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This is Brent of the Brookbush Institute
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bringing you guys a muscle length test.
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In this video we're going to go over the
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gastroc soleus length test. I'm going to
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show you guys how to take that maybe one
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step further, and maybe determine whether
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the peroneal and fibularis muscles or
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the posterior tib is restricting plantar
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flexion. We're also going to talk about
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the strengths and weaknesses of this
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particular muscle length test. I'm going
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to have my friend Melissa come out, she's
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going to help me demonstrate. Now the
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idea behind this test is just our
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knowledge of anatomy. So if let's say I
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did the overhead squat assessment, I
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determined that the lower extremity was
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the cause of my issues. I did goniometry
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for dorsiflexion I got a
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restriction, and now I'm trying to figure
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out which muscle is restricting
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dorsiflexion, so I can target my
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intervention there. If my knee is in
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extension I have lengthened the one
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plantar flexor that actually crosses the
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knee, which is the gastrocnemius. So the idea
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here is if i push into dorsiflexion and
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it's restricted knee extension, there's a
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good chance the gastrocnemius is involved. I'm
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then going to compare that to putting
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Melissa here in knee flexion, did I gain
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dorsiflexion, was dorsiflexion the same.
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If dorsiflexion is still restricted then
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maybe it's one of the dorsi flexors that
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does not cross the knee, like the soleus.
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If I gained a bunch of dorsiflexion back
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with knee flexion, then I have a pretty
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good idea that the one muscle that
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restricts plantar flexion that i
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shortened is actually responsible, which
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in this case is the gastrocnemius. Now I might
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be able to even take this a step further.
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If i push somebody into dorsiflexion,
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actually let's put them back in this
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position, since neither your posterior
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tib nor your fibularis / peroneal
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muscles cross the knee we can leave it
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in this position. If I pull into
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dorsiflexion this way and I evert the
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ankle, that would shorten the peroneal
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muscles. If I shorten the peroneal
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muscles a little bit i would have more
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slack, which means i might be able to
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gain dorsiflexion. If that were the case
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if i push you into eversion and i
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gained some dorsiflexion, then I know her
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peroneals are contributing to this
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restriction in plantar flexion. Now I
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can do the same thing with the posterior
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tib, although the posterior tib is rarely
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a restrictor of plantar flexion because
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it's rarely short and overactive. I could
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go into inversion and see if that gained
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me dorsiflexion, in Melissa's case
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that does not. Alright so we could take
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the gastroc soleus length test up a
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notch and add fibularis and posterior
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tib, but there is one glaring flaw to
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this test and we need to discuss it. The
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truth of the matter is, in this position
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regardless of the fact that my gastroc
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is now lengthened, my soleus as well as
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my other plantar flexors do not cross
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the knee, so they could care less whether
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my knee was extended or flexed. What this
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means is is let's say for an example my
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soleus is tight, my soleus is short and
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overactive, i'm going to be restricted in
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this position and i'm also going to be
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restricted in this position. I'm going to
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be restricted if i evert, i'm going to be
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restricted if I invert. If my soleus is
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restricted you will get no other
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information from this test, all you will
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know is that the soleus and potentially
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all of the other plantar flexors are
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contributing to Melissa's lack of dorsiflexion.
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In fact the only results that
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give us any information from this
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particular exam is if I get more range
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of motion when I get into knee flexion,
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meaning my gastroc is the primary
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culprit restricting dorsiflexion. If my
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soleus is not the primary culprit then I
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also may get that differentiation
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between the peroneal and posterior tib. I
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know that was a lot to take in, that's a
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lot of if's, then's. So let's take it all the
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way back down to the simplest part of
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this exam, this is supposed to be gastrocnemius,
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this is supposed to be soleus. The truth
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of the matter is, is this is all plantar
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flexors, this is all plantar flexors
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minus the gastrocnemius. If you get a change
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from here to here, then there's a good
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chance that your gastroc is the primary
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restrictor. If your gastroc and soleus
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are out of the equation right, they don't
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seem to be the ones restricting
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dorsiflexion, because you gain a
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dorsiflexion in this position, you can
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then try the eversion-inversion thing
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to see where some of that other
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restriction might be coming from. Alright
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guys so that's a fairly complicated way
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of getting through this muscle length
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test, but I think if you give it some
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practice, you give it some thought, you'll
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start to see how you can use this test
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to potentially differentiate some of the
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structures that are restricting
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dorsiflexion, after you've done your
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goniometric assessment so that you can
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narrow down your corrective exercise
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intervention, or if obviously if you're a
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therapist or licensed professional, what
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manual techniques you're going to use to
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help gain dorsiflexion back. I look
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forward to talking to
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you guys more. I hope this test adds a
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little more accuracy to your