many people will tell you that 3 hours a time 5days is no good for you but I will say as someone who coaches fighters thats just not true
first of all, 3 hours is way too much for good health.
After an intense 45 minute workout your stress hormone are too high.
Also, remember athletes over train, and many use roids to counter balance this. And many are beat up when they get old.
I like to fight myself, however, I'm not going to give a coach any advise.
However, real fights don't last long.
You'll never fight for 3 hours. More like minutes.
So if you can go all out, just say you can run a five minute mile, you'll probably have all you need for endurance, except that fighting requires all your muscles, not just legs.
I prefer 45 minutes workouts instead of long ones, and go hard (do sprints instead of slow cardio).
I could give you a weight training routine that would probably make you puke, even if you're in great shape.
eat slow digesting/low glycemic carbs, except for after workout, you can have some higher glycemic carbs.
rotate your carbohydrates every few days (low, mid, higher) to keep your body from adjusting.