Glycogen is what powers strong muscle contractions. If you have no glycogen in your muscles, you're not utilizing your workout to its full potential.
And gluconeogenesis is the body's answer for when we don't have stored muscle glycogen on hand. There's also liver glycogen too. If you're in a fasted or ketogenic state and not the sloppy transition period (keto dieters know what this feels like - it's hell), then you should be fine. In fact, I get a wicked rush of brutal retard strength when I train fasted.
I like training fasted now but not completely deprived of muscle glycogen. I think there's advantages to both, and my personal preference is to stay lean as hell and train fasted more often than not. I don't abstain from carbs completely. I like getting them in post workout because the body is more tolerant and it doesn't spill over into fat as much because of the way my meals are structured.
If during the day I'm fasting and feel too flat or weak, if I eat carbs it gives me a body pump because of how lean I am. I think people value carbs way too much. They're not essential for humans, and they're not super important for bodybuilders either. If you're on drugs like trenbologna and lots of GH, you can eat close to unlimited carbs and it goes to all the right places though. I'm training on nothing but testosterona at the moment, but when I'm on trenbologna I eat a lot more carbs.
