Ep 169: Dose your NMES for success, with Drs Elanna Arhos & Naoaki Ito (part 1)

[00:00:00] Professor Laura Moseley is running three face-to-face courses in North America in 2024. He's visiting Vancouver, San Francisco and New York City in late September and early October this year. The two day courses are designed to help you embed the latest in pain science in education in your clinical practice.

[00:00:21] Check out the show notes to see Professor Moseley's program in each of these three iconic Canadian and US destinations. Yes, you heard correctly the latest in pain science in education in person with Professor Laura Moseley, September and October 2024.

[00:00:43] Hello and welcome to JOSPT Insights, the podcast that aims to help you translate quality research to quality practice. I'm Claire Ardern, the editor-in-chief of the Journal of Orthopaedic and Sports Physical Therapy. It's great to have you listening today.

[00:00:58] Neuromuscular electrical stimulation or NMES doesn't quite seem to have had the coverage it deserves based on just how effective NMES is when it comes to helping patients and athletes recover their quad strength after injury.

[00:01:17] And I wonder whether we've been a bit guilty of lumping NMES in the quote-unquote passive modalities basket, from which some interventions have really fallen by the wayside in musculoskeletal rehabilitation. Therapeutic ultrasound, I'm looking at you.

[00:01:33] Today, I'm joined by two of the many bright stars in the galaxy of next generation clinician scientists.

[00:01:40] Dr Elana Ahus and Dr Nao Ito are both PhD alumni of the University of Delaware, where they and their many excellent colleagues, led by Dr Lyns Nidamakla and now Dr Karan Silbernegel,

[00:01:54] have really pushed us all to do much, much better when we design and implement rehabilitation programs for athletes and active people with lower limb injuries.

[00:02:04] Elana and Nao led a fantastic clinical commentary that walks through all you need to know to get the best out of NMES for the athletes you work with. And over the next two episodes of JOSPT Insights, we're doing an NMES masterclass.

[00:02:20] Dr Ahus is a postdoctoral research associate at The Ohio State University. Her research is focused on clinical and biomechanical outcomes after ACL rupture and reconstruction, especially post-traumatic osteoarthritis and gait adaptability.

[00:02:36] Dr Ito is a postdoctoral research associate at the University of Wisconsin, Madison, and his expertise is in applying advanced imaging techniques, wearable technologies and electrotherapy to improve rehabilitation after knee injuries. Dr Nao Ito, Dr Elana Ahus, welcome to JOSPT Insights. Thank you, Clara. Thanks for having us.

[00:02:59] Yeah, thanks for having us. It's a pleasure to have you on the podcast and today we are talking about neuromuscular electrical stimulation. And I would say one of the very consistent drumbeats from the University of Delaware approach to rehabilitation, particularly for lower limb and ACL injuries,

[00:03:18] has been just how important NMES is as a tool in our musculoskeletal rehabilitation toolkits. You have all at University of Delaware been terrific advocates for NMES at conferences and in your teaching.

[00:03:33] And I think what makes this work most impactful is that you've done the research to back it up. There's a whole bunch of research that's supporting these recommendations.

[00:03:43] And that's why today I'm so pleased to have you both join me on JOSPT Insights to unpack some of that research and then to really get into the clinical recommendations and suggestions for how people can implement the very strong research into their clinical practice.

[00:03:59] So Elana, let's start with you. Why do you think that clinicians should know how to use and more importantly use NMES in their clinical practice?

[00:04:09] So I guess just before I even answer this question, I appreciate your introduction and I just want to really give credit where credit is due that a lot of this work that we're standing on is the work of Dr. Ellen Snyder-Mackler dating back to the 90s.

[00:04:21] So now and I had a conversation after CSM a couple years back where we were realizing in our interactions with clinicians and researchers at different universities that there's not really this clear application use of NMES.

[00:04:34] And so potentially some of its helpful effects are being overlooked because it's not always being applied and dosed in the correct way or in the way that's going to bring up them, bring about the most improvements in quadrature strength and function.

[00:04:49] So really that's a long wind up to your question, which the why is some of the best evidence that we have for improving quadrature strength and inhibition. We will link to the clinical commentary that we've recently published on the JOSPT website.

[00:05:05] We'll put some links in and I will flag for people now that not only is there a written clinical commentary, there are a whole bunch of videos to go alongside the clinical commentary that will bring to life even more what we're talking about today so that people can feel really confident when they go into the clinic that you can see exactly how to set the NMES up, where do you put the electrodes and how to get it to work for you well in the clinic.

[00:05:28] Alana, I'm going to stick with you. Can you walk us through the evidence, really the research evidence that's underpinning this very strong recommendation that comes through in clinical practice guidelines supporting using NMES?

[00:05:41] So some of the earliest work that we know of that was done in NMES was an early study again back in 1990s measuring the effects of high intensity NMES versus low intensity NMES, both in addition to ongoing strength training through rehabilitation program.

[00:05:58] This really showed that high intensity dosage is what's necessary to recover quadrishibs muscle force production in those early phases of rehab.

[00:06:06] And then from there, similar work compared intensive strength training programs to high intensity NMES and high volitional exercise compared to low intensity NMES and these results kind of continue to corroborate this fact that high intensity NMES really had the best outcomes,

[00:06:22] followed by high level volitional exercise and strength. And then the low intensity NMES group really lagged behind these two groups. So this is kind of some of the clearest evidence we have that the intensity really matters when we're applying NMES.

[00:06:35] And since some of those early studies, there've been a lot of reviews looking at the use of NMES plus traditional rehab and strength programs and showing its effectiveness in restoring quadrishibs muscle strength compared to just traditional rehab alone.

[00:06:49] And I guess the most recent CPG we have is the 2017 Knees Stability and Lismat Coordination CPG where NMES was rated A, meaning strong evidence there too.

[00:06:58] And I'm really glad that you point us to the intensity as a critical factor here and we will get into the intensity and how to dose all of those sorts of things a little bit later on in our chat.

[00:07:11] What sort of clinical populations are we talking about here now? Who are the athletes or the active people or the patients for whom you would suggest people consider using NMES?

[00:07:22] A lot of the evidence is behind ACL injuries. So that's one of the populations that we really know that the quads shut down, they're inhibited and their atrophy didn't weak.

[00:07:32] And their full evidence is kind of built upon that. That being said, it's really anyone with quad weakness. The first step to really identify who needs it is to know who has weak quads.

[00:07:43] So really a lot of times with any sort of knee related pain, the first line of defense in terms of our objective assessments is to get some sort of a knee strength measure.

[00:07:52] And we're really looking at anyone that has a deficits that are lower than 80% as NMES is part of their treatment plan early on, at least until they get to above an 80% quadriceps strength index.

[00:08:04] And of course we talk about the knee right now but can apply this in other muscles as well, whether it's at the calf or patients with Achilles tendonopathy, rotator cuff tendonopathy, other orthopedic injuries that can really the concepts translate over.

[00:08:18] Yeah and I think folks who are working with neurological populations will recognise stim particularly for people post stroke with shoulder issues. So there are certainly other clinical populations aside from the sports, more sports or sports focus populations that we're focusing on today.

[00:08:38] Now what do you need to get started with NMES? What's the typical kind of setup that would work for most people in your typical outpatient sports or orthopedics clinic?

[00:08:50] Let's talk about two components. One is obviously the stimulator which I think we can dig into a little later but the other component is what I brought up earlier about testing your strength to get to the high intensity we talked about.

[00:09:03] It's easy to kind of underestimate what high intensity means. A lot of people tend to get satisfied with this visible contraction of the quad and kind of leave it at that.

[00:09:12] But really what we recommend and while the evidence isn't the most clear what constitutes of high enough, we're targeting at least 50% of their volitional maximum contraction at the time of injury or when you see them in the clinic.

[00:09:26] So we would have to set them up ideally on an isokinetic dynamometer. Unfortunately this isn't something that's accessible for everyone in clinical practice. So the video does include a couple alternative setups using a handheld dynamometer or potentially even using a one rep max on any extension machine.

[00:09:43] That being said there's a lot more little devices that are things like a crane scales or other inline dynamometers that are becoming affordable that can connect to an app that can measure strength.

[00:09:55] So that's really the minimum is to start off by measuring strength and then we can talk about kind of the devices and what else do we need in order to get to the stem.

[00:10:04] Now that's great and I'm really glad that you raised the issue of the good strength measure to begin with. I was surprised when you said that you would even consider using NMES right up to 80 or even above 80% limb symmetry.

[00:10:18] So injured side compared to uninjured side and I guess that's really underscoring why it's so critical to get a good baseline measure of quads strength.

[00:10:27] And I also like how you're framing it that ideally the isokinetic dynamometer and then if you if you don't have access to that there are some other tools to use including handheld dynamometry. Okay, so I've got the equipment I'm privileged.

[00:10:43] I work in a clinic where I've got access to isokinetic dynamometer. So I've done my trustworthy strength measure of quads strength.

[00:10:51] Alana let's start with you what's next how do I get the preparation and the setup right to make the NMES work as comfortably as possible for the athlete I'm working with.

[00:11:03] One of the first things you'll want to do is to clean the skin where the electrodes are going to be adhered to with some soapy water to help the contact with the electrode. And then we really recommend using larger three by five inch electrodes for maximal patient comfort.

[00:11:17] So just giving a bigger surface area for the force to really disperse to on the quadriceps motor points. And now can you walk us through how you figure out the motor points where exactly or does it matter where exactly I put those electrodes on the quadriceps.

[00:11:33] Sure, so it's not necessarily feasible to figure out where the exact motor points are in the clinical setting but I think we all have a pretty good idea from looking at the textbook diagrams of where the motor points are.

[00:11:45] Approximately what we're trying to stay is kind of stay central to the thigh and distally kind of on the medial side more so where the vessus mediae Alice's motor points kind of collect.

[00:11:54] And ideally you want to spread out the pad placement a little more to get a little bit of a penetration deep into the thigh musculature that way you get a little more activation of the vessus intermediates or theoretically that's kind of what we're trying to get at.

[00:12:08] And this is something that Lynn has played with for years and kind of figured out this ideal pad placement so we can absolutely trust her words and the experiments she's done to get to this ideal pad placement.

[00:12:21] That's really reassuring because I remember learning about NMS at physio school and we spent a lot of time actually calculating where motor points were and trying to figure out changing the pad placement to get at different motor points.

[00:12:35] And it sounds like now you're suggesting that the larger electrode pad is not only a bit more comfortable for the patient. It's also going to help you spread that current out so that you can get the greatest benefit or bang for your buck so to speak.

[00:12:49] Yeah, that's exactly correct. And the other thing to know is, you know, once you start doing the intervention and if you're not getting the best contraction there's nothing wrong moving the pad around to kind of fine tune your placement as well.

[00:13:00] This is going to differ from a patient to patient case to case scenario. There's a little bit of wiggle room there but for majority of patients once you get it in those rough estimate positions those bigger pads like you said Claire would cover the motor points that we're trying to get at.

[00:13:14] But really once you start feeling that the pads aren't getting placed or aren't sticking very well then it is time to change it but alternatively of course resources are scarce so it's fine to tape it down strap it down to get a little better contact.

[00:13:29] Once these pads start to wear down patients will start complaining a little bit more about you know hot spots within their pads and it's just a little less comfortable so that's the other thing to consider as well.

[00:13:40] So yeah it's finding that balance between getting the contact as good or as solid as possible. You'd like to have as much contact as possible with pressure down if you have loose spots underneath it that's actually what creates hot spots around where the contact is lacking.

[00:13:57] Got it. That's great. Now Alana can you tell us a little bit about the position of the person where to how to position the pelvis how to stabilize which bits to stabilize how to make the setup as comfortable as possible for the person who's receiving the NMS.

[00:14:14] Backing up a little typically we would do an MVIC and maximal contraction before using NMS for dosage and so the this kind of relates to both of those the setup where you want to make sure that you're stabilizing the pelvis with if you're on an isokinetic

[00:14:31] dynamometer you have a belt strap that you can typically use to stabilize if you're setting this up on a plinth or on a one rep max with the knee extension machine you're going to want to make sure that you're using a belt or something to really keep the pelvis down and stabilized there too.

[00:14:46] Same thing with the lower leg and making sure that you're keeping them stabilized there either wrapped around the arm of the knee extension machine the pad that you're pressing into or around the leg of the plinth and we have in that video I think you can visualize that a lot better than I'm probably explaining it.

[00:15:08] So those both are key and then just making sure that your setup is repeatable over time so again with the isokinetic dynamometer you can set to 90 degrees of knee flexion a little bit or sorry to 60 degrees of knee flexion a little bit easier and know that you can repeat that using a go knee but if you're moving to an extension machine or then to a handheld setup you might want to consider using 90 degrees of knee flexion if the patient can

[00:15:34] get it because that's a lot more repeatable than probably trying to get into that 60 degrees range either way just making sure that your setup is repeatable over time so that you're consistent with your application of NMES is great and then with that being said also making sure that your force transducer what's reading the

[00:15:54] force is perpendicular to the force so that you're getting an accurate reading when you're if you're using a handheld dynamometer. Great now I'm thinking here that I'm not certain whether these contractions are happening through range or isometrically so now what do you suggest.

[00:16:12] So from a dosing perspective isometric is kind of the gold standard to make sure that you're able to reach that 50% of your MVIC with NMES alone.

[00:16:22] You can dose based on a one rep max using a new extension machine if that's really the only resource available in which case you would essentially have them do a one rep max on the new extension machine see how heavy they go and then reduce that weight down to 50%

[00:16:40] and then to use that NMES to get involuntary contraction with just the stem at that level. The ideal scenario is the isometrics just because the length tension relationship changes throughout the range of motion.

[00:16:51] Great that's really helpful thanks for clarifying. I think there's a bit of discussion in the community and also people are uncertain whether NMES is something that you superimpose over a voluntary contraction or whether this is purely a contraction that's mediated by or that occurs through the NMES so Alana can you start us off with that discussion please.

[00:17:16] When we are talking about NMES and we've talked about earlier even in this episode today is dosage and dosage is really that key parameter of applying NMES and NMES being effective for the purpose of strengthening the quadriceps.

[00:17:28] It's nearly impossible to achieve the correct dosage that 50% or more of the patients MVIC when NMES is being applied over an active contraction so typically you're going with you know what's tolerable to the patient at that point and so using NMES with a resting in a resting position and overlying it not on a voluntary contraction really allows you to make sure that you are getting NMES to a measurable 50% force output.

[00:17:57] And then on top of that some of the biggest differences just physiologically are the order of the motor unit recruitment and how that's different when you consider a volitional contraction compared to an actually electrically elicited contraction.

[00:18:10] You know this is the question we've gotten the most since this paper came out and you know surprisingly the first response we get from a lot of people as they come up to us and say oh no we've been doing NMES wrong all this time.

[00:18:21] And that's not necessarily true right what we're promoting is this more involuntary type of an approach but there's nothing wrong doing the NMES to be imposed on the strengthening exercise and all these other things.

[00:18:34] The message we want to put out there is that NMES is a standalone intervention in this passive form is what has the strongest evidence and this is in addition to all the rest of the exercises we do.

[00:18:44] It's a really important message so thank you both for helping get that message out there certainly when I learnt about NMES we were learning as a superimposed NMES superimposed over a voluntary contraction.

[00:18:58] So I suspect for quite a few people this is something that is different and knowing that it's safe that this is backed by a lot of a very long and storied body of evidence is a really important thing and can help you feel much more confident when you start to get that message.

[00:19:14] So I think we can start to think about implementing NMES in your clinical practice or changing your clinical practice if you've been someone who has been using NMES superimposed over a voluntary contraction.

[00:19:26] Now I think we're at the point in our discussion where we need to talk about intensity which we've talked about dosing and intensity is very closely related to dosage so how do we figure out the intensity here?

[00:19:39] Like Alana said the evidence is that the higher intensity the better. That seems to be the consistent trend and really in order to achieve that high intensity we don't know necessarily what that threshold is.

[00:19:54] The literature is kind of gray in terms of what that exact number is and this is exactly why we recommend at a minimum of 50% MVIC in voluntary contraction with NMES alone and ideally higher if you can.

[00:20:09] Honestly the first line of defense even if you're not measuring to know whether you're at the intensity that's appropriate is that it's going to be uncomfortable.

[00:20:17] This is a communication piece that you have to have with the patient beforehand and it's really the first part of introducing the intervention to the patient.

[00:20:27] We know that it's hard to get to that 50% intensity and so even at the beginning the first few sessions that you're using NMES and throughout you should really be checking in with the patient during that time and seeing if they're able to dial up the intensity even more throughout the session from when you started it.

[00:20:42] Often you get used to it and then you can add bump it up a little bit.

[00:20:46] And then the other thing when considering intensity over time is that really we should be redosing NMES for that patient's current MVIC when they're in that session so whether that's week 3, 4, 7, 8 whatever they're at that session dosing to that intensity and not to the same marginal intensity as the beginning of when you started the intervention.

[00:21:07] So Alana, does that mean you need to retest quad strength every single session? Yeah, you know ideally in a perfect world with a lot of time. Yes, we would be retesting every single session and we know that that's not always how this works.

[00:21:21] So even if you can retest it once a week so that you're getting current numbers and really with a lot of these patient populations we should be retesting quadriceps strength fairly often to know where these patients are testing it at least once a week will give us information.

[00:21:36] So that's really what we need to appropriately dose NMES. Now you've got the lowdown on why you need NMES in your rehab toolkit and you've got a handle on how to figure out dose and intensity.

[00:21:49] Join us next week as we discuss how to support patients to get the most out of NMES. We also talk about some of the common stimulators on the market and Alana and now share their tips for choosing the equipment that's best for your clinic.

[00:22:08] Thanks for listening to this episode of JOSPT Insights. For more discussion of the issues in musculoskeletal rehabilitation that are relevant to your practice, subscribe to JOSPT Insights on Apple Podcasts, Spotify, Tune In, Stitcher, Google or your favourite podcast app.

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