If "Hitting the Wall" depends on duration, not distance, do Elites have to deal with it?

In a interview Wilson Kipsang said something like it's not till the last two kilometres in the marathon that he starts to feel anything. I'll try to find it.

Found the interview, it's the first question.

https://youtu.be/_R0Fomzeh-M

I'm fairly sub-elite/national class but I have run 2:19:50 this year and been top 17 at Boston and Chicago.

However, I'm pretty sure elites hit the wall (and feel quite a bit of pain like we all do). I've seen all sorts of guys going sub 5-min pace for 20 miles and then start walking and doing the zig-zag jog (when you get really dizzy and hypoglycemic) in the last 10km of marathon majors.

I think very well trained guys are pretty good at managing carb intake, hydration and are very good at burning fat though. They can ride that fine line for 1.5-2 hours.

If you train 120+ miles a week and do 22-24 mile depletion type Long Runs fast (Canova style) you are probably going to be pretty well "Fat adapted." in general.

If one runs a good race they may " scrap up against the wall" but there is minimal slowdown in the last 10km.

There is a basic "work output" of moving one's body 20-22 miles....a simple displacement. Do it fast and you are working at a higher power...do it slow and you are working at "lower power." Now of course there are relative rates of intensity/HR, the ability to store glycogen, and RQ (% of fat burning at different paces/intensity).

Elites are generally racing a marathon a lot closer to their Lactate Threshold (esp if half marathon best is around 60-min)...they are pulling a high relative HR.

Less trained (less fat adapted) and "slower runners" usually don't have the same efficient Running Economy around marathon pace. They can bonk earlier at like 16-18 miles if they go out too fast....so maybe a little earlier. Sometimes simple "sheer muscle" failure or dehydration causes them to cramp up around then anyway though...along with things like over-heating etc.

I think most people will start of feel a bonk coming on by mile 23-24 (even if taking in carbs during the race)...and if they don't its because they didn't start fast enough and aren't going 100%!

theJeff wrote:

I assume that your body doesn't really know how far it has run, but it knows how long it has been working... so, if that switch comes around, say 2.5 hours for the average human, it is possible that elite marathoners simply don't have to deal with that phenomenon?

Directly, hitting the wall has nothing to do with either the distance or the time you are running.

Think about the analogy with the car. You have limited fuel tank capacity but you can choose to drive at different RPM. If you will drive at 6000 rpm you will burn the entire fuel much faster compared to cruising at 2000 rpm. Of course there are factors like hills and wind that can influence this but generally it depends only on the consumption rate.

The same principle applies to humans. There are limited capacity of glycogen that can be stored in our fuel tanks (muscles, liver). The faster you run (the bigger is your relative effort) the more glycogen you burn each second to sustain that effort. At some point (around LT) there is a moment after which you will start burning glycogen exponentially faster as anaerobic glycolysis is very energy expensive metabolic pathway (but it produces large amounts of energy very fast).

At true marathon effort fuel storage will be enough for close to 2 hours of running.

At true half marathon effort the fuel usually lasts for around 60 minutes.

Once you step in anaerobic zone, the glycogen consumption rate becomes exponentially larger but you usually can't hit wall in shorter runs because the fatigue that arises from anaerobic effort (induced from metabolic end products like H+) comes faster then glycogen stores would allow you to run.

The faster you run, the faster you need to burn through your glycogen stores. Thus it is a function of both speed and duration.

The reason you don't hit the wall in a 10K or a half when fit is you can't run fast enough to use up all your glycogen in a short timeframe. You run into other limits ("lactic") first.

Of course it happens to elites, if you follow major marathons you see it all the time...

Well that is exactly what I said in my post. You basically hammered the same thing over again.

qw wrote:

Well that is exactly what I said in my post. You basically hammered the same thing over again.

And you, the master of the universe, forbids him to do that?

I think since Boston was so slow people had different nutritional needs that they werent ready for and thats what caused so many to drop out

Surely there is more to 'hitting the wall' than just glycogen? It is often mainly down to pure muscle damage/fatigue.

The body can keep going a lot longer than 20 miles on energy stores alone but muscles get torn up much faster. Imagine doing a marathon on a constant 2% grade down hill. Most runners would run with far lower heart rates and use less energy due to the help of gravity but I guarantee they'd all 'hit the wall' and probably before 20 miles too... why? Their quads will have been turned to jelly.

Essentially, hitting the wall is just where you cannot maintain the same stride rate/length and so slow down. Of course this can be related to energy but most of the time it's muscular or nervous system fatigue.

Not just carbs wrote:

Surely there is more to 'hitting the wall' than just glycogen? It is often mainly down to pure muscle damage/fatigue.

Essentially, hitting the wall is just where you cannot maintain the same stride rate/length and so slow down. Of course this can be related to energy but most of the time it's muscular or nervous system fatigue.

No, as qw stated above, hitting the wall is running out of fuel. The car analogy is excellent. If it was just muscular or nervous system fatigue then every sprinter hits the wall at about the 80 metre mark of a 100 metre sprint. I don't run marathons any more as I could never avoid hitting the wall. In my last marathon, some 30 years ago, at about mile 21 I was on pace for a sub 2:50 time. 200 yards later I was walking, I finished in 3:15.

Raddison wrote:

Not just carbs wrote:

Surely there is more to 'hitting the wall' than just glycogen? It is often mainly down to pure muscle damage/fatigue.

Essentially, hitting the wall is just where you cannot maintain the same stride rate/length and so slow down. Of course this can be related to energy but most of the time it's muscular or nervous system fatigue.

No, as qw stated above, hitting the wall is running out of fuel. The car analogy is excellent. If it was just muscular or nervous system fatigue then every sprinter hits the wall at about the 80 metre mark of a 100 metre sprint. I don't run marathons any more as I could never avoid hitting the wall. In my last marathon, some 30 years ago, at about mile 21 I was on pace for a sub 2:50 time. 200 yards later I was walking, I finished in 3:15.

Yes but what happens if the car's engine blows up? It can be full of fuel but if the engine is done for it ain't going anywhere. Sprinter's may actually hit the wall too in that respect... it's just the race is so short their momentum gets them over the line but the can still slow drastically in those last 25m (percentage wise that isn't too dissimilar to when people slow in a marathon.) I'm sure you've seen enough 800m races to see guys 'hitting the wall' with 100m to go and crawling in. Have they run out of the fuel too?

We're splitting hairs a bit but I don't see why slowing down for longer races is suddenly 'hitting the wall' but for shorter races it isn't. The result is the same. You slow down significantly and there are a myriad of factors causing the fatigue.

The difference in the rate of glycogen burned per mile at various paces really isn't that high.

Elite runners tend to be able to get deeper into the marathon before depeleting glycogen for some of the reasons that they are elite in ge first place: above average running economy, disproportionate amounts of leg muscle relative to their overall size, lower weight.

You basically have two stores of glycogen: liver stores and muscular stores. You can only use the muscular stores from those muscles hat are actively engaged. The lighter you are, the less work you have to do to move your body at a given pace and thus less energy consumed.

So when you see a 120 pound 5' 8" guy with an narrow frame and limited upper body muscle, a guy who has great running economy at a cellular level, and a guy who (despite being skinny) has a disproportionate amount of leg muscle, you end up with a perfect combination for extending the range of that athlete before glycogen depletion.

I think the last few posts are accurate. Hitting the Wall doesn't just have to be about glycogen. It can also be body temperature, muscle fatigue, too high of a HR for too long, lactic acid, simply just tired of running, etc etc.

theJeff wrote:

My understanding of this may be way off, so feel free to correct / educate me:

The horribly painful feeling towards the end of a marathon, or "hitting the wall", is essentially a physical response to your body's running out of glycogen for fuel and having to switch to fat (and muscle?) stores for food.

I assume that your body doesn't really know how far it has run, but it knows how long it has been working... so, if that switch comes around, say 2.5 hours for the average human, it is possible that elite marathoners simply don't have to deal with that phenomenon?

Or, are they just that much better at dealing with the pain than mere mortals? Do I even have the right idea?

It's definitely not the same. And the fatigue isn't just from glucose depletion. It also has to do with muscle fatigue due to overuse and impact forces.

Also elites are better than any others at utilizing fat as fuel, meaning their glucose stores (which are larger than sub elite) last longer.

But they still hit the wall, just not as dramatically and later in the race.

Touching on Rupp's training a bit. It's advantageous to go 23-27 miles for a long run since it would train the body to utilize glucose and fat stores optimally. However I feel by running on soft terrain so much he isn't quite training his body as well for dealing with impact forces. But they seem to know what they're doing so I wouldn't say I'm completely on point in that regard.

I suppose this is somewhat subjective in that it all depends on how you define "hitting the wall" but I would distinguish between the gradual and cumulative effect of exertion over time and the sudden onset of the effects of glycogen depletion. The former is gradual while the latter is more acute - thus the idea of "hittting a wall."

Fatigue can be more readily managed through training whereas glycogen consumption rates are relatively less trainable.

I've bonked and I've cramped up late in a race. The former was like hitting a wall (and worse), the latter was more frustrating, but less dramatic.

The key to not hitting the wall is to keep your eyes open and on the path ahead of you. You run into trouble if you are looking down at your feet as this is when walls tend to jump up in front of you.

Now if you happen to see a wall in front of you and you are unable to avoid hitting the wall. The key is to avoid lettting your face hit the wall first. Brace for impact with your arms.

Hope that helps.

The car engine blowing up analogy is closer to tearing a hamstring. Hitting the wall is more than just slowing down due to exertion, it is suddenly running out of energy. It also happens very quickly, you can feel great and be thinking that you are going to get a really good time and then within a couple of minutes you have barely enough energy to move your legs. It is a very frustrating sensation because you don't feel exhausted as such, your breathing is fine and your pulse is normal, nor do your legs feel wrecked. Physically you feel you can still do it and the walking is really easy. But as soon as you start to run again you find there is no energy to drive the legs at any speed above walking.

My two cents: If we eat well before the race with a good carbo load thursday, friday and saturday , we will have about 500 gr

of glycogen stored in our muscles and liver .Now 1gr of glycogen give us 4 kcal , so 500gr give us 2000 kcal.

Running cost is about body weight x km. So for example 10k race 60kg x10 = 600kcal (no problem with the fuel

is not even a good thing going into the race with 500gr of glycogen in our muscles and liver cos glicogen keep also water in our body so we can have a kilo or more of weight to carry along in the race.

21km 60kg x21 =1200kcal (also here no problem)

42km 60kgx42= 2520kcal Here only the glycogen dont let us reach the end of the race at our given pace we need energy

from fat .

But let's look to an elite runner like Eliud Kipchoge 1,67 x 52 kg

42k 52 x 42= 2184 kcal a runner like Kipchoge can run a full marathon almost using only glycogen with a little help from fats. And using only glycogen he can run far as about 39km!!!!

But if we take an other runner probably not elite of 70kg

42k 70 x 42= 2940 kcal

Using only glycogen he can run far "only" 28 or 29 km . So he needs a lot of help from fats to complete the marathon.And we know

that this is not easy.

I want to share one anecdote from my training group-club. There are three guys with pb of about 35' and 36' in 10k

and 1:18 in the half and since three years they try the marathon and they are fighting to stay under 3 hours .

Their body weight is about 70 kg

There are also three girls with pb of 38' in 10k and 1:23 in the half and at their first marathon made 2:52, 2:54. 2:56

Their body weight is about 50kg.

Same coach and same training.

There are not to much secret about it, they just need less calories to complete the Marathon and so they need little help from fats to complete the race.

While in race where fuel is not a problem the things are different.

2:10 guy hitting the wall

https://www.youtube.com/watch?v=dfpO7jJTEvo