I just simply want to know, how long does it take to loose all fitness?

Question

Iam 16 and i run. i can run 3.6 miles in 28 minutes and i can run 2 miles in 13 minutes. Hopefully one day i wanna be a Royal Marine just like my Dad, but i know iam too hard on myslef. Also i swim miles.

Answer 1

That's kind of a relative question.  Technically if you lose all fitness you are dead.  Each week that goes by that you don't run your muscles atrophy.  If you aren't active at all they get worse.  So you could stay in shape by doing other sports, and still be fit, but your running muscles wouldn't be as bad as if you idn't run at all.  Hope that helps.