But the brain can ONLY burn glycogen, so eat yer carbs, people.

[flexagon]

Gymnastics was kind of quiet this week. I'm getting worse again at everything involving momentum, but better at kicking or straddling to handstand and being able to hold it (often not at all, but more and more often for a couple of seconds at least). Tonight, just once, I kicked one and held for a count of 8... in yoga that would have been noticed and possibly clapped for, but there nobody even noticed. I really miss yoga.

Reading about metabolism is kind of confusing me. The NASM book says that the oxidative (aerobic) energy pathway kicks in when a muscle has been used for more than about 30 seconds (and has eaten up all its stored ATP and readily available glycogen), and also that it uses carbohydrates and fat. That got me wondering, do you have to eat carbs to burn fat? A few websites about lipid metabolism later, I'm not sure what the NASM book was talking about. I do know now that lipids have to be mobilized (gotten out of fat cells) before they can be metabolized, and that epinephrine (adrenaline!) is one of the key players in lipid mobilization. So now I have another idea for my future gym: scary movies playing in front of the cardio machines. ;)

Comments

[webrat.livejournal.com]

scary movies playing in front of the cardio machines. ;) - Just get a pack of vicious dobermans or something on chains behind the exercise machines. That'll get your heart going.

[dilletante.livejournal.com]

i seem to remember having the impression that aerobic excercise could burn carbs or fat or both, whichever was available. as distinguished from anaerobic excercise which could only make use of carbs? i don't remember the source for this, though it might have been stumptuous-- the context was whether to do cardio or weights first if you were doing both.

[flexagon]

Yeah, there is a lot of stuff on stumptuous. According to the NASM book, a cell basically needs ATP (adenosine triphoshate) for energy. This can come from free-floating ATP in the cell (easiest), then from breaking down local glycogen into ATP, then finally from the aerobic pathway which, in this context, just seems to means something harder that requires more chemical reactions and transport of energy-bearing substances. Lipid metabolism is especially complex.

According to everything I can find, all the macronutrients get turned into acetyl CoA at some point and from there they can become ATP.

Adrenaline

[islenskr.livejournal.com]

I've read that too much adrenaline in your system too often can cause all sorts of yucky things to happen: blood sugar/insulin getting messed up, weight gain, insomnia...exercise alone produces enough adrenaline to get your body burning fat.

Have you ever read any books by the guy who came up with the Zone Diet? He explains a lot about metabolism. I believe Dr. Andrew Weil explains quite a bit, too. As I understand it, you do have to eat carbohydrates and fats in order to burn fat, but if you eat too much (too many calories worth), the leftovers are stored as fat.

Ooooh, and there's that other guy who sometimes appears on PBS whenever there's a fundraiser...darn, I can't remember his name. He does a sort of lecture type show on metabolism, exercise and losing weight. I'll let you know when my brain is more forthcoming with his name.