A new study says that young athletes between the ages of eight and 16 could take up to two years to fully recover from a concussion.

The study was published in Future Science journal, , by York University concussion experts who determined that children can suffer from after-affects for more than two years after the initial injury.

“Performing motor tasks, guided by what we see, is crucial in skill-based activities such as sports,†Lauren Sergio, a professor at the faculty of health at York University, said in a news release. “The current return to sport assessment doesn’t test to see if the injured person has regained this ability.â€

According to Sergio, the lack of a motor-skills test after a concussion results in many children returning to sports and physical activities before they are fully recovered. Previously, children who no longer exhibited any active symptoms were allowed to rejoin their teams in only a few weeks.

Researchers studied two groups; one with 50 children who had experienced a concussion at some point in their lives and the other with 49 children who had never experienced a concussion.

The groups did the same two activities involving their cognitive motor skills with a dual-touchscreen laptop. The first task had the target location and motor action aligned while the second task was not aligned. This required simultaneous thinking and action for successful performance.

“We noticed significant difficulty in completing the tasks among those with concussion history,†said Marc Dalecki, a postdoctoral candidate and the lead author of the study.

According to Dalecki, it took most of the children in the study at least two years after the initial hit that caused their concussion to have a similar performance as children without a history of concussions.

According to the findings, youth aged eight to 18 are more vulnerable to concussions and due to their developing brain are more neurologically fragile than adults.