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