Why does my small ring feel so big in the cold?

David Kerber writes:

In article oxvnd.119085$R05.43462@attbi_s53,
says...
........ shrinkage? ô¿Ô¬

But really, here's a thought. Would the air density difference (say
from 80º to 20º) substantially alter the amount of oxygen you get
in each breath? If so, colder temps would make oxygen intake more
efficient. Or put another way; in high temperature air you would
receive less oxygen per breath.

Oxygen intake isn't the limiting factor, anyway; oxygen *transport*
(by your red blood cells) is much more limiting. If you measure the
amount of oxygen in the air you exhale, your body is only pulling a
few percent of its oxygen content, no matter how hard you are
working.

Using Miguel Indurain as an example, he was 80 kg and had an
astonishing VO2 max of 88ml/kg/min (published in VeloNews during
Indurain's run at the top; an exercise physiologist I know had a
colleague that tested Greg Lemond at Ball State University, who hit 90
ml/kg/min). If I've done my math right, Indurain's VO2 would be 7.04
l/min of O2 uptake. He had a functional lung capacity of about 8
liters- so at maximum exertion he'd breathe maybe 320 liters of air a
minute (assuming about 40 breaths a minute).

So, at 320 liters per minute there would be 67.2 liters of O2
available. If he was absorbing 7.04 liters of the 67.2, then he was
extracting only 10.4% This seems low to me, so further research brings
us to:

http://home.hia.no/~stephens/ventphys.htm

which suggests that 320 liters per minute is a major overestimate of
Indurain's maximal ventilatory volume and that 200 liters might be
more reasonable. That's still a lot of air. Assuming 200 liters,
Indurain would then be absorbing about 17% of the available oxygen.
It also indicates that Indurain's VO2 max was significantly higher
than the elite rowers the author mentions on the Web site- 7.04
liters per minute compared to the rowers' 5.09 while cycling. Wow.

Also of interest:

http://home.hia.no/~stephens/cycling.htm

In article ,
says...

....

Oxygen intake isn't the limiting factor, anyway; oxygen *transport*
(by your red blood cells) is much more limiting. If you measure the
amount of oxygen in the air you exhale, your body is only pulling a
few percent of its oxygen content, no matter how hard you are
working.

Using Miguel Indurain as an example, he was 80 kg and had an
astonishing VO2 max of 88ml/kg/min (published in VeloNews during
Indurain's run at the top; an exercise physiologist I know had a
colleague that tested Greg Lemond at Ball State University, who hit 90
ml/kg/min). If I've done my math right, Indurain's VO2 would be 7.04
l/min of O2 uptake. He had a functional lung capacity of about 8
liters- so at maximum exertion he'd breathe maybe 320 liters of air a
minute (assuming about 40 breaths a minute).

So, at 320 liters per minute there would be 67.2 liters of O2
available. If he was absorbing 7.04 liters of the 67.2, then he was
extracting only 10.4% This seems low to me, so further research brings
us to:

http://home.hia.no/~stephens/ventphys.htm

which suggests that 320 liters per minute is a major overestimate of
Indurain's maximal ventilatory volume and that 200 liters might be
more reasonable. That's still a lot of air. Assuming 200 liters,
Indurain would then be absorbing about 17% of the available oxygen.

If someone like Indurain is only using 17% of the available O2, then us
normal humans are probably going to be well below 10%.

It also indicates that Indurain's VO2 max was significantly higher
than the elite rowers the author mentions on the Web site- 7.04
liters per minute compared to the rowers' 5.09 while cycling. Wow.

Compared to road cycling, rowing has a large anaerobic component, since
the races only last a few minutes, so I wouldn't expect a particularly
high VO2max. Marathoners would be a better comparison.

--
Remove the ns_ from if replying by e-mail (but keep posts in the
newsgroups if possible).

In article ,
says...

....

Oxygen intake isn't the limiting factor, anyway; oxygen *transport*
(by your red blood cells) is much more limiting. If you measure the
amount of oxygen in the air you exhale, your body is only pulling a
few percent of its oxygen content, no matter how hard you are
working.

Using Miguel Indurain as an example, he was 80 kg and had an
astonishing VO2 max of 88ml/kg/min (published in VeloNews during
Indurain's run at the top; an exercise physiologist I know had a
colleague that tested Greg Lemond at Ball State University, who hit 90
ml/kg/min). If I've done my math right, Indurain's VO2 would be 7.04
l/min of O2 uptake. He had a functional lung capacity of about 8
liters- so at maximum exertion he'd breathe maybe 320 liters of air a
minute (assuming about 40 breaths a minute).

So, at 320 liters per minute there would be 67.2 liters of O2
available. If he was absorbing 7.04 liters of the 67.2, then he was
extracting only 10.4% This seems low to me, so further research brings
us to:

http://home.hia.no/~stephens/ventphys.htm

which suggests that 320 liters per minute is a major overestimate of
Indurain's maximal ventilatory volume and that 200 liters might be
more reasonable. That's still a lot of air. Assuming 200 liters,
Indurain would then be absorbing about 17% of the available oxygen.

If someone like Indurain is only using 17% of the available O2, then us
normal humans are probably going to be well below 10%.

It also indicates that Indurain's VO2 max was significantly higher
than the elite rowers the author mentions on the Web site- 7.04
liters per minute compared to the rowers' 5.09 while cycling. Wow.

Compared to road cycling, rowing has a large anaerobic component, since
the races only last a few minutes, so I wouldn't expect a particularly
high VO2max. Marathoners would be a better comparison.

--
Remove the ns_ from if replying by e-mail (but keep posts in the
newsgroups if possible).

David Kerber writes:

In article ,
says...

...

Oxygen intake isn't the limiting factor, anyway; oxygen
*transport* (by your red blood cells) is much more limiting. If
you measure the amount of oxygen in the air you exhale, your body
is only pulling a few percent of its oxygen content, no matter
how hard you are working.

Using Miguel Indurain as an example, he was 80 kg and had an
astonishing VO2 max of 88ml/kg/min (published in VeloNews during
Indurain's run at the top; an exercise physiologist I know had a
colleague that tested Greg Lemond at Ball State University, who hit
90 ml/kg/min). If I've done my math right, Indurain's VO2 would be
7.04 l/min of O2 uptake. He had a functional lung capacity of
about 8 liters- so at maximum exertion he'd breathe maybe 320
liters of air a minute (assuming about 40 breaths a minute).

So, at 320 liters per minute there would be 67.2 liters of O2
available. If he was absorbing 7.04 liters of the 67.2, then he
was extracting only 10.4% This seems low to me, so further research
brings us to:

http://home.hia.no/~stephens/ventphys.htm

which suggests that 320 liters per minute is a major overestimate
of Indurain's maximal ventilatory volume and that 200 liters might
be more reasonable. That's still a lot of air. Assuming 200
liters, Indurain would then be absorbing about 17% of the available
oxygen.

If someone like Indurain is only using 17% of the available O2, then
us normal humans are probably going to be well below 10%.

I'm not sure that's necessarily the case, but I had't found any hard
numbers. I'm quite sure it's been measured. One Web site of "science
for the layman" type stated that room air contains about 21% oxygen
and exhaled air contains about 15%. If that's correct, we absorb
about 25% of the oxygen in each breath. A little further hunting
today came up with a figure of exhaled air containing about 15.5% O2-
which does again suggest that we absorb about 25% of the available O2
at rest.

I could see how O2 absorption per breath could actually be reduced
under exertion, when breathing becomes more rapid. The time involved
for red blood cells to dump off CO2 and uptake O2 wouldn't change, but
air exchange is much more rapid. We might exchange efficiency for
higher volume at maximal exertion.

It also indicates that Indurain's VO2 max was significantly higher
than the elite rowers the author mentions on the Web site- 7.04
liters per minute compared to the rowers' 5.09 while cycling. Wow.

Compared to road cycling, rowing has a large anaerobic component,
since the races only last a few minutes, so I wouldn't expect a
particularly high VO2max. Marathoners would be a better comparison.

David Kerber writes:

In article ,
says...

...

Oxygen intake isn't the limiting factor, anyway; oxygen
*transport* (by your red blood cells) is much more limiting. If
you measure the amount of oxygen in the air you exhale, your body
is only pulling a few percent of its oxygen content, no matter
how hard you are working.

Using Miguel Indurain as an example, he was 80 kg and had an
astonishing VO2 max of 88ml/kg/min (published in VeloNews during
Indurain's run at the top; an exercise physiologist I know had a
colleague that tested Greg Lemond at Ball State University, who hit
90 ml/kg/min). If I've done my math right, Indurain's VO2 would be
7.04 l/min of O2 uptake. He had a functional lung capacity of
about 8 liters- so at maximum exertion he'd breathe maybe 320
liters of air a minute (assuming about 40 breaths a minute).

So, at 320 liters per minute there would be 67.2 liters of O2
available. If he was absorbing 7.04 liters of the 67.2, then he
was extracting only 10.4% This seems low to me, so further research
brings us to:

http://home.hia.no/~stephens/ventphys.htm

which suggests that 320 liters per minute is a major overestimate
of Indurain's maximal ventilatory volume and that 200 liters might
be more reasonable. That's still a lot of air. Assuming 200
liters, Indurain would then be absorbing about 17% of the available
oxygen.

If someone like Indurain is only using 17% of the available O2, then
us normal humans are probably going to be well below 10%.

I'm not sure that's necessarily the case, but I had't found any hard
numbers. I'm quite sure it's been measured. One Web site of "science
for the layman" type stated that room air contains about 21% oxygen
and exhaled air contains about 15%. If that's correct, we absorb
about 25% of the oxygen in each breath. A little further hunting
today came up with a figure of exhaled air containing about 15.5% O2-
which does again suggest that we absorb about 25% of the available O2
at rest.

I could see how O2 absorption per breath could actually be reduced
under exertion, when breathing becomes more rapid. The time involved
for red blood cells to dump off CO2 and uptake O2 wouldn't change, but
air exchange is much more rapid. We might exchange efficiency for
higher volume at maximal exertion.

It also indicates that Indurain's VO2 max was significantly higher
than the elite rowers the author mentions on the Web site- 7.04
liters per minute compared to the rowers' 5.09 while cycling. Wow.

Compared to road cycling, rowing has a large anaerobic component,
since the races only last a few minutes, so I wouldn't expect a
particularly high VO2max. Marathoners would be a better comparison.

In article ,
says...

....

which suggests that 320 liters per minute is a major overestimate
of Indurain's maximal ventilatory volume and that 200 liters might
be more reasonable. That's still a lot of air. Assuming 200
liters, Indurain would then be absorbing about 17% of the available
oxygen.

If someone like Indurain is only using 17% of the available O2, then
us normal humans are probably going to be well below 10%.

I'm not sure that's necessarily the case, but I had't found any hard
numbers. I'm quite sure it's been measured. One Web site of "science
for the layman" type stated that room air contains about 21% oxygen
and exhaled air contains about 15%. If that's correct, we absorb
about 25% of the oxygen in each breath. A little further hunting
today came up with a figure of exhaled air containing about 15.5% O2-
which does again suggest that we absorb about 25% of the available O2
at rest.

I could see how O2 absorption per breath could actually be reduced
under exertion, when breathing becomes more rapid. The time involved
for red blood cells to dump off CO2 and uptake O2 wouldn't change, but
air exchange is much more rapid. We might exchange efficiency for
higher volume at maximal exertion.

Good point, and one I hadn't thought of. At a given O2 consumption rate
(= exertion level), the higher air exchange rate would raise the average
O2 concentration of the air in the lungs, increasing the average rate of
diffusion through the membranes.

--
Remove the ns_ from if replying by e-mail (but keep posts in the
newsgroups if possible).

In article ,
says...

....

which suggests that 320 liters per minute is a major overestimate
of Indurain's maximal ventilatory volume and that 200 liters might
be more reasonable. That's still a lot of air. Assuming 200
liters, Indurain would then be absorbing about 17% of the available
oxygen.

If someone like Indurain is only using 17% of the available O2, then
us normal humans are probably going to be well below 10%.

I'm not sure that's necessarily the case, but I had't found any hard
numbers. I'm quite sure it's been measured. One Web site of "science
for the layman" type stated that room air contains about 21% oxygen
and exhaled air contains about 15%. If that's correct, we absorb
about 25% of the oxygen in each breath. A little further hunting
today came up with a figure of exhaled air containing about 15.5% O2-
which does again suggest that we absorb about 25% of the available O2
at rest.

I could see how O2 absorption per breath could actually be reduced
under exertion, when breathing becomes more rapid. The time involved
for red blood cells to dump off CO2 and uptake O2 wouldn't change, but
air exchange is much more rapid. We might exchange efficiency for
higher volume at maximal exertion.

Good point, and one I hadn't thought of. At a given O2 consumption rate
(= exertion level), the higher air exchange rate would raise the average
O2 concentration of the air in the lungs, increasing the average rate of
diffusion through the membranes.

--
Remove the ns_ from if replying by e-mail (but keep posts in the
newsgroups if possible).