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-: So, if we look at what we call like the
NI Mechanical Tension Theorem, as a mechanism for why
we see the things that we see in research that suggests
this effective reps theory is a thing,
we're looking at this is just a ton of factors that go
into the mechanical stimulus at a fiber level, okay.
And as we approach higher intensity efforts,
aka we approach failure, we would theorize that
the mechanical tension at the fiber level
is what is going to be increasing.
That is kind of our tension theory.
And this would essentially explain why we can get
hypertrophy stimulus at a wide variety of rep ranges.
Is because if what's happening is that as we get closer
to failure, the tension on the individual fibers is
going up, that would explain why those are the reps that
regardless of rep range start to become stimulatory
for mechanical tension or mechanic transduction.
The things that are the main driver
of the hypertrophy pathway.
So to help you understand this mechanical tension a little
bit more, we're going to separate the tension from the
whole muscle from the fibers and try and give you guys
an illustration of what's going on.
So when we look at whole muscle tension, we're talking
tendon to tendon mechanical tension.
So that's literally the tension that the entire
muscle imparts, which is going to be directly proportionate
to the load or resistance that it is acting on.
So basically, it's gonna be higher and lower reps
where using more load, and it's gonna be lower
and higher reps where using less load.
Now, so this is directly correlated to load.
And this is not what we're talking about when we talk
about mechanical tension, and I think that's something
that gets lost a lot in terms of people talking
about the mechanical tension stimulus, and not quite
understanding that the mechanical tension, the main sensors
that we're going to be looking at from mechanical tension
perspective, are not gonna be the ones
that are affected by the total tendon to tendon tension.
They're going to be with the ones
that are at this fiber level.
So when we look at fiber mechanical tension, we're talking
about the individual muscle cells.
So with muscles, cells and fibers are essentially referred
to as the same thing.
And so within these we have the sarcomeres.
And the thing that kind of connects a sarcomere
to another sarcomere, sarcomere is basically,
like one contractile unit that's got all the little
creepy crawly guys, the actin myosin that are going to,
produce the sliding filaments, whatever thing
you wanna go with in terms of your
contractor theory of choice.
But basically that's where the actual mechanical work
is done is in between these Z lines, right?
So if we kind of look at this fiber being pulled out,
you see the Z line here, the Z line here,
and this is an expansion.
This is where we would have
those mile filaments overlapping and actually
doing the contractor work.
And so they're pulling on the Z lines.
And so one of the main areas that we have
mechanical receptors is built right in that Z line.
It's not the only area, but I just wanted to illustrate that
when we're talking about fiber mechanical tension,
we're looking at the sensors that are actually on these
individual fibers or within them.
And those are gonna be the ones where when we impart enough
tension on them, that they're gonna do what we call
mechanotransduction, which is they're going to take that
mechanical stimulation, and turn that into a
biochemical signal that then can be used
to drive these pathways that will lead to the hypertrophy
or the recovery of responses that we want the adaptations
that we are going for.
So, our N1 Mechanical Tension Theorem, as we call it,
simplistically is based off of fiber tension, right?
And that fiber tension is based off of, well,
how many fibers are acting on a resistance?
And what is that recruitment versus resistance ratio.
So, we're basically taking the stance that the
more resistance that's being imparted on a smaller group
of fibers means that the net tension on those fibers
is going to be higher.
And, you know, to kind of help you just like
understand this, from a tension perspective,
like of the muscles creating tension.
If we look back at this line, like there's two things
that are needed for tension
when we're talking about muscle tissue.
One is gonna be well,
what's pulling on the two ends?
What force are we having to overcome?
The other thing is gonna be like, but how much force are we
actually acting on that external thing
by internally contracting?
So the amount of tension is going to be limited to the
ability to actually recruit a contraction
within those sarcomeres.
If those sarcomeres don't have the biochemical ability
to initiate the mechanical contraction, well, then they
can't produce much tension.
So the only tension you would get stimulated on that would
be like, just like if it was just being
stretched end to end.
And that's gonna be a different stimulus, but it's not gonna
be what we would consider probably the most
potent mechanical signal for hypertrophy.
So we need those two things, we need to be able to have
a certain amount of resistance that we have to overcome.
And then we also need to have the ability
to recruit that tissue.
And so when we talk about recruitment and having this
recruitment to resistance, there's a lot of complex nuanced
things that are going on neurologically, biochemically,
structurally, all at once.
So as you're doing a set,
you're working through your reps.
As you start to fatigue, you have thousands
of fibers within that muscle,
and they're all acting on that load.
And what happens is, is that you're never using
all of them at once.
Your nervous system is using a certain amount of them.
How much of them it's using at once depends on the load
you're using and how you wanna act on it.
And what happens is as some of those start to fatigue,
you have fewer available and your nervous system actually
starts to try and recruit more tissue and that's where it
starts to look at recruiting even more
or higher threshold motor units.
And so, as we start to fatigue, the nervous system is asking
more, but because some of these sarcomere
are now biochemically unable
to respond to the nervous system
and do the mechanical work, right?
Is that now that work has to be done
by less and less tissue.
And what you will see is that the rep speed or velocity that
you can move a load at starts to slow down.
And that's a representation of well, okay, if fewer fibers
are able to act on this load, they're not going to be able
to move it as fast.
So velocity data is another real cool way to kind of look
at what kind of coincides with this
effect of reps theory, hard sets theory, et cetera.
So for practical purposes, without like spending weeks
going deep into biochemistry and some of the stuff
that I mean, to be honest, like the mechanical center area
of research is one of the ones where there's
a lot being done right now.
But we still don't have the exact mechanisms
on a lot of these things.
We have some pretty, pretty good theories that at least help
us kind of imagine how this principle would work.
And that's kind of how our theorem is based on.
But for practical purpose, we're gonna assume that, okay,
the more fibers acting on a resistance, the less tension
per individual fiber, where if we had less fibers acting
on that same resistance, they would have
to be producing more force.
So theoretically, we would decrease the mechanical tension
stimulation hypertrophy if we were like,
if we had more fibers acting.
But the fewer fibers acting,
we're gonna stimulate those individual myofibril more.
Okay, so our goal is get to fiber level tension.
And to help illustrate what that would look like.
Let's look at a model here where what I've done is
I've put three muscle fibers on an arbitrary load
that I've just labeled 90, we'll say it's 90 pounds,
even though I don't even know if that's realistic for you
to be able to pull 90 pounds with three muscle fibers.
Probably not.
So this is just a simplified example.
And what I've done is I've overlaid the mechanic
or the effective reps curve, right on here.
Let's say we got this 90 pounds,
and we start working with it.
And our nervous system and for the sake of this model
is able to recruit all three of these fibers.
And so that means those three fibers, they're producing
their internal tension, but there's only 90 pounds so that
ends up being like 30 pounds of resistance on each.
So the actual amount of tension is not, now we could get
into the physics of this or whatever.
But the thing that you'll see is that well, it'll move
at a higher velocity.
So just the complicated things for any physics Nazis
out there, is that yeah, I understand that the movement is
a part of this equation too.
But for keeping it simple, we're just gonna say that that's
30 per muscle fiber, okay?
Now, we're doing this and this guy over here he reaches
a point of fatigue.
So that means now the load is now distributed
across these two guys.
So now instead of it being 30 per, this 90 divided by three,
it's 45 per 'cause it's this 90 divided by the
two remaining bright red fresh muscle fibers here.
Well not completely fresh, but you get the idea.
And what we'll see is the velocity will then start to drop
because these guys are not gonna be able to move the load
as fast even though they're still able to move it, okay?
But this load is now gonna be imparting
more resistance and therefore, between the internal tension
or the internal contractile forces and the extra resistance,
our net tension on that fiber is likely going up.
Now, we dig deeper into fatigue, and we only got this
one guy remaining, he can still move the load,
but he moves it really slow.
But now all 90 pounds are being imparted on him.
So we're gonna see much slower velocity of movement,
we're going to see
you're not going to be able to do much more reps after this.
You'd like, you're approaching failure, absolute failure
at this point in time.
But you're getting a crap load of stimulus in this guy.
You're getting three times the mechanical tension
that you were over here, per se.
So likely, what exists is that
those mechanical receptors aren't gonna respond
to immodest tension, there's gonna be
a certain threshold of tension that needs to be exhibited,
for that to become a stimulus.
For that tension, to transfer into a mechanical stimulus
for us to get that mechanotransduction.
And that likely occurs somewhere around here on that
effective reps curve where we probably see velocity drop
if we overlap that data.
Which fingers crossed, we're gonna do some internal research
to actually look at that.
And look at how that correlates with EMG
and oxygen de saturation and whatnot and kind of tell
as much of the story as possible.
We have a lot of pieces done separately,
and we're gonna try and overlap them.
And pretty sure this is exactly what we're gonna see.
So, as we dig deeper into that fatigue, that resistance
to recruitment ratio is gonna start shifting into where
there's more tension on the smaller amount of fibers, right?
We're getting higher resistance, less recruitment.
And when I say recruitment here, I'm talking about not what
the nervous system is trying to do, but what it's
successfully actually able to get to contribute.
Because you will see the nervous system, like in terms
of amplitude, especially like on an EMG, you'll see things
start to go up as they reach fatigue, because that's as
we're getting in this scenario.
If you imagine instead of three fibers, it's like we got
thousands of fibers, it's gonna start trying to reach out
beyond these three guys to do the job.
It's gonna try and find another guy to replace this guy
over here that got fatigued.
And this is all kind of happening 'cause an important thing
to understand and this is probably a little advanced
for this course, but there's this thing,
it's called motor unit cycling.
And basically your nervous system is shifting around,
not only like which motor units it's controlling,
but also maybe like which muscles it's using,
and when they're synergistic muscles and stuff that can go.
So it's always trying to find more fresh things to be able
to contribute to the work as certain things start
to fatigue, 'cause biologically, it's not a good thing
for us to ever take tissue to complete fatigue
'cause it disrupts our function.
So our nervous system is designed to try and recruit help
elsewhere whenever possible. which is why our body always
likes the path of least resistance.
So there's this thing, this motor unit cycling,
that can happen.
And in the low levels, this is what essentially allows us
to keep performing an exercise because like say if you were
a long distance runner, you just kept going back to the same
muscle fiber over and over and over every step.
That muscle fiber would fatigue, just like it would
in a heavy resistance training setting in the gym.
But what happens is that you don't use the same fibers
every set like some guys are always getting resting
when the other guy's working.
And you're kind of cycling through.
And when you're at a low enough intensity,
you're able to kind of recover
and other motor units, other muscle fibers at the same rate
that you're working others and you're able to sustain
that activity like for a long duration.
So basically, when we're looking at it personally,
we're always gonna be in excess of that threshold.
But if you're working in say lower intensity,
higher reps, they're still some of that
motor unit cycling occurring here.
So, the next thing I wanna look at is
looking at this when we're using different loads.
So if we take the example that I gave
and what we say is that, we'll say that the max actually,
for these fibers is 45.
We'll say that's
their failure point.
Is they can't do more than 45.
So if I'm using 90, once I dropped down to this point,
I'm gonna reach task failure.
Meaning that at this point, I won't be able
to do the movement anymore.
So once I get to the point where I'm stimulating these
two guys, as soon as one of them is done, I'm done.
I don't get to go from here to here, because this is now
actually occurring maybe say over here.
Because I'm at the maximal stimulus
for these two fibers.
So I'm essentially stimulating both of these at once.
Now, let's say I was using 45 pounds, it would take me
more reps because I would have to work with longer
to fatigue these two guys, but then I would get to a point
where I could still put that maximal stimulus
on this remaining fiber.
And this is likely, the thing that's going on where we can
see that people are able to achieve hypertrophy
at different rep ranges and different loading as long as
they're going close to failure,
'cause they're still getting to a point
where they're getting us above threshold stimulus
of tension on those fibers.
From my perspective, these things are not equal.
One, there's different biochemical, neurological adaptations
and things that aren't gonna go with training heavy
versus training light and higher reps.
Another thing to consider is that when you're doing like
heavier loads, you're getting to this point where you are
probably above that threshold
for multiple fibers relatively early.
And so what I would venture to say is if we're actually
looking at the effective reps window, is there's probably
a smaller window, but it's affecting a higher number
of fibers for heavy loads.
And then when we get over here to these lighter loads,
is there's probably a greater window.
But over that window of effective reps,
the volume of stimulus is smaller because you're just not
stimulating as many fibers with those fibers
to a greater degree.
But you could still get a good enough volume of tension
stimulus by going to failure because the fatigue
and the drop of the fibers is gonna get you to the point
where you are stimulating the individual fibers.
The argument there, and this is, I'm gonna give you
my personal anecdotes on this.
Once I kind of wrap my whole mind around this
mechanical tension stimulus thing, you know, years back,
I just got rid of really high rep sets,
just stopped doing them.
And what I started focusing on is getting to that
fatigue state in a more efficient manner in terms
of what I considered.
And by more efficient, I mean, I got there with fewer reps.
And I got there in a way where I thought I could accumulate
more effective reps on that way there.
So, instead of doing 30 reps,
what I would do, and this is, you know, I said I wouldn't
talk about a bunch of specialty sets, but I'm gonna
reference some of them here.
Is that I would do a drop set, a superset, a cluster set,
something like that, so that I could work at a
higher intensity, somewhere like this.
And once I got to this state, knowing that there would still
be room to work and hit more muscle fibers by either
dropping load or switching to a different exercise that
I could use either less load or a different resistance
profile that was more dependent
on other muscle fibers et cetera.
I would rather instead of doing 30 reps, I would rather
say like, well, what if I can do like six reps of this
and then drop and do six to eight more reps or whatever.
And accomplish, like, more effective reps
in half the total reps.
And then maybe not have to do as many sets
or whatever it may be.
That's been something I've found to be very effective,
more enjoyable, et cetera.
Obviously, gonna keep saying principles, not rules here.
It's not the only way to do it.
Definitely, there may be cases where because you're trying
to reduce load for some reason or whatnot that you may
choose to go the other route and say like, no, I wanna use
the less load and the higher reps, et cetera.
You might just wanna like keep things simpler.
Which it's definitely easier to track a straight set
than it is a superset or a drop set or whatnot.
But hopefully now with some of these principles
you're starting to see that like, well, hey, if I calculated
the tangible data with that superset, or drop set
or whatever, and I start to include some of these
subjective matters, when we talk about including say RPE,
RIR, velocity, et cetera.
That I can get a pretty good idea of how I'm progressing
in these more complicated set and rep protocols.
And maybe use that as a way of getting a little bit
better results, being a little bit more time efficient.
You can use a variety of reasons to argue for either
direction once we get into the psychological aspect of it.
But my personal experience and what I've seen with clients
and the coaches that I mentor, is that once you start
utilizing this, you just don't really find the value of just
straight high rep sets anymore.
That's something that we've seen over and over
and over again.
So we're about 20 minutes here.
I'm gonna cut it here and then we will continue talking
about the N1 Mechanical Tension Theorem.
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