A
Andy Coggan
Guest
"Frank Day" <[email protected]> wrote in message
news:[email protected]...
> "Andy Coggan" <[email protected]> wrote in message
news:<[email protected]>...
> > "Frank Day" <[email protected]> wrote in message
> > news:[email protected]...
> > > "Andy Coggan" <[email protected]> wrote in message
> > news:<[email protected]>...
> > > > "Frank Day" <[email protected]> wrote in message
> > > > news:[email protected]...
> > > >
> > > > > the abilty to exercise is not limited by the heart or lungs but, rather, by the ability of
> > > > > the muscles
being
> > > > > exercised to extract oxygen from the blood. It is the muscles in
the
> > > > > legs and arms that go anaerobic (ischemia) and not the heart,
> > > >
> > > > And the reason, ultimately*, that the muscles fail is because the
heart
> > > > can't provide them with enough O2-carrying blood. This is proven by
the
> > fact
> > > > that per mass of active tissue, both blood flow and O2 uptake are
much
> > > > higher during small muscle mass (e.g., one leg kicking) vs. large
muscle
> > > > mass exercise.
> > >
> > > It is true that the heart can't provide the tissues with enough O2 carrying blood, but this
> > > isn't because the heart can't deliver more blood, but because there isn't enough capillary
> > > density to deliver the blood flow required by the tissue.
> >
> > ******** - as I told you, per unit of active tissue muscle blood flow is
as
> > much as three-fold higher during small muscle mass exercise (e.g., 1 leg kicking) vs. large
> > muscle mass exercise (e.g., cycling). This clearly demonstrates that there must be active
> > vasocontriction even in
exercising
> > muscle, a point proven by studies using vasodilating drugs. The reason
for
> > this vasoconstriction is apparently to maintain blood pressure: since cardiac output cannot
> > increase beyond that observed at/near VO2max, the
body
> > can't "allow" a large amount of muscle to fully vasodilate because then perfusion pressure
> > would fall.
>
> I would love to see that study that showed that a leg was able to do three times more work being
> used alone than when being used in concert with the other. That would mean we should all be
> pedaling with just one leg because 3 times 1 is more than 1 times 2. Or, was it just shown that
> blood flow was increase but oxygen utilization wasn't. Or what. Blood flow is not power. Your
> study proves nothing as regards this argument.
I said flow, not power, and the data directly refute your claim that VO2max is limited by the
capacity of muscle to accept blood flow.
> > As Loring Rowell put it: the heart's job during exercise is to maintain
the
> > highest possible blood pressure against the smallest possible peripheral resistance.
> >
> > >The heart can only deliver as much as the capillaries in the tissue will allow. If you train
> > >harder you can develop more capillaries and more blood flow can ensue and performance will
> > >increase. The heart adapts to this increased load. This is called training effect.
> >
> > While capillarization does increase with training, this is but one
factor
> > contributing to the improvements in VO2max/performance. More
importantly,
> > changes in capillarization are not required to achieve increases in
VO2max.
> > This is shown, e.g., by the fact that acutely increasing convective O2 deliverly via EPO
> > administration, transfusion, hyperoxia, or even
expansion
> > of plasma volume (in an untrained person) increases VO2max w/o,
obviously,
> > any change in capillary density.
>
> All you say doesn't change the fact that the ability to utilize oxygen is limited by the local
> tissue conditions, which includes hemoglobin concentration, oxygen saturation, capillary density,
> mitochondrial density, contractile element density, etc. etc. The healthy heart does not change,
> affect or limit any of these things because it changes in concert with the same stimulation
> (training). It always has a little in reserve.
Stating it over and over and over again doesn't make it so, Frank. Go read the scientific literature
on the subject and you'll see that I'm right and you're wrong.
Andy Coggan
news:[email protected]...
> "Andy Coggan" <[email protected]> wrote in message
news:<[email protected]>...
> > "Frank Day" <[email protected]> wrote in message
> > news:[email protected]...
> > > "Andy Coggan" <[email protected]> wrote in message
> > news:<[email protected]>...
> > > > "Frank Day" <[email protected]> wrote in message
> > > > news:[email protected]...
> > > >
> > > > > the abilty to exercise is not limited by the heart or lungs but, rather, by the ability of
> > > > > the muscles
being
> > > > > exercised to extract oxygen from the blood. It is the muscles in
the
> > > > > legs and arms that go anaerobic (ischemia) and not the heart,
> > > >
> > > > And the reason, ultimately*, that the muscles fail is because the
heart
> > > > can't provide them with enough O2-carrying blood. This is proven by
the
> > fact
> > > > that per mass of active tissue, both blood flow and O2 uptake are
much
> > > > higher during small muscle mass (e.g., one leg kicking) vs. large
muscle
> > > > mass exercise.
> > >
> > > It is true that the heart can't provide the tissues with enough O2 carrying blood, but this
> > > isn't because the heart can't deliver more blood, but because there isn't enough capillary
> > > density to deliver the blood flow required by the tissue.
> >
> > ******** - as I told you, per unit of active tissue muscle blood flow is
as
> > much as three-fold higher during small muscle mass exercise (e.g., 1 leg kicking) vs. large
> > muscle mass exercise (e.g., cycling). This clearly demonstrates that there must be active
> > vasocontriction even in
exercising
> > muscle, a point proven by studies using vasodilating drugs. The reason
for
> > this vasoconstriction is apparently to maintain blood pressure: since cardiac output cannot
> > increase beyond that observed at/near VO2max, the
body
> > can't "allow" a large amount of muscle to fully vasodilate because then perfusion pressure
> > would fall.
>
> I would love to see that study that showed that a leg was able to do three times more work being
> used alone than when being used in concert with the other. That would mean we should all be
> pedaling with just one leg because 3 times 1 is more than 1 times 2. Or, was it just shown that
> blood flow was increase but oxygen utilization wasn't. Or what. Blood flow is not power. Your
> study proves nothing as regards this argument.
I said flow, not power, and the data directly refute your claim that VO2max is limited by the
capacity of muscle to accept blood flow.
> > As Loring Rowell put it: the heart's job during exercise is to maintain
the
> > highest possible blood pressure against the smallest possible peripheral resistance.
> >
> > >The heart can only deliver as much as the capillaries in the tissue will allow. If you train
> > >harder you can develop more capillaries and more blood flow can ensue and performance will
> > >increase. The heart adapts to this increased load. This is called training effect.
> >
> > While capillarization does increase with training, this is but one
factor
> > contributing to the improvements in VO2max/performance. More
importantly,
> > changes in capillarization are not required to achieve increases in
VO2max.
> > This is shown, e.g., by the fact that acutely increasing convective O2 deliverly via EPO
> > administration, transfusion, hyperoxia, or even
expansion
> > of plasma volume (in an untrained person) increases VO2max w/o,
obviously,
> > any change in capillary density.
>
> All you say doesn't change the fact that the ability to utilize oxygen is limited by the local
> tissue conditions, which includes hemoglobin concentration, oxygen saturation, capillary density,
> mitochondrial density, contractile element density, etc. etc. The healthy heart does not change,
> affect or limit any of these things because it changes in concert with the same stimulation
> (training). It always has a little in reserve.
Stating it over and over and over again doesn't make it so, Frank. Go read the scientific literature
on the subject and you'll see that I'm right and you're wrong.
Andy Coggan