Want To Avoid Soccer Head Injuries? Try Reducing Air Pressure In The Balls
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Lionel Messi of FC Barcelona and Cesc Fabregas of Chelsea jump for a header during a UEFA Champions ... [+] League match. (Photo by Chris Brunskill Ltd/Getty Images)
Getty Images Here’s a possible way to get a head in soccer without knocking yourself out. Deflate your balls.
Yes, simply making your balls a little softer by letting some air out of them could reduce the risk of concussion when using your head in soccer (otherwise known as football), according to a study recently published in the scientific journal PLOS ONE. The study also found that you don’t want your balls to be wet either, but more on that later.
Although soccer is known as football everywhere outside the U.S., the game is not just about da feet. Another big part of that game is using that melon that sits on top of your body to propel the ball forward. For example, this FIFA TV segment showed how the Netherlands’ Robin van Persie headed off Spain during the 2014 FIFA World Cup in Brazil:
Using your noggin to do such feats isn’t without its risks. After all, imagine what would happen if you went around hitting things with your head like billiard balls, beer bottles, paint buckets, and Dwayne “The Rock” Johnson statues. Studies have found that between 4% and 22% of all injuries in soccer are head injuries. These include bruises and lacerations as well as concussions. In fact, a study published in the Clinical Journal of Sports Medicine found that men suffer 1.1 concussions for every 1,000 hours that they played soccer whereas women had an even higher rate, 2.6 concussions per 1,000 player hours.
Such findings prompted a team of researchers from Purdue University (Joshua Auger, Justin Markel, Dimitri D. Pecoski, Nicolas Leiva-Molano, Thomas M. Talavage, Larry Leverenz, Francis Shen, Eric A. Nauman) to set up a motion capture system with an integrated force plate to measure the impact force that could be generated by kicking a soccer ball. In case you’ve never set up a motion capture system with an integrated force plate in your bedroom for example, such a system consists of a laptop computer connected to a pad that can measure the force at which the pad is struck along with a camera that can film what’s happening.
Tine De Caigny #6 of Belgian Women's National Team jumps for a header during a game against the ... [+] United States Women's National Team at Banc of California Stadium on April 07, 2019 in Los Angeles, California. (Photo by Katharine Lotze/Getty Images)
Getty Images The team had to have balls to do this study as well, a total of six balls. Four of them were Adidas Starlancer balls with a pair of these balls being size 4 and the other pair being size 5. The remaining pair were special “lightweight” balls that EIR Soccer had donated to the research team. These balls were mid-sized at 4.5. So basically the team used three pairs of balls of different sizes.
Experiments consisted of research team members kicking each soccer ball with different degrees of force at a two meters distance from the force plate. Each kick was supposed to propel the ball to hit the force plate in a direct perpendicular angle. They didn’t want their balls to go sideways. Thus, the team had to adjust their balls accordingly and repeat any misfirings.
The team tried this at four different soccer ball pressures: 0.27, 0.55, 0.83, and 1.10 bar (4, 8, 12, and 16 psi). Basically, some of these were pumped up kicks and others less so. If you happen to know a lot about pressure (soccer ball air pressures, that is), you’ll recognize that the 0.27 bar (4 psi) is below what manufacturers recommend for soccer balls. As you may have learned from “Deflategate,” each sport that uses inflatable balls has guidelines as to what air pressures should be used for their balls. Deflategate is when New England Patriots quarterback Tom Brady was accused of having his team’s balls deliberate deflated during the 2014 American Football Conference Championship Game. That may have left the Patriots’ balls softer and easier to grab, throw and catch, which could have been a distinct advantage and made it harder for their opponent, the Indianapolis Colts, to win. The NFL ended up playing hardball with the Patriots for these infractions, suspending their quarterback, Brady for four games, stripping them of two draft picks, and fining them $1 million.
New England Patriot fans reference "Deflategate" when supporting their team prior to Super Bowl XLIX ... [+] at University of Phoenix Stadium on February 1, 2015 in Glendale, Arizona. (Photo by Elsa/Getty Images)
Getty Images The Purdue University team wasn’t just trying to replicate Deflategate in a different type of football. Rather, they wanted to get a sense of different factors may affect the resulting impact force that a ball can make. To do this, the research team repeatedly kicked their balls. For each ball size at each pressure, the researchers performed 50 kicks towards the force plate. That meant a total of 200 kicks for each ball size. All told, the team kicked their balls a total of 600 times. For each kick, the force plate could measure how much the force was with them.
Here’s a video from Purdue University of this ball-kicking set of experiment:
Not surprisingly, harder kicks resulted in greater impact force. You should realize this if you’ve ever had your balls kicked. Of course, this finding has little practical value when it comes to protecting against concussions and other head injuries during a soccer game or football match. You can’t tell soccer or football players “kick the ball softer” or “don’t make the ball travel so fast.” Similarly, “I missed the header because I was waiting for the ball to slow down” wouldn’t be a great excuse to tell your coach.
Here’s the deflating news though. There was a strong correlation between ball inflation pressure and the subsequent impact force for all the differently sized balls. In other words, the lower the air pressure, the lower the impact force. For example, kicking a professional regulation size 5 soccer ball inflated at 1.10 bar (16 psi) resulted in an average peak impact force of 3606 N compared to an average peak impact force of 2895 N when the ball had a pressure of 0.55 bar (8 psi). That was a 20% decrease in the average peak impact force.
Cristiano Ronaldo (C) of Juventus FC competes for a header with Juanfran of Atletico Madrid during ... [+] UEFA Champions League Round of 16 second leg football match between Juventus FC and Club Atletico de Madrid. Juventus FC won 3-0 over Club Atletico de Madrid. (Photo by Nicolò Campo/LightRocket via Getty Images)
LightRocket via Getty Images Of note, for each inflation pressure, the special lightweight ball had lower impact forces than the other balls. This may be a situation where being a lightweight is better.
Since the weight of the ball did seem to affect the impact force, the team also checked what would happen if they dipped their balls in water. That’s because playing soccer can make your balls wet in more ways than one. For example, a soccer ball rolling on a wet field can be a bit like a sponge. It can end up absorbing water and gaining weight as a result. The National Collegiate Athletic Association (NCAA) Soccer Rule Book does account for this possibility, specifying that a regulation soccer ball should be between 14 ounces (396.9 grams) and 16 ounces (453.6 grams) at the beginning of a game and not exceed 16.75 ounces (474.9 grams) any time during the game. Clearly, water is the main concern here since soccer balls don’t tend to munch on junk food during a game.
As a typical soccer or football game will last 90-minutes, the research team submerged each ball halfway (to the midline of each ball) in water for a total of 90-minutes. Every 15 minutes, they weighed and then rotated their balls every 15 minutes. As expected, each ball got heavier, the longer it stayed in the water. It would have been really weird had the balls actually lost weight while soaking in water. Swimming can help you lose weight but soccer balls typically don’t swim.
Most the weight gain happened during the first 15 minutes of being in the water. During this time, the size 4 ball increased in weight by 16.3%, the special “lightweight” ball by 5.7%, and the size 5 ball by 22
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