Injuries may be more common in kickboxing than in traditional boxing, mixed martial arts or other contact sports, a recent study suggests.

On average, kickboxing has an injury rate of about 40 for every 1,000 minutes of playing time, or about 2.5 injuries an hour, the study of U.S. competitions found.

That's about as dangerous as karate, but exceeds the typical injury rates of 1 per hour or less for mixed martial arts, boxing, taekwondo or judo, said study author Reidar Lystad, a researcher from Central Queensland University in Sydney.

"To the best of my knowledge, the (kickboxing) injury rate in the present study is greater than those recorded in all previous studies of injuries in popular full-contact combat sports," Lystad said by email.

Kickboxing is a contact sport that allows both kicking and punching from a standing position. Competition rules can vary, and some contests may allow grappling, the use of knees or elbows, leg kicks or leg sweeps and throws, Lystad notes in the Orthopedic Journal of Sports Medicine.

Contests are usually scheduled for three to five rounds, each lasting about two to three minutes with a one-minute rest in between rounds. Some professional contests can be scheduled for up to 12 rounds.

To assess kickboxing injury rates, Lystad analyzed data collected by the Nevada Athletic Commission from 2000 to 2014 on 481 professional and amateur fighters.

Over the study period, there were a total of 974 athletic exposures (AEs) - competitions or practices with a potential for injuries - which took place over a combined 9,562 minutes and resulted in 380 injuries.

The type of injury and body part hurt often wasn't specified in the data. For cases where this data was available, 71 percent of injuries were cuts and 21 percent were lacerations. The most commonly injured parts of the body were the head and lower limbs.

Injury rates for professional kickboxers were more than double the rates for amateurs.

One shortcoming of the study, however, is that it lacked data on the severity of injuries.

It's also possible that concussion data was inaccurate, because only one was reported even though approximately two of five contests ended in knockouts or technical knockouts when referees determined one fighter could not safely continue.

Still, the findings highlight the need for more research on the frequency of severity of injuries in kickboxing, which might help fine-tune safety and injury prevention policies in the sport, Lystad writes.

Based on the results, kickboxing injury rates appear nearly 10-fold greater than those in most National Collegiate Athletic Association (NCAA) sports, said Dr. Suraj Achar, associate director of sports medicine at the University of California at San Diego School of Medicine.

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For NCAA games, overall injury rates are 13.8 injuries for every 1,000 games or when an injury is possible, Achar, who wasn't involved in the study, said by email. For NCAA practices, the rate is just 4 injuries for every 1,000 practices when this is possible.

By this measure, which isn't adjusted for the number of minutes athletes played, the kickboxing study found an injury rate of 390 for every 1,000 games or practices.

"Men's wrestling and football have the highest injury rate, but these only approximate 26 to 35 injuries per 1,000 athletic exposures," Achar said.