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Hey everyone. Hope all is well. Here is the citation for the article we will be discussing this month.
Vega toro AS, Cools AM, De oliveira AS. Instruction and feedback for conscious contraction of the abdominal muscles increases the scapular muscles activation during shoulder exercises. Man Ther. 2016;25:11-8.
During the shoulder weekend course, we spoke a lot about scapular muscle activation and re-training. I thought this article was interesting because it added to anecdotal observations that I have seen regarding core activation and shoulder strength.
So, Let’s get to the article
It starts with a quick review of previous studies that show that minimizing the upper trap ( UT) to serratus (SA) ratio can improve serratus selective strengthening. They also note that activation of ipsilateral external obliques (OE) can increase activation of the SA by transferring mechanical tension to the SA tendon. One study tried thoracic and pelvic external supports but these did not change the UT/SA ratio, so the authors want to look at what happens with conscious activation of the core muscles.
Methods: N= 65 young healthies. Surface EMG electrodes were placed bilaterally on UT, middle trap (MT) , lower trap ( LT), SA, rectus abd (RA), external obliques (OE), and internal obliques (OI). All of the sensor placements seem reasonable, but have a look at the OE and OI placement: “The OE muscle sensor was placed 15 cm lateral to the umbilicus with bars parallel-oriented to the muscle fiber’s direction, just below the convexity of the 10th rib. The OI sensor was placed below the external oblique electrodes and just superior to the inguinal ligament.”
They performed MIVCs for all muscles involved in random order to get a baseline, and then measured muscle activity when performing 5 exercises: isometric inferior glide, isometric low row, wall slide, wall press, and knee push up.
They found the following:
conscious abdominal contraction increased activation of RA, OI, and OE in all exercises, which makes total sense.
SA significantly increased its activity in all 5 exercises with core activation.
All three parts of the trapezius did not increase activation with isometric exercises and core activation, and all there parts of the trapezius DID significantly increase their activation with the dynamic exercises (wall slide, wall press, knee push up) with core activation.
SA had its highest MVIC with the isometric exercises with core contraction.
Therefore, the authors conclude that isometric exercises for the SA with core activation cues could be a good way to retrain scapular muscles as this isometric exercise does not increase trapezius muscle activation.
Okay!
A few points I’d like to discuss:1. Take a look at Table 2. You can see that the Internal oblique by far has the most activation and largest increase in activation for every single exercise. Also, the LEFT internal oblique is also significantly higher activation than the right internal oblique in all conditions. All subjects are right handed. What the heck is going on here? Is the placement of the electrode picking up transverse abdominis activation? The authors note a previous association between external obliques and serratus ipsilaterally. Is it possible that a relationship exists between serratus and internal obliques contralaterally? Is this just a measurement fluke? This is not mentioned at all in the discussion of the paper.
2. Again, internal obliques really kick in hard when attempting to do core activation. You know when you try to palpate the transverse abdominis medial to the ASIS… how confident are you that you are really palpating TA and not the internal oblique?
3. How do you typically attempt to re-train or increase serratus activation in your patients? Does this study make you re-think how you are teaching or cueing your exercises for serratus?
4. The authors note in the limitations of the study that pain may alter the normal activation patterns of these force couples. Are you aware of any research on how pain alters these activation patterns in the scapula?
5. How can we take this and apply it to the clinic? I want to use those isometric exercises with core activation with patients with SA weakness, but it also makes me want to really cue core activation for all scapular rehab, as SA was facilitated significantly6. Anecdotally, In lifting, bracing the core is an easy way to increase your military press or bench press max by a few pounds and feels more stable. I had used this cue before, and its well known in those circles, but its nice to know there is some good evidence behind it. Do you have any other cues that you’ve used with lifters to facilitate better scapular or GH mechanics? I also use the “break the bar” cue in the bench press or military press to increase RTC activation, but I am not aware of any studies that show this actually happens.
Cheers! Hope to have a good discussion about this article!
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Great post Scott! As I read your discussion, PNF patterns and principles come to mind..(PNF is for orthopedic patients too!). I am going to contribute to the ‘discussion’, referencing your comments under #1 with a few pictures. Thoughts?
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1)I think it would be reasonable to associate the left IO activity with the subjects being right handed and that the ipsilateral association of EO and SA may be related to contralateral activation of IO. It is surprising that the authors did not explain this as part of the discussion, especially since the IO was shown to be the most active muscle throughout their testing.
2)Good question. Based on this study and anatomy I think it’s hard to say with any confidence that you are only on one muscle when palpating the abdomen. Most of the time when I teach patients to isolate core muscle I’m more worried that they are not using their RA for everything and going into a mini-crunch. I think research is showing that isolating core muscles isn’t a largely effective intervention technique and many patients struggle with this intervention, so with some patients I think it’s better to skip this step all together and work on general core activation instead of breaking it down.
3)I use wall-slides all too much probably. I am going to start adding the isometric SA exercises. I gave those out to a couple patients yesterday and they seemed to respond well to them.
4)No, but this sounds like an interesting read.
5)It obviously depends on the patient and how much SA plays into their dysfunction. If they are someone with SA weakness and that is driving their presentation, then starting with the isometric exercises seems like a great place to start. However, if they have poor motor control then breaking down their functional activity into smaller tasks and focusing on scapular kinematics with some core activation might be the best intervention for them.My response for question 1 explains my thought process for the pictures Myra posted, but also Go Steelers.
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1. I think like Erik said, it makes some sense that if there is an association between ipsilateral shoulder motion and ipsilateral EO then there likely would be contralateral IO activation as well in order to reinforce that particular postural correction.
2. Honestly I have vary little confidence in being able to accurately palpate TA versus IO, especially in any patient that has a BMI over 25 (a large number of patients). Typically what I am looking for is 1. can the person contract without firing their RA and 2. can they hold a contraction with diaphragmatic relaxation.
3. I use several different SA exercises in the clinic, including the push up plus, sidelying flexion, scapular DB punch. I think that the isometric exercises presented here might be great options for irritable shoulders that still need scapular strengthening. I have one gentleman in his 50’s right now who has a labral tear and multiple comorbidities, and this is the second time he is trying conservative management because his ortho is hesitant to operate on him currently. He doesn’t tolerate a lot of therex but obviously needs to improve these force couples. I think both of these isometric exercises would be great options for him.
4. I tried to quickly search for this issue specifically and couldn’t find anything, but would be interested in what others might have found.
5. I think that this just highlights the importance of performing more complex and compound movements for shoulder rehab if appropriate for the patient. I bet that doing a squat into a shoulder extension probably reproduces increased abdominal contraction and facilitation of scapular stabilizer contraction as well. I like the idea of performing more isolated movements earlier in the rehab process, but I think that cueing for abdominal contraction during more complex movements really should be our focus.
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I rarely, if ever, address or cue core activation with scapular shoulder exercises. It makes complete sense as we know movement pattern are more complex than just picking a exercise with high EMG activity for the muscle we want to target. We don’t function in isolation as this article demonstrates. I think I will be cueing core activation with shoulder exercises now. Good find Scott.
I’ve attached an article regarding EMG changes of scap muscles in patients with acute shoulder pain. The other article discusses kinematic changes in scap and GH movement in those with shoulder pain.
As far as palpating the TA goes, I’m pretty sure we all agree we cannot confidently palpate the TA without IO. Like August said, looking for core contraction without RA is typically appropriate I think.
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When I read this article and looked at the thread I could not help but think about the muscular slings that Rusty Smith talked about last year and how we should incorporate this into our assessment and functional treatment. Continuing with Myra’s theme, developmentally this certainly makes sense. I am wondering how many of you residents take into account these type of muscular activation patterns and utilize them in treatment – for example, using the upper quarter patterning with lower quarter symptoms and vice versa. Thoughts?
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Being from LC I should probably have a better answer for this, but sadly I do not. I cannot say that I have specifically thought about muscular slings during interventions, but I have noticed pain and dysfunction with rotational motions in a number of my patients with LBP. I have found interventions that simulate they functional rotational activity with cueing for motor control have help tremendously. I chose they activities for the reason of selecting interventions based on function, but in reflection I can see how they would be activating these systems.
Some examples would be similar to these exercises:
Once again, Go Steelers and Happy Thanksgiving y’all.
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The talk of slings reminded me of a case study I read in one of John Gibbon’s books. He talked about a runner he was seeing for shoulder pain. The only time the pt had shoulder pain was about 4 miles into her run. The pain lasted for a little while after the run but then would resolve until the next run. During his exam, he checked the glute activation of the pt in prone. He noted decreased/delayed glute max activation of the contralateral side. After a couple weeks of glute activation exercises and cuing the pt was able to run painfree.
So, was it because the ipsilateral lat was overactive trying to compensate for the deficient glute leading to shoulder dysfunction? It would make sense that the lat was pulling the UE into greater shoulder extension during arm swing potentially leading to a repetitive impingement phase with each arm swing.
Has anyone treated or seen something similar to this, where treating a body region most would typically think was unrelated to resolve a patient’s complaint?
I can recall treating a R handed pt with R LBP that occurred after several sets of a tennis match and occurred during his backhand swing. After getting a subjective hx, the pt reported previously having a RCR on the L shoulder. After assessing L shoulder ROM, he continued to significantly lack IR ROM. Hip IR was symmetrical and not limited. So was his lumbar spine possibly rotating more during his backhand swing because of the shoulder deficiency leading to facet dysfunction? Well, after treating his shoulder to improve IR ROM and showing him self mobilizations he could perform prior to his matches, his back pain resolved.
I find these cases interesting and difficult for myself to pick up on early on in a pt’s treatment. Has anyone else had cases like this in nature?
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