Electromyographic Biofeedback Tracings
Hi again, Bestie! Last time, we talked about surface electromyographic biofeedback (sEMG BF). If you missed that talk, catch up here. Today, we’re still chatting about sEMG BF, but we will be going into the specifics of pelvic floor muscle activity and what you should or should not expect to see on your biofeedback screen.
What does surface EMG BF look like on screen?
There are a bunch of different brands that offer sEMG BF devices. Different physical therapy clinics will likely use different brands or devices. Some are more high-tech while others are more low-tech. You can find success with any type of biofeedback if you know what you’re looking for. Your provider should explain to you how their particular biofeedback setup works and they should be holding your hand during the entire session. Below, I’ve provided some images that might help you understand what you’re looking for during a biofeedback session. Remember, these images might look very different from the specific biofeedback brand and device you are used to, especially if you have been using a lower-tech option.
In this image, we are looking at normal resting activity of the pelvic floor muscles (PFMs). Notice that even when the PFMs are “resting” or not contracting, there is still some muscle activity. This baseline resting activity should typically fall between 2 and 4 microvolts. Anything more than that might signify pelvic floor tension or an overactive pelvic floor. If your resting activity is at zero, there might be something wrong with the device or set up, as you should see some level of resting activity.
In this image, we are looking at normal fast-twitch elevation of the PFMs. This is what we want to see when we ask for quick PFM contractions. Notice how the rise between resting level and maximum contraction is significant (around 20 microvolts) and that between each contraction, the PFM activity returns to resting. If you have a hard time returning to that full resting position between each contraction, this could be a sign of pelvic floor dysfunction and something to work on in your biofeedback training. Also take note that none of the lines we see are perfectly straight. There will always be slight variations in the moment-to-moment muscle activity in any of the body’s muscles. We are more interested in trends and averages than we are in perfectly straight lines.
Taking a look at the image here, we can observe that it is similar to the image above, but with longer sections of elevation. This is what we want to see during slow, prolonged contractions. As we talked about last time, when “uptraining” or strengthening the PFMs, it is important to work on both power and endurance. The PFMs should be able to contract and hold that contraction for at least 10 seconds. We can use biofeedback to start to train these prolonged contractions. The image represents a patient who is able to contract and hold their PFM contraction well for 5 seconds and then rest for 5 seconds before beginning the next contraction. Notice that the line at the top during contractions is fairly consistent, at just over 15 microvolts. This consistency is what we want to see in these types of exercises. Over time, you would work on building up to 10 second holds at a time with 5-10 seconds of rest between each contraction.
Here, we’re looking at a biofeedback sample of someone correctly bearing down or lengthening the PFMs. This is one of the ways we can work on PFM “downtraining” or relaxation. We want to see the line representing muscle activity stay flat, or depress slightly. In this exercise, we do not want to see an increase in muscle activity, as that would be indicative of PFM contraction rather than relaxation.
Now, let’s look at a few images that represent abnormal muscle activity. First, this image represents heightened PFM resting activity with occasional muscle spasms. Remember, normal PFM resting activity should be between 2 and 4 microvolts. In this case, the patient is starting around 6 or 7 microvolts and has occasional spikes of activity without actively trying to contract the PFMs. We would commonly see this on sEMG BF in patients that suffer from pelvic pain, dyspareunia, vestibulodynia, urinary urgency, or bladder pain.
Next, take a look at this image representing poor PFM endurance. This patient is working on 5 second contractions, but they can really only maintain their contraction for 1-2 seconds before losing that full contraction due to fatigue. As we mentioned above, we want the top line of the contraction to be relatively consistent across. What we are seeing here is a decrease in the muscle activity as time moves forward. This is commonly seen in patients suffering from PFM weakness which is common in stress urinary incontinence (SUI) and pelvic organ prolapse (POP).
Lastly, take a look at this image representing poor elevation during quick PFM contractions. In this image, we can see that the patient does not seem to have a forceful contraction and they are only increasing PFM muscle activity from about 4 microvolts at rest to about 10 microvolts at maximum contraction. This is commonly seen in patients with PFM weakness, similar to above. In this case, we would want to work on improving PFM power and muscle recruitment.
There are so many more patterns one could observe on an sEMG BF screen. Today, we’ve covered the basics and some of the most commonly observed abnormalities. When you work on sEMG BF with your provider, they will be sure to explain to you in real-time what the images are representing. Also, I think most folks find biofeedback pretty intuitive once they try it out. All-in-all, I think sEMG BF can be a fun and useful addition to a pelvic health plan of care, as long as it is supplemented by a broad range of other techniques. My patients have had a lot of success with biofeedback and it is really cool to be able to see your hard work paying off in real-time.
We’ll talk soon, I’m sure.
XOXO,
Your Pelvic Bestie
*The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a qualified health provider regarding any questions you may have about a medical condition or health objectives.
