Let me get this right - you push yourself to almost total exhaustion for 2-2.5 hours, wearing a helmet and probably sweating like a firehose, and you are not allowed to drink? For 2-2.5 hours?? That's your problem right there, if I read your situation right. I don't know if you can drink enough fluid to last thru a workout like that.

How long have you been low carbing? It took me over half a year to get my energy back to where it was on carbs. Some people get more energy very quickly, some, like me, it takes a while. Maybe because my metabolism wasn't wrecked yet before LCing. I dunno.

I'm taking Kenpo karate. It's not nearly the workout like yours, but I love it. We spend alot of time learning defenses against various personal attacks, like front-hand grabs, punches, or head locks. What kind of martial-art is Kendo?