Training for top level Amateur boxers is a lot different to training for a 12 round pro fight.
The Rounds duration is different. Amatuer top level is 4rounds x 2mins, Pro is 12rounds x 3mins.
So when your training Amateur you have to condition yourself to be ready for 4 rounds of non stop boxing, where-as with 12 rounds of Pro you have to condition yourself to be able to have endurance for the full 12 rounds. Although the break in between rounds is the same of 1 minute.
Running: I was recently at a High Performance Training Seminar for amateur boxing in Ireland and the coaches told us that - it is really useless to a top class amateur to jog 6 miles everyday (the typical sterotype).........as with Amateur Boxing its really a stop-start fight. You need to be able to give 100% for 10 seconds, then relax (now when I say relax means you back off your opponent hands up tight, complete concetration - waiting for your opening), and give 100%, relax, 100%, relax. So the running an amateur boxer would do would be 100% flat out for say 100metre, slow, 100%, Slow, 100%, Slow:
An excellant example was a running session I learned from a great trainer Kenny Miller (here is his website www.zatopek.freeserve.co.uk)
Take a football pitch - 1 lap = jog the width, sprint the lenth, jog the width, sprint the lenth.
Do 8 laps...........excellant for Amateur boxing because its that Sprint, Relax, Sprint, Relax!!!