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EMS TENS parameters for effective quadriceps rehabilitation


For rehabilitating quadricep atrophy (following knee replacement, in an otherwise fit and healthy person) with a portable EMS TENS machine...

What are the most effective settings for pulse width, Hz, ramp, on and off times, and overall duration?

With a 2 channel machine, where would you recommend placing each pair of electrodes?

Would you recommend the same settings for both channels or different?

Many thanks


1 month ago

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Prof James Bellew
Prof James Bellew

KS, Assuming amplitude remains constant, increasing the phase (pulse) duration increases the phase (pulse) charge or amount of electrical energy delivered. Thus a more robust effect as you have noticed. We use 400usec phase duration with 100usec interphase interval in otherwise healthy post-operative and post-injury patients with excellent elicitation of quads. We use NMES until the pt is able to perform a volitional contraction at a level of force we deem acceptable for that specific pt and that time in their rehab. Motor point location is well described in a recent paper by Gobbo et al where the concept of functional motor points are discussed versus anatomical motor points. Functional motor points are described as the location where the most robust muscular response is found for the least amount of electrical energy. The Gobbo paper references Botter et al who mapped functional motor points of the quads. The two papers I mention both show images of these motor points. Thus, there are clusters of motor points in all the individual quad muscles. Keep in mind though that NMES is not directly depolarizing the skeletal muscle but rather the motor nerve to the muscles. You will see a large variety of recommendations for electrode placement but there remains a lack of universal agreement. I believe this is due to individual pt variability with functional motor point locations. Thus, one electrode placement site may be more or less effective for one pt versus another. Specific to TKA, read the papers of Lapsley (Jennifer, I believe) for more details specific to TKA.


Thank you all for your educative help.

A few follow-up questions:

From a lay persons point of view I've noticed that increasing the pulse width seems to have the most noticeable effect on the apparent strength of the contraction. Is there any reason (not to use the maximum that my machine will allow - 400us?

My machine will, support different parameters on each channel. Is there any merit it setting separate parameters for each channel (e.g. one type of stimulation for one vastus medialis and another for vastus lateralis, concurrently? Would this help avoid the training effect?

Finally, I'd appreciate some help identifyng the motor points for optimum electrode placement (mine are small, 2 per channel). Prof Ronzio mentions vastus medialis and rectus [femoris] - rectus and vastus lateralis, but I've seen many different photos/diagrams on the internet, that don'r mention the rectus femoris.

Does it make any difference where the positive and negative electrodes are placed

Cliff Eaton
Cliff Eaton

Hi KS I regularly use NMES in the management of TKR and ACLRs with great success, supporting the plethora of evidence to support this intervention. I use the Chattanooga Compex NMEs unit, starting with the Disuse Atrophy programme, twice a day with six hours between treatments. The paramenters are: 380us pulse width, 6s on 7 s off, 35Hz, 1.5s ramp up and 0.75s ramp down. My clinical reasoning for this choice is that with TKRs there has usually been a period of reduced exercise due to pain resulting in muscle atrophy. Depending on the amount of atrophy, I would use this programme daily for 7-10 days. During this intial phase we are increasing the plasticity of the neuromuscular pathways. After this initial period I change to Reinforcement programme. The parameters are: 380us pulse width, 4s on 10 s off, 75Hz, 1.5s ramp up, 0.75s ramp down. Exercise prescription should be advised by your Physiotherapist. Filopovich et al showed that by combining NMEs to resistance training achieved 40% additional strength gains after a 6 week period. Electrodes should be applied to Vastus Lateralis (ch 1) and Vastus Medialis (ch 2). Prof Bellow is quite right when he says that NMES has been shown to be most effective when unable to do volunatry active exercise. However, this statement is borne from clinical trials, which have subjects sedentary. Clinical trials showing the effects of combining NMES with active exercise are rare - I only know of one. This is because there is a real risk of producing Delayed Onset Muscle Soreness (DOMS), therefore getting ethical approval would be very difficult. Clinically though I can provide masses of anectodal evidence to support combining NMEs with your prescribed exercises. My only caveat is that you will get a training effect especially if including eccentric quads work e.g sit to stand exercise, in a very short s[pace of time. I advocate that you start with five minutes of combined exercise only, using the maximum tolerable intensity. I commence this intervention after the initial 7-10 days using the Disuse Atrophy programme There are plenty of ideas for incorporating NMEs on You Tube Good luck with the rehab Cliff

Prof James Bellew
Prof James Bellew

Excellent question. Assuming your goal is to strengthen the quads, the force-frequency relationship for the quads is 50-80Hz (Gregory et al 2007, Muscle and Nerve 35(4):504-509. Pulse change is the resultant of the pulse duration and pulse amplitude (i.e. the x and y coordinates when diagramming a pulse). The area within the pulse shape (again when diagrammed) represents the phase charge and phase charge has been well evidenced to be a primary determining factor in elicited muscle force (Scott et al multiple papers). Our lab has published a few papers supporting longer versus shorter pulse durations up to 900usec. If using burst modulated AC (eg Russian or Aussie currents), there is good evidence for 1000Hz carrier frequency and burst duty cycle of 10-20% versus 50% used in conventional Russian current. There is not universal consensus on how much amplitude must be used, but most would agree that that elicited contraction must produce enough force to promote positive adaptation and thus gain in strength. Once a patient can voluntarily activate the quads at a level sufficient for promoting positive adaptation, the benefit of NMES diminishes. Best evidence for NMES is during period when patient is unable to voluntarily activate muscle to produce sufficient force. Hope this helps.


Many thanks for your reply Professor, Up to what frequency is it effective to increase?

Prof Oscar Ronzio
Prof Oscar Ronzio

Hi KS. You should start with low frequency (5 Hz) and a PW of 300 us due to artrogenic inhibition. Ramp: 1 s On: 4 s Off: 8 to12 s 15 minutes at least. If no fatigue appears you should increase the frequency and the total time. Placing: vastus medialis and rectus - rectus and vastus lateralis. Best, Oscar

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