Normally military phonetic vernacular. However, in the case where a guy purposely will go on a long distance run when he doesn't/does use long distance running as a form of exercise simply for the purpose of 1) finding a hot girl that has been sighted on a specific running rout or 2) believes that hot girls will be running in a specific place or on common running routs.
Chuck: Bill I don't know how you are going running again after the 6 miles you dominated
Bill: I know man but I gotta check into this smokin hot chick that I heard runs at the park every afternoon. It won't be a tough run cuz I'm just going on a Fox Trot. I will probably take my dog as well just to increase my chances of getting this girl to stop and talk.