question for the scientists...

IIRC, I think there are 4 or 5 grams of water stored in association
with each gram of glycogen as well. I'm not sure how that would figure
into you're "fully hydrated" part of the question. Also could you
really just burn glycogen and no fat?

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

Quoted message said:

I was just wondering, if one were to stay fully hydrated but consume
minimal calories during a ride, could detect the depletion of one's
glycogen stores on a scale?
Is there more to this calculation than sugar = 4kcal/g? So say your
powertap says you used 2000kcal, that's 500g of glycogen?

Couldn't be ALL glycogen, because the body also burns some bodyfat. If you
take an a.m. weight every morning, and a post exercise weight and graph
them, you should be able to get a pretty good idea of how much glycogen you
have when you are fully loaded and somewhat less than that. I seem to float
anywhere up to about 3 pounds of glycogen. If I lose more than that on a
ride, then I am probably dehydrated.

Cat who is not a scientist, sorry ;<

yeahyeah said:

I was just wondering, if one were to stay fully hydrated but consume
minimal calories during a ride, could detect the depletion of one's
glycogen stores on a scale?
Is there more to this calculation than sugar = 4kcal/g? So say your
powertap says you used 2000kcal, that's 500g of glycogen?

You're also burning fat. 3500 Kcal (=dietary calories) per pound of
fat, or 7.7 Kcal/gram. The body's efficiency is about 20-25%, so if
you ride at 200 watts for an hour, you put 200*60*60 = 720,000 joules
into the pedals, or 720 KJ. That means you burned about
2900-3600 KJ of energy in total. 1 Kcal is 4.2 KJ so you burned
about 690-860 Kcal. I think this is all the powertap can do - it
converts average power and time into calories using some
assumed number for your efficiency.

However, I don't think you can detect this on a scale. People don't
have smokestacks to dispose of non-gaseous combustion products,
even if we fart a lot. When you "burn" fat or glycogen, you're
producing a bunch of waste products and some CO2 and H2O
(see the Krebs cycle for more details). Some of the gases
presumably can get carried off by respiration, but I don't see
how you could ever separate the balance of these glycolysis
products from the intake/outgo of water during a ride. I'm sure
when I lose weight during a long ride, it's water.

Quoted message said:

I'm sure
when I lose weight during a long ride, it's water.

Ride with Kunich and you could lose maybe 180 lbs of [censored].

bjw said:

The body's efficiency is about 20-25%

<Troll>
Unless you're LA in which case you can train your efficiency to improve
dramatically beyond this level.
</Troll>

Quoted message said:

you ride at 200 watts for an hour, you put 200*60*60 = 720,000 joules
into the pedals, or 720 KJ. That means you burned about
2900-3600 KJ of energy in total. 1 Kcal is 4.2 KJ so you burned
about 690-860 Kcal.

Not being a physicist or physiologist, I get fascinated easily by
(presumably) mundane aspects of this. For example, the remarkable difference
in power that goes into heat versus that which goes into mechanical work.
And not just wrt the human body, e.g., it still blows my mind that the
kinetic energy a rider has going downhill at 50 mph can be bled off so
quickly by braking, thus heating up the rim and brake pads, etc. I also
thought about this issue last weekend after freezing (almost literally) in
the rain and hail at the Central Valley Classic in Fresno. Does a rider's
energy expenditure increase when riding in extremely cold situations?
Especially if not riding hard?

Quoted message said:

However, I don't think you can detect this on a scale. People don't
have smokestacks to dispose of non-gaseous combustion products,
even if we fart a lot. When you "burn" fat or glycogen, you're
producing a bunch of waste products and some CO2 and H2O
(see the Krebs cycle for more details). Some of the gases
presumably can get carried off by respiration, but I don't see
how you could ever separate the balance of these glycolysis
products from the intake/outgo of water during a ride.

Be a man and take a muscle biopsy after every ride!

BTW, I recommend any non-experts interested in this kind of physiology buy
the book "Exercise Physiology" by McArdle, Katch, and Katch. It is very
understandable by non-scientists and has lots of nice graphs and pictures.
At least it might make you *think* you understand this stuff!

Mark

Shouldn't you be over posting in "Why do I climb faster in the drops?"

Quoted message said:

I think this is all the powertap can do - it
converts average power and time into calories using some
assumed number for your efficiency.

PowerTap only displays energy (KJ) expended based on measured power and
elapsed time, it doesn't do conversion to calories. As I recall, some
of the Polar HRMs display an estimate of kcals expended. I don't know
if they take advantage of the power module when it's installed.

JLS

Tom Kunich said:

Shouldn't you be over posting in "Why do I climb faster in the drops?"

Why would I spend my precious internet cafe time answering legitimate
questions instead of taking potshots at you?

Once, on a ride where I ate a mid-ride lunchtime burrito, I had to climb a
hill to get to the nearest bathroom. You didn't see me asking why I
climbed faster with the drops.

Yes, but those kj's convert nearly 1 to 1, so they're fine to use.

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

Quoted message said:

Tom Kunich said:

Shouldn't you be over posting in "Why do I climb faster in the drops?"

Why would I spend my precious internet cafe time answering legitimate
questions instead of taking potshots at you?

Once, on a ride where I ate a mid-ride lunchtime burrito, I had to climb a
hill to get to the nearest bathroom. You didn't see me asking why I
climbed faster with the drops.

So what you're saying is that it irritates you that the French are turning
more Conservative?

bjw said:

Quoted message said:

The body's efficiency is about 20-25%

Mark Fennell said:

<Troll>
Unless you're LA in which case you can train your efficiency to improve
dramatically beyond this level.
</Troll>

Your troll sucks. You forgot the keywords higher cadence.

Donald Munro said:

bjw said:

Quoted message said:

The body's efficiency is about 20-25%

Mark Fennell said:

<Troll>
Unless you're LA in which case you can train your efficiency to improve
dramatically beyond this level.
</Troll>

Your troll sucks. You forgot the keywords higher cadence.

Not to mention the fact that Armstrong's gross efficiency, at least as
reported by Coyle, never exceeded 24%.

Andy Coggan

Quoted message said:

Not to mention the fact that Armstrong's gross efficiency, at least as
reported by Coyle, never exceeded 24%.

That phrase, "not to mention"? I do not think it means what you think it
means.

Mark Fennell said:

Not being a physicist or physiologist, I get fascinated easily by
(presumably) mundane aspects of this. For example, the remarkable difference
in power that goes into heat versus that which goes into mechanical work.
And not just wrt the human body, e.g., it still blows my mind that the
kinetic energy a rider has going downhill at 50 mph can be bled off so
quickly by braking, thus heating up the rim and brake pads, etc. I also
thought about this issue last weekend after freezing (almost literally) in
the rain and hail at the Central Valley Classic in Fresno. Does a rider's
energy expenditure increase when riding in extremely cold situations?
Especially if not riding hard?

Well, I am a physicist, but not a physiologist, so I had to
learn about this stuff too. I knew the various power formulas
but had never thought much about their application to cycling.
I think the first thing that really impressed me was something
in "Bicycling Science" where they calculated the cooling power
of airflow from riding at a typical cruising speed, and I was
surprised by how high it was. Later when I got a trainer I
discovered how true that is, of course.

I also find the amount of power that gets dissipated as heat
impressive. It makes sense since we all know that you don't
need lots of warm clothing when riding hard, but it's still
useful to quantify - riding at 200 W is like having 600 W of
heater inside your vest (minus your base metabolic rate).
Something Amit noted in rbr once is that you usually see
the pros wearing less clothing during their race than the
Cat 4s, which makes sense since the pros are putting out
more power and burning more fuel at the same metaboolic
efficiency (so why doesn't the oh-so-efficient LANCE have
to wear a jacket all the time?)

I think extremely cold situations make it hard to ride at
full power, but no idea why. The Eastern Front demoralizing
effect of knowing a chilly death is imminent? But just on a
comfort level, wet and cool is worse than dry and cold.

Quoted message said:

Quoted message said:

I don't see
how you could ever separate the balance of these glycolysis
products from the intake/outgo of water during a ride.

Be a man and take a muscle biopsy after every ride!

Yeah, if you want to measure glycogen depletion, but if
you really want to measure the weight balance of all these
waste products, you probably have to weigh your [censored] too.
I don't think even LANCE weighed his [censored].

In article
<[email hidden]>,

Quoted post said:

Yeah, if you want to measure glycogen depletion, but if
you really want to measure the weight balance of all these
waste products, you probably have to weigh your [censored] too.
I don't think even LANCE weighed his [censored].

He can weigh himself.
Hey! You started it.

--
Michael Press

email hidden said:

I think extremely cold situations make it hard to ride at
full power, but no idea why.

I heard recently somewhere that it was non-essential use of shoe
booties. Anything more than baggies across the toes is to be avoided.

Curtis L. Russell
Odenton, MD (USA)

[email hidden] says...

Quoted message said:

Also could you really just burn glycogen and no fat?

When you say "no fat", I assume you mean "0", not just some small number.
Basically, when exercising, you're gonna burn some fat. How much varies from
individual to individual, heart rate, yada yada. But reducing fat burning to
zero isn't gonna happen. Of course, I knew a guy that went overboard with his
training and diet scheme and by the time he collapsed, his body fat was under a
percent. You can't burn what you ain't got, so he'd probably burn less fat than
someone like me that has a decent stockpile.

[email hidden] says...

Quoted message said:

I'm sure when I lose weight during a long ride, it's water.

Agreed, water has to be the majority of the typical weight loss, but it has to
be possible to lose measurable fat on a long ride, like say a 4 hour ride or an
8 hour ride. It is even possible to lose measurable muscle mass on a long hard
ride.

[email hidden] says...

Quoted message said:

(so why doesn't the oh-so-efficient LANCE have
to wear a jacket all the time?)

For a few years (long ago) I got kind of over-psyched about riding faster and my
body fat got down to the 3-4% range (granted no big deal for some people but a
major event for me). I remember having to wear a jacket in fairly warm summer
weather.

Quoted message said:

I don't think even LANCE weighed his [censored].

He probably woulda, but Lafferty kept snatching it.