One of the big physiology things that we saw physiological change we saw, we saw
change in, in, in maximum cardiac output.
That's the only way I can explain that that VO two max went up.
Right.
And so the question becomes, well, how do you, how is well-trained athletes?
How'd you get an increase in, in, uh, cardiac output.
Um, and, and just take one step back, you know, um, the reason why things
like blood doping, other things work is because we're improving the oxygen
delivery to the working muscle in.
Endurance performance.
That's really the only thing you can do, that's really gonna improve
true performance very quickly.
And that's why, like all these athletes have, have focused
on their red blood cells.
Um, another way of doing us increase your cardiac output and, uh, your
max heart rate, your peak heart rate.
That's not going to change.
You really don't change that much at all.
The only way you can change the stroke volume.
So the question becomes, how do you change stroke volume?
We know that with, um, when someone exercises, an untrained person starts
training, one of the real big things happens or they're changing the
blood flow back up to their heart.
That creates a little more, uh, that over time creates a
little bigger left ventricular.
Chamber.
Um, this is, uh, the volume overloading basically, but it takes time and
you get a little bigger chamber that gives you for every beat.
You get a little bigger stroke volume.
And so what we think is because we have these people that remain really
well hydrated, um, during their, um, heat acclimation protocols, um, they
were doing a lot of this heat training.
Uh, we had saw a priest consider very, very good, but not overwhelming
increases in plasma volume that they were training now with higher blood volume.
And we think that caused some little, little bit increase in
the stroke volume and that result in increasing cardiac output.
So all the groups that have kind of no, on, on the cardiac output,
as well as weekend, the, I won't go into the technical details of how
we do it, but it's a noninvasive way, the gold standard non-invasive
way to look at cardiac output.
Um, there's other ways that are easier to go, but they're, they're not as good
documents.
Can I ask a quick question?
W when you talk about improved cardiac function, I've seen studies where
they attribute that to not a change in the volume of the left ventricle,
but a change in the muscle thickness.
So that greater pumping capacity is that.
Does one typically take place over the other or do they happen concurrently?
How does that work?
It kind of happened concurrently.
Yes.
And there's been some great work by, um, a woman who doesn't
do performance physiology.
Miguel Horowitz has looked at some of the ISO form changes in the muscle that
happens with heat acclimation, and that may have some better contractility.
Um, what happens is, um, it's kind of a law of applause.
And so if you have, um, the wall tension.
Is a function of the diameter of your chamber.
And so if you start increasing the volume of that chamber, then the
wall, in order to maintain wall tension appropriately, you have to
have a thickening of the ventricle.
So we know that as, as, as people endurance training, it's,
it's debatable whether strength training does this or not.
But with endurance athletes, I'm almost always going to see a
thickening of the left ventricle.
So, what that does is, is maintain the wall tension.
So the left ventricle is getting overstressed during contraction because
they'll have a full contraction.
Um, but it's also, um, uh, uh, allow you to have to maintain, uh, the full
end-diastolic volume is what you have at the end of filling of the heart.
And systolic volume is the end of contraction.
So if you have.
The ability to have a full contraction, but you've increased the MBSR volume.
Now you've got a bigger stroke volume difference between the two.
Okay.
Explanation
is really good and clarified a lot of things for me.
Thank you.
Good.
Sure.
Yeah.
So basically you're what's happening.
What you think is at the heart is beating more blood for every beat,
and that is an increasing the aerobic or the oxygen in your system that
you can then use to go faster.
Yes.
In, in those athletes and under those conditions?
Yes.
Okay.
So since we're on the topic of physiology, maybe you can clarify one more thing.
So I understand that with heat acclimation, one of the big changes
that enhances performance is that we get this increase in plasma volume,
but as plasma volume increases.
And that means we have more blood volume and therefore the potential
to have greater cardiac output, then we still have the same number
of red blood cells in the same.
Amount, maybe not the same concentration, but the same amount
of hemoglobin and therefore the same oxygen carrying capacity.
So I don't understand how more watery blood would translate to greater
oxygen delivery to the muscle.
If it seems like that this, the amount of oxygen should be the same as that,
or might warm up, what am I missing
there?
No.
So you're, you're spot on Chad.
And that was the original concern we had working with data and bits in time.
When you look at it and you say, okay, we might create an increase
in plasma volume and therefore how the reduction in the hematocrit.
And then that's really the percentage of red blood cells
you have in your sample of blood.
But that's also number of red blood percent of red blood
cells for any cardiac output.
So take it a high level athlete, really high level athlete.
They might have a cardiac output of a very high valleys be 40, right.
40 liters per minute.
Um, and so that means that in one minute at max cardiac output, they're
going to have 40 liters of blood circulating and I should use better.
40% of that would be red blood cells, approximately.
Right.
Um, so if you he'd acclimate.
That number might come down a little bit.
It's your PR your question is spot on.
Would you have, you know, you're delivering less blood red blood
cells or that given cardiac output.
So, but what we saw was an increase in cardiac output.
So now, if you say we got a slightly, uh, more dilute blood, if
you will, but you have an increase of 43 or 44 liters per minute.
Now you're delivering more red blood cells per minute basis.
Got it.
And that's what it was going to be.
So essentially every beat, you're getting little more, more red blood
cells, but we have measured per minute basis and you're getting a few
extra liters of circulating blood.
So, so that's, uh, it's a difficult concept to, for trying to wrap your
mind around and we've spent a lot of time trying to figure that out,
but that's, that's what we observed.
And a few others have seen that as well.
Okay.
Thank you for that.
That's awesome.
I've always wondered that too.
Uh, cyclists and runners, we care a ton about weight, right.
And we've talked about increasing plasma volume and it was interesting
about how much weight did these people gain, um, in the intervention group.
Wow.
So, um, I don't actually remember the exact,
I know it's 200 milliliters, so a little less than half a
pound.
Yeah.
So, so I can remember exactly what I was going to go back and say,
well, how much was it plausible?
I'm expansion was that weight change?
Um, and so, yeah, we care a ton about weight.
Um, but at the end of the day, that.
Is not really going to be a huge performance benefit.
I mean, you take any high-level cyclists and you say, if I take a half pound
away from you, would you prefer that?
If I say I'd like to take, make your bike half pound lighter, would you like that?
And performance increase, then there's there then absolutely.
There's gonna be this incremental improvement performance.
And you know, and I've heard you talk about how you were.
If you had done something different, you had to get win by two seconds more.
You would have taken it in.
You would taken first for second or something like that.
Yeah, there's a lot that goes into actual performance on the line, of course.
Right.
Um, but when someone's doing, uh, an hour time trial, um, especially on a flat
course, the weight's not going to make a difference, even on hilly courses, a half
pound versus having higher cardiac output.
I'll take the higher cardiac output any day.
Yeah.
These well, your results.
Show it too.
With the lactic threshold improvements, the walk kg.
Totally worth the extra water weight in every single situation.
Even on this, like a 10% climb, if you're ever seen this would
still be better for you than worrying about the plasma increase.
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