(CNN) -- A new football study has found that a small change in one area of the sport -- kickoff rules -- may lead to a significant reduction in concussion rates.
A research letter published Monday in the medical journal JAMA said that after the Ivy League athletic conference changed its rules in 2016 to move the kickoff and touchback lines in games, there was a reduction in the concussion rate among players.
Specifically, the average annual concussion rate in the college conference was 10.93 per 1,000 plays during kickoff before the rule change. It dropped to 2.04 after, the researchers found.
"What that translates to is about a 69% reduction in the rate of concussion," said Douglas Wiebe, first author of the research letter and a professor of biostatistics and epidemiology at the University of Pennsylvania's Perelman School of Medicine.
In comparison, the researchers found that for other play types, the average annual concussion rate was 2.56 before the rule change and 1.18 after, which was not a significant difference.
"To see that rate of concussion went down that much, very strongly in kickoff returns relative to other types of plays over the same period, we think it's an example of a public health intervention that was part of a large collaboration between injury epidemiologists and coaches and athletic trainers," Wiebe said.
The kickoff return play poses a risk of concussion -- a type of traumatic brain injury caused by a blow to the head -- because it involves players running at speed toward each other over a long distance, the researchers noted.
In 2015, kickoffs accounted for 6% of all plays but 21% of concussions in the Ivy League conference, the researchers said, referencing data published in the journal Injury Prevention.
The next year, the rule change called for moving the kickoff line from the 35-yard line to the 40 and the touchback line from the 25-yard line to the 20.
Small change tied to significant reduction
For the study, researchers analyzed data from the Ivy League's concussion surveillance system, identifying concussions occurring during in-conference regular season games from 2013 through 2017.
The Ivy League itself includes eight schools: Princeton, Dartmouth, Yale, Columbia, Pennsylvania, Harvard, Brown and Cornell.
The researchers evaluated each concussion by what type of play caused it and when it occurred, whether before or after the 2016 rule change.
The rule change was introduced as an experiment, Wiebe said.
"They weren't sure what was going to happen, but they thought it had a chance to be protective," he said.
The research had some limitations, including that the kickoff rule changes were only in the Ivy League, and so the findings may not generalize beyond the conference.
Also in 2016, another new rule eliminated full-contact hitting in practices in an effort to reduce overall injury rates.
"This rule likely did not differentially affect activities during different types of plays during competitions and hence would not bias this analysis," the researchers wrote in the study.
The research was part of the Ivy League-Big Ten Epidemiology of Concussion Study, an ongoing initiative of the Big Ten-Ivy League Traumatic Brain Injury Research Collaboration to look at concussions across sports.
As part of that initiative, "something that was surprising -- not surprising but exciting for us -- is that we have enough data that we're really able to look at this outside of a case by case basis and that we're able to look at this over the course of several years after the rule was put in place," said Bernadette D'Alonzo, a co-author of the new research and a clinical research coordinator at the University of Pennsylvania's Center for Clinical Epidemiology and Biostatistics, and the Penn Injury Science Center.
'Preventing concussion is much easier than treating concussion'
The study was "well-done," and the findings "make sense," said Dr. John Leddy, a primary care sports medicine physician and clinical professor at the University at Buffalo in New York, who was not involved in the study.
"It shows just how powerful rule changes can be in preventing concussions," said Leddy, who is also medical director of the University at Buffalo Concussion Management Clinic.
"That's important because you're going to get concussions in football, but if you can develop rules that reduce the risk, then preventing concussion is much easier than treating concussion," he said.
He added that more research could help shed light on whether other rule changes in football have been or could be associated with reductions in concussion.
For instance, "what the Ivy League and other divisions in NCAA football have done is limit the amount of contact in practices, because some of the concussions occur during the practice week, not just in games," he said.
It's too early to attribute the fall in concussions seen in the new research to just one rule, said Joseph Clark, professor of neurology and rehabilitation medicine at the University of Cincinnati who was not involved in the new research letter.
He called the recent findings "a step in a positive direction" but added that more work needs to be done.
"Other research has shown similar falls in concussion rates even before the 2016 rule changes," he said. "Finding out what rule, policy, culture, practices, education, et cetera, will help mitigate concussions will take a bit more work than examining one rule change."