Marathon fuel

anders said:

I, too, must confess my absolute ignorance of any literature that
suggests fat (for energy use of, by endurance athletes) is slower to
replace than glycogen - and my common sense is boggled by how this
could be so (unless one is an anorectic on a complete fat-free diet)
even on a(n entirely theoretical) cumulative basis.

If one burns 50 gm of fat on a run, that is close to the recommended
daily limit of fat intake. Since one also uses fat for fuel constantly,
one would eventually reach a deficit if the intake wasn't increased. Now
how long it would take to reach that deficit obviously depends on a
variety of factors including how much excess one has to begin with. And
what I was trying to say (maybe not very clearly) is that over time if
one does multiple long runs depending on fat for fuel without increasing
the normal store, one will eventually reach the point of deficit (become
skinny!). That may be a good thing for some, but if you're already at
your optimal body weight/mass, it's not. And the less body fat one has,
the more critical a deficit is. So sitting down after running and eating
100 gm of fat to make up what I lost and cover my basic daily needs,
after EVERY long run (when I do several a week)is a lot harder than
taking in some carbs during the run to slow the fat burn during the run.

Quoted message said:

But back to the marathon long runs: the whole, or at least the main,
reason why they are there - especially for the novice - is to improve
the ability to use fat for energy at one´s marathon pace, right?

That's one reason. But again, my point was that to speed recovery and be
able to do long runs more frequently, don't allow yourself to become
depleted when running, which means taking in something during the run.

Quoted message said:

And if one begins to suffer and slow down, it´s because the run has
been too fast for the fat-burning system to deliver the desired
percentage of energy - and therefore that run has been far from optimal
trainingwise, right?

Quoted message said:

Now, would maintaining that pace with the help of an energy drink or
snack help to achieve the desired physiological adaptions - or would it
be better to slow down?

I think you should do both types of runs. Faster paced where you rely on
glycogen and slower where you learn to burn fat. But first, you have to
get to the point where you can utilize fat optimally and that is not an
overnight process. I go back to the original poster who was struggling
with 16M runs and had a marathon in a month. My advice was and still is
that ONE way (in addition to slowing down, taking walking breaks, etc)
to possibly help, is to take in some fuel during the run. I believe this
will help him during that run and leave him better able to run
effectively (as opposed to junk) sooner.

--
- The Trailrunner

Anti-Spam Alert: If you wish to reply, cut the *BS*

Trails of the Diablo Valley
*Running - Hiking - Nature*
http://www.geocities.com/yosemite/trails/6016/

Donovan Rebbechi said:

Not wrong at all. The above is a verbatim quote from my first response to OP.

Then I never saw that.

Quoted message said:

Quoted message said:

Here's the complete text of my original message on this topic
which was in response to your response to Mike C:

Donovan: "Why would you want to what ? Complete a training run without
GU ? Because it costs money, and you don't (or shouldn't) need it."

Yes, the point is that I'm explaining to Mike C why *I* don't take GU on long
runs.

But you didn't say "I" you said "you" implying (at least to me) anyone.

Quoted message said:

I don't see how the above context changes anything. You clearly think
that anyone who doesn't fuel on the run is an idiot.

And looking back at it, I'm as guilty as you are for saying "you"
instead of clarifying that it was "stupid" in a general sense not to
take something that might help in order to save a buck.

--
- The Trailrunner

Anti-Spam Alert: If you wish to reply, cut the *BS*

Trails of the Diablo Valley
*Running - Hiking - Nature*
http://www.geocities.com/yosemite/trails/6016/

anders said:

Quoted message said:

(...) Even as trained as we are, burning fat is

a

Quoted message said:

slower process than burning carbs and, I believe, likewise replacing

fat

Quoted message said:

is also slower.

Aren´t you making a leap from an accepted truth onto an unsupported
assumption?

As an experiment of one, I can tell you for me it's a truth. If you want
to test it for yourself, do a long depletion run to the point where you
bonk and can't run anymore. Then take in some carbs and see how fast you
recover before you can begin running again. Then do another long run
until you bonk. This time take in only fat and see how long it takes to
start running again. I've been there, done that, so can tell you the answer.

--
- The Trailrunner

Anti-Spam Alert: If you wish to reply, cut the *BS*

Trails of the Diablo Valley
*Running - Hiking - Nature*
http://www.geocities.com/yosemite/trails/6016/

The Trailrunner said:

If one burns 50 gm of fat on a run, that is close to the recommended
daily limit of fat intake.

For a relatively sedentry person.

The point of this "recommended daily limit" is to constrain caloric intake,
based on the premise of a fairly low fat diet.

Quoted message said:

Since one also uses fat for fuel constantly,
one would eventually reach a deficit if the intake wasn't increased. Now

Oh boy, this sounds a lot like the "low fat diet" myth. You will not lose body
fat unless you burn more *calories* than you consume. If you have a low fat
diet, but your intake and energy use are well-matched, your body has at least
two ways to balance the equation: one is to simply make greater use of glycogen
stores (which are greater since the lack of fat is matched by an excess of
carbs) to spare fat, or convert extra carbs to fat.

Quoted message said:

how long it would take to reach that deficit obviously depends on a
variety of factors including how much excess one has to begin with. And
what I was trying to say (maybe not very clearly) is that over time if
one does multiple long runs depending on fat for fuel without increasing
the normal store, one will eventually reach the point of deficit (become
skinny!).

There you go again with the "fat burning" myth.

Quoted message said:

Quoted message said:

Now, would maintaining that pace with the help of an energy drink or
snack help to achieve the desired physiological adaptions - or would it
be better to slow down?

I think you should do both types of runs. Faster paced where you rely on
glycogen and slower where you learn to burn fat. But first, you have to
get to the point where you can utilize fat optimally and that is not an
overnight process. I go back to the original poster who was struggling
with 16M runs and had a marathon in a month. My advice was and still is
that ONE way (in addition to slowing down, taking walking breaks, etc)
to possibly help, is to take in some fuel during the run. I believe this
will help him during that run and leave him better able to run
effectively (as opposed to junk) sooner.

Your advice, as stated above is just fine. What I take issue with are your
woefully ignorant comments about nutrition, and your unsupported theory (in
fact contradicted by facts I've brought up) about lipid metabolism taxing
recovery.

There are some theories that are at least plausible from a naive standpoint
that one could make up about why bonking isn't a great idea, but yours ain't
one of them.

Cheers,
--
Donovan Rebbechi
http://pegasus.rutgers.edu/~elflord/

Tony said:

Quoted message said:

The physiology text I have shows a 50/50 split at 85% VO2. The number does
trend upwards in favor of intramuscular deposits as intensity increases. So
you'd be looking at no more than ~50gm or so for a 2hr run.

Thanks, just to be clear, that's 50% bodyfat and 50% intramuscular fat at
85% VO2?

Yes. Body fat is actually "plasma triglicerides", so these can come from body
fat stores, but also any ingested supplement would add to this supply (and
also make it more readily usable)

Quoted message said:

As has been stated elsewhere in this thread, fat is being burned as a
primary fuel all the time by most parts of the body, while the brain alone
burns only glucose or ketones. As I understand it, when one begins to run,
the increased metabolism necessary for running kicks in and the fat burning
system becomes warmed up to suppy more fat to the legs after 10-15 mins.
Before this glycogen is burned by the running muscles more than fat.

Yes, in fact there's a general trend towards less glycogen usage as time
increases. The trend keeps going for quite a while (up to 2hrs or more I think)
but it drops like an exponential taper -- the biggest drop is in the first
several minutes.

Quoted message said:

Thus at an easy pace, the body will attempt to preserve glycogen by ramping
up the metabolism of body fat. Your physiology text indicates that
intramuscular fat is also preserved at lower intensites. So if the muscles
and metabolism are well trained for endurance, one can train at a low
intensity for many hours while utilizing mostly body fat and then come back
the next day and do the same thing.

Yes.

Quoted message said:

At higher intensities, both muscle glycogen and intramuscular fat are
utilized in higher percentages than at lower intensities, while the burning
of body fat drops in percentage. At what intensity does this start to become
significant? It must vary to some extent with each individual.

Glycogen usage varies very widely between individuals, so different studies
may report very different findings, especially since some studies may use
elite athletes as their subjects (they make good subjects since they can
stay on-task for a long time)

Some people burn nearly all glycogen even at very low intensities. These people
would probably have a hard time completing a marathon.

Quoted message said:

For longer endurance workouts the intramuscular fat could indeed become
depleted, and might take longer than glycogen to replenish. I've read that
this can take a few days (trying to remember where).

I suppose it's possible. I've never seen it mentioned as an issue for recovery
purposes though, and I did search my pile of books (exc physiol text, Daniels,
Noakes)

Cheers,
--
Donovan Rebbechi
http://pegasus.rutgers.edu/~elflord/

The Trailrunner said:

Donovan Rebbechi said:

Not wrong at all. The above is a verbatim quote from my first response to OP.

Then I never saw that.

Quoted message said:

Quoted message said:

Here's the complete text of my original message on this topic
which was in response to your response to Mike C:

Donovan: "Why would you want to what ? Complete a training run without
GU ? Because it costs money, and you don't (or shouldn't) need it."

Yes, the point is that I'm explaining to Mike C why *I* don't take GU on long
runs.

But you didn't say "I" you said "you" implying (at least to me) anyone.

Quoted message said:

I don't see how the above context changes anything. You clearly think
that anyone who doesn't fuel on the run is an idiot.

And looking back at it, I'm as guilty as you are for saying "you"
instead of clarifying that it was "stupid" in a general sense not to
take something that might help in order to save a buck.

OK fair enough. Thanks for clarifying.>

Cheers,
--
Donovan Rebbechi
http://pegasus.rutgers.edu/~elflord/

Donovan Rebbechi said:

Oh boy, this sounds a lot like the "low fat diet" myth. You will not lose body
fat unless you burn more *calories* than you consume.

And by increasing the amount one runs (which is what started all this
when I suggested increasing the frequency of long runs), one will burn
more calories than one normally does. To offset that one will have to
consume more calories.

Quoted message said:

but your intake and energy use are well-matched, your body has at least
two ways to balance the equation: one is to simply make greater use of glycogen
stores (which are greater since the lack of fat is matched by an excess of
carbs) to spare fat, or convert extra carbs to fat.

But if you don't burn it in the first place, you don't have to convert
something to it, which takes time. Glycogen stores are can be converted
to energy almost immediately while if they are first converted to fat
and then used for energy, takes a lot longer. So what I'm saying is that
by taking in fuel during the run to replace the glycogen being used and
thus limit the reliance on fat for fuel, one reduces the need to replace
as much fat later. So the carbs one takes in post run go directly to
glycogen replacement and as much doesn't have to be diverted to fat
replacement.

--
- The Trailrunner

Anti-Spam Alert: If you wish to reply, cut the *BS*

Trails of the Diablo Valley
*Running - Hiking - Nature*
http://www.geocities.com/yosemite/trails/6016/

The Trailrunner said:

anders said:

Quoted message said:

(...) Even as trained as we are, burning fat is

a

Quoted message said:

slower process than burning carbs and, I believe, likewise replacing

fat

Quoted message said:

is also slower.

Aren´t you making a leap from an accepted truth onto an unsupported
assumption?

As an experiment of one, I can tell you for me it's a truth. If you want
to test it for yourself, do a long depletion run to the point where you
bonk and can't run anymore. Then take in some carbs and see how fast you
recover before you can begin running again. Then do another long run
until you bonk. This time take in only fat and see how long it takes to
start running again. I've been there, done that, so can tell you the answer.

No-one's questioning your experience, in fact I can volunteer some data that
supports your experience. For example, Noakes reports examples where people
have bonked in long races, and been able to resume running *immediately* after
taking in carbs. Noakes did an "experiment" which involved not taking adequate
carbs prior to comrades, and not taking carbs during the race. He bonked badly
at 50km. He was able to continue immediately after taking some carbs. I would
predict that your experience would be replicated by anyone who tried.

Unfortunately, I don't believe that your experience supports your theory (that
fat stores take longer to replenish).

The reason that taking in fat will not help a whole lot is that taking in fat
will not do very much to restore glycogen supplies. Your fat stores will get
restored just fine, but since you're still in a depleted state, you still can't
do very much.

Since we seem to agree that glycogen depletion is linked to slowing down, I
would argue that the best explanation for your experience is that taking in fat
does not help restore glycogen levels.

Cheers,
--
Donovan Rebbechi
http://pegasus.rutgers.edu/~elflord/

You might want to check this info- it helped me figure out how to get thru
my first marathon
http://www.carbboom.com/education/marathon_calc.php

"Drew" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I'm looking for diet tips on how to fuel my body for a marathon. My
heart and lungs are fine on long runs however my legs start to give up
after about 16 0r 17 miles. any tips would be greatly appreciated as my
race is on june 12th.

Dan Stumpus" <[email hidden]> wrote:

"TheTBR" <[email hidden]> wrote in message

news:[email hidden]...

Quoted message said:

Dan Stumpus" <[email hidden]> wrote:

Quoted message said:

Just had to join in this food fight... Trailrunner (who clings to

his

Quoted message said:

anonymity)

Quoted message said:

-------------------

Quoted message said:

CHEAP SHOT ALERT!!!

You should talk!

----------------

There you go again. Attacking the messenger instead of addressing the
message.

What you did was a cheap shot attack against TrailHead, regardless of
whether you want to admit it or not. It doesn't matter who pointed this
out, fact is it is true.

The Trailrunner said:

Donovan Rebbechi said:

Oh boy, this sounds a lot like the "low fat diet" myth. You will not lose
body fat unless you burn more *calories* than you consume.

And by increasing the amount one runs (which is what started all this
when I suggested increasing the frequency of long runs), one will burn
more calories than one normally does. To offset that one will have to
consume more calories.

Right.

Quoted message said:

Quoted message said:

but your intake and energy use are well-matched, your body has at least
two ways to balance the equation: one is to simply make greater use of
glycogen stores (which are greater since the lack of fat is matched by an
excess of carbs) to spare fat, or convert extra carbs to fat.

But if you don't burn it in the first place, you don't have to convert
something to it, which takes time. Glycogen stores are can be converted
to energy almost immediately while if they are first converted to fat
and then used for energy, takes a lot longer.

Correct, but doesn't help you much.

Quoted message said:

So what I'm saying is that
by taking in fuel during the run to replace the glycogen being used and
thus limit the reliance on fat for fuel, one reduces the need to replace
as much fat later. So the carbs one takes in post run go directly to
glycogen replacement and as much doesn't have to be diverted to fat
replacement.

OK, but that just amounts to saying that if you take in more calories during
the run, you don't need to take in as many after the run. And sure, I agree
with that.

Cheers,
--
Donovan Rebbechi
http://pegasus.rutgers.edu/~elflord/