Restoring Muscle Function with Biofeedback

On this episode of the #AskMikeReinold show, I’m joined by Russ Paine to talk about the use of biofeedback in rehabilitation to restore volitional muscle contraction. To view more episodes, subscribe, and ask your questions, go to

#AskMikeReinold Episode 216: Restoring Muscle Function with Biofeedback

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Show Notes


Mike Reinold: Welcome back, everybody to the latest episode of the Ask Mike Reinold Show. I am here today, we’re going to flip the script again, and we’ve been doing this a bunch lately with obviously the COVID pandemic going on and us staying at home. Instead of us all being at Champion and answering your questions with my team there, what I’ve actually gotten to do is to team up with some of my friends and colleagues around the nation and ask them some questions. So instead of you guys listening to my garbage all the time and all my stupid answers, it’s time for me to ask some questions to some of the smart people that I know too.

Mike Reinold: So, today we have a very special guest, my good friend Russ Paine from Houston, Texas. Russ is the Director of Sports Medicine at UT Physicians Sports Medicine Group. I hope I said that well. You guys have probably heard me talk about Russ in a lot of my presentations because a lot of the things that I’ve learned and I’ve done on the scapula and, heck, lots of things on the knee and neuromuscular control rehabilitation, all these things I’ve learned from Russ and people all the time. But Russ, to me, is one of those groups of like godfathers in sports’ physical therapy that have been very influential to me. So if it wasn’t for the pandemic, I feel like we wouldn’t be doing these things, right Russ? But it’s great to have you on the show, so welcome.

Russ Paine: Thanks, Mike. Happy to be here.

Mike Reinold: Yeah, it was awesome. So a few years ago now… It’s been, what? How many years since the mTrigger came out?

Russ Paine: I think we hit the market two years ago.

Mike Reinold: Two years?

Russ Paine: We’ve been developing it for five years, so it’s been on the market for a year and a half, two years.

Mike Reinold: Nice. So, Russ has teamed up with another friend of ours, Brian Prior, that has done some good work with the light care laser and stuff like that. But they’ve teamed up together to come up with a new biofeedback unit called the mTrigger. And if you’ve followed me for some time, I’ve been talking about this now for years with Russ and been trying to help get the word out because what a lot of people don’t know is that people like Russ and I, and a lot of our friends, we use biofeedback a ton, even though it’s not readily available on the market. But we love biofeedback for postop patients, even some of our injured people that didn’t have surgery. But Russ, why don’t we start with that? Tell us a little bit about biofeedback. What happened to biofeedback and why did this fade away? Why is biofeedback not as common as it used to be?

Russ Paine: Well, I’d disagree with you a little bit that it never was a big thing.

Mike Reinold: Right, that’s a good point.

Russ Paine: It was over shadowed by muscle stim. So it didn’t come and fade away, it’s just been gradually building over a period of time. And I was one of the few people that used it. I use a little handheld biofeedback because I just didn’t feel like I was getting results with muscle stim, and I’ve had 13 knee surgeries. So I’ve tried all this stuff to get your quad back and all I put muscle stim on, I said, “Oh, that looks good, but I can’t make my own muscle.”

Mike Reinold: Right.

Russ Paine: So I started using biofeedback and I realized that my patients were getting better so much faster. I’ve seen all pro athletes and I see athletes that have had an ACL reconstruction in the NFL and they’re a year and a half postop and they come to me and they can’t do… They’ve got an extensor lag.

Mike Reinold: Crazy.

Russ Paine: They can’t even do a straight leg raise. And my patients don’t have that problem because we address that in the beginning. Part of the reason is that the devices were expensive too.

Mike Reinold: Right.

Russ Paine: They were two or $3,000 for a device and it really wasn’t that very user friendly. And the muscle stim market was so big. The reason the muscle stim market was so big, it was because it was a rental, reimbursable product and made millions and probably billions of dollars. So tons of money was issued to help support that as a rental product for research. There’s only a few articles on biofeedback because biofeedback got cut loose as a code. The actually code is still there, but most people, most insurance companies don’t reimburse because the psychology and psychiatric group abused that code for relaxation and that type of thing. So insurance company said, “We’re not paying for that.”

Mike Reinold: That’s crazy.

Russ Paine: So now we use the neural muscular code when we use biofeedback. So instead we do therapeutic exercise, manual therapy, and then neuromuscular code is what we use for biofeedback. So that makes senses, there’s really not a code for biofeedback that really works. Even though there is a code, most people don’t reimburse for it. But I think this is a… Since I’ve learned more about it, it’s a new wave concept that’s spreading through to understand the science behind why biofeedback works maybe even better than muscle stim.

Mike Reinold: Right.

Russ Paine: So when you have my device, which is very sophisticated, user friendly people can come in and download the app on their phone and get to work with it. They see the results and people that are really in tune with. Our patients love this device. And it’s up to your creativity, what you can do with it. So it’s all about starting to diminish the atrophy and inhibition that occurs day two postop. I’ll use the biofeedback for day two postop up to three months postop. Every time they come in, they get 10 minutes of quad setting. And our goal is to recruit more motor units.

Mike Reinold: Right.

Russ Paine: And that’s why my patients all do well. That’s one reason.

Mike Reinold: Right. And we all know that people, especially the complicated procedures, the big pain and the swelling in the knees and other joints, we all know that they have a terrible time with volitional control. So it’s funny, you hear other people struggling, or they say like, “Hey, contract that quad. “You’re like, “Yeah, no, I know I’m supposed to contract quad, I can’t. I haven’t been trained to do that well.” So we’ve been big fans of biofeedback just along the way, because I think it’s great that it works for volitional control, but a device like yours, like the mTrigger, it gives you feedback immediately of how much muscle contraction you’re performing. It’s biofeedback, that’s the whole point of it. It’s not just let’s turn on a neuromuscular stem and crank it up as high as we can, but let’s see how much you can press and you can contract.

Mike Reinold: And we know through all the research, that effort goes up when you have an immediate feedback and you see that and you know the outcomes comes back. So it’s great for volitional control. For me, I think a lot of the new grads and students in physical therapy just haven’t been exposed to it a little bit. So we know there’s neuromuscular stem. Why don’t you tell people that maybe haven’t worked with biofeedback much, what’s the difference on the inside between biofeedback and neuromuscular electrical stem, that NMES? What’s happening to the body differently on these two?

Russ Paine: Well, another point to make, just to finish it with one of your point was that patients like to grade themselves too.

Mike Reinold: That’s true.

Russ Paine: They come in and they’re like, “Oh my God, I can’t even make this leg go up hardly at all. I’m only at 300 microvolts.” And then they’d come in the next week, they’re at 1200 microvolts. So that’s another motivational thing.

Mike Reinold: Yeah.

Russ Paine: So the difference, I think, between the two devices is a scientific thing. And we’ve done a little… I did a little lecture that Mike’ll share with you that goes into detail on this, but it’s all about volitional contraction versus electrical muscle stim distally contracting.

Mike Reinold: Right.

Russ Paine: So when you have a volitional contraction, you use your brain. And we now know that there’s a decrease in cortical input in an ACL injured patient or anybody that has a swollen knee. So when you start with the cortex and go through the cortical pathways down to the femoral nerve, you’re involving the entire system. So that’s one thing that’s different. When you put electrodes on your muscle, it’s a distal brain. It’s on your quad. So that’s why you can’t put muscle stim on and wake up with a big muscle or big abs or whatever.

Mike Reinold: Right.

Russ Paine: And so the other thing it does is when you put electrical muscle stim on, this stimulates the largest diameter axons. Okay. So Mike, what is got the largest diameter axon the fast twitch or the slow twitch?

Mike Reinold: That’s type two. Right?

Russ Paine: Right.

Mike Reinold: That’s good…

Russ Paine: Good job.

Mike Reinold: That was pretty good. You got me nervous there, but type two.

Russ Paine: Type two. Okay. So what is the most inhibited muscle fiber type? Is type one or the slow twitch muscle fiber types are the ones that are inhibited the most. And that has been proven several times. So if you just stimulate the fast twitch and don’t get to the slow twitch, you never really start with this volitional order of recruitment. And when you make a volitional contraction, the first muscle fiber top that fires is the slow twitch. So an isometric contraction starts with slow twitch. And if you’re bench pressing or are doing a big squat, you bring in the fast twitch. And that’s a good thing to do because it develops muscle fiber size. But if you don’t start with the proper order of recruitment between slow twitch, to medium fast twitch, to high end fast twitch, then you never establish that hierarchy. And you never really reverse the inhibition.

Mike Reinold: Right.

Russ Paine: So over a period of time, patients start to get a volitional contraction. But have you ever tried to have a volitional contraction with the muscle stim? It’s hard.

Mike Reinold: Right.

Russ Paine: It’s hard to do. And that’s what we tell our people to do. I want you to work with the muscle stim, but they’re like, “Well, I think I’m doing it, but I’m not really sure.” But when you use biofeedback, you get immediate feedback and you start this order of recruitment to go from slow twitch, building up really strong contraction eventually to fast twitch. So that’s the science behind it in a nutshell.

Mike Reinold: Now, what do you do with somebody that is super acute? So they’re just days within surgery and they have zero volitional contraction. Do you ever use some NMES for a little bit to help them get over that hump? Or do you still go right into biofeedback?

Russ Paine: It’s not because I’m prejudice, its because it works. So I haven’t put a muscle stim on a patient in probably, I don’t know, maybe five years.

Mike Reinold: That’s awesome.

Russ Paine: So what I will do in that case is, we’re having them with their knee in full extension, the quadriceps in the shortened position, and they can’t make a muscle. It’s hard to do.

Mike Reinold: Right.

Russ Paine: If you’ve got a swollen, painful knee. Maybe they can do a leg rise. When you do a leg raise, the EMG goes way up. So I’ll shoot them over the edge of the table because they typically don’t have really any range of motion restrictions. In the video, you’ll see, in my presentation, we set a two day postop patients that couldn’t do a raise, couldn’t do a quad set over the edge of the table. And we had one of the top Texans quarterback that you know of that was having difficulty after his ACL. And I said, “Doctor Lowe, man, we’re having a difficulty ….” Sit him over the edge and have him do an active knee extension. So that’s what I do.

Mike Reinold: Yeah.

Russ Paine: Sit them over the edge, and if they can bend to 70 degrees or so, the peak EMG activity of your quad during an active knew extension is between 90 and 30 degrees on an active knee extension is out near full extension, but it’s at 30 degrees. So we do 90 to 40 and they can fire their muscle in that position.

Mike Reinold: That makes sense.

Russ Paine: Another trick you can do is have them in the gravity eliminated position. So just bring their knee up and full extension to a 90 degree position, just like we do with a rotator cuff repair, have them in gravity eliminated and try to hold their limb in that position and have them try to pick their heel up off your hand.

Mike Reinold: That’s great.

Russ Paine: That’s another tool. But the easiest thing to do is sit them over the edge of the table. You’re not going to blow the graft out.

Mike Reinold: No. They can’t even control the quad.

Russ Paine: With no resistance. And you’re not even getting their full extension. Now, if you had them do a 50 pound knee extension machine, maybe.

Mike Reinold: Yeah.

Russ Paine: But with this… That’s why people don’t do because you got so ingrained to orthopedic surgeons brain that knee extensions are bad for ACLs, but it’s not a problem in the acute stage.

Mike Reinold: Right. Yeah, no, I agree. So obvious implications for the knee. Especially ACL. We’re having patients that have quad strength deficits for months down the road. Who knows if we had just layered this on earlier to get volitional control earlier, would strengthen conditioning at the two, three, four, five month mark been much more effective? It’s mind blowing to think what we may have missed.

Russ Paine: It’s a variable that we have not looked at in the past.

Mike Reinold: Right.

Russ Paine: Now, there are EMG devices that were five to $8,000 where you could do a true EMG test, but there’s never been anything that is quick and dirty, that you can look at the neural muscular deficits. And that’s what we’re doing right now. And our goal is to compare our strength deficits that we see when we test them at six months postop in our followup program, and compare those strength test is to the EMG deficits.

Mike Reinold: Right.

Russ Paine: In my patient population, typically around two to three months we’ve gotten rid of the neuromuscular deficits.

Mike Reinold: That’s great.

Russ Paine: But as I said before, people jump the gun, they don’t restore strength and they jumped into functional movements and functional exercise and these swells, they had no e center control, they can’t decelerate and I’m putting them on the biofeedback and they’re fricking 50% deficit in their neural muscular control.

Mike Reinold: Right.

Russ Paine: That’s a variable that I think this is a wave of a mentality that I think people will adopt once they see it and once we publish things that this is one variable that we need to take off the shelf.

Mike Reinold: Right. And you know what it makes sense too, because if you look at how a quad functions, if you can barely do a quad set and a straight leg raise, and then you immediately jump into the gym and start doing some exercise, just because it’s week X, then you’ve missed the boat. But that’s the really neat thing about biofeedback in general though, is it’s not just an exercise tool, but you can quantify, you can quantify the contraction. You can compare side to side, you can look for a neuromuscular deficit. So this isn’t just a tool to rehab with, this is a tool to almost use as part of your evaluation process, too.

Russ Paine: Right. And we spent a little extra money to put in that neuromuscular deficit test because I thought it was important…

Mike Reinold: There you go.

Russ Paine: … To do a two channel biofeedback instead of one channel so we can do that comparison. So the other thing we’re doing in the next year is we’re partnering with a company called BlueJay, and they do home networking with patients, it’s HIPAA compliant. So eventually the patient will be able to download the app on their phone and they’ll have a folder of their EMG data that we can share, and we can pull it up and look at it together. The physician can see that. And this is one thing that if you guys have a mTrigger out there that are listening to this, I’ll put these numbers down in my notes objectively.

Mike Reinold: Right. Sure.

Russ Paine: So instead of saying, “Quads a little bit better, better muscle tone.” I’ll put, “They started at 700 microvolts, now they’re are 1200 microvolts EMG.” So this is an objective criteria that allows us to document a patient’s progress. And the patients love it. They like to see the numbers that they’re getting better.

Mike Reinold: Yeah, no, that’s really neat. And we’ve talked a lot about using it on a muscle group to get a muscle groups volitional control back and to get it stronger down the road. Another neat thing that I do with biofeedback, I wanted to throw at you and then see if you have any other creative things. But the fact that it’s two channel, I like to do certain exercises with two different muscle groups on two different channels. So making it up off the top of my head, but maybe say a hip extension and we have some of the pads on the low back and some of the glutes. And I say like, “Look, I want you to do this bird dog for a hip extension. I want to see glutes and less back.” I want to make sure that we’re doing it right. Or the right core is firing or heck even upper trap, the lower trap ratios. What other neat ways do you use it? Because I’m sure you’re even more creative than I am.

Russ Paine: Well that’s for sure.

Mike Reinold: Good answer. That was good.

Russ Paine: No, you’re Mr. Creativity. So I’ll learn a lot from you. One thing that’s really helpful is to use it with prone planks, for teaching people to do a lumbar stabilization program. So you want to fire your abdominals and your erector spinae together to brace with that.

Mike Reinold: Right.

Russ Paine: And so you teach people neutral spine positioning, you teach them to brace, but they don’t really know whether they’re firing or not. But with the mTrigger you use two channels, you can see exactly what’s going on and you say, “Well, you’re not really firing your abs.” “Well, I think I am.” But I said, “You need to get that… Oh your erector spinae is going down.” So you can use it for that. That’s a really good, I don’t see that many spine patients, I see a few, but the spine therapists are crazy with it.

Russ Paine: Now strength and conditioning is a whole nother ball game. And it’s a really good tool for performance individuals that are strength coaches and also personal trainers. It’s a great tool for them. With regard to the shoulder, posterior cuff and the lower trap are two great sister muscles that work together with different activities. I’ve got a bunch of videos that I think you’ve seen so that we can fire the posterior cuff and at the same time, try to get a posterior sculpting of the scapula. Now Phil Page has used it for limiting upper trap activity along with lower trap, so some people believe that the upper trap maybe like an antagonist of what you’re trying to achieve. So you can use one channel for inhibition, the other channel for contraction.

Russ Paine: Now, another thing we’ve been doing reasonably well, if you have bilateral knee patient, you can use two channels. And the patient can do both of those knees simultaneously during the rest period of one, do the other one. You know me, I’m brutal. The other thing you can do is you can do quadriceps and hamstring contractions, but I don’t do a co contraction. I do 15, 10 seconds of quad, and when the quad relaxes, do a hamstring isometric. We never do hamstring isometrics.

Mike Reinold: Right.

Russ Paine: But hamstrings are a really important muscle group, we forget about that. But it’s really up to your creativity. That’s the beauty of this device is you can think of things to do. And the other fun thing to do is put it on the serratus anterior and try to prove some of these research articles that you’ve seen that this climbing of the wall with your elbows against the wall, what do you call that? I can’t remember. Does that increase your serratus activity? And sure enough, it does.

Mike Reinold: Right.

Russ Paine: What about the dynamic …? Which one’s a better exercise? What about rowing or what about manual resisted external rotation? So you can prove it to yourself. So it’s a fun tool.

Mike Reinold: Right. And everybody’s different. When we look at those studies and we look at a mean of a group of subjects. You may find that one exercise is better than another for a certain person. So the more individualized the better. So awesome. So this is my favorite episode right here, because one, I don’t have to talk the whole time, it’s fantastic to actually ask smarter people questions. But Russ is the man on biofeedback. And this mTrigger device is really amazing and ridiculously affordable. There’s no reason why everybody shouldn’t be using this. I just think people don’t know about it. So hopefully we can get some awareness to this because it’s something that some of the best sports physical therapist I know are using. So the best are using it, I think it’s something everybody should use it.

Mike Reinold: So we learned about the science behind it. We learned about why it’s better than neural muscular stim and some creative ways to use it for a bunch of different things. Thank you, Russ. I appreciate you taking the time out of your schedule and the freaking pandemic that we’re having to do that. So thank you very much.

Russ Paine: Thanks, Mike.

Mike Reinold: Yeah.

Russ Paine: Thanks for having me.

Mike Reinold: Awesome. Yeah. And if you have any more questions like this, even though I asked all the questions, but if you have questions too, you know what to do, go to, click on that podcast link, and you can fill out the form to ask us questions. Be sure to rate and review this on iTunes and Spotify. And we will see you on the next episode. Thanks so much.

How to Restore Volitional Muscle Control

To properly function after an injury or surgery, returning strength back to the involved muscle groups is always essential. In fact, strength is often used as one of our main objective findings we look at when evaluating an injury, or assessing someone’s ability to return to sport.

One thing that any sports physical therapist definitely knows about injuries is that muscle function is almost always inhibited afterward. This is especially true after a surgery.

But why?

Why does quadriceps strength go down after ACL surgery? And why does it often take so long to come back?

I recently got together with my friend Russ Paine from Houston, TX to record a presentation for my Inner Circle on the use of biofeedback in rehabilitation. Russ is one of the best sports physical therapists around and has rehabbed countless NFL, NBA, and MLB stars that you would definitely know. So he has seen a ton of ACLs in high-level athletes in his career.

The loss of strength after an injury was something we talked about, here’s a clip of Russ explaining what happens:

I thought this was really important to understand, and Russ alludes to this at the end. But, when faced with this loss of strength acutely after an injury or surgery, we often perform neuromuscular electrical stimulation to help regain muscle function.

But is there a better way?

Russ and I think so, and often use biofeedback with our athletes. The difference between NMES and biofeedback comes down to volitional control of the muscle.

Russ explains more in this clip from his presentation:

As you can see, biofeedback does a better job at stimulating volitional muscle control. Honestly, this may be the key to early phases of our rehabilitation process.

Rather than using NMES to stimulate the muscle, we can use biofeedback to actively work on improving volitional control.

Get Started with Biofeedback

mTrigger Biofeedback

Until recently, using biofeedback was a little bit harder to do. The devices were old, clunky, and expensive. But Russ and his crew have developed the mTrigger Biofeedback device, which I really think is a game-changer. It’s so easy to use, effective, and affordable. And lucky for you, mTrigger is also giving my readers an additional 10% off:

If you want to keep learning more about biofeedback. Check out Russ’s last article on my site on Why You Should Be Using Biofeedback in Rehabilitation or better yet, watch his full Current Concepts on the Use of Biofeedback in Rehabilitation presentation in my Inner Circle.

Why You Should Be Using Biofeedback in Rehabilitation

This week’s article is an excellent guest post from my friend Russ Paine, PT, discussing why and how we should be using biofeedback in our rehabilitation patients.  Russ and I are both big fans of biofeedback but unfortunately, it’s fallen out of favor because insurance companies don’t reimburse it. But that doesn’t mean it’s not effective.  And now, there’s a new biofeedback device, the mTrigger, that uses an app on your phone that is amazingly easy to use and affordable. I think this is going to be a real game-changer.  And mTrigger was nice enough to offer my readers 10% off if they use coupon code REINOLD! More details below, but check out the article and our video first!

Why You Should Be Using Biofeedback in Rehabilitation

I have been involved in the evaluation and treatment of sports medicine injuries for 33 years.  I have been very fortunate to have a “true” sports medicine practice that predominantly includes professional, college, high school, amateur, and aging athletes.  Having this type of clientele has forced me to explore and pursue restoring full function in the timeliest manner, being very careful to not cause harm using an aggressive approach.  

I believe that one of the secrets to having a successful return to sports with minimal adverse effects is fully restoring muscle function.  

Although many aspects of our field have seen excellent advancements and growth, we continue to combat one of the most difficult challenges following injury and surgery, muscle atrophy, and weakness.  

Restoration of muscle function should not only be measured by muscle force output and scores obtained on functional tests but neurological function. In my practice, establishing normal neurological function following knee surgery is goal number one for our patients’ initial step on the path toward a successful return to function.  

The Use of Biofeedback in Rehabilitation

So how do I do this?  The use of biofeedback is my preferential method of attacking the neurological deficit following surgery or injury.  

New advances in biofeedback devices have recently allowed the ability to provide a general assessment of the patients’ EMG neurological status. The subjects’ ability to fire the inhibited muscle may now be conveniently measured by recording EMG activity of the involved extremity and comparing this to the opposite normally functioning muscle group.

The primary rationale for the use of biofeedback is the belief that the patient should begin to use their own “electrical system” as soon as possible through a volitional contraction. 

The concept known as the order of recruitment lends support to the use of biofeedback to enhance volitional contraction.  This order is based on the size principle. Heinemann’s size principle states that under load, motor units are recruited from smallest to largest. In practice, this means that slow-twitch, low-force, fatigue-resistant muscle fibers are activated before fast-twitch, high-force, less fatigue-resistant muscle fibers.  

When using a biofeedback device, the clinician sets the goal for the inhibited muscle so that a strong voluntary effort is required by the patent for each contraction.  This is visible to the patient and forces a strong contraction to reach the pre-set goal. I believe that voluntary contraction using biofeedback produces the greatest results in restoring muscle function early.

Biofeedback or Neuromuscular Stimulation?

Neuromuscular electrical muscle stimulation (NMES) is often used to stimulate muscle contraction.  There is a vast amount of literature supporting NMES for use during rehabilitation. Until recently, NMES has been a reimbursable modality, thus there was much financial support to research its’ effectiveness.  

Biofeedback has not been reimbursable and that may have had an effect on the comparative lack of literature.  One article from Draper and Ballard supports the use of biofeedback over NMES.  This article compared the two modalities during ACL rehabilitation.  After 6 weeks, the biofeedback group was shown to provide greater quadriceps isometric muscle strength than NMES treated group.

I believe in the use of NMES if a patient is unable to make any voluntary contraction, which sometimes happens following ACL reconstruction surgery.  But, once a patient is able to produce a voluntary contraction, detected by the biofeedback, we immediately switch the patient to biofeedback.

When using NMES, all nerve fibers are stimulated simultaneously.  This, in my opinion, is not as effective as biofeedback because the order of recruitment from small to large diameter nerve fibers is not sequential as is the case with voluntary contraction.  NMES actually recruits the large-diameter nerve fibers first because they are more excitable, as large diameter axons have less resistance to firing. Atrophy of muscles has predominate effects on the slow-twitch smaller diameter Type I  fibers, so recruiting these muscle fibers is critical to reverse the effects of muscle inhibition and atrophy.

How to Use Biofeedback in Rehabilitation

I use biofeedback on virtually every knee patient that has decreased neurological EMG output.  As previously mentioned, we are able to use a new device to provide a side to side assessment of EMG activity.  

This information as also very educational and motivational to the patient as they can see the actual deficit via visual EMG numbers between normal and involved.  

Cycles of 10 seconds on and 10 seconds off are utilized during the 10-minute biofeedback session.  My instructions to the patient for quadriceps re-education are to “tighten your muscle and force your knee straight”.  Progress is continued to be monitored on a weekly basis to measure the change in EMG activity, as shown using the biofeedback application.  

The mTrigger Biofeedback device that we use utilize has an amplifier that sends the measured EMG activity via a Bluetooth signal to an android or IOS device with the appropriately downloaded software application.  

This mTrigger is available for home use as well as clinical use.  Patient reported motivation using this type of biofeedback product is very high as they can actually visualize their intensity of muscle contraction when performing home exercise programs.  There seems to be an interesting psychological connection between the use of one’s personal smartphone or computer pad and their muscle activity.

Lack of extension of the knee has been shown to have an adverse effect on knee function.  Loss of extension alters the gait pattern and can produce abnormal stresses to the patellofemoral joint.  Due to a lack of quadriceps control, many quad inhibited patients will ambulate with a flexed knee gait pattern.  

The use of biofeedback can be used to combat this common malady often associated with post-op care of the knee.  Lacking quad control, patients’ are unable to eccentrically control the knee flexion moment that occurs during single-limb balance.  A quad inhibited patient will assume this flexed knee position because they “know” the position of the knee during single-limb balance.

This sets up the knee for a co-contracted state and presents as muscle splinting until normal muscle tone and function are restored.  This muscle splinting will continue to exacerbate the lack of extension in the knee. Biofeedback can be very effective at addressing this issue.  

With muscle splinting, we want to teach the patient to relax the hamstring muscle during knee extension stretching, thus negating the effect of a contracting hamstring muscle.  The patient is placed in a prone position, with both patella over the edge of the table. Electrodes are placed over the hamstring muscle. Unlike the inhibited quadriceps muscle where we are trying to elicit a more perfect contraction, the biofeedback unit is now used for relaxation purposes.  As the patient uses the relaxation mode of the unit and learns to control the overly active hamstring contraction immediate increase in passive knee extension is observed.

This position is maintained for a 10 minute period.  Once the patient has “learned” to control the hamstring overactivity, a lightweight may be applied for the 10-minute period to produce a low-load long-duration stretch.  Change in knee extension can be measured using heel height difference measurement technique. Dale Daniel described this measurement and showed that 1cm of HHD = 1 degree of flexion contracture.

Note from Mike: That’s a great example of how you would use biofeedback to work reducing muscle activity.  It’s not always used to increase activity. Another way we use it is to use both channels together on 2 different muscle groups.  Imagine doing a bird dog or glute bridge with the pads on the glutes and low back. You would focus on performing the drill with high glute activity and low back activity.  It’s pretty neat.

Return to Play

Return to play is a hot topic in rehab right now.  It’s difficult to determine if the athlete is ready to return to sport.  There are many obstacles when assisting your athlete to the ultimate goal of returning to sport with pre-injury level of performance.  

Too often, a shift is made during the rehabilitation process to more functional activities and reduced emphasis on strengthening.  If your patient continues to possess a decreased EMG signal compared to the normal side, it will be highly unlikely that they will be able to resume the pre-injury level of function.  

With biofeedback, we have a tool that makes certain that we have completed one of the early critical steps in the process of rehabilitation – restoring and measuring the normal neurological function of the inhibited muscle group.  Don’t allow decreased EMG function to be one of the obstacles to continue to linger.

The mTrigger Biofeedback Device

I thought that was a great article from Russ.  Many don’t even realize how impactful biofeedback can be as it has fallen out of favor.  Here’s a great video from Russ and I demonstrating the mTrigger device and talking about how and why we use biofeedback:

As you can see, the new mTrigger device is so simple to use and completely affordable.  That has always been a limitation in biofeedback devices, they were just to clunky and expensive.

mTrigger biofeedback device

If you want to get started using biofeedback, mTrigger was nice enough to offer my readers 10% off their purchase, making this even more affordable.  Click the link below and be sure to use coupon code REINOLD to get your 10% off

About the Author

Russ Paine, PT, is known for his experience in sports medicine with special interests in injuries to the knee and shoulder, as well as golfing injuries and conditioning. His client list includes many professional athletes who have sought his expertise to help them recover to their prior level of function. Russ has a long career in sports medicine, having served as rehabilitation consultant to the Houston Astros, Houston Rockets, and NASA. Currently the Director of Sports Medicine Rehabilitation at UT Physicians in Houston, TX, Russ continues to devote his time to research and education while maintaining a busy sports medicine clinical practice.  Russ was inducted into the Sports Physical Therapy Hall of Fame in 2018. As a well-established author and lecturer on topics related to sports medicine, he has lectured at over 500 meetings in the US and abroad. He has published 25 chapters in textbooks and over thirty research articles in peer review journals.