i've noticed over time that when i do sprints instead of regular runing, i seem to put on more muscle faster. only thing is, i like sprints and all, but i'm in the military and i'm tested on the 2 mile run. i dont have any problem passing it, but i still wanna get more 2 mile runing sessions in for endurance. what can i do to stop from loosing mass when i run? do i need to just eat a meal with more calories a couple hours before i run?