
It’s not a perfect physics example, but demonstrates how the two forces together create much more stress.
Going with your example, you could use a cylinder of modeling clay and hit it squarely in the front. It is a classic tackle. Now hit it off center and downward, you should see both compression and twisting and on the back of the cycliner sheering, that is, striations and seperations. Much like the type of hit a special teams player would experience when blocking for a punter.
I left out the dimension of length in the calucation of torque. so mass x acceleration x distance from a point (fulcrum’s length).