The respective branches of the U.S. military encourage getting into shape prior to going to basic training. I’m trying to remember the source, but I read that the USMC encouraged recruits to start weight training prior to going off the Parris Island, or San Diego. I for one lost 40 pounds before I went to Lackland for basic, lot of cardio and marching with the 65 pound ruck.
A series of my son’s friends went into USMC over a period of about a year and a half or so, five altogether. The fifth one in was the star of his recruit class, due to he had taken all of the advice the other four had for him before boot camp.
Good idea, just for self defense. We punished the slackers when we ran.