Keep muscle but work on my cardio endurance...?

Question

I'm going into the Air Force Academy in 4 years (I'm a freshman, 15) and I need to get my 1.5 mile run down to about 8 minutes MAXIMUM, and I want to keep my muscle...any ideas how I can REALLY increase my cardio workout and cardio endurance and keep my muscle...they're kind of bulky..enough to excel at the physical tests.

Answer 1

To keep muscle, eat protien!

Answer 2

you need to focus on running a longer distance in the same amount of time vs running for a longer distance. this is how you increase the VO2Max most effectively and preserve lean body mass