-: Now we're gonna talk about actually metabolizing,
breaking down ATP and how those buffer systems work.
So if we look at ATP metabolism, we're gonna have our
first buffer which is essentially going to be the
creatine system.
Remember I said our ATP storage that we have
so whatever we currently have, that's like our checking
account and this creatine is gonna basically serve almost
like a credit card function.
So if I have ATP that gets broken down, ends up ADP
so I've used it, used one of those phosphates.
What creatine is going to do is,
it is actually gonna donate a phosphate.
So if we look at creatine, yet creatine plus one phosphate
is what it's normal structure looks like and ATP is gonna
have, ATP is three phosphates,
when it gets broken down we'll have just the two phosphates.
So I just wrote the math in terms of the phosphates down
here below.
So we've got ATP plus creatine which is two phosphates plus
one phosphate.
They're gonna use an enzyme called Creatine Kinase
and what's gonna happen is this guy is gonna donate its
phosphates so you end up with this ATP molecule.
Now, so the three phosphates
and the creatine no longer has a phosphate.
So basically it's like a credit reserve,
so the creatine donated its phosphate but now it no longer
has another phosphate to give.
So I will eventually need to replace that but
what this allows me to do is it allows me get back
from ADP to ATP really fast and really efficient.
So the more creatine I have around with phosphate bound
as creatine phosphate,
the more ATP that I can replace almost instantaneously
as I use it so we're looking at like very short
high-intensity work.
This will have a lot to do with being able to sustain
high-intensity performance.
It won't do a lot for, you know, long term endurance
but for short term high-intensity performance this allows me
to function at a very high rate, you know, much longer.
When I say much longer I'm talking
a few seconds in this case, not minutes like we would in
a longer set or even tenths of seconds.
The second buffer I have uses an enzyme called
Adenylate Kinase,
and what this is actually going to do is it's actually going
to metabolize two ADPs so two of the two phosphate versions.
So if I have two ADPs so that means I would have had two
ATP and I would have used a phosphate of each of them,
so I took two threes, broke down into twos.
So now I have four phosphates distributed
amongst two molecules.
But I can really, if I wanna use energy,
I need the three phosphate version.
So what do I do?
I have this enzyme that will essentially take one of these
groups of two and donate one to the other, leaving now
a three to one.
So I add the same number of phosphates but I went from
having no ATP left, no usable energy here,
so now I have another molecule usable energy as ATP.
The leftover molecule is that one
that we just mentioned briefly
in cellular metabolism which is AMP.
If you remember, that was an extremely potent activator
of AMP Kinase, so AMPK.
With that going up, metabolic activity is going to go
through the roof in terms of cellular metabolism because
when I got into this case, I hadn't just used a little bit
of energy, I'm now creating a big energy deficit 'cause
I didn't just break down ATP into ADP,
I broke it down even further, so that tells myself that we
are depleting fuel really fast. So fast that we've had to
break all, some of our molecules down all the way to
the point where they're missing
two of their three phosphates.
So that's gonna take way more to recharge AMP than it is
gonna be ADP 'cause I had to add two phosphates back to it.
My cell recognizes that we're burning energy very fast
and that's going to be a very important messenger when
we're looking at how does this type of training affect
my metabolic rate?
How does it affect AMPK and all of the
adaptations that occur with that?
So that's my second buffer.
So creatine is the first one that kind of replaced energy
right away, which helps me sustain performance and then
so that I don't just like fall off and I'm no longer able
to perform.
I have this other enzyme that essentially helps me
cannibalize the leftover ADP
to keep going a little bit longer.
But obviously, if you imagine we had, say we had 20 ATP
and we broke all of those down.
If I had 20 creatine, I could recharge those all
so I'd have the same energy output.
However, if I already taxed that process
and I need to run this,
I can only run it at half.
So if I have, you know, 20 ADP left over,
I can only actually make 10 ATP with this mechanism.
So instead of recharging all 20, I can basically take half
break them down to AMP and get the other half
so my amount of energy that's available
will drop down.
So that means the intensity of work that I would be doing
once I get to this,
is actually going to be dropped
by this ratio actually half.
Biochemically we look at...
We don't I think get quite to that point,
like our body kind of has some regular (mumbles)
mechanisms in there
but understand that this mechanism cannot restore
the intensity to the level that the creatine can do.
So as this is happening I'm getting into a state
of fatigue where I'm losing performance in terms of how much
intensity, how much metabolic work I can do in terms
of rate of metabolism there.
Right, so I'm going to be slowing down my energy production.
So now I'm gonna take this and we're going to include the
context of the mitochondria so you can see kind of how
this is being shifted around and ultimately what then the
consequences are gonna be to our mitochondria 'cause this
is the thing that has to then recycle
and replace all of this.
So at rest I have full stocked ATP, full stocked creatine,
so three phosphates and a single phosphate on the creatine.
Once I start actually doing some muscle contractions,
I'm gonna break off two of those phosphates and now
I've taken ATP to ADP and those phosphates are going to
be sent down to the electron transport chain
so that they can be reattached to ADP later.
In the short term, okay because I need to recharge that
fast so what I'm actually gonna end up doing is I'm gonna
take those creatine phosphates and I'm gonna add them to the
ADP, recharge them in ATP but then that creatine also needs
recharge so it's gonna head back down and its going to get
colocalized on the mitochondrial membrane to be recharged
as well.
So I've got my mitochondria and if it's doing things,
If I'm sending fuel like at my citric acid cycle running
and it's fueled the electron transport chain,
what it's going to do is it's gonna reattach the phosphates
to the ATP, I'm sorry to the ADP and to the creatine.
So I'll end up back at stage zero so the mitochondria
takes the fuel, runs the citric acid cycle which fuels
the electron transport chain and those phosphates get
to go back to where they originated from
so it will recharge all of that.
Now, that's if the energy demand had ceased
so I was no longer requiring more energy,
so we had that other buffer (mumbles).
So let's go back a step and let's say we are here,
we've used the energy but there's still a demand.
I'm still training, my set is not over yet,
I'm continuing to demand energy.
Now all I have left is these ADP.
How do I get more energy?
Or am I just done, that's it, it's over?
This is where that Adenylate Cyclase comes in.
I get that switched over, I donate one phosphate from
one ATP to the other so now I have some usable energy
and I have an AMP, that highly activated signaling molecule
that's really gonna stimulate AMPK and get that metabolism
running up and tell myself like, "man we need some glucose,
we need some fuel coming in here," 'cause this essentially
is the signaling molecule that is gonna tell AMPK to tell
this guy "hey, what are you doing? Get this recycling thing
going and get it going faster because we're burning through
energy really fast."
So this guy right here, this AMP is going to be very
important for getting more fuel in here.
We're gonna look into that into more detail when we actually
get into this system as a whole.
But let's continue on this process.
I will shift over right, that other phosphate is going
down here and now I'm left with essentially two unusable
sources of fuel, so now that cell has reached exhaustion,
like complete exhaustion at that point in time,
complete failure.
From the metabolic standpoint it's not gonna be able to
contract or any more until this mitochondria can
start replacing some of that fuel.
Now keep in mind, this guy is always working.
It's just you're demanding energy at a rate that exceeds
this so eventually if you're burning fuel faster than the
mitochondria can replace it,
you will ultimately end up in this situation at some point
in time unless you stop your set
short of metabolic fatigue which is different than other
types of fatigue.
But from a metabolic fatigue standpoint, this is what you
get when you've expanded all of your energy and by that
I mean, you've kept going at a rate that's faster than
what your mitochondria can replace it,
regardless of how much fuel is coming in.