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Thread: Low carb/fat adapted muscle glycogen page

  1. #1
    chronyx's Avatar
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    Low carb/fat adapted muscle glycogen

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    Food/sport geek question!

    Once the body has switched over to fat metabolism, does the muscle glycogen stay 'topped up', only being used when needed for strength/explosive movements?

    Or do you still need to top up carb stores?

    Personal anecdotes as well as hard science welcome.

  2. #2
    Tawny's Avatar
    Tawny is offline Senior Member
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    Interesting question...right now, I'm still trying to get back in fat-burning mode after the holidays (lower energy right now), but back in November/early December, I could run 7 miles steady, and still have energy to sprint at the end. I never felt the need to replenish with a banana or other carb afterward, either. Before becoming primal, I would always feel the need to eat a banana after a run, but that might have just been part of my CW thinking...

    I also can't remember the last time I experienced the shakes common with glycogen depletion - this used to happen to me at the end of speed workouts all the time. Even this past week's sprint workout wasn't bad, I just didn't go as hard because of general fatigue.

    I'm really glad you asked this question, can't wait to hear other responses...

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    iniQuity is offline Senior Member
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    Very interested in this topic as well. I find I just feel better with some starchy carb esp when I lift...

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    I am interested to know this as well. I have nothing particular to add from personal experience, but I don't notice any degradation in performance with heavy weights or HIIT. Even though I don't eat high carb stuff.
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    chronyx's Avatar
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    Well I managed far more pull-ups today than I was expecting, and a PB for military press; all with the familiar ketosis taste in my mouth.

    Keep your replies/experiences coming!

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    lecz0r's Avatar
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    I don't claim to know the end-all answer here and I'm still a newb but based on what I've gathered... my opinion is this. I suspect most people in most situations will be fine without needed to 'carb-up'. Your muscles will surely use their stores, especially with HITT, unless all you are doing is very mild, not too long cardio stuff. The frequent/semi-frequent depletion of glycogen is a pretty good idea, something that Art De Vany mentions in his recent book. In my opinion one of the only times I can think of that 'carbing up' is a good idea is with really demanding cardio stuff like marathons or triathlons. If you are gonna go work out for 30 or 60 minutes then go home, eat, and read a book - more glycogen is not required right now so no big deal, gluconeogenesis will take care of it. But the catch is you don't want that process to eat away at or hinder your muscle growth.

    Whether your body is fat adapted or not isn't really the issue... the question is, is glucose available to replete glycogen? Although perhaps an argument could be made that 'fat adapted' translates into more efficient gluconeogenesis.

    If glucose levels are insufficient, then your body will ramp up gluconeogenesis to create the required glucose. The raw materials for this can come from pyruvate, lactase, glycerol, and the amino acids alanine and glutamine. All this stuff comes from muscles and/or protein sources (amino acids). But the process is not as efficient and takes some time as opposed to simply having the glucose freely available in the first place, hence the suggestion about extended work versus short intense work.

    Ah, well no one wants their muscles catabolized. So the idea then is to provide your body the raw materials when it needs them so it doesn't go looking at your muscles for them. The gist I get with this is to make sure to eat a good chunk of protein after a hard workout and/or use a good branch chain amino acid supplement. This is part of the logic behind the leangains method. You workout fasted (ie low glucose levels), you take a good dose of BCAA right before the workout and right afterwards (giving gluconeogenesis some buffer materials it needs to get by for a while) then eating your biggest meal, with lots of protein after the workout. As the meal is digested, glycogen stores will be replenished and you are good to go with little or no harm done to muscle growth. However, if you are gonna go beat the crap out of yourself again in a few hours or even the next day - going straight to carbs is probably a better idea.

    A cool side note - recall glycerol is important for the process... which is obtained by breaking down triglycerides in fat. Think about that for a sec...
    Another cool side note - During intense, brief energy needs phosphocreotine is used before glycogen then glucose uptake. More bang for your buck, so to speak.

    My personal anecdote follows all of this logic and I've seen no drops in performance so long as I give myself plenty of time to recover (not just glycogen stores, but also muscle repair and growth), usually 3-6 days. But if I workout back to back days or do more metabolic stuff, it seems to help to have more carbs w/ the meals. I've been using this style of training/eating for a few months and have been happy with the results thus far.

    Some similar discussion
    http://training.fitness.com/nutritio...ons-32235.html
    leangains.com

    Info sources
    http://themedicalbiochemistrypage.or...eogenesis.html
    http://rpi.edu/dept/bcbp/molbiochem/...t2/bioener.htm
    http://rpi.edu/dept/bcbp/molbiochem/...2/gluconeo.htm

  7. #7
    chronyx's Avatar
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    Whoa. If we're going to get an answer I think it's that! Thanks!

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    lecz0r's Avatar
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    Haha, always be skeptical!
    I'm not a doctor or biologist or anything. This is just what I've put together as making sense in my head from learning about this stuff from people who are.

    At this point in time though, I'm pretty psyched and geeked out on this stuff. It's really cool to see information come together from various sources and make some logic sense as to whats going on. Not to mention testing it on myself and tweaking things like... like a lab experiment. I never would have guessed anything like this when I first was like... 'what the hell is this paleo stuff?!'

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    That's exactly how I understood it Lecz0r!

  10. #10
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    I don't really know, but I eat an all meat diet and my muscles work just fine.

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