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pre race (half marathon) meal (Read 3099 times)

    Many people fade badly at the end of half marathons.  It's not primarily because of low glycogen levels any more than the typical fade at the end of a 5k is.

     

    I think it is possible to experience a glycogen bonk in a HM but doing so requires running significantly too fast for for the first 8-10 miles.  I'm pretty sure I've done this on occasion.  I this case, the primary problem has nothing to do with pre-race or in race nutrition and the runner would have faded anyway (and probably had already begun to fade) had he not bonked.

    Runners run.

      Many people fade badly at the end of half marathons.  It's not primarily because of low glycogen levels any more than the typical fade at the end of a 5k is.

       

      I think it is possible to experience a glycogen bonk in a HM but doing so requires running significantly too fast for for the first 8-10 miles.  I'm pretty sure I've done this on occasion.  I this case, the primary problem has nothing to do with pre-race or in race nutrition and the runner would have faded anyway (and probably had already begun to fade) had he not bonked.

       

      In one of my HM's last year, my main goal was to PR.  There was nothing more I wanted to do.  I was in the middle of training for the CIM with a training group and everybody in our group was running this particular HM.  My previous PR was 1:44:38.  I had high hopes for myself.  Because our group had been doing speed workouts every Wednesday, I was shooting for a time close to 1:40.  I started with the 1:40 pacer and maintained a pace between 7:20 - 7:30 for the first 6.5.  Then, I slowly started losing it.  The next mile I fell to under 8.  Then I picked it back up, but miles 10-13 were a struggle like I've never experienced before. 

       

      I even had thoughts of just walking it in because everything in my body felt out of whack.  Granted, this October day turned out to be hotter and much more humid than normal, but my body was giving out for the first time in a race.  As soon as I finished, I immediately cramped up.  Twenty minutes later, I got the chills, felt very weak, had stomach cramps, and had to lay down.  Almost felt like the flu.  Not sure what exactly happened, but I'm sure it was a combination of things.  Hey, I still PR'd by 10 seconds though.

        I was not clear in my use of the term "maximal effort".  The maximal effort required to race a good HM or M is lower than the maximal effort required to race a 100 meter, and the proportion of glycogen use as a fuel source differs across these.  When I used "maximal effort", I intended to imply the single most maximal effort you can produce, not the maximal effort required to race a given distance. That maximal effort would not be sustainable more than a handful of meters due to other factors that cause exhaustion.

        The rate of glycogen use relative to fat use as an energy source, as you know, directly correlates with effort.  The higher the effort, the more that energy comes from glycogen rather than fat.  The effort required to use glycogen as the sole glycogen source is a true maximal effort.  Think something like a 100 meter sprint.  A 5k effort is not maximal, but is still fairly high and uses a high proprotion of glycogen to fuel, but cannot be sustained more than 5k (by definition).  By time you have adjusted your effort down to the maximal effort required for a HM or a M, you are using quite a bit of fat to fuel your run.  You still need glycogen, sure.  But that does not mean you need an extra fuel source.

         

        I'm not sure we even have decent definitions for the terms effort and intensity.  Aren't they purely subjective?

        Well at least someone here is making relevance to the subject.

          In one of my HM's last year, my main goal was to PR.  There was nothing more I wanted to do.  I was in the middle of training for the CIM with a training group and everybody in our group was running this particular HM.  My previous PR was 1:44:38.  I had high hopes for myself.  Because our group had been doing speed workouts every Wednesday, I was shooting for a time close to 1:40.  I started with the 1:40 pacer and maintained a pace between 7:20 - 7:30 for the first 6.5.  Then, I slowly started losing it.  The next mile I fell to under 8.  Then I picked it back up, but miles 10-13 were a struggle like I've never experienced before. 

           

          I even had thoughts of just walking it in because everything in my body felt out of whack.  Granted, this October day turned out to be hotter and much more humid than normal, but my body was giving out for the first time in a race.  As soon as I finished, I immediately cramped up.  Twenty minutes later, I got the chills, felt very weak, had stomach cramps, and had to lay down.  Almost felt like the flu.  Not sure what exactly happened, but I'm sure it was a combination of things.  Hey, I still PR'd by 10 seconds though.

           

          Yeah, it sounds like you had a bunch of things going on, probably including dehydration.  Congrats on gutting it out for a PR though.

           

          But you bring up a good point--when in marathon training many of us are going around in a constant state of partial glycogen depletion and fatigue as it is.  In this case, recovering your glycogen stores (and energy level in general) has more to do with tapering your training for a couple/three days before a hard effort like racing a half, than with what you eat in the days before.

          Runners run.


          I'm back!

            The most comprehensive discussion I know of about these issues is Chapter 3 of Noakes' Lore of Running, "Energy Systems and Running Performance" (all 83 pages of it!). But Noakes is not the easiest to read; also he seems to contradict himself from time to time. And he seems to have a bit of an agenda here as well.

             

            Can anyone recommend any other good reading?

              Aren't they purely subjective?

               

              Not the way he's using it. Effort and intensity can be describe in terms of a percent of an an individual's maximum race pace for a given distance, for example % of 5k race pace.  Using this definition, marathon pace or effort is less intense, i.e. slower, than 5k pace and there's nothing subjective about it.

              Runners run.


              A Dance with Monkeys

                Correct, Mikey. That i what I meant.

                 

                And in this case, since the metric is 100% glycogen as a source of fuel, the maximal effort is relative to a true maximal possible effort for the individual, such as would be required to race a 100 meter run.


                HobbyJogger & HobbyRacer

                  So, look, if the correct way to give your 100% to a HM run is to go out at 100M sprint effort, then, yeah, I think what you eat right beforehand is going to affect your results. Well, maybe not your time, as much as the exciting visual results I think you can look forward to somewhere in the first mile.

                  It's a 5k. It hurt like hell...then I tried to pick it up. The end.

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