There's concern more than one in 10 concussions in children under-16 are going unreported, ACC says.
ACC will have a team at the week-long AIMS Games in Tauranga, which started on Sunday, to teach how to detect and manage concussions.
Once a year the Bay of Plenty city becomes ground zero for school sports as 11,000 athletes from New Zealand, Asia and the Pacific compete in 23 different sports.
ACC injury prevention leader Kirsten Malpas said more than 10 percent of concussions that occur at the games could fly under the radar.
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Malpas told Newshub concussion can occur without a direct blow to the head.
"It can be a blow to the body that just jolts around enough that shakes the brain inside the skull."
Malpas said there are still too many concussions going unseen and untreated. Research indicates that more than one in 10 concussions in children are going unreported, she said.
"There's also the issue of re-injury," she told Newshub. "If they have one concussion, and it goes unreported, the risk of another concussion, or an injury to another part of the body increases quite a bit."
A brain injury is an invisible injury or "ghost concussion", Malpas said.
"They [children] can basically start to slip behind on everything in life," she said. "Their schoolwork can suffer.
"It can really have quite an impact on somebody's personality."
In June, ACC said it was concerned by a "dramatic increase" in young sporting stars becoming injured.
Since 2008, there had been a 60 percent increase in sports-related injuries in kids aged between 10 and 14 - twice as high as the average across all age groups.