Wondering if this is normal and if you guys have suggestions on improving this: When I train, I can go like (this is after warming up for 30 minutes, etc) 4 minutes of full contact sparring before i start getting really tired. If i go another 2 minutes I can barely keep my hands up. Its the kind of tired where I feel almost like puking and can't catch my breathe. THe weird part however is that after 3 minutes of resting I'm usually back and have tons of energy and power again. Do you think that my lung capacity is weak? (My lung did collapse a few years ago when i was just sitting around one day with friends, but I got that fixed after going to the hospital) Maybe i'm not breathing right when I spar? Because its not like my muscles are giving out on me cuz i have power and energy once i rest for a little.