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Hi, everybody. My name's Jo Gibson and I'm a clinical physiotherapy specialist working at the Liverpool Upper Limb Unit in Liverpool in the UK and also a consultant in private practice. Tonight, the subject is sleeper stretchers. So, Julia posted on the Clinical Edge public page and said, "Do I still advocate sleeper stretches?" And there's certainly been some fairly passionate defenses of those on the page today. So, I'm going to talk a little bit about the background, a little bit about what the evidence is around them and really where they fit or don't fit in my practice.

Now, I think if we look at posterior shoulder tightness as an entity, if you like, there's no doubt we can measure it very effectively. Whether we use internal rotation in abduction or whether we use cross adduction or even a low cross adduction stretch, there are lots of studies showing us that actually as long as we standardise our start position, we can measure it very effectively.

But why would we want to measure it? There are quite a few studies showing the correlation between posterior shoulder tightness, a worsening in tightness and development of scapular dyskinesis, if we think that's relevant. There are also studies showing us that a GIRD or a side-to-side difference of 20 degrees or more or in some studies 15 degrees or more, so that's ostensibly in this position.

So again, at the side-to-side difference of 15 or 20 degrees greater also seems to correlate with weakness in the external rotators but also a relative change in the ratio between external rotation and internal rotation. And in throwing athletes it definitely seems to correlate highly with a loss of eccentric external rotation strength.

So, it definitely seems to show us something. Interestingly, also there's some work done by Olivier et al and a couple of other authors that have also looked at the correlation with developing a positive GIRD in relation to lower quadrant injury, and also the predictive value in crickets of having a positive GIRD and that as a predictor for a non-contact lower quadrant injury. So, it would seem that posterior shoulder tightness does tell us something, but what actually does it tell us? And is it simply the issue in terms of we need to address the tightness or is it just a window to something else?

Now, if we look at the evidence about posterior shoulder tightness, the bottom line is the majority of it has come from baseball pitching or overhead athletes and there was no doubt that if you measure posterior shoulder tightness and look at the comparison side-to-side in overhead athletes, at the beginning of the season there's no doubt that those have a significant side-to-side difference have up to a four times greater risk of developing shoulder pain in the subsequent season.

Now, that sounds pretty convincing and it's a similar figure for developing elbow injury. But I think we have to be very honest. Those studies come from some very respected researchers such as Kevin Wilk and Lintner et al, but actually a recent systematic review done by Keller et al in 2018 actually failed to show any true causation of having posterior shoulder tightness and actually predicting overhead injury that lacks statistical significance. So, it's a little bit like external rotation weakness.

If you have posterior shoulder tightness and you have a sudden increase in load in terms of training volume or fixture congestion, then if you have posterior shoulder tightness, it does seem that your risk is greater. In certain select groups, certainly a baseball pitching group, there's probably more convincing evidence, but that Keller et al systematic review actually incorporated over 2000 overhead athletes and was unable to show any true causation. So, I think that's important to consider.

There's lots of things looking at what's the best stretch and what gives you the most effective stretch. But one of the issues is a lot of this is done in normal populations without pain.

If you listen to Kevin Laudner and Phil McClure who are great American researchers who have looked a lot of posterior shoulder tightness, then one would advocate the cross adduction stretch as being the most effective, the other would advocate the sleeper stretch. But the issue is when we see the increase in range of movement, when people stretch over a four to six-week period, three stretches twice a day for that period of time, we see increases of between three and seven degrees, which are really tiny increases in the great scheme of things. Again, we don't know if that's clinically significant so we kind of need more work done in pathological populations to understand.

It would seem that if you do stretches with an overhead population, it does seem to have some preventative value. But again, we lack big numbers studies and actually those people who had pain and seeing if it changed the outcome of their shoulder pain. Now there's no doubt it continues to be suggested as part of maintenance and a common feature of interventions for shoulder pain. And as you're probably aware, there has been a couple of studies that have actually looked at the prevalence of posterior shoulder tightness, even in our normal shoulder pain populations, so a non-sporting population. Now we have to try and understand what's driving this shoulder tightness. Interestingly, if you look at some studies on pitchers or on swimmers, if you measured their GIRD before a training session and measure it afterwards, there's an immediate loss of range after a training session. Interestingly, it only maintains for about 24 hours.

If you do an intervention, if you get them moving, do some thoracic rotation, a general kind of warmup drill, you can actually resolve that restriction almost immediately. So, we need to start questioning what is it that's driving that stiffness.

There's no doubt that much of the emphasis on sleeper stretches and cross adduction stretches has really come from the belief that essentially that posterior shoulder tightness very much relates to capsular changes. So, it was believed that because of the massive eccentric load on that shoulder at the end of throwing, tensile loads on the shoulder that we've got hyperplasia, we got fibrosis and true changes within the capsular tissue.

Now, that kind of makes a lot of sense and there's also studies that show if you do sequential imaging of endurance swimmers or people who lift very heavy weights in the gym, we'll see some gradual thickening of that posterior bursa and some reactive capsular changes in response to that.

The problem is we don't know at what point they become pathological and it varies massively between different patient groups so we can see those features, but what does it mean to us clinically? Now, when this question was posted on the Clinical Edge Facebook page, Penny was very kind of keen to defend poster stretches and said it had a massive role in her practice and that for patients it really brought them in because they could see immediate changes.

There's no doubt that we see lots of studies that talk about the role of manual therapy, of using ice, using dry needling, using muscle energy techniques, lots of different things to effect an immediate change in those GIRD or cross adduction measurements. There's actually a study recently published by Romano et al that showed the actually doing SI joint stretches was as effective or more effective in some overhead athletes than actually doing a sleeper stretch in improving their glenohumeral internal rotation range.

But if we're getting immediate changes, actually what are we influencing? There's another study recently by Toran et al and I'll post some of these on the Facebook link that again show that adding stretching to our usual treatment for subacromial pain in the normal population may also have some benefit but again, not massive number studies.

So, I guess, guys, what we have to ask ourselves, there is some evidence that is a feature of people with shoulder pain. There is definitely evidence that if you have it you may have a slightly increased risk of developing shoulder pain if you throw a ball or do an overhead sport and there's also no doubt that if you add it into an intervention and you change that GIRD, so there is a change in GIRD, I'm not sure we can say the stretching is causing that, but definitely if there is an improvement over a period of time that also seems to correlate with an improvement in symptoms.

But what are we stretching? So, the first thing I would say is if we look at the posterior capsule particularly, the bottom line is in arthroscopic studies when they looked at the capsule of people with a positive GIRD, they were unable to demonstrate any evidence of capsular fibrosis in the majority of that cohort. The only people that they were able to demonstrate any true capsular change were a small group of elite throwers at the very end of their throwing career. So, we lack an evidence base for true capsular fibrosis in that posterior inferior aspect of the capsule. And clearly that's what we're stretching when we're up here and more that pure posteromedial part of that posterior capsule in this position.

Again, studies failed to demonstrate any true fibrosis in that group. Now, the other thing that we see is people report these immediate changes when they do any sort of intervention to that posterior shoulder, and of course that's very satisfying, but what that tells us is it's not driven by the capsule.

There's absolutely no doubt if we have true capsular hyperplasia, true capsular fibrosis, as we see in maybe somebody with a true frozen shoulder, somebody who's got postoperative reactive changes and that very small percentage of throwers that might have it at the end of their career. The bottom line is you need a lot of me on a tiny area like this to get any deformation in that capsular tissue. A manual therapy and actually the stretches our patients do actually just are not going to have an effect.

The other thing that we have to consider in our throwing population is the concept of retroversion. So, if you've thrown from a very young age, we know because of the torsional load on your humerus and actually on the growth plates that you can actually get retroversion and it doesn't resolve as you get older. What's the effect of that?

Well, it will shift your total range of rotational range, so if you had somebody that presented to you who was a thrower that had a reduction side-to-side, it would be absolutely essential to look at the total range of rotational movement and see whether or not the total arc was comparable side-to-side or whether that deficit actually was maintained when you compare those two ranges, a very important consideration.

Now, clearly if somebody's got retroversion, we can't change it, and so how do we know it's adaptational? Well, if you follow people up over time, whether it's elite tennis players, elite throwers, baseball pitchers, whatever, and also rugby players interestingly, and some cricket players, we know that they do develop a reduction in their internal rotation range over time. As I say, it's very important to be clear whether or not that's a bony adaptation if they've done their sports from a very young age, because in that case, we obviously can't do anything about it.

We can't change the bony anatomy, but similarly in terms of a posterior capsular tightness, actually what most of these things would suggest is it doesn't actually relate to the capsule. It's more a muscle stiffness problem. In terms of true capsular change, we just don't know at what point it becomes pathological, but what's interesting is that when we do look at that posterior shoulder tightness, the threshold for when it potentially causes problems varies from sport to sport. There's a general acceptance that a side-to-side difference of between 15 and 20 degrees does increase your risk of developing shoulder injury. However, we don't know what happens if you do an intervention for that.

Now, what is the driver if we do all those interventions like muscle energy techniques, manual therapy. I know myself, I have a video where I show mobilising the cervical spine, doing some gentle massage, doing some recruitments of the cuff through range, all those three interventions improve somebody's very positive GIRD. Three different patients, always a positive GIRD, all significant improvement, very much like Penny reported on the Facebook page. Basically, that is because it's a muscle stiffness issue. There are several studies now using very posh tools like elastography, which you can do either without sound or with MRI and both basically look at muscle stiffness and that's been shown very clearly.

There are theories as to what drives that muscle stiffness. Remember if muscles are fatigued, they'll rest in their shortened position so it could potentially be the posterior cuff is fatigued and therefore resting in its shortened position. A recent editorial viewpoint by Kevin Hall and John Borstad suggested that maybe it was protective so that muscle stiffness was protective in people with shoulder pain as a result of glenohumeral joint capsule afference. But if we're honest, we don't really know. But we do know that it's a muscle stiffness issue because fundamentally it changes so quickly with any of our interventions.

So, does that mean we shouldn't be stretching? There's no doubt a lot of patients like stretching, it gives them a good feel where they're stiff in the joints and we do see some immediate changes. However, if that muscle stiffness is driven by a muscle that's tired or muscles that aren't strong enough to do their job, then arguably we'll get better value from actually re-educating the muscles themselves and this is where it's confusing when we tried to extrapolate stuff from the literature.

The bottom line is when stretching has been added in, it's been added in into other interventions and so actually we don't know if it's the muscle exercises people do or the stretches themselves that have the most benefit. There is no doubt increasing questioning of the effectiveness of stretching as a standalone modality and certainly for me, my concern about things like a sleeper stretch as simply that it puts the joints in a position which if it's already painful, whams the humeral head up into the underside of the rotator cuff.

I'm not telling you not to do a sleeper stretch. It doesn't figure as part of my rehabilitation, but that's because if I've got somebody who's got muscle stiffness driving that glenohumeral internal rotation deficit, the bottom line is I know if I just get their cuff and their scapular muscles doing their job through range, I will change that restriction.

Studies that show doing thoracic rotation and upper limb movements have a similar effect. Probably relate to the fact that we know if we initiate our shoulder exercises with the thoracic spine, we get better local recruitment. Some clubs are using the GIRD as a measure of whether or not athletes have recovered, both on returns at play, but also after a training session before they do another training session. They test they're GIRD, they do a switch on drill, they see if the GIRD changes. If it does and it's restored back to normal, then they can carry on. If it doesn't, they would interpret that as saying that the athlete is still fatigued and they need a little bit more recovery time.

So, it would seem that the GIRD in terms of muscle stiffness is a useful objective measure. Certainly, for me, if I've got athletes going back to doing a training session, I'll do a quick screen on the pitch and remember it has been shown to correlate highly with glenohumeral external rotation weakness. However, that weakness could just be driven because the muscle's fatigued and if we get it doing its job again, we seem to get a quick recovery. So as a measure of your exercise prescription and its efficacy, it definitely seems to have a role and it also seems to be a useful measure of whether or not the rotator cuff is coping with what it's being asked to do.

However, what I would say to you is if it's a muscle stiffness issue, we're can get far better value from targeting the muscle system and actually reeducating that to do its job and make sure that patient has the capacity and the endurance to do the thing that they want to do.

Now when it comes to true capsular restriction, this is a really interesting one because if we look at frozen shoulder, we do have some studies that shows if patients do sustained stretching, particularly with the addition of damp heat, then over a period of eight weeks, as long as they do it four or five times a day and a minimum of five reps, they may get some benefits. So, in a patient that was postop with true capsular stiffness, if we had somebody who'd had a true frozen shoulder with some posterior stiffness then perhaps that would be a role.

But in patients that we're trying to target a part of the capsule more specifically, so let's say it is this posterior inferior capsule across adduction, one thing that seems to be giving us a little bit more promise is the concept of eccentric exercise. We recognise that trying to deform the capsular tissue is not without its flaws because simply we don't have enough force, if you like, to get any elastic deformation in that structure.

It's very difficult for patients to affect that too and it requires a lot of stretching, a lot of sustain to actually get any change. We don't have a massive evidence-based for eccentrics in the upper quadrants at the moment, but there is some emerging evidence that's really been translated from the lower quadrant suggesting that we can get fibral lengthening or sarcomerogenesis as a response to heavy load eccentrics.

So, if you can imagine if I got somebody lying down, I usually do this with a band attached round their foot, the knee bent up, the arm supported, so I'm really targeting that posterior cuff and essentially, I'm going to take them into external rotation, straighten my leg out. So now I've got maximum load and then control that eccentric phase to get a lengthening effect at the back of the shoulder.

Now the studies that I've looked at in the lower quadrant actually showed that they only needed to do that three times a week using a dosage of three sets of six or three sets of eight, which isn't a huge amount. I have to say if I use it in my post-ops or people with a true capsular component, I tend to get them to do it every day and they'll generally start to see a significant change within about four weeks.

Why when doing some initiation work with these patients do some respond to internally directed rotation and others external rotation despite having glenohumeral internal rotation deficits? I think because what we see in any of these range of movement restrictions are ostensibly, unless we've got somebody with a history of, let's say, an elite athlete at the end of their throwing career, somebody who's had surgery, somebody who's had a frozen shoulder or somebody who's had trauma, stiffness that we see is generally muscle mediated.

So, what we know is essentially I could treat somebody's neck, treat somebody's glenohumeral joint, do some massage, do muscle energy technique, do some dry needling. I'm not advocating you should do any of those things, but essentially, they all share the same thing as they modulate muscle stiffness.

So essentially what I would say is let's base what we understand from the current literature which is generally the posterior cuff just needs to get doing its job and we may need to make sure that shoulder has the capacity to do what somebody can do. And actually, if we just get that system working differently and remind the cuff to do its job, then ostensibly we resolve a lot of these stiffness issues almost immediately.

Ann Cools has done a lovely study recently showing that just doing external rotation through range with a loop of TheraBand through range several times is a very nice way of just getting the scapula and the rotator cuff muscles engaged in a way that replicates people without shoulder pain and again, if I do that as an intervention in my clinic, it's very rare that that doesn't have a significant improvement on that internal rotation deficit.

I think in terms of what Penny said on the public Facebook page, if patients see that this is stiff, you do an intervention and they see it's lots better, of course it's a great way to get them on board. But for me, if I can do something active that's about them getting their muscle system working in a different way to get that change, then that's very empowering that they can do that for themselves and then it becomes a useful measure for me of the effectiveness of my exercise prescription.

So more about modulation. I think anything we do is about modulating muscle stiffness. I'm not sure if modulating is a bad word these days, but the bottom line is if we give the shoulder sensory input, if we even use a visual cue, an auditory cue, we do something we put our hands on, do any of the interventions we've talked about, all these things seem to modulate muscle stiffness. Probably in terms of giving patients confidence, probably in terms of challenging their movements and expectation, there are lots of potential mechanisms. But for me, the reason I ostensibly target the posterior cuff in the majority of my patients is purely because I think that's where the evidence based supports the majority of deficits are.

In terms of the post fracture patient, if I had somebody who was post fracture with secondary capsular stiffness, so true capsular fibrosis, which is likely given the trauma involved or the mechanism or energy involved, then I would be looking ... Stretching may have a role but I would actually be looking more to those eccentric exercises as long as pain isn't preventer of that. So, guys, what I would say to you is if you have somebody with a positive GIRD, if you're working in sport, there is no doubt that it does ... if it changes or it deteriorates and gets worse, there is no doubt that if you do something about it, you're probably going to have a positive effect on reducing the likelihood of your athlete developing pain.

If we're honest, the threshold for pathology is different in different athletes, but it certainly seems to have some relevance in monitoring. What we need to look at I think is whether actually interventions that are designed to address fatigue rather than just looking at addressing the impacts of that fatigue in terms of stiffness, then potentially we'll get better outcomes long term. But if you have somebody with shoulder pain who isn't an elite athlete, what does GIRD tell you? Well, if it changes when you do anything and it changes significantly, it's telling you it's just muscle stiffness and it's not a true capsular component. If somebody has a history of trauma, of surgery, long, long standing shoulder pain or a true frozen shoulder, then it may truly be capsular and then you might want to look at a slightly different intervention. Because stretching is probably going to take your patient at least eight weeks before they start to see any significant difference based on the current evidence base.

So, guys, that's a real whistle stop tour through the posterior capsular stiffness. There's a couple of great resources, a lovely view point in the Journal of Orthopedic Sports and Physical Therapy by Kevin Hall and John Borstad, which is a lovely summary of some of the current thinking around this. For me, there's no doubt, I'll often look at it as a measure. As I say with my athletes, going back to sport, it's a useful measure of the effectiveness of my exercise prescription, but also how they're coping in terms of endurance. And as I say, in terms of my normal population, again, it's potentially a nice measure of the effectiveness of my exercise prescription, but I don't use it as frequently in that particular group because I don't expect them to have a true capsule driver to their stiffness.

So, guys, thank you so much for those who have posted questions and I really hope you found the content useful. See you again very soon. Bye for now.