Have you ever thought that heavy weightlifting is only for bodybuilders,
power lifters or certain types of athletes? Well, in today's video,
we're going to find that this is definitely not the case and no matter who you are you should
likely be including some form or variation of heavy resistance training into your routine.
Now, you still might be pushing back and saying "wait a minute Jonathan,
I do things like consistent long distance running,
throw in some weight training throughout the week but it's of a lighter weight or lighter load,
maybe even throwing in some yoga in there". Well, still probably not enough.
We'll talk about why this is by taking a look at the muscles, discussing aging and of course,
talk about how we could add this type of training to a current routine or even a new routine.
It's going to be an important one, so, let's jump right into this anatomical awesomeness.
[Intro]
So, first let's start with the "why". Why do these skeletal muscles require heavy resistance training
and therefore why should all of us participate in this? Well, maybe you've heard some alarming
statistics that starting in our 30s, we can lose anywhere from three to five percent of our muscle
mass per decade but when we get to our 50s, we can lose as much as 10% of our muscle mass per decade.
That's quite alarming and kind of scary to think about but you might also be thinking "well wait,
can't we combat that or at least slow that process down through exercise?" and the answer
is yes and that's one of the main points of this video but many of the other forms of
exercise just aren't as effective at preserving muscle mass like heavy resistance training is.
So why is heavy resistance training better at preserving muscle mass than the other types of
exercise? Well, the answer to that lies in how muscles actually work. So, let's use the biceps
brachii muscle as our example here but keep in mind we can apply this information to any
of the other skeletal muscles that we would be working out or exercising but if we were
to take a look at this whole biceps muscle, the whole muscle is going to be made up of thousands
of string like cells called Muscle Fibers and you could just even call them muscle cells.
So, if I use those terms interchangeably we're talking about the same thing but these
muscle fibers have an amazing ability to contract and when they contract,
this would cause a pulling on the bone via the tendon and that would
move your skeleton in certain directions depending on what muscle you're contracting.
Now, another thing that's important that we talk about with these muscle
fibers is that if we analyze the muscle fibers within this muscle,
we would see that some of them are classified as fast twitch muscle fibers and others are
classified as slow twitch muscle fibers and this is definitely important to our muscle mass story.
So, why do the different fiber types matter when it comes to a reduction in muscle mass
as we age? Well, let's go over some of the characteristics of these fiber types and then
we'll bring that together. The fast twitch muscle fibers, as the name implies, contract with more
velocity and more force and tend to have a greater diameter when compared to the slow twitch fibers.
Now, one of the dry backs of the fast twitch fibers is that they fatigue rather quickly
and we do have to acknowledge to all the anatomy and physiology Geeks out there
that we could further classify or subdivide the fast twitch fibers but that's for another time.
The slow twitch fibers contract with less velocity, less force and have a smaller
diameter but they are fatigue resistant; they're great for endurance type activities. So again,
how does this relate to reduction of muscle mass as we age? When we have this reduction of muscle
mass, it's not like the mass reduction is uniform between the fiber types and what I mean by that is
it's not like 50% of that reduction in muscle mass comes from the slow twitch if the other 50 comes
from the fast twitch. It is actually much more biased to the fast twitch fibers meaning we lose a
much greater proportion of the fast twitch fibers as we age as compared to the slow twitch fibers.
So, this probably raises another question for you; why do we lose such a greater proportion
of the fast twitch fibers versus the slow twitch fibers with aging? Well, a big part of this answer
has to do with the sequence in which the nervous system recruits the slow twitch fibers versus how
it recruits the fast twitch fibers and this will also help us to understand why certain
activities do a better job at recruiting or engaging those fast twitch fibers.
So, let's get into this by talking about the nervous system, motor recruitment
and pencils[00:04:09] but real quick I want to talk about this cool device on
the back of my arm by saying thank you to the sponsor of today's video Nutrisense.
Nutrisense is a continuous glucose monitoring program that monitors your blood sugar levels
which are more appropriately referred to as your blood glucose levels. It does it
through this nifty little device called a Continuous Glucose Monitor or CGM that goes
on the back of your arm or for you anatomy nerds out there, on the posterior brachium.
The CGM then easily syncs with the nutrisense app which allows you to
monitor your blood glucose levels throughout the day and see how things like food, sleep,
exercise and even how stress impacts your blood glucose levels. For me, it was very interesting
and a lot of fun to do little foods experiments to see which types of foods might spike my blood
glucose levels. Probably not a big shocker what that ice cream was going to do but it was also
awesome to see how exercise, like stimulating those fast twitch muscle fibers could affect
those blood glucose levels which could help provide valuable Insight on things like how I
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So, how does the nervous system and motor unit recruitment help us to better understand why we
lose a greater proportion of fast twitch fibers? And what in the world did I mean by pencils? Well,
here are the pencils and this is representing a full muscle like
the biceps. You can totally tell that it resembles the real biceps but really we're
just using this to help us understand motor unit and motor unit recruitment.
So, pretend this is a whole biceps like a cross section through it. Each
of the pencils is representing an individual muscle fiber. The ones
that I colored with black sharpie are representing the fast twitch fibers,
the ones that I didn't color in black sharpie are representing the slow twitch fibers.
Now, I do want to just mention that we could go through individual muscles throughout the
body and we would see that each muscle has a different proportion of fast twitch versus
slow twitch and even between individuals we could see a difference in those proportions.
Now, we could make the argument that a muscle that has a higher proportion of
fast twitch fibers might be at greater risk of reduction but let's not focus
too much on that and just focus on the principle of how these different fiber
types are recruited and that'll also help us with activity choice with exercise.
So, to do this we need to define what a motor unit is. A motor unit is the motor neuron and
the muscle fibers that it controls. Now, two important things with this:
one that we understand that each muscle is subdivided into multiple motor units. So,
for example this little grouping of fast twitch fibers would be its own motor unit
and then we could come over here and say this grouping of slow twitch fibers would be its
own motor unit and each one of those motor units would be controlled by a different motor neuron.
The other reason why this is so important is because there's this thing called The All or
Nothing principle and what the All or Nothing principle says is that when that motor neuron
fires or sends the signal, every muscle fiber that it controls will contract at full force and so,
think about how important that is now to have individual motor units or the
whole muscle broken down into multiple motor units because think of the opposite - what
if we had one motor neuron controlling every single muscle fiber per muscle? So
like one giant motor unit per muscle. You could see that that would be a big problem
for the signal being sent into that muscle because every time that motor neuron fired,
every single muscle fiber of the muscle will contract and we'd be contracting at full force
with every single muscle and that would be a problem with force modulation, right?
But because we have these muscles broken down into individual motor units,
it really helps us to modulate force based upon the activity we're engaging in or if you know,
I'm lifting a probe versus a very heavy weight. So, let's actually use this example
of me lifting the probe or curling the probe as compared to say like curling a heavier weight.
Now, I do want to mention or at least clarify because I kind of alluded to this earlier that
the motor units are going to be subdivided into fast twitch motor units that you can see and
even slow twitch motor units. So maybe a slow twitch motor unit here, slow twitch motor unit
over there but we're not going to have this mixing and matching within the motor units - fast twitch
motor units slow twitch motor units. And what we find is that when we start to lift a weight
or engage the muscles, the first motor units that we recruit are the slow twitch motor unit.
So, let's say I've got a 10 pound weight and I start to curl it, I'm likely only going to need
my slow twitch motor units to move that weight. Let's say I increase it to 15 or 20 pounds,
I'll recruit some more of those slow twitch motor units and I'm going to continue to do
this until I've exhausted all of my slow twitch motor units, meaning I've recruited
all of them and if I continue to increase the weight, then I'll start tapping in and
recruiting the fast twitch motor units in sequence as I continue to increase the load.
So, this gives us the idea of why we need some level of heavy resistance to actually
even stimulate and engage those fast twitch motor units or fast twitch muscle fibers and
one of the other things that we can do because we can get creative beyond just doing heavy lifting,
we could also engage these fast twitch muscle fibers and recruit these fast switch motor units
by doing things that are fast and explosive. Think like a vertical jump or a full-fledged
sprint and one quick thing I want to address about our little pencil muscle model here is that you
actually don't have a motor unit that is this small, meaning a motor neuron only controlling
like five or six muscle fibers, that's just, again for a learning device here, the motor units,
FYI and the biceps are more like one motor neuron controlling over a thousand muscle fibers.
So, now we have a pretty good idea as to why these fast switch fibers are mostly contributing to this
overall loss of muscle mass as we age and in many cases, they're contributing to pretty much all of
it when we're comparing that to the slow twitch fibers. Now, you probably have come up with some
ideas about activities or exercises that we could choose from to help stimulate or at least preserve
some of these fast twitch fibers and we're definitely going to talk about those exercises in
just a second but I do want to approach this from like a lifestyle approach or a lifestyle example.
Let's say we had a person in their 50s or 60s and they're actually relatively active; they're doing
chores around the house, maybe they're working out in the yard doing gardening yard work,
you can see that a lot of those activities would recruit and stimulate those slow twitch fibers but
the majority of household activities or activities of daily living don't really require recruitment
of those fast twitch fibers and so, if this person isn't also incorporating like a strength training
routine into their week, you could see how those fast twitch fibers could go for extended
periods of time without being stimulated thereby contributing to that loss over time and as we age.
And let's take this a little bit further - let's say we have someone who's doing more
than just the activities of daily living, they also have an exercise routine and
some of their exercise choices could be like steady state cardio at a moderate intensity.
They're working but they could still hold a conversation while they're running or
cycling or maybe they picked yoga or maybe someone also picked something
like a form of resistance training but lighter loads with higher repetitions.
Now, let me be clear, there is nothing wrong with these exercise choices. There's obvious benefits
to them, things like cardiovascular improvements, improvement in mobility and flexibility and even
improvements in muscular endurance. So, if you like doing these types of exercises,
continue to do them. It's just that we could sprinkle on some addition exercise choices
to give us some amazing benefits to helping preserve and maintain these fast twitch fibers
and another cool thing is that it actually takes much less than most people think.
The amount of work required to maintain and even make improvements in the strength of
these fast twitch fibers is about 10 to 15 working sets per muscle group per week. Now,
that's not a lot in my opinion and some of the data is even showing that this
could be as little as 10 working sets per muscle group per week.
Now, the amount of load or weight that we would need for this type of training
is a weight that's heavy enough that you could only lift like four to eight repetitions. Now,
once we start getting to that seven to eight range and crossing beyond that,
we're getting to this strength versus hypertrophy cross over here and so, a lot of people who really
want to focus on strength will even increase that weight to where they could only do it
maybe like two to six repetitions. The point is it has to be a relatively heavy load for you.
Now, what's interesting about this is that we could spread these working sets throughout
the week in a creative way or some people will actually lump them into one day. For example,
the endurance athletes will often do a dedicated strength training day for their legs because
they've got so many other things going on with their legs with endurance training because they're
on their feet running or cycling but again, you can get pretty creative with all this.
Now, I do want to acknowledge another thing with the endurance community that yes there are
naturally days where you increase the intensity because you increase the speed of the run and you
can start pulling in some of those fast twitch fibers as the speed increases in the run or if
you're on a bike but there's still going to be a percentage of those fibers that we're likely not
tapping into, so again the benefit of this High Resistance strength training is going
to be there or we could also get a little bit creative with some explosive exercises.
Including explosive exercises into this type of training is where it really gets fun in my opinion
because it even opens up the doors wider for more variety and more fun while you're exercising and
working out. So, remember when we mentioned how we recruit the muscle fibers one of the main ways was
to increase the load and the more load we add the more we have to recruit those fast twitch fibers.
The other way was to do something as fast or as explosive as possible like a full-fledged
sprint or a vertical jump. So, you could get creative with these 10 to 15 working
sets where maybe on one day you did a squad[00:14:08] or a squat variation of
heavy weightlifting of five to eight sets and then another day you decided to do box
jumps which would work those same muscle groups in this explosive manner but kind
of change the variety and have some fun with different exercise choices.
For the upper body you could do bench press one day and then on another day you could do
explosive medicine ball throws against a wall right in front of you. And so again,
a lot of fun, things that you can kind of mix and match to
kind of test your abilities and have some fun with this type of training.
So, let's wrap this up with two thoughts. Well, one of them is more of a concern
because some people are concerned that this type of training might get their muscles too big. Now,
some of you are out there probably thinking "Well, why wouldn't you want your muscles to
get big?" well, there are plenty of people who are not under that
umbrella and think "Okay, I don't want big muscles. Can I get these strength benefits
without getting huge?" if you will and the answer is yes. This form of training,
this type of strength training or true strength training doesn't cause a huge adaptation as far
as hypertrophy or an increase in muscle size. You can get great increases in strength without
increasing the size of the muscle very much, again with this type of training.
People who are trying to build muscle as far as size, they call this hypertrophy again,
they're going to need a lot more volume than 10 working sets throughout the week;
increased repetitions and increased sets Etc. So,
for those of you who are concerned about that, don't worry too much about that.
The other thing I want to mention and talk about is foot speed. And what do I mean by
foot speed? Foot speed is definitely important from an athletic perspective but I want to focus
on it from the perspective of aging and let me bring it up like this - maybe some of you
have had a parent or grandparent or another loved one who's tripped and fallen later in
their life and a lot of the times this can be very detrimental especially if they break a
bone. You often hear about how bad it is when someone breaks a hip later in life.
Remember we're talking about all these fast twitch fibers that are contributing to this
loss of muscle mass as we age and these are the fibers that can contract with the most
velocity contributing to our speed. When we trip when we're in our 20s or even 30s,
a lot of the times we have the foot speed to catch
ourselves with our feet without actually falling onto our hands or anything else.
So, what if we were able to help preserve these fibers and therefore the speed later
in into life and help reduce the risk of falls and tripping and you could do
this again by recruiting these fast-fitch fibers with heavy lifting you could even
have somebody do things like doing Hopscotch type activities in the gym or you're having
them bounce their feet or move their feet from box to box as quickly as possible
helping to preserve that foot speed and again, potentially helping to reduce the risk of falls.
And thanks for watching everyone. Hopefully I learned something new and
useful from watching this video. If you're interested in checking out Nutrisense,
that link is in the description below and let's engage those fast twitch muscle fibers of our
forearm and hand muscles so that you can quickly click the like and subscribe button as well as
type like the flash in the comment section. Yes, that was nerdy. We'll see you in the next video.