“If the ball has too high of a pressure, gets too waterlogged, or both, it actually turns into a weapon. Heading that ball is like heading a brick,” said Eric Nauman, a Purdue professor of mechanical engineering and basic medical sciences with a courtesy appointment in biomedical engineering.
The Purdue study (published in the journal PLOS One) cites other research on the frequency of concussions caused by heading the ball and "found that inflating balls to pressures on the lower end of ranges enforced by soccer governing bodies such as the NCAA and FIFA could reduce forces associated with potential head injury by about 20%."
FIFA rules stipulate a soccer ball's weight must be not less than 14 ounces and no more than 16 ounces. The Purdue study suggests that balls getting wet can quickly surpass the weight limit -- and increase head injury risk. While ball velocity "contributes the most to how hard a ball hits," ball pressure and water absorption are easier control.
The research included tests with balls sizes 4, 4.5 and 5.
"This was a very simple experiment," Nauman said. "But there just hasn’t been much data out there on these issues, and that’s a huge problem.” The next step would an experiment replication outside of the lab.
The study focused on PSI within FIFA's regulations, but one wonders how frequently youth soccer is played with balls inflated over the maximum.
Have you ever seen a youth referee measure the balls' PSI?