Bilateral effects of 6 weeks’ unilateral acupuncture and electroacupuncture on ankle dorsiflexors muscle strength: a pilot study. Arch Phys Med Rehabil. 2012 Jan;93(1):50-5. Zhou S1, Huang LP, Liu J, Yu JH, Tian Q, Cao LJ.
Normally I could completely disregard this paper because I am not a fan of acupuncture and agree with Colquhoun and Novella that acupuncture is theatrical placebo [free full text]. I have been meaning to blog on Colquhoun/Novella’s article itself as it is fascinating, such that I highly recommend anyone to just read it. Among MANY other critiques of acupuncture, my favorite being that Chairman Mao was quoted as saying, “Even though I believe we should promote Chinese medicine, I personally do not believe in it. I do not take Chinese Medicine.” The other notable, and relevant to this blog, finding is that 100% of articles originating in China find acupuncture to be as or more effective than anything they are comparing it too. So either, like the ghost hunters on cable TV, the Chinese are “just really good researchers” or there is some severe publication bias regarding acupuncture coming out of China.
So the article in question deals with electroacupuncture, which is basically a TENS or EMS machine hooked up to acupuncture needles, and while I have never tried it, I don’t doubt that it works. In my experience, and in a lot of research studies (conducted outside China) TENS works some, and EMS works a lot. In this paper I think some truth slipped out (if you read the full article but not seen in the abstract) that electroacupuncture applied to the sham/fake acupuncture points actually worked better for increasing strength than did applying it to the real acupuncture points. Per their illustration, it appears that needles for the sham acupuncture points were being placed in the middle of the tibialis anterior (TA) muscle belly, while the real acupuncture points were on the medial edge of the TA muscle. So after 6 weeks of treatment 3 times per week, the real acupuncture point group increased stimulated leg strength 35%, while the contralateral (other, unstimulated) leg increased 32%. In the sham/fake acupuncture points, strength increased almost twice as much: 64% in the stimulated leg and 55% in the contralateral (other, unstimulated) leg. The acupuncture group, real acupuncture, without electric stimulation still increased strength 46 and 49% in the poked and unpoked legs respectively, which if you ask me is either Chinese bias or just the power of placebo. It’s unfortunate that they did not include a sham acupuncture/no stimulation group, and it’s a greater shame that even if they did, many would still give the study the stinkeye due to what appears to be a long history of extra-ordinary publication bias.
Also of interest to me was the needles were placed really deep 20-30 mm, which is plus or minus an inch. The stim machines used constant-current square waveform, pulse duration of 1 ms (1000 uS, which is pretty wide), 40 hz frequency, turned up as high as was tolerable (mA reached not given). For strength I would prefer other parameters myself, but their described parameters sound like they would elicit tetanic muscle contractions that should increase strength. I was interested to know what mA they were using because I thought the needles being placed directly in the muscles might require less electric stimulation per a given contraction than with surface electric muscle stimulation electrodes that I like to use. On the other hand, I’m not sure I would want my muscle contracting very hard and scrunching up on any needle stuck 2-3 cm inside my muscle. So, I was disappointed they didn’t say, but my curiosity is mostly academic anyway as surface electrodes, such as my rubber carbon electrodes, have no trouble whatsoever eliciting very strong muscle contractions.
This gets me to the other thing I wanted to talk about, motor points, which is an apparent point of contention. Should you put your electrodes on motor points or on the muscle belly (center) of whatever muscle or portion of a muscle you want to work? You will see charts in books or on the web showing where they think motor points are or where electric stimulation electrodes should be placed. Motor points are individual, such that the charts probably just get you close, but you’ll often miss with small electrodes.
I learned how to search out motor points in physical therapy school by using a special probe, or the low tech way which is to use your finger. By placing a large dispersive electrode on the patient, sticking the other electrode to the therapist’s hand then closing the circuit by wetting the finger and rubbing the finger on the patient targeted body part to find the point where they get the greatest muscle twitching you find the motor point. The good news is that IT DOES WORK, and in doing so you will find motor points where smaller amounts of electric stimulation yield better contractions. The bad news is that it’s a mildly tedious process, which in my experience isn’t worth the effort. The other good news is that with modern electric stimulators using wide pulse duration, biphasic square wave alternating current and large rubber carbon electrodes, finding motor points is, in my experience, unnecessary. The electric stimulation itself doesn’t hurt so much, it’s just the muscle contractions are so intense that it’s the contraction force that limits you rather than the tingling sensation of the electric stimulation. Hooking up a good machine like the EV-906 or a great machine like a Globus with 3.5” circular (or greater) rubber carbon electrode and muscles are going to contract muscle just fine. Plus, with motor points being all over the place, the larger electrodes you are probably covering a number of them anyway. Finally, sometimes those motor points can just be annoying. Sometimes, for example, when doing core electric stimulation where I generally put 4 of those 3.5” pads on the rectus abdominus, 2 on the obliques and 2 on the spine extensors, sometimes you will hit a spot just perfect on the rectus that feels super intense. If I am using my new favorite criss cross electrode placement (where I pair one my rectus abdominal electrode of one channel with the opposite side spine extensor or oblique) it will limit how much I can turn up that channel and how much I can therefore stimulate my back/oblique muscles. Plus, for a larger muscle areas like rectus abdominis, quadriceps, or hamstrings I like a lot of pads, 4 in fact, to most fully contract the muscles. And while I have my favorite placements, I think there is something to varying the placements and connections so the electric stimulation input isn’t always the same.
So when I read the recent (2014) review article on motor points and electric stimulation where they conclude that it’s “essential for optimizing neuromuscular electrical stimulation use” I think ehh. Either their settings aren’t optimal, or their pads are too small. When I went and read the paper they based their conclusions on, it turns out they were using a pulse duration of only 100 uS, and 4 cm (area = 16 square cm) gel electrodes. Gel electrodes have been shown to be inferior in conductance and comfort to rubber carbon even when the size is equal and the size they used is 1/4 what I prefer. The 4 cm gel electrodes they used the size of the cheapest pads that come with a machine. After having tested the small gel electrodes on myself, and later on patients, I no longer use them. I favor 3.5” (~9 cm) circular pads (for general use) which have a surface area of 63 cm, about 4 times as much. So I would expect the combination of factors would explain much of why they needed to use motor points, while I don’t. So if you want to take the time to search out motor points on yourself or your patients, I say go ahead. However, if you want to save a few minutes with every application use large rubber carbon electrodes and I expect you won’t be missing much if anything. My year (plus) of using EMS on myself, and putting it on a lot of patients, I’ve tried just about everything. One last advantage I can think of about strapping on rubber electrodes is that if you don’t like where it is you can adjust it a little bit by just pushing it, while a sticky gel electrode needs to be peeled off and reapplied.
So there’s some research that I find interesting, but due to my experience I still disregard it. If I change my mind in the future I’ll be sure to post about it.
As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.
Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.