This is Brent of the Brookbush Institute, bringing you another muscle
length test. In this video we're going to do the lat length test.
Now the lat length test we use to determine if the latissimus dorsi is one
of the muscles restricting shoulder flexion. I'm then going to show you some
of the if-then scenarios, that will help you determine whether the lats, the
shorter internal rotators of the shoulder, or both are involved. I'm going
to have my friend Melissa come out, she's gonna help me demonstrate. So what the
lat length test really is, is a shoulder flexion test. It's just a very quick
shoulder flexion test, just like shoulder flexion goniometry. Alright so what I'm
gonna have you do, sorry start here, laying flat. I'm going to have you try to
bring this part of your forearm back to the table in front of you. Alright
there you go, so you guys see. We know that normal shoulder flexion is between
100 and 185 degrees, so she's missing some shoulder flexion right.
The lat length test part comes in and it goes, if you really push it, can you
push it, just go all the way down to the table, go for it. Alright she pushes
her arms down and does this, did you guys see all this lumbar extension. I have to
start thinking to myself all right the muscles that could restrict shoulder
flexion, I got the teres major, subscapularis, the latissimus dorsi
pectoralis major probably not likely in this position. Of those muscles, which one
crosses the lumbar spine, well the lattisimus dorsi crosses the lumbar
spine. Not only does it cross the lumbar spine, but it will cause lumbar extension,
which is exactly what I saw. So when I told Melissa to go ahead and push it, or
I could even add a little overpressure, obviously you wouldn't want to do that to a
painful shoulder. But if you added a little overpressure and it pulled her into
lumbar extension, I know that she ran out of room from her lats, and had to shorten
it somewhere else. So this would be a positive lat length test. I know that the
lats are one of the structures that could be restricting her shoulder
flexion. There's another way to go about this,
we'll start over. This time we'll put her in a hook lying
position. Now hook lying position posteriorly tilts the pelvis a little bit,
flattens up the lumbar spine and it kind of anchors the pelvis
a little bit, so that lumbar extension is not as easy to get in this position. Now
I have her go ahead and pull this way, and usually what you'll have is in that
same individual, somebody will actually look like they're even more restricted
and shoulder flexion. I could test to see how much the lats are contributing to
this by going okay, let's go ahead and bring your legs up, push you into a
posterior tilt, and you guys see how when I pushed her into a posterior tilt her
arms came up a little bit. That's a pretty good sign that her lats are
contributing to the restriction on her shoulders. So that's all the lat length
test does. Is the lat one of the muscles restricting shoulder flexion, the problem
with that is, is it doesn't do all that much for us from a practical application
standpoint. I still don't know if it's subscapularis and teres major
contributing to this. So how would I figure that out? Well I could go back to
my goniometry, if you guys remember shoulder external rotation is done here.
Alright, why shoulder external rotation? Well subscapularis, teres major,
latissimus dorsi are all internal rotators. But if i go and put the arm
back in ninety degrees of shoulder abduction, i just shortened the lats a little
bit right. It's like halfway through a lat pulldown. So these structures that
are more likely to restrict this range of motion in this position are the
shorter external rotators. So if I had positive lat length tests, and then I did
external rotation and she had full 95 degrees, I might be able to deduce that
it's the lats restricting her shoulder flexion, and
the short internal rotators, teres major and subscapularis. If I had a
positive lat length test and she only had 85 or 80 degrees of shoulder
external rotation, then I know it's probably teres major, subscapularis and
latissimus dorsi. If I had a negative lat length test right, so that's
I did those lat length tests, she had restricted shoulder flexion but
pulling you into a posterior pelvic tilt, or laying your legs flat didn't change
anything. So pulling your legs this way didn't cause your arms to come up, laying
your legs flat didn't cause your lumbar spine to go into extension right, that's
a negative lat length test. But I came over here and she was still restricted
in internal rotation, then I know it's not my latissimus dorsi but my short
internal rotators that are causing a restriction in shoulder flexion. You
guys catch all that. So let me review this a little bit. If I had positive lat
length test, negative shoulder external rotation. So somebody had normal external
rotation, then it's probably just the lats. If I had positive lat length test, and
somebody had reduced shoulder external rotation, they had a limit in external
rotation, then it's probably not only the latissimus dorsi, but the subscapularis
and teres major. If I didn't get a positive lat length test, but I have a
restriction in external rotation, then it's probably the subscapularis and teres
major, and not the lats. Now on a side note, if we take this back to movement
impairment, generally speaking the only time I find
that the lats are tight without the subscapularis and teres major coming along
for the ride, is when latissimus dorsi over activity is not stemming from upper
body dysfunction, but from lumbo-pelvic hip dysfunction.
In other words somebody has an anterior pelvic tilt maybe with some low back
pain, and you notice limited shoulder flexion, however that limited shoulder
flexion is caused from over activity of the latissimus dorsi as a lumbar
extensor, and your intervention, your corrective exercise, your physical
therapy, your therapeutic modalities should be focused on trying to fix an
anterior pelvic tilt, not this. I'm willing to bet that if it's upper-body
dysfunction that's causing the limit in shoulder flexion, but not only will your
lats be tight, but so will your teres major, and your subscapularis along with
potentially your anterior tippers of your scapula. Now if you guys want to
know how to differentiate between lumbo-pelvic hip complex and upper body
dysfunction, go check out the videos on the overhead squat assessment,
particularly the overhead squat assessment sign clusters. You'll see one
for upper body dysfunction, one for lumbo-pelvic hip dysfunction, one for
lower leg dysfunctional, one for asymmetrical weight shift. Go over the
ones for upper body and lumbo-pelvic hip. I think you'll be able to differentiate
those two dysfunctions, go back and start thinking about the lat length test
versus external rotation goniometry, and think about how those play out positive
or a negative lat length test, restricted or normal external rotation. I think
before you know it you'll have a shorter list of muscles that could be
restricting this motion. Which means less release techniques, less lengthening
techniques, and less mobilization techniques that you'll need, which means
a more refined program, a more effective program, a more efficient program and
hopefully better results. I'll talk with you guys soon.