Glycogen depletion run update

I’ve done four long runs now in a glycogen depleted state and I’m starting to feel encouraged about how they are going. Here’s an update:

Suffice it to say, I’m happy that I have gone down this path. Will it all be worth it? I won’t know until marathon day (Dec. 2) but I’m glad I’ve given it a try.

Anyone else tried glycogen depletion long runs yet? What’s your experience? 





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  1. says

    This is SO interesting to hear first hand experiences of this type of training. Can’t wait to see how it all plays out in the actual race. Do you end up fueling during the race? That’s one thing I was never clear on with the approach.

  2. says

    I still find this concept intriguing. Although on a much smaller scale I’ve played with eating/not eating prior to runs and have found that I too do better without eating. I have yet to to it on longer runs along with not fueling during long runs because I’ve always been told “you do it that way”. Next time I’m training for a longer distance I think it will be worth a try. Thanks for the inspiration.
    Heidi @BananaBuzzbomb recently posted..Buzz: Tap Water Is Bad For YouMy Profile

  3. Katie @ msfitrunner says

    I love that you are doing this and updating on it – I do most of my runs in a glycogen depleted state, or without fueling. I love it. The weekday runs are done that way mostly because I don’t want to wake up early to eat breakfast before heading out at 4:45am for a 10 mile run. But, my long runs, I do without fuel and it’s really great. I’ve been doing this since the spring, so I’m really hoping that by the time NYCM gets here, I’ll be in good shape and it will make a difference!!
    Katie @ msfitrunner recently posted..I Was Busy…Learning, Living, Long RunningMy Profile

  4. says

    Well unfortunately even after your marathon, you will not know if running in a glycogen depleted state (GDS) made any type of difference.

    I’ve done my own research on the subject and have done many many of my training runs fasted. During some points of my training I bet even half of my runs have been done fasted. I have no doubt my body uses more fat and stores more glycogen because of that training, however I have no way to actually prove this.

    The issue I’ve come across is this; While running in a GDS it is simply more difficult to run faster. Or on the other hand, research CLEARLY shows that supplementing with carbohydrates even during short runs, increases performance. Now, you and I could potentially be missing out on performance gains because we cannot run as fast/well in a fasted state, EVEN THOUGH we are increasing the ability of our body to burn fat, spare glycogen, and store glycogen. Would doing that 16 mile long run 10 or 20 seconds faster per mile make a difference? It’s definitely possible.

    Another thing to consider is your body will be more beat up and require more recovery after a fasted run than a fueled run. You could potentially be hindering your next few workouts by doing fasted long runs. Again, theory, but something to consider.

    This is why I have moved my fasted runs to my short recovery workouts instead of my long runs. Instead of running for an hour+ fasted, I’ll do my short 30 minute regeneration workouts after an overnight fast.

    Now, this is of course all theory as well. None of this can be proved without research in a lab.

    However, the overriding principle is that the ultimate goal of training should be to increase your confidence. Even if all I said above is true, if doing fasted long runs is making you more confident in your abilities to successfully run, than they are doing their job!

  5. says

    I’m so happy that these runs have been going well for you!! I like the idea of doing long runs both ways – I think if you were to do them all in the GDS, you would be hurting yourself on race day – just like you said – b/c your body is not used to the fuel. I commented on your previous GDS post that I’ve done a bunch like this too. One thing I’ve noticed is that when I did use fuel / water on runs, I found I had to use the bathroom DURING the run – something that I’ve never had a problem with before…So maybe my body was already adjusting to not having anything and the introduction of some fuel made it go crazy. I don’t think we will ever really know b/c there are so many factors that go into each specific run…
    Anyway, looking forward to seeing how the marathon plays out – and more importantly – how you feel during the race!!!
    PS. LOVE the painting behind you in the vlog =)
    Michele @ Nycrunningmama recently posted..Best Week of Pregnant Running (38 weeks)My Profile

  6. says

    It’s encouraging to hear your success with glycogen depletion runs. I am always tentative with fueling during a run because my tummy gets sensitive, and have wondered if I can just push through without having to do as much Gu as other sources might recommend I take.
    Jen @ ConcreteNCoffee recently posted..Sunday FundayMy Profile

  7. says

    Do you have access to FUEL testing?? If you tested now – at least you would know the percentage of fat you are burning at different running paces. Definitive data is always nice and eliminates the guess work.

    My boyfriend did a FUEL test in late June and then changed his diet and has been running glycogen depleted long runs (he’s training for a 50 miler). In June he was burning 95% carbs/5% fat due to his crappy diet. The 2nd (after) test is scheduled for Sept 18th. I’m anxious to see the results.

    Here’s a link to a FUEL testing people in our area. Note the chart of the ultra runner – at a 7:42 pace he burns 85% fat/15% carbs – 6:40 pace he burns 78% fat/22% carbs and at 5:53 he burns 62%fat/38 carbs. Very efficient.
    brg recently posted..Crazy for mtn biking & moose sightingMy Profile

  8. says

    I do all my week day runs without food before or during and I have done my last 18 and 17 miler without either as well. I actually prefer no fuel before and during because at least that way I don’t have to worry about my stomach being messed up. Honestly I can’t tell if I feel much different. I am usually tired at the end of a long run even when I take fuel during. I finished my 17 miler with my fastest mile this weekend, so I managed to pull that off. My challenge is going to be forcing myself to fuel on some upcoming long runs to prepare my stomach for NYC. I have yet to find a fuel I love that doesn’t make my stomach upset…
    Beth @ Miles and Trials recently posted..Upcoming Race and NYC TrainingMy Profile

  9. says

    this is interesting and i’m definitely open to the concept. obviously on race day you’d fuel, but i assume this training will prep your body to burn more efficiently during the race. i also would assume that as you do them more you will get ‘used’ to them as you have said you seem to be doing. or maybe you ate better the night before? are you including that in your “research” too? (jw). anyway, thanks for sharing!
    lindsay recently more sufferingMy Profile

  10. says

    I have done some run when they are 1.5 hours or less and it feels good.

    That being said the weather has been very favorable. Has that played any role in your runs perhaps?

    It would be interesting to see how the glycogen depletion runs work in the middle of the summer where you are sweating like mad.

    And by glycogen depleted we are talking about doing nothing more than drinking water on a run correct?
    Jason @ Cook Train Eat Race recently posted..It Finally Happened!!!!My Profile

  11. says

    I started doing this deliberately during my Houston cycle last year, but I’ve always done it sort of informally because of my intestinal issues when I eat before runs (and my weekday runs are so early that I just don’t have time to eat before them). So it wasn’t a big leap for me to start thinking about it. During the Houston training, I did two types of long runs: the no-fuel kind where just getting the distance in was the goal and fast-finish ones, where I *did* fuel in order to practice race-day strategy. The combo seemed to work for me. I had no issues during my race and set a PR.
    Terzah recently posted..A Scolding from the CoachMy Profile

  12. says

    Good stuff Amanda! Back at the beginning of the year Kevin and I paid careful attention to Glycogen levels and particularly doing some key long runs at depleted levels.

    I honestly feel this was very important as to why I bonked at mile 24 instead of miles 20-22. My body was burning more fat instead of Glycogen because it was trained to do it that way.

    Pete Pfitzinger has some excellent info about Glycogen and Glycogen depletion runs in the Advanced Marathoning Book. Which, knowing you, is probably located front and center on your book shelf!
    Jeff Irvin recently posted..Ironman Mont-Tremblant Nutrition and Predicted TimesMy Profile

  13. says

    Thanks for the update! I was wondering how it was going. I’ve done GD not purposely just that I wake up super early during the week for my runs and don’t have time to let things digest. As I get my mileage back up, I might have to give this a try just to see. Can’t wait to hear how the rest of training pans out!
    Angela @ Happy Fit Mama recently posted..Chasing the Runner’s HighMy Profile

  14. says

    I’m very curious and interested in this. I don’t think I’m ready to tackle this just yet, but I have a full marathon now finally on the books next year and I would like to start fine-tuning my fueling methods more. I’d like to at first start ‘depleting my stores’ in the beginning of the week and build up ‘fresh’ stores for the weekend long runs. It’s hard for me to cut out carbs for a couple days though, so there will be some will power involved, ha ha! I thought maybe starting off with Sun-Tues low to no carb. How are you doing the depletion process?
    Christina recently posted..How to pack a healthy school lunchMy Profile

  15. says

    I told my friend about these and he gave it a try last weekend. I’ll have to send him your links as I’m sure mid 16 mile run I may have been mumbling.

    Great video and congrats on feeling stronger as it goes on. You are an adaptable zipster!

  16. says

    Please correct me if I’m wrong, running glycogen depleted means you run on an empty stomach? Last year I had many GI issues during my long run and somebody told me to cut down my food intake by half. I felt better. Since then I reduced it even more and now I only eat one applesauce before my long run and only drink Gatorade during my run. On a hot day, I take a salt stick. Last weekend I did a 20 miler like this and felt great!! Am i doing a glycogen depleted run?
    Christine recently posted..The Perfect Long RunMy Profile

  17. Mike says

    Great experiment! Interesting, I’m reading the book Iron War and just read a chapter about studies that show the mind quitting before the body, actually way before the body. Makes me wonder if I really bonked on a long ride last year or my mind just told me I did and wasn’t mentally tough enough to say no.