Energy balance in ultra endurance

[simonp]

http://www.iutasport.com/files/articles/Energy%20Turnover%20at%20the.pdf

Interestingly hypoalbuminaemia is mentioned as a possible consequence of extreme endurance. My legs were a bit swollen during both Mille Cymru and LEL. I lost that water weight in a few days.

The quoted calorie figures are quite scary. 17,000 calories expended per day.

[Alouicious]

It was closer to 18,000 kCals per 20 hour day riding.

That's 900 kCals per hour which sounds about right.

A lot of money spent telling us something we already know.

[vorsprung]

17 or 18 thousand kcal is for riding at race speeds
For LEL/PBP at audax speeds less calories would be used
They mention skeletal muscle being used as an energy source too.  I take magnesium tablets ( hammer nutrition Anti Fatigue Caps ) during long events to prevent this

[Alouicious]

What one does for ultra-endurance rides is…

Topo the whole route.
Get a measure of the drag characteristic ( CdA ) and mass of the vehicle.
Get a measure of how fast your gonna ride along the flat and up hills ( from previous experience ).
Do the sums to work out energy expenditure based on a 'finite element' breakdown of the route.
Decide where you are going to stop.
Eat accordingly.

Those were the days, eh?


The conclusion is stating the cyclist had an energy deficiency. ie, he didn't eat enough and his skeletal muscles were used as fuel.

His dietician should be sacked.


From the lab tests, he gave an RMR of 2.42 kCals/min, or 3480 kCals in 24 hrs.

They fed him just about double this on the 'flat' days. They thought he was 50% efficient ??

[vorsprung]

The conclusion is stating the cyclist had an energy deficiency. ie, he didn't eat enough and his skeletal muscles were used as fuel.

His dietician should be sacked.

You are being a little harsh on the poor dietitian
18,000 kcal a day is quite a lot to eat whilst riding (probably) 22.5 hours out of 24 as fast as possible

[simonp]

They quoted 1.25g/min of carbohydrate absorption. This is around the limit of what can be achieved. Without intravenous supply, they were never going to be able to meet his energy needs.

[Alouicious]

The conclusion is stating the cyclist had an energy deficiency. ie, he didn't eat enough and his skeletal muscles were used as fuel.

His dietician should be sacked.

You are being a little harsh on the poor dietitian
18,000 kcal a day is quite a lot to eat whilst riding (probably) 22.5 hours out of 24 as fast as possible

I know what you're saying. Its not just eating that ammount. The body has a rate at which CHO is absorbed for use. Some say its 1.5g / min ( 6 kCals/ min ) so if the cyclist's energy expenditure was aimed at 8 - 10 kCals / min, or at climbing efforts, 15 - 18 kCals / min, there not much chance of him getting enough kCals of CHO into the blood.

After 10 days of this punishment, it is not at all surprising the guy lost muscle mass.
It may have been advantageous, ( for future competitors ) to bulk up muscle on the upper half of the body. Mind you, the Sierra and the Rockys are early in the route and that extra mass might be a hindrance rather than a help  

[mattc]

17 or 18 thousand kcal is for riding at race speeds
For LEL/PBP at audax speeds less calories would be used
They mention skeletal muscle being used as an energy source too.  I take magnesium tablets ( hammer nutrition Anti Fatigue Caps ) during long events to prevent this

It would be useful to know what factors encourage fat-burning over muscle-burning. (apart from your power output).

I expect I know the answer "Hammer Nutrition" would give!

This business:
The body has a rate at which CHO is absorbed for use. Some say its 1.5g / min ( 6 kCals/ min )
Presumably that is some sort of average figure. So you could say that a 'good' team dietician would measure this figure for all his/her athletes.

Also, I wonder if on long events this should feed into one's pacing strategy? In general, you get from A-to-B fastest (for the same calories) by pushing a bit harder uphill then easing off downhill (cos of wind resistance). By how much is very diff to calculate:

But if your success on a long event is affected by burning skeletal muscle, perhaps you should cap your power on the climbs even more than is optimal on a 1-day event? Or plan an 'energy budget' for each day based on the maximum you can get through your stomach?

[vorsprung]

It would be useful to know what factors encourage fat-burning over muscle-burning. (apart from your power output).

It's my impression that at moderate levels of effort, a small amount of glycogen and a largish amount of fat are burned.  Ignoring the mechanisms by which the fat is used, fat can either come from your diet (preferred) or your body fat reserves.  As well as this the there is a small amount of amino acids that are burned for fuel.  The body is a wondrous thing and can use all kinds of sources as fuel.

So, just in the same way as if fat from the diet is preferred to fat from body fat, amino acid from food is preferred to the breakdown of skeletal muscle.

Therefore to stop skeletal muscle breakdown, eat properly.  If you can't eat properly then eating stuff rich in similar sorts of amino acids that are generated from skeletal muscle breakdown might help a little.

I would guess that the weird mix of fuels that the body will run off is the source of some of the odd dietary cravings we get when riding these events

[PloddinPedro]

........ skeletal muscle being used as an energy source too.  I take magnesium tablets ( hammer nutrition Anti Fatigue Caps ) during long events to prevent this

Interesting. Do you notice much benefit from taking this, or is it one of those subtle things, a bit like electrolyte tablets, where you notice it more if you don't take them? (Does that make sense? Sort of?!)

[simonp]

Naively, I'd have thought taking a drink containing protein would work better. Whats the evidence for magnesium?

High 5 do (or did) a carb + protein drink. They (and torq) do a maltodextrin + fructose drink. Both are claimed to be better than maltodextrin only.

[Alouicious]

Naively, I'd have thought taking a drink containing protein would work better. Whats the evidence for magnesium?
High 5 do (or did) a carb + protein drink. They (and torq) do a maltodextrin + fructose drink. Both are claimed to be better than maltodextrin only.

Its lighter than taking Iron.... 


I'm meeting David Brailsford tomorrow. I'll ask him.

[vorsprung]

........ skeletal muscle being used as an energy source too.  I take magnesium tablets ( hammer nutrition Anti Fatigue Caps ) during long events to prevent this

Interesting. Do you notice much benefit from taking this, or is it one of those subtle things, a bit like electrolyte tablets, where you notice it more if you don't take them? (Does that make sense? Sort of?!)

It's impossible to tell.  I am a sample of one.  Last couple of years on long events I have taken "Anti Fatigue" capsules, electrolyte powder and eaten solid food.  I also take 500mg L-Carnitine per day during events.  If I have an energy crash or run out of food I use a recovery drink called "Amino Load" which is mostly carbs but apparently contains some predigested/easily absorbed amino acids.  I use "Amino Load" during events, not as a post event recovery thing

With this regime of food/drink/tablets I feel fine and go great.  I think I go better.  But I might just be fitter or something.

I figure that as the "Anti Fatigue" caps contain basically magnesium and potassium these are good electrolyte things to have in excess anyway.  All the stuff I take isn't going to do any harm, worse case I piss it out without it having any effect

In the past I have overloaded with carb rich drinks and got stomach cramps.

I have a discussion of my long distance riding feeding/chemical habits on my blog
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