Concussion rates vary widely across youth sports, with the greatest injury risk in higher-contact games like rugby, hockey and football, a new research review finds.

Overall, young athletes experienced an average of no more than one concussion for roughly every 5,000 minutes of participation time, according to the analysis of previous research on injuries in popular youth sports. That amounts to around one injury for every 67 hours of practice and competition.

The concussion rate was about 18 times higher than average for rugby, five times greater for hockey, and roughly double for American football, the study found.

"This is likely because rugby, hockey and American football are all sports that involve more frequent contact to the body and head," said senior study author Paul Ronksley of the University of Calgary in Canada.

"Contact sports such as these pose a greater risk to athletes for sustaining head trauma while activities such as volleyball, baseball and cheerleading inherently involve less contact or opportunity for both purposeful and accidental collision between players," Ronksley added by email.

Even though the overall concussion rate may not seem high, these injuries still impact many children and teens. As many as 45 million youth participate in sports outside of school, and at least 7 million U.S. teens play high school sports each year, the researchers report in the British Journal of Sports Medicine.

Ronksley examined the relative concussion risk for some of the most popular youth sports: American football, rugby, hockey, lacrosse, soccer, basketball, baseball, softball, wrestling, field hockey, track, taekwondo, volleyball and cheerleading.

Altogether, they reviewed data from 23 previously published studies on concussions in these sports, and then did a pooled analysis of injury rates from 13 of the prior studies.

For each of the sports, they looked at concussion rates based on minutes of athletic exposure (AE), which includes competitions or practices with the potential for injury.

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The overall concussion risk across all of the sports included in the analysis was 0.23 injuries per 1,000 AEs.

By comparison, the concussion risk per 1,000 AEs for rugby was 4.18, while it was 1.2 for hockey and 0.53 for American football.

At the lower end of the spectrum in terms of injury potential, the concussion risk per 1,000 AEs for volleyball was 0.03, while it was 0.06 for baseball and 0.07 for cheerleading.

One shortcoming of the study is that the researchers based calculations on assumptions about total participation time in some sports, which may have overestimated the risk of concussions in hockey. It may be more in line with football, the authors concede, nonetheless, these sports, along with rugby, would still be the activities with the highest concussion risk.

Researchers also lacked data on the injury risk based on age or information on how many concussions occurred during practices versus competitions.

"Concussions can occur in any sport," noted Tamara Valovich McLeod, co-author of the National Athletic Trainers' Association position statement on management of sport concussions and director of athletic training programs at A.T. Still University in Mesa, Arizona.

"It makes sense with higher levels of contact to have higher concussion rates, but that doesn't mean kids should stop playing sports," Valovich McLeod, who wasn't involved in the study, said by email.

Parents should ensure that teams and leagues in which their children compete promote safety, which might include having an athletic trainer to evaluate and manage injuries as well as emergency action plans for handling concussions and prevention education for athletes and families.

"There are numerous physical, social, and psychological benefits for children and adolescents who participate in sports," Valovich McLeod added.