Military personnel are physically active people, so you will see sprains from pick up games or shin splints from running. My brother is a mechanic in the Army so scraped knuckles are a common injury for him. My husband is retired from the Army and 20 years of running had its toll on his knees. My uncle broke his leg doing martial arts. On the front lines the incidence of injury goes up along with the seriousness of the injury.
Well, considering that sick call was typically fairly full most of the time, I would say its pretty high. But if you mean what are the odds you will be injured through action of the enemy, that's quite a bit lower, closer to 15-20%. Lets take the 21.5 million people who have served in the military. Of that number, 3.5 million have service connected disabilities, according to the VA. There are over a million (1.6) who have served either in Afghanistan or Iraq or both. 45 percent of them are claiming compensation for service-related injuries, which is twice the rate of the 21 percent from the earlier Gulf war (Desert Storm, 1991). More than a third of these claims are being accepted; many of the claims are on average for 8 injuries, including PTSD. . Evidently these wars have resulted in more wounds and more injuries than previous wars, or perhaps it's more accepted to apply, or the economy is worse. We also should include the over 6200 dead from these Gulf wars. Considering the increasing level of lethality, and that battlefield injuries are often survived, it would appear a 1 in 5 odds are a rough estimate.
Hey, if you are thinking of being in military, you should NOT thing about injury or death. You are going there for 'duty', not just for fun... And you know what duties a militaryman has. If you worried about your life, you should never be in military.