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Caffeine May Impede Blood Flow During Exercise



 
 
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  #1  
Old January 20th 06, 12:37 AM posted to rec.running
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Default Caffeine May Impede Blood Flow During Exercise


POSTED: 2:32 pm CST January 17, 2006

If you're a caffeine addict, chances are your blood flow isn't what it
could be.

A new Swiss study suggests that the equivalent of two cups of coffee
reduces the body's ability to boost blood flow to the heart muscle
during exercise.

The small study, which included 18 young, healthy volunteers, is
published in Tuesday's issue of the Journal of the American College of
Cardiology.

Caffeine didn't affect blood flow within the heart muscle while the
participants were at rest. But blood flow measurements taken immediately
after exercise were significantly lower after the participants had taken
caffeine tablets.

Although caffeine is a stimulant, these results suggest that coffee may
not necessarily boost athletic performance.

"It may be a stimulant at the cerebral level in terms of being more
awake and alert, which may subjectively give the feeling of having
better physical performance," said Dr. Philipp Kaufmann, a researcher
from the University Hospital Zurich. "But I now would not recommend that
any athlete drink caffeine before sports. It may not be a physical
stimulant, and may even adversely affect physical performance."

Kaufmann also said the results raise concerns about possible effects of
caffeine in people with heart disease.


http://content.onlinejacc.org/cgi/co...tract/47/2/405
  #2  
Old January 20th 06, 01:11 AM posted to rec.running
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Default Caffeine May Impede Blood Flow During Exercise


Cover your eyes, doug...

Bumper wrote:

POSTED: 2:32 pm CST January 17, 2006

If you're a caffeine addict, chances are your blood flow isn't what it
could be.

A new Swiss study suggests that the equivalent of two cups of coffee
reduces the body's ability to boost blood flow to the heart muscle
during exercise.

The small study, which included 18 young, healthy volunteers, is
published in Tuesday's issue of the Journal of the American College of
Cardiology.

Caffeine didn't affect blood flow within the heart muscle while the
participants were at rest. But blood flow measurements taken immediately
after exercise were significantly lower after the participants had taken
caffeine tablets.

Although caffeine is a stimulant, these results suggest that coffee may
not necessarily boost athletic performance.

"It may be a stimulant at the cerebral level in terms of being more
awake and alert, which may subjectively give the feeling of having
better physical performance," said Dr. Philipp Kaufmann, a researcher
from the University Hospital Zurich. "But I now would not recommend that
any athlete drink caffeine before sports. It may not be a physical
stimulant, and may even adversely affect physical performance."

Kaufmann also said the results raise concerns about possible effects of
caffeine in people with heart disease.

http://content.onlinejacc.org/cgi/co...tract/47/2/405


As a vasoconstrictor I would think it interferes
with blood flow anyway to other body areas.

Caffeine amounts in coffee varies though. Now if
you're drinking Mountain Dew, 200 mg isn't hard to
ingest.
  #3  
Old January 20th 06, 01:56 AM posted to rec.running
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Default Caffeine May Impede Blood Flow During Exercise

On Thu, 19 Jan 2006 18:11:02 -0700, Tom Phillips
wrote:

Cover your eyes, doug...


I'd rather he pulled up his pants...
  #4  
Old January 20th 06, 05:58 PM posted to rec.running
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Default Caffeine May Impede Blood Flow During Exercise


"Tom Phillips" wrote in message
...

Cover your eyes, doug...


I've seen this study but I have seen other studies to show valued
benefits. Since I have been drinking Coke and Mountain Dew for 15 years
without any problems, other than the senility of age, I'll need more
than one study to prove to me the error of my ways.

-DougF


  #5  
Old January 20th 06, 07:22 PM posted to rec.running
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Default Caffeine May Impede Blood Flow During Exercise

You've probably seen more of the study than what I posted. Were the
participants athletes or just common clave who happened to be in fair
shape, and was there any long term indications, ie, been drinking coffee
and running for thirty years so the negative effect was lessened. This
certainly the first tempest in a coffee pot study about java that might
wind up being contridicted upon further analysis. Which now sets to to
wondering how fast caffeine burns out the system, etc. Certainly not
enough from one study make me change anything.

Doug Freese wrote:

"Tom Phillips" wrote in message
...

Cover your eyes, doug...


I've seen this study but I have seen other studies to show valued
benefits. Since I have been drinking Coke and Mountain Dew for 15 years
without any problems, other than the senility of age, I'll need more
than one study to prove to me the error of my ways.

-DougF

  #6  
Old January 20th 06, 09:48 PM posted to rec.running
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Default Caffeine May Impede Blood Flow During Exercise


Bumper wrote:
POSTED: 2:32 pm CST January 17, 2006

If you're a caffeine addict, chances are your blood flow isn't what it
could be.

A new Swiss study suggests that the equivalent of two cups of coffee
reduces the body's ability to boost blood flow to the heart muscle
during exercise.


So what if that'st true? Is that the limiting factor in performance?
Maybe only in events that depend on VO2Max. Not anything on the
anaerobic end of the scale, or the aerobic respiration end of the
scale.

The small study, which included 18 young, healthy volunteers, is
published in Tuesday's issue of the Journal of the American College of
Cardiology.

Caffeine didn't affect blood flow within the heart muscle while the
participants were at rest.


Which kind of casts doubt on all the rest of the results right away. If
caffeine had a clear effect on the cardiac blood flow, this would show
up by itself from mere ingestion of caffeine.

But blood flow measurements taken immediately
after exercise were significantly lower after the participants had taken
caffeine tablets.


That's /after/ exercise. As in, someone took home the chrome already,
so it's irrelevant.

Maybe there is less blood flow because less flow was /needed/ to that
tissue following exercise?

And that could indicate that the caffeine actually had some /benefit/.
Less blood flow could indicate superior recovery.

Although caffeine is a stimulant, these results suggest that coffee may
not necessarily boost athletic performance.


A fit individual will have less overall blood flow throughtout the body
after exercise than an unfit one, because his heart rate will recover
faster.

Does that suggest that being fit may not necessarily boost athletic
performance?

What about the lower heart rates of fit individuals? We could claim
that ``exercise has a detrimental effect on heart rate!''

A heart rate of zero is bad, right? Very, very bad. And a heart rate of
43 is closer to zero than a heart rate of 68, right?

So, exercise is bad.



Kaufmann also said the results raise concerns about possible effects of
caffeine in people with heart disease.


I.e. an irrelevant population for our purposes.

  #7  
Old January 21st 06, 12:32 AM posted to rec.running
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Default Caffeine May Impede Blood Flow During Exercise



Doug Freese wrote:

"Tom Phillips" wrote in message
...

Cover your eyes, doug...


I've seen this study but I have seen other studies to show valued
benefits. Since I have been drinking Coke and Mountain Dew for 15 years
without any problems, other than the senility of age, I'll need more
than one study to prove to me the error of my ways.



"In the end we're going to win [the public] over
because we're going to sell them cheap books and
legally addictive stimulants."

Tom Hanks in You've Got Mail (sorry. couldn't resist
as it was playing on TBS last night.)
  #8  
Old January 21st 06, 12:37 AM posted to rec.running
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Default Caffeine May Impede Blood Flow During Exercise



Kaz Kylheku wrote:

Bumper wrote:
POSTED: 2:32 pm CST January 17, 2006

If you're a caffeine addict, chances are your blood flow isn't what it
could be.

A new Swiss study suggests that the equivalent of two cups of coffee
reduces the body's ability to boost blood flow to the heart muscle
during exercise.


So what if that'st true? Is that the limiting factor in performance?


It the blood that carries oxygen to muscles.
Less oxygen, less performance. From the
abstract it appears though the results are
based on ingesting 200 mg in one dose, which
at minimum is 2.5 cups of coffee, mountain dews,
etc. at once.

As with most things the amount consumed is a
factor.

Maybe only in events that depend on VO2Max. Not anything on the
anaerobic end of the scale, or the aerobic respiration end of the
scale.

The small study, which included 18 young, healthy volunteers, is
published in Tuesday's issue of the Journal of the American College of
Cardiology.

Caffeine didn't affect blood flow within the heart muscle while the
participants were at rest.


Which kind of casts doubt on all the rest of the results right away. If
caffeine had a clear effect on the cardiac blood flow, this would show
up by itself from mere ingestion of caffeine.

But blood flow measurements taken immediately
after exercise were significantly lower after the participants had taken
caffeine tablets.


That's /after/ exercise. As in, someone took home the chrome already,
so it's irrelevant.

Maybe there is less blood flow because less flow was /needed/ to that
tissue following exercise?

And that could indicate that the caffeine actually had some /benefit/.
Less blood flow could indicate superior recovery.

Although caffeine is a stimulant, these results suggest that coffee may
not necessarily boost athletic performance.


A fit individual will have less overall blood flow throughtout the body
after exercise than an unfit one, because his heart rate will recover
faster.

Does that suggest that being fit may not necessarily boost athletic
performance?

What about the lower heart rates of fit individuals? We could claim
that ``exercise has a detrimental effect on heart rate!''

A heart rate of zero is bad, right? Very, very bad. And a heart rate of
43 is closer to zero than a heart rate of 68, right?

So, exercise is bad.



Kaufmann also said the results raise concerns about possible effects of
caffeine in people with heart disease.


I.e. an irrelevant population for our purposes.

  #9  
Old January 21st 06, 01:00 AM posted to rec.running
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Posts: n/a
Default Caffeine May Impede Blood Flow During Exercise

IIRC, the study included 18 participants. I suppose it's an
interesting take but I'm sure we'll see the next study shortly that
says caffeine cures cancer and will stop speeding bullets...in other
words, it's hard to give this one much weight.

Mike C


Doug Freese wrote:
"Tom Phillips" wrote in message
...

Cover your eyes, doug...


I've seen this study but I have seen other studies to show valued
benefits. Since I have been drinking Coke and Mountain Dew for 15 years
without any problems, other than the senility of age, I'll need more
than one study to prove to me the error of my ways.

-DougF


  #10  
Old January 21st 06, 04:11 AM posted to rec.running
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Posts: n/a
Default Caffeine May Impede Blood Flow During Exercise


Tom Phillips wrote:
Kaz Kylheku wrote:

Bumper wrote:
POSTED: 2:32 pm CST January 17, 2006

If you're a caffeine addict, chances are your blood flow isn't what it
could be.

A new Swiss study suggests that the equivalent of two cups of coffee
reduces the body's ability to boost blood flow to the heart muscle
during exercise.


So what if that'st true? Is that the limiting factor in performance?


It the blood that carries oxygen to muscles.


The only flow they measured was the blood flow to cardiac muscle (the
heart), after excercise.
It is still unknown what the blood flow was during excercise.

Less oxygen, less performance. From the
abstract it appears though the results are
based on ingesting 200 mg in one dose, which
at minimum is 2.5 cups of coffee, mountain dews,
etc. at once.

As with most things the amount consumed is a
factor.


And measuring the right thing is a factor too. This study just isn't
good enough to worry over.


go out and enjoy the run
Ed

 




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