A simple rule change in Ivy League football games has led to a significant drop in concussions, a study released this week found.

After the Ivy League changed its kickoff rules in 2016, adjusting the kickoff and touchback lines by just five yards, the rate of concussions per 1,000 kickoff plays fell to two from 11, according to the study, which was published Monday in the Journal of the American Medical Association.

Kickoffs, during which players sprint down the field and can knock into each other at full speed, had previously represented an outsize number of concussions.

The study comes amid a broader push to adjust kickoff rules at all levels of football and offers a strong indication that touchbacks can help reduce the risk of head injury in a sport grappling with the competing priorities of entertaining its audience and keeping its players safe.