Ep 210: REVISITED: Dose your NMES for success, with Drs Elanna Arhos & Naoaki Ito

[00:00:06] Insights, the podcast that aims to help you translate quality research to quality practice.

[00:00:12] I'm Clare Ardern, the Editor-in-Chief of the Journal of Orthopaedic and Sports Physical Therapy.

[00:00:17] It's great to have you listening today. As 2024 wraps up and the JOSPT Insights team

[00:00:26] are taking a few weeks break, we're taking the opportunity to revisit a few of the episodes

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[00:01:13] listeners each week. Listeners, you'll hear us back with new JOSPT Insights episodes in your

[00:01:19] feed in January. Until then, our very best holiday wishes to you and those you love. And here's

[00:01:25] today's episode. Neuromuscular electrical stimulation or NMES doesn't quite seem to have had the coverage

[00:01:33] it deserves based on just how effective NMES is when it comes to helping patients and athletes

[00:01:39] recover their quad strength after injury. And I wonder whether we've been a bit guilty of lumping

[00:01:45] NMES in the quote unquote passive modalities basket from which some interventions have really fallen by

[00:01:52] the wayside in musculoskeletal rehabilitation. Therapeutic ultrasound, I'm looking at you.

[00:01:58] Today, I'm joined by two of the many bright stars in the galaxy of next generation clinician scientists.

[00:02:05] Dr. Ilana Ahos and Dr. Nao Ito are both PhD alumni of the University of Delaware, where they and their

[00:02:13] many excellent colleagues led by Dr. Lynn Snyder-Mackler and now Dr. Karin Silbernagel have

[00:02:19] really pushed us all to do much, much better when we design and implement rehabilitation programs

[00:02:25] for athletes and active people with lower limb injuries. Ilana Ahos and Nao led a fantastic

[00:02:32] clinical commentary that walks through all you need to know to get the best out of NMES for the

[00:02:37] athletes you work with. And over the next two episodes of JOSPT Insights, we're doing an NMES

[00:02:43] masterclass. Dr. Ahos is a postdoctoral research associate at the Ohio State University. Her research

[00:02:51] is focused on clinical and biomechanical outcomes after ACL rupture and reconstruction, especially

[00:02:57] post-traumatic osteoarthritis and gait adaptability. Dr. Ito is a postdoctoral research associate at the

[00:03:04] University of Wisconsin-Madison and his expertise is in applying advanced imaging techniques, wearable

[00:03:11] technologies and electrotherapy to improve rehabilitation after knee injuries. Dr. Nao Ito, Dr. Ilana Ahos,

[00:03:21] welcome to JOSPT Insights. Thank you, Clara. Thanks for having us. Yeah, thanks for having us.

[00:03:26] It's a pleasure to have you on the podcast. And today we are talking about neuromuscular

[00:03:31] electrical stimulation. And I would say one of the very consistent drumbeats from the University

[00:03:37] of Delaware approach to rehabilitation, particularly for lower limb and ACL injuries, has been just how

[00:03:45] important NMES is as a tool in our musculoskeletal rehabilitation toolkits. You have all at University

[00:03:53] of Delaware been terrific advocates for NMES at conferences and in your teaching. And I think what

[00:04:00] makes this work most impactful is that you've done the research to back it up. There's a whole bunch

[00:04:05] of research that's supporting these recommendations. And that's why today I'm so pleased to have you both

[00:04:11] join me on JOSPT Insights to unpack some of that research and then to really get into the clinical

[00:04:17] recommendations and suggestions for how people can implement the very strong research into their

[00:04:22] clinical practice. So, Ilana, let's start with you. Why do you think that clinicians should know how to use

[00:04:29] and more importantly, use NMES in their clinical practice?

[00:04:34] So I guess just before I even answer this question, I appreciate your introduction and I just want to

[00:04:39] really give credit where credit's due that a lot of this work that we're standing on is the work of

[00:04:43] Dr. Olin Stein and Mackler dating back to the 90s. So, Nau and I had a conversation after CSM a couple

[00:04:49] years back where we were realizing in our interactions with clinicians and researchers at different universities

[00:04:55] that there's not really this clear application use of NMES. And so, potentially some of its helpful effects

[00:05:03] are being overlooked because it's not always being applied and dosed in the correct way or in the way

[00:05:09] that's going to bring about the most improvements in quadrature strength and function. So, really,

[00:05:15] that's a long wind up to your question, which the why is it's some of the best evidence that we have

[00:05:21] for improving quadrature strength and inhibition? We will link to the clinical commentary that we've

[00:05:28] recently published on the JOSPT website. We'll put some links in and I will flag for people now that

[00:05:33] not only is there a written clinical commentary, there are a whole bunch of videos to go alongside

[00:05:37] the clinical commentary that will bring to life even more what we're talking about today so that

[00:05:42] people can feel really confident when they go into the clinic that you can see exactly how to set the

[00:05:48] NMES up, where do you put the electrodes and how to get it to work for you well in the clinic.

[00:05:54] Alana, I'm going to stick with you. Can you walk us through the evidence, really the research evidence

[00:05:59] that's underpinning the very strong recommendation that comes through in clinical practice guidelines

[00:06:04] supporting using NMES?

[00:06:06] So, some of the earliest work that we know of that was done in NMES was an early study again back

[00:06:13] 1990s, measuring the effects of high intensity NMES versus low intensity NMES, both in addition to

[00:06:20] ongoing strength training through rehabilitation program. This really showed that high intensity

[00:06:25] dosage is what's necessary to recover quadratured muscle force production in those early phases of

[00:06:30] rehab. And then from there, similar work compared intensive strength training programs to high

[00:06:36] intensity NMES and high volitional exercise compared to low intensity NMES. And these results kind of

[00:06:42] continue to corroborate this fact that high intensity NMES really had the best outcomes, followed by high

[00:06:48] level volitional exercise and strength. And then the low intensity NMES group really lagged behind these

[00:06:54] two groups. So this is kind of some of the clearest evidence we have that intensity really matters when

[00:06:58] we're applying NMES. And since some of those early studies, there have been a lot of reviews looking at

[00:07:04] the use of NMES plus traditional rehab and strength programs and showing its effectiveness in restoring

[00:07:09] bodybuilderships muscle strength compared to just traditional rehab alone. And I guess the most recent CPG

[00:07:16] we have is the 2017 knee stability and movement coordination CPG where NMES was graded, A, meaning

[00:07:22] strong evidence there too.

[00:07:23] And I'm really glad that you point us to the intensity as a critical factor here, and we will get into the

[00:07:30] intensity and how to dose all of those sorts of things a little bit later on in our chat. What sort of clinical

[00:07:37] populations are we talking about here now? Who are the athletes or the active people or the patients for whom

[00:07:44] you would suggest people consider using NMES?

[00:07:47] A lot of the evidence is behind ACL injuries. So that's one of the populations that we really know

[00:07:53] that the quads shut down, they're inhibited and they're atrophied and weak. And there's evidence is kind of

[00:07:59] built upon that. That being said, it's really anyone with quad weakness. The first step to really identify who

[00:08:05] needs it is to know who has weak quads. So really a lot of times with any sort of knee related pain, the first line of defense in terms of our objective

[00:08:14] assessments is to get some sort of a knee strength measure. And we're really looking at anyone that has a

[00:08:20] 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%

[00:08:27] quadriceps strength index. And of course, we talk about the knee right now, but you can apply this in other muscles as

[00:08:34] well, whether it's at the calf for patients with Achilles tendinopathy, rotator cuff tendinopathy, other orthopedic injuries that

[00:08:41] can really, the concepts translate over. Yeah. And I think folks who are working with neurological

[00:08:47] populations will recognize stim, particularly for people post-stroke with shoulder issues. So there are

[00:08:54] certainly other clinical populations aside from the sports, more sports or sports focused populations that

[00:09:01] we're focusing on today. Now, what do you need to get started with NMES? What's the typical kind of setup

[00:09:09] that would work for most people in your typical outpatient sports or orthopedics clinic?

[00:09:16] Let's talk about two components. One is obviously the stimulator, which I think we can dig into a

[00:09:21] little later. But the other component is what I brought up earlier about testing your strength.

[00:09:25] To get to the high intensity we talked about, it's easy to kind of underestimate what high intensity

[00:09:31] means. A lot of people tend to get satisfied with this visible contraction of the quad and kind of leave

[00:09:36] it at that. But really what we recommend, and while the evidence isn't the most clear what

[00:09:41] is what constitutes of high enough, we're targeting at least 50% of their volitional maximum contraction

[00:09:48] at the time of injury or when you see them in the clinic. So we would have to set them up ideally on

[00:09:54] an isokinetic dynamometer. Unfortunately, this isn't something that's accessible for everyone in clinical

[00:09:58] practice. So the video does include a couple alternative setups using a handheld dynamometer or

[00:10:04] potentially even using a one rep max on any extension machine. That being said, there's a lot more

[00:10:10] little devices that are things like a screen scales or other inline dynamometers that are becoming

[00:10:18] affordable that can connect to an app that can measure strength. So that's really the minimum is

[00:10:23] to start off by measuring strength and then we can talk about kind of the devices and what else do we need

[00:10:28] in order to get to the stem. Now that's great and I'm really glad that you raised the issue of the good

[00:10:34] strength measure to begin with. I was surprised when you said that you would even consider using an MES

[00:10:39] right up to 80 or even above 80% limb symmetry. So injured side compared to uninjured side. And I guess

[00:10:47] that's really underscoring why it's so critical to get a good baseline measure of quad strength. And I

[00:10:53] also like how you're framing it that ideally the isokinetic dynamometer and then if you don't have

[00:10:59] access to that, there are some other tools to use including handheld dynamometry.

[00:11:04] Okay, so I've got the equipment. I'm privileged. I work in a clinic where I've got access to

[00:11:10] isokinetic dynamometer. So I've done my trustworthy strength measure of quad strength. Alana, let's start

[00:11:17] with you. What's next? How do I get the preparation and the setup right to make the NMES work as comfortably

[00:11:26] as possible for the athlete I'm working with? Alana One of the first things you'll want to do is to

[00:11:30] clean the skin where the electrodes are going to be adhered to with some soapy water to help the

[00:11:35] contact with the electrode. And then we really recommend using larger three by five inch electrodes

[00:11:41] for maximal patient comfort. So just giving a bigger surface area for the force to really disperse to

[00:11:46] on the quadriceps motor points. And now, can you walk us through how you figure out the motor points

[00:11:53] where exactly, or does it matter where exactly I put those electrodes on the quadriceps?

[00:11:59] Sure. So it's not necessarily feasible to figure out where the exact motor points are in the clinical

[00:12:03] setting, but I think we all have a pretty good idea from looking at the textbook diagrams of where

[00:12:09] the motor points are. Approximately what we're trying to stay is kind of stay central to the thigh

[00:12:13] and distally kind of on the medial side more so where the vestus medialis motor points kind of collect.

[00:12:20] And ideally you want to spread out the pad place a little more to get a little bit of a penetration

[00:12:24] deep into the thigh musculature. That way you get a little more activation of the vestus

[00:12:29] intermedius or theoretically that's kind of what we're trying to get at. And this is something that

[00:12:34] Lynn has played with for years and kind of figured out this ideal pad placement so we can absolutely,

[00:12:40] you know, trust her words and the experiments she's done to get to this ideal pad placement.

[00:12:46] That's really reassuring because I remember learning about NMES at physio school and we spent a lot of

[00:12:52] time actually calculating where motor points were and trying to figure out changing the pad

[00:12:58] placement to get at different motor points. It sounds like now you're suggesting that the larger

[00:13:03] electrode pad is not only a bit more comfortable for the patient, it's also going to help you spread

[00:13:09] that current out so that you can get the greatest benefit or bang for your buck, so to speak.

[00:13:14] Yeah, that's exactly correct. And the other thing to know is, you know, once you start doing the

[00:13:19] intervention and if you're not getting the best contraction, there's nothing wrong moving the

[00:13:22] pad around to kind of fine tune your placement as well. And this is going to differ from a patient

[00:13:27] to patient case to case scenario. There's a little bit of wiggle room there, but for majority of

[00:13:32] patients, once you get it in those rough estimate positions, those bigger pads, like you said,

[00:13:36] Claire would cover the motor points that we're trying to get at. But really once you start feeling

[00:13:42] that the pads aren't getting placed or aren't sticking very well, then it is time to change it.

[00:13:48] But alternatively, of course, resources are scarce, so it's fine to tape it down, strap it down to get

[00:13:53] a little better contact. Once these pads start to wear down, patients will start complaining a little

[00:13:57] bit more about, you know, hot spots within their pads and it's just a little less comfortable. So

[00:14:03] that's the other thing to consider as well.

[00:14:05] So yeah, it's finding that balance between getting the contact as good or as solid as possible.

[00:14:12] You'd like to have as much contact as possible with pressure down. If you have loose spots

[00:14:17] underneath it, that's actually what creates hot spots around where the contact is lacking.

[00:14:22] Got it. That's great. Now, Alana, can you tell us a little bit about the position of the person,

[00:14:29] where to, how to position the pelvis, how to stabilize, which bits to stabilize,

[00:14:33] how to make the setup as comfortable as possible for the person who's receiving the NMES?

[00:14:40] Backing up a little, typically we would do an MVIC, a maximal contraction before

[00:14:45] using NMES for dosage. And so this kind of relates to both of those, the setup where you want to make

[00:14:52] sure that you're stabilizing the pelvis with, if you're on an isokinetic dendomometer,

[00:14:57] you have a belt strap that you can typically use to stabilize. If you're setting this up on a plinth

[00:15:02] or on a one rep max with a knee extension machine, you're going to want to make sure that you're using

[00:15:07] a belt or something to really keep the pelvis down and stabilized there too. Same thing with the lower

[00:15:13] leg and making sure that you're keeping them stabilized there, either wrapped around the arm of

[00:15:21] the knee extension machine, the pad that you're pressing into or around the leg of the plinth.

[00:15:27] And we have in that video, I think you can visualize that a lot better than I'm probably explaining it.

[00:15:33] And so those both are key. And then just making sure that your setup is repeatable over time. So again,

[00:15:38] with the isokinetic dendomometer, you can set to 90 degrees of knee flexion a little bit, or sorry,

[00:15:45] to 60 degrees of knee flexion a little bit easier and know that you can repeat that using a go-knee.

[00:15:49] But if you're moving to a knee extension machine or then to a handheld setup, you might want to

[00:15:56] consider using 90 degrees of knee flexion if the patient can tolerate it because that's a lot more

[00:16:00] repeatable than probably trying to get into that 60 degrees range. Either way, just making sure that

[00:16:06] your setup is repeatable over time so that you're consistent with your application of NMES is great.

[00:16:13] And then with that being said, also making sure that your force transducer,

[00:16:18] what's reading the force is perpendicular to the force so that you're getting an accurate

[00:16:21] reading when you're, if you're using a handheld dynamometer.

[00:16:25] Great. Now I'm thinking here that I'm not certain whether these contractions are happening

[00:16:31] through range or isometrically. So now what do you suggest?

[00:16:37] So from a dosing perspective, isometric is kind of the gold standard to make sure

[00:16:42] that you're able to reach that 50% of your MVIC with NMES alone. You can dose based on a one rep max

[00:16:50] using a knee extension machine if that's really the only resource available, in which case you would

[00:16:56] have them do a one rep max on the knee extension machine, see how heavy they go, and then reduce

[00:17:02] that weight down to 50% and then to use the NMES to get involuntary contraction with just the stim at

[00:17:09] that level. The ideal scenario is the isometrics just because the length tension relationship changes

[00:17:14] throughout the range of motion.

[00:17:16] Great. That's really helpful. Thanks for clarifying. I think there's a bit of discussion in the community

[00:17:22] and also people are uncertain whether NMES is something that you superimpose over a voluntary contraction

[00:17:29] or whether this is purely a contraction that's mediated by or that occurs through the NMES. So Alana, can you

[00:17:38] start us off with that discussion, please?

[00:17:41] When we are talking about NMES and what we've talked about earlier, even in this episode today,

[00:17:45] is dosage and dosage is really that key parameter of applying NMES and NMES being effective for the

[00:17:52] purpose of strengthening the quadriceps. And it's nearly impossible to achieve the correct dosage

[00:17:57] that 50% or more of the patient's MVIC when NMES is being applied over an active contraction. So

[00:18:04] typically you're going with, you know, what's tolerable to the patient at that point. And so using NMES

[00:18:10] with a resting, in a resting position and overlying it not on a voluntary contraction really allows you

[00:18:16] to make sure that you are getting NMES to a measurable 50% force output. And then on top of that,

[00:18:24] some of the biggest differences just physiologically are the order of the motor unit recruitment and how

[00:18:28] that's different when you consider volitional contraction compared to electrically elicited contraction.

[00:18:34] You know, this is the question we've gotten the most since this paper came out. And, you know,

[00:18:40] surprisingly, the first response we get from a lot of people is they come up to us and say,

[00:18:44] oh no, we've been doing NMES wrong all this time. And that's not necessarily true, right?

[00:18:49] What we're promoting is this more involuntary type of an approach, but there's nothing wrong doing

[00:18:54] the NMES superimposed on the strengthening exercise and all these other things.

[00:18:58] The message we want to put out there is that NMES as a standalone intervention in this passive form

[00:19:04] is what has the strongest evidence. And this is in addition to all the rest of the exercises we do.

[00:19:10] It's a really important message. So thank you both for helping get that message out there. Certainly,

[00:19:15] when I learned about NMES, we were learning as a superimposed, NMES superimposed over a voluntary

[00:19:22] contraction. So I suspect for quite a few people, this is something that is different. And

[00:19:27] knowing that it's safe, that this is backed by a lot of a very long and storied body of evidence is

[00:19:35] a really important thing and can help you feel much more confident when you start to think about

[00:19:40] implementing NMES in your clinical practice or changing your clinical practice if you've been

[00:19:45] someone who has been using NMES superimposed over a voluntary contraction. Now, I think we're at the

[00:19:52] point in our discussion where we need to talk about intensity. We've talked about dosing and

[00:19:57] intensity is very closely related to dosage. So how do we figure out the intensity here?

[00:20:04] Dr. Justin Marchegiani Like Elana said, the evidence is that the higher intensity,

[00:20:10] the better. That seems to be the consistent trend. And really, in order to achieve that high intensity,

[00:20:18] we don't know necessarily what that threshold is. The literature is kind of gray in terms of what that

[00:20:23] exact number is. And this is exactly why we recommend at a minimum of 50% MVIC,

[00:20:28] the involuntary contraction with NMES alone, and ideally higher if you can. Honestly, the first line

[00:20:35] of defense, even if you're not measuring to know whether you're at the intensity that's appropriate,

[00:20:41] is that it's going to be uncomfortable. This is a communication piece that you have to have

[00:20:45] with the patient beforehand. And it's really the first part of introducing the intervention to the patient.

[00:20:52] Dr. Justin Marchegiani We know that it's hard to get to that 50% intensity. And so even at the beginning,

[00:20:57] the first few sessions that you're using NMES and throughout, you should really be checking in with

[00:21:00] the patient during that time and seeing if they're able to dial up the intensity even more throughout

[00:21:05] the session from when you started it. Often you get used to it, and then you can add and bump it up a little

[00:21:10] bit. And then the other thing when considering intensity over time is that really we should be

[00:21:16] re-dosing NMES for that patient's current MVIC when they're in that session. So whether that's week

[00:21:22] three, four, seven, eight, whatever they're at that session, dosing to that intensity and not to

[00:21:28] the same original intensity as the beginning of when you started the intervention.

[00:21:32] Dr. Justin Marchegiani So Alana, does that mean you need to re-test

[00:21:35] quad strength every single session? Dr. Alana Yeah, you know, ideally in a perfect

[00:21:40] world with a lot of time, yes, we would be re-testing every single session. And we know that

[00:21:44] that's not always how this works. So even if you can re-test it once a week so that you're getting

[00:21:49] current numbers, and really with a lot of these patient populations, we should be re-testing

[00:21:54] quadriceps strength fairly often to know where these patients are. Testing it at least once a week

[00:21:59] will give us the information we need to appropriately dose NMES.

[00:22:05] Dr. Justin Marchegiani So now you've got the lowdown on why you need NMES in your

[00:22:09] rehab toolkit, and you've got a handle on how to figure out dose and intensity.

[00:22:14] Dr. Justin Marchegiani Join us next week as we discuss how to

[00:22:17] support patients to get the most out of NMES. We also talk about some of the common

[00:22:22] stimulators on the market, and Alana and Now share their tips for choosing the equipment

[00:22:27] that's best for your clinic.

[00:22:29] Dr. Justin Marchegiani Thanks for listening to this episode of

[00:22:34] JOSPT Insights. For more discussion of the issues in musculoskeletal rehabilitation that are relevant to

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