Hey, this is Sandy. And Randy?
And we're here on AT Corner. Being an Ath Eye trainer comes
with ups and downs and we're here to showcase it all.
Join us as we share our world in sports medicine.
Welcome back to another episode of AT Corner.
For this week's episode, our Education episode will be
focused on the core, but not the core that you would normally
think of. We're talking about the core in
the foot, the intrinsic foot musculature.
And like Randy said, this is an education episode and it is ACU
episode. So if you're listening to it as
it comes out in your athletic trainer, you can actually claim
this as category AC US. Thank you to athletic training
chat and clinically pressed. So if you're interested in
those, make sure you head down to the show notes episode
description wherever you're listening.
Go ahead and the link is down at the bottom to do the quiz and
course evaluation. So as with any education episode
that refers to any muscle or joint or anything, we're going
to describe the anatomy specific to the intrinsic foot
musculature. And then we're going to describe
how the intrinsic foot muscles kind of what their role is in
stabilizing the foot. And we'll just discuss some of
the rehab techniques to improve our intrinsic foot muscle
activation and strength. Awesome, So why don't we get
started with the anatomy? Yes, let's do it.
Who doesn't love a little anatomy in the morning?
So I feel like it's been such like a big like buzzword lately,
the intrinsic foot muscles, right?
I feel like maybe maybe not as popular as it was maybe a couple
like a few years ago, but I still feel like some people are
kind of already starting to be in tune with it.
But essentially the intrinsic foot muscles are just the small
muscles that originate and insert on the foot, right?
They're very local. They they're basically chilling
there. And there are both dorsal and
planter intrinsic muscles, but most of the research does focus
on more of the planter aspect. I don't know if anyone really
talks about the dorsal intrinsic foot muscles.
Yeah, it's not really talked about a lot.
And plus like the planter aspect, I feel like there's more
going on to look at. So there's you could say there's
probably more, they're more involved.
And there's like deeper layers, where's the top of the foot?
Really, there's just a lot of bone.
Exactly. There's there's a lot there.
Right, right. And like you said, right, So
there are deeper layers and there's actually 4 layers that
actually lie deep to the plantar fascia.
How it's kind of broken down are those first two layers.
Those first two kind of superficial layers are really
parallel with the longitudinal arches.
So this is like your abductor halicus, abductor digiti minimi,
flexor digitorum brevis. And then the next layer you have
the quadratus plantae, which almost kind of follows the
plantar fascia. It kind of comes off the
calcaneus and starts to go towards the toes, but not all
the way to the toes. And that one actually inserts
into the flexor digitorum longus tendon.
So it actually helps kind of stabilize that tendon and help
make that tendon perform more efficiently.
I mean that this, this is super helpful to know obviously for
whatever population you're working with, but especially if
you're working with performing artists, like a lot of times
they are going to have you'll, you'll commonly see either like
tendonitis in the feet, like a flexorhalicus longus tendonitis
or, or some sort of musculature. Or if you're dancing barefoot,
or if you're doing a lot of plantar flexion, you know
there's a lot of things that can happen to the surrounding
musculature that also then bleeds into the intrinsics.
For sure. And I feel like like the
performing arts kind of realm is probably a little bit more
familiar with this concept than probably like team sport
athletes who think this is probably witchcraft.
We start having them do the exercises.
Right, right, right. As you go deeper are kind of
those last two layers really kind of align a little bit more
with the transverse arches, not necessarily completely.
This is like your abductor Halicus oblique, which I'm sure
everyone had that on their bingo card of muscles they remember,
and then the actual inner OCI muscles.
All right, So as I started the episode, right, these muscles
are kind of viewed as like a core, right?
And when you really kind of break it down, if you start
thinking of like, oh, well, what do the Multifidi do?
And like transverse abdominis and stuff like that, right?
These muscles act in the same way.
They're very local. They're very small and you know,
the, the, the idea is, oh, they should be kind of similar with
the multifid I do in the spine. They should be stabilizing,
right? And what this is kind of
referred to in the research is like the foot core system and
they kind of broke it down similar to the spine, right?
So it's made-up of three elements.
So your passive elements are like your, your Bony structures,
your ligaments that support the arch.
The active is obviously the musculature.
And then kind of that the nervous system or the neural
subsystem, which is just the nervous system and how it
interacts with the, the nerves or with the muscles.
And really the planar intrinsics kind of play 2 roles.
Obviously the active because they're muscle, but also because
they're smaller muscles within the foot themselves, they also
have a big kind of neural subsystem component because
there are a lot of muscle spindles within them within
those muscles that help kind of feed information to the central
nervous system about the type of stretch that's going on at the
foot. So it kind of gives your body a
good idea of what what's happening at my foot.
I mean the foot really gives you so much information just in
basic gait. Yes.
And another thing that kind of gets forgotten are the plantar
cutaneous nerves within the planter aspect of your skin of
your foot are highly innervated. So you get a lot of sensory
information from just the skin of your foot, let alone the
actual muscles within the arch that help kind of, again, guide
your foot on, letting you know where you are in space, what
kind of surface you're stepping on, what is it uneven?
How to react to that surface? Yeah, exactly right.
So the overall goal of these muscles is just to provide
stability to the longitudinal arch and it actually does assist
in transferring energy during propulsion.
Most people kind of view this like idea from like the plantar
fascia, like that whole windless mechanism, like kind of acting
as a spring. But actually a lot of it does
come from tension from the foot intrinsic muscles.
And without them, the plantar fascia really wouldn't be able
to do the job that it would be able to do.
So you can already kind of start to hint if we have dysfunction
there, it might piss off the plantar fascia.
So what you're also saying is the if these help with
propulsion, then intrinsic muscles can also therefore help
with Sprint speed. It could help with performance
as well. Absolutely.
That's how you get by in with your athletes.
Yeah. And it it makes things more
economical. So if you're a distance runner,
right, your whole idea of is you want to be moving as efficient
as possible. These muscles help with that.
So how these muscles kind of function during gait?
Again, the goal is, hey, let's keep the foot stable, right?
If the foot's stable, you're able to propel more force,
there's less wasted energy, all that stuff.
And where you really kind of see these muscles tend to like have
their peak activity is towards the end of the stance phase.
So this is when you're starting your heel's starting to get off
the ground, your toes are starting to extend, all right?
So the idea is it's placing a stretch, right?
You're getting a little eccentric contraction, which is
very, very forceful anyways. And this is really kind of what
kind of led the idea of like, oh, these muscles might be a
little more involved in the propulsion of the foot.
You know, it's not just the plantar fascia doing all the
work. If anything, these are probably
doing a little bit more to help take pressure off of that
passive kind of tissue. Another idea to kind of look at
too is some of these muscles do have longer tendons, right?
Which means when they add tension, there's a lot bigger of
a spring that can happen. So again, add a little attention
to that tendon, it stretches and then it recoils.
Bam. The only thing is you can't
really do eccentric muscle contraction of intrinsics.
I mean, it's, it's just. Yeah, it's just that's hard.
You're right, right? If anything, it's more like
hopefully you activate them and hopefully it transfers to that
type of muscle contraction, right?
But again, it does show the idea of man, if these muscles fail,
right? It it might lead to the plantar
fascia doing too much and then you get those plantar fascia
issues right. It was interesting that that was
pretty consistent. Late stance phase tended to be
where a lot of high activity was at and a lot of them that's
where they peaked at like that was the highest of their
activity. There is some stuff that showed
a few of them, a few of the intrinsic muscles had some high
activities like right at like heel strike or like where the
almost early stance where you're actually starting to load the
foot but not quite mid stance. And I think the idea behind that
is it's preparing the medial longitudinal arch for the
collapse that occurs during mid stance, right?
It's help preparing to control instead of your foot just
flopping on the ground. Yeah, we can't have.
That no, I can't have that. We weren't ready for these sound
effects this morning. I was not ready for that sound
effect. Right.
So I think that's the kind of idea, but also you have to
remember when we look at muscle activities, right, a lot of it
is done by surface EMG. Well, a lot of these muscles are
really close together and so there could be a lot of
crosstalk. So surface EMG studies are
really limited and actually like giving you a good sense of
what's truly happening. So they do try to do like fine
wire EMG where they actually inject like a sensor into the
muscle. But then obviously you have this
like fine wire thing in your muscle and you're told to OK,
now go ahead and walk with this. That's.
Yeah, some people don't feel, but some people can't tolerate
that so. So there's a lot of limitations
to this research, but the idea is kind of you at least have a
general idea and it does make sense of, OK, let's prepare the
foot to actually accept weight, right?
So that's the gist of just, OK, what are these muscles doing
during gait? And again, the idea support the
arch, right? Make sure we can control it.
And if we know anything about the foot, right, it kind of sets
the table for everything else, because that's our first contact
with the Earth. And I think just to almost
preface this, I know we're going to talk a little bit more about
it later, but the goal of this is obviously to provide a
foundation. But also when you're thinking
about this foundation, really start to apply it in your mind
of things that like things you see in rehabilitation are like,
OK, if we know that these are helping us prepare to accept
weight, then think about like your post op athletes or your
freshly acute athletes that maybe you're not weight bearing
and then you're going to be placing weight on that foot and
just like weight shifts and stuff like that.
So kind of it's not necessarily meant to change your rehab, but
just kind of have a different approach in your thought process
in your rehabilitation. Oh yeah, that's a good idea.
Like before you like like someone who was immobilized for
a while Or like I said, post op before they start putting an
actual weight bearing. Maybe we should wake these bad
boys up. I mean, we really should be.
They're really not. That's a good question.
That's a good. Thought this is not necessarily
something you have to do when you're weight bearing.
Yeah, for sure. And we'll talk a little bit more
about that too. And there's another video that
we're we're going to talk about too.
Yes, my little throwback so those that's the anatomy of it
and what's interesting is again, it does really serve that kind
of support role to all our extrinsic muscles like our post
post tib flexor hackness longus flexor digitorum longus because
at a certain point in the gate cycle, right, they're not in a
good position anymore to help with that propulsion that comes
from like the calf, right. So again, these the unsung
heroes of gate basically. So as we kind of start looking
at the rehab of OK, what do, what do we do?
Like, what am I supposed to do with this, right?
And there are actually some tests to actually kind of
identify, OK, who actually has like weak intrinsics.
Now you can actually evaluate this.
It's they're not the best, but it gives you an idea.
Some of it is just looking at posture, right?
If they have a flat foot like PES plainus, right?
The assumption is OK, they probably do have weak intrinsic
foot muscles. Again, it's an assumption, so it
may not actually be true. Also claw feet, right?
If they have like really like curled toes, right, that it can
be an indicator of that as well. But there are special tests,
which I thought was pretty wild. First one is a is called the
paper grip test as basically you put a paper on the ground and
the patient flexes their toes and then you pull the paper
away. So if they have weak intrinsic
muscles, the idea is the paper doesn't tear, just kind of
slides out, whereas. I feel like you really have to.
What kind of, I guess, do you have to start the tearing of the
paper first? I feel like that's really hard
to. No, I don't think so.
I think they got to lock in and then you pull in it like, or at
least it like crumples like, you know, you see the resistance.
OK, so you get some resistance. I feel like tear, like tearing
paper, like just. That's what you're looking for,
Yeah, so. Maybe we'll have to test this.
Yeah. So if they don't, if there's not
really resistance or it doesn't really grip the paper, then OK.
I can see that. Intrinsic muscles are trash,
right? And then there's also the
knuckle test. So the wording on the knuckle
test in the article was weird. So it might change a little bit,
but essentially the patient flexes the metatarsal phalangeal
joints, and you're looking to see if the heads basically pop
out, so making knuckles in your foot.
Now, again, here's where the wording was weird.
If the metal metatarsal heads showed, like if you saw them,
the test was positive. But that indicates that they
have strong intrinsic muscles. OK.
Which is weird to me because I feel like that would be negative
because you're looking for weakness.
And then obviously if the heads don't show, like that was a sign
of, oh, you have weakness, right?
Because it you didn't actually get the curl of that joint.
You mostly just got the joint pushing down.
I don't know. So it did, it did show a
relationship with the paper grip test.
So that's how they kind of were like, OK, yeah, I see it test
the same. Thing this is, is this have to
be done on the like flat on the floor or is it?
Not this one, the knuckle test. You can have them.
Just relax. Yeah, again, the problem is they
just don't like the wording. And then also these tests are
limited as well because Flexorhalicus longus and flexor
digitorm longus also perform these actions.
So it. And they're probably going to
take over. Take over.
So it's almost like how valid are these for the actual
intrinsics? It's kind of up in the air,
right? It's not like they necessarily
looked at like compared it with like EM GS to show if there
really were activated or anything like that, right?
I feel like that's a really, I feel like this is just a plug
for the Flexorhalicus longus. If you are not as familiar with
that muscle, it's there's such a great involvement of the FHL in
gait and just support of the arch and great toe and countless
things. So like this isn't your plug,
your action item in the middle of the episode to go.
If you don't know what the flexor holicus longus is or
where it runs, go find some anatomy.
Go find where it runs and where it originates and where it
inserts and and start to notice like in your foot.
Patients start looking at where if that is part of the problem
because it's something that's really easy to target.
For sure and I I feel like we should do an episode on flex.
I would love that. But also too the posterior Tib
too. I mean, if you look at the
insertion theoretically, it's literally everything on the on
the planar side of the foot catches everywhere, right.
And so yeah, like you said, like even though they're not they're
technically extrinsic muscles, they do have a really large role
in also helping support support that arch are.
We ready to go in rehab? Yep.
So now that we've identified that, oh, those are those bad
boys aren't doing their job anymore, now we got to do
something about it. And in general, there's kind of
four exercises that kind of been viewed to be used for intrinsic
foot muscle strength, or at least that have actually been
researched. I was going to.
Say tow yoga. And then there was another one.
They referred to it as toga. Toga.
Which I thought was funny. I don't know why.
So actually this is our plug. We did an episode on this like
way back when, I think one of our first years doing this
podcast, episode 72. It must have been like season 2
or something maybe probably actually.
So we did bonus content where we actually filmed ourselves doing
a whole episode or for that plantar fasciitis episode.
But there is a video that you can actually learn Toyoga.
It's episode 72 and we will link it down in the show notes below
for sure. And that one's also eligible for
CU. So if you go on
clinicallypressed.org, you can find it in the courses and it's
it's bonus content. So in the actual episode, I
can't remember if it was like .5 or .75, it might have been .5.
And then whatever the bonus content is, it adds like .25 to
your CU. So if you do both, then you get
like however many, yeah. So the exercises are toe spread.
So it's actually splaying your toes, great toe extension.
And that's great toe extension alone, right?
So it's just should be the great toe, not your toe came up and
all your little toes came up. Now it's just should be just
great toe and then there is just little toe extensions.
So again, just the little toes great toe stays down and then I
feel like this one, it has become pretty popular, the short
foot I. Feel like it is, but it also can
be one of the hardest for people to.
Pick I was going to say this one is just just motor learning Hell
for for people that that are doing it for the first time they
look at the best part is the looks athletes have when they do
this. They're literally just like
staring daggers at their foot as they're doing this to try and
get this done correctly. I think that's some of the fun
of it too though, like when you're 'cause I think it helps
or helps with that buy, you know, just like man, this is
actually really difficult. Why can't I do this?
I can't do this right. Oh yeah.
And then they look like when you explain it to them, they're
like, huh, What? Yeah, just do this.
I can't. I think we did short footer arch
doming in the. Well, I think we did.
I mean, you are pretty good at toy yoga.
Thanks. You're highly skilled at the
movements. You guys can test out your
skills. And what was really nice is the
literature that actually looked at like, OK, how do these
muscles activate during these exercises?
Actually showed a lot of them just activate all like pretty
much all of them have the same level of activation no matter
what exercise you choose. So it's not like you're this
one. I'm preferring to activate this
one over this one. No, like they tend to kind of
activate all together with them, which is kind of cool.
So you don't have to feel like you have to change it up too
much. Like you, you give these, Hey,
you're, you know, you're hitting what you need to hit, right?
I mean, it was really cool how they kind of identified.
That one of the studies used functional MRI so you actually
could actually identify each individual intrinsic foot muscle
that is. Pretty cool on its.
Activation, yeah, so like it really kind of took out the
guesswork on like oh surface EMG or fine wire EMG.
And again, it takes away that pain that sometimes is that is
accompanied. With because also pain.
If you have pain then obviously it's going to change your which
then it's like how? How true is this?
Absolutely. How true.
Yeah, no, that's a good point for sure.
So the studies that actually kind of looked at the the
effects of, OK, what if we do these strengthening and really
kind of looked at like 4 to six weeks, right.
So what did it look like at that point?
It just seems so long. Yeah.
And again, it's not like every day, right?
I think they did it like every other day, three days a week, or
it was like something like that. And training was shown to
improve the motor control there of these movements.
So the movements got easier, they got better at them.
They actually showed decreased navicular drop.
That's great. Yeah.
Improved balance and just overall foot strength improved,
right. So that sounds great to me.
Sign me up for that. One interesting thing that some
of the studies did look at, which is kind of an interesting
concept and actually might help with those like kind of
beginning stages of someone learning how to do this, is
looking at how neuromuscular electrical stimulation, so like
settings like Russian and stuff like that, how does that affect
our activation of these muscles during rehab?
That's a really good point. I've never thought to do Russian
on your. Foot, right.
And really there was no difference at the end of like
the trial, right? Like at the end of four weeks,
both groups did the same whether they did it on their own or
whether they had the neuromuscular electrical
stimulation to help. They still were able to increase
their strength decrease like all that stuff.
But what was interesting was the neuromuscular electrical
stimulation group saw the improvements, the initial
improvements in their ability to do all that two weeks sooner.
I mean, that's solid. Yeah.
That makes all the difference. Yeah, for sure.
Especially like in a sports season.
Yeah. And I the idea is kind of the
same as like when you have post ACL, right, You can't really as
much, as much as you really want to, you can't fire that quad.
So we do like Russian neuromuscular electrical
stimulation to help trying to get the body to remember how to
do that. It's same thing, same idea as
this. That's really cool.
Also, I think going back to that last point, I think this is also
something to stress with the people who you're working with
after they're doing this rehab. Like if someone has a flat foot,
like they're going to continue to have a flat foot, that's like
not our goal of changing that anatomy.
But if you do have a flat foot or, and and that's coming from
an increased navicular drop, you are going to want to strengthen
that. Whereas if you have a more like
if you have a higher arch that's a lot more rigid, you're going
to want a lot more flexibility. So I think just also having that
education piece also helps within this rehab because then
you're making strides and knowing that the attainable
goals that these athletes, patients, whoever you're working
with are trying to get to. Yeah, because I think that's
important to remember, like, 'cause like Pez, plaintiffs are
like, you know, flat feet. Sometimes that's just that's
anatomical. Sometimes that's just how their
foot developed. And you're not necessarily going
to change change that. You know.
So yeah, for sure. Also, what I thought was
interesting is just with like that neuromuscular electrical
stimulation, right? It also triggers that kind of
neurological input from from the foot and help kind of increases
that kind of reflexibility of the foot because remember there
are a lot of muscle spindles in there, right?
So if we can get it to actually be able to react to a sensory
kind of stimulus like stem, you should be able to see it's that
reflex pathway get better, especially if it's already been
diminished. 1 interesting thing is they compared it one just
even one session of neuromuscular electrical
stimulation and even just one session of it they saw
improvements and just how it activated.
That's awesome. But they also compared it to
like like a sham group. So they just did 10s, right.
So 10s just, oh, just you feel the tingle.
That's great, right. So like not trying to get muscle
contraction. And the the group that just had
10s on their on the planar surface of their skin did
improve balance. I could, I could see.
Why? Yeah, because the cutaneous
receptors were firing and, you know, and increased the sensory
input to the brain, and the brain was all about it.
And it was like, I know I can be efficient now.
I mean, ever since you brought up, I think in the I don't
remember what episode 'cause it wasn't tens 10s was a long time
ago that. Was a long time.
Ago, there was an episode more recently that you talked about
putting 10s on with rehab. Yeah.
And that's changed, like that's changed my practice.
Well, I'm glad, yeah. But yeah, so I thought, I
thought that was interesting. And, you know, right now we're
taking a neuromechanics class and it just really kind of, I
don't know it I, I felt like I, I could see that link and it was
like, oh, I know why that happened.
Talking about H reflexes and stuff, right?
Oh, the H reflex. So in general, what what could
we kind of use this kind of rehab concept for like any
pathologies that you could see this being beneficial And really
it is a lot of just lower extremity in general.
So it really doesn't have to just be foot issues.
You could really expand from there.
They've looked at chronic ankle instability slash ankle sprain
and saw improved balance and improved self reported function.
So the patients felt better. It could be used for
patellofemoral pain. That's just pause for saying
like that's crazy. I love this connection of how
like the foot can help with like a different joint.
Yes. And I mean, I know that we
talked about like it's all connected, but like just seeing
this right here and just taking a moment to recognize like the
impact of like the core of the foot can really and like you do
gait with everyday activities. Like you're usually walking on
your feet. I assume for most people you're
walking on your feet. The fact that it has so much
impact up the chain. Yeah, for sure.
And like obviously there's the Pez Planus component to it,
right? If you're, if you're, if you
have an uncontrolled arch, right, it's putting a lot of
rotational stress on to the Patel femoral joint.
But also just from thinking like the aspect of like this is where
the foot is, where the initial absorption of force is going to
be. And if it's not going to be
efficient, it's got to go somewhere and it could just go
right up to the chain to the knee to absorb that force,
right, right. And really when this is applied
to patellofemoral pain, they saw a decreased pain.
And obviously those that had an avicular drop or a significant
navicular drop, they saw a decrease in that.
This, I mean, the knee, you really have to think about like
the where is the alignment coming from?
It's either coming from the hip or it's coming from the ink.
The foot, yeah. Yeah, for sure.
The knee's not just doing this on its own.
And then, of course, plantar fasciitis, plantar fasciopathy,
right, help kind of support that passive tissue.
And again, we've already kind of talked about how this
musculature might actually be doing a lot to take load off of
the plantar fascia that maybe we're not necessarily accounting
for. Sweet.
So what's your action item from this?
The intrinsic foot muscles are just very important to movement
and we should probably be considering them for most of our
lower extremity rehab. And if you have someone who's
having a hard time trying to activate them, don't give up on
them, just throw them on some rush.
Especially that short foot man. Yeah.
Yeah, that's short foot. It takes a lot of just
dedication to that bad boy. Yeah, action item.
Check out our bonus content of plantar fasciitis so you can
learn toe yoga yourself if you haven't already or toga is some
like to call it also action item.
Check out the flexor halicus lungs.
I know it's not a foot intrinsic muscle, but it's important in
foot musculature and gait and repetitive plantar flexion.
There's so much it's important and so check that muscle out
while you're while you're looking at the rest of the
intrinsic muscles. Again, if you guys are
interested in the CU clinically pressed and athletic training
chat. Thank you again so much.
We have this LinkedIn the show notes below or in episode
description wherever you're listening.
If you're interested in the in the references Randy used for
this episode. How many about did you use for
this one? I think we.
Got to about 20. Nice or got close to it.
OK, so those will be on our website again linked below.
Everything is in the show notes which also is a great plug for
our Med bridge if you are interested in like a more long
term subscription of Cusi think we have about 35.
I think we have about 35 just for AT corner.
Totally smokes. Yeah.
So it so you can't, you can't do all of them through us yet.
But we have about 35 right now which are all up on
clinicallypressed.org. But if you're interested in like
a more long term subscription like a one year which this is a
reporting year but also accounts for next reporting cycle since
you'll have it through the part of the next reporting cycle, you
can use code 80 corner for $101.00 off Med Bridge.
Yeah, and some subscriptions also have like a lot of other
cool features that you can use for your practice too.
And with that, oh, we also do different types of episodes, not
all C us obviously, but we also have story episodes with stories
from real athletic trainers. We are soon doing a softball
stories episode. So make sure you keep an eye out
on our Instagram stories if you want to submit your softball
stories. And I think that's it.
Thank you for helping us showcase athletic training
behind the tape. Bye.