FSM stands for Frequency Specific Microcurrent. It uses extremely gentle electrical currents — measured in millionths of an amp (microamps), similar in size to the currents your own cells naturally produce — matched to specific tissues and conditions. The current is so small that most people feel little or nothing at all. This is quite different from a TENS machine, which works at a much higher intensity to mask or block pain signals. FSM doesn't try to override your body; it works quietly, at the same subtle electrical level your body already uses to repair itself.
What makes it "frequency specific" is that each setting pairs two frequencies: one chosen for the condition we're addressing (for example, inflammation or scar tissue), and one for the particular tissue we're working with (a nerve, a muscle, the lining of the gut). It's this careful pairing that gives the method both its name and its precision.
The idea behind it
Every cell in your body carries a tiny electrical charge and communicates through electrical signals — in a real sense, your cells are like tiny rechargeable batteries. When tissue is injured, inflamed, or stuck in a long-standing stress pattern, that charge drops and the signalling becomes sluggish. This is part of why some injuries seem to "get stuck" and refuse to settle, no matter how much you rest them.
A frequently cited laboratory study (Cheng, 1982) found that microcurrent in this gentle range increased the production of ATP — the cell's main energy currency — by as much as 500%, while stronger currents actually reduced it. In other words, with this kind of energy, gentler isn't weaker; gentler is the whole point. FSM aims to support the cell's own repair work — encouraging tissue healing, easing inflammation, and helping to settle pain — by meeting the body in the language it already speaks.
Where the frequencies come from
FSM didn't begin with a single inventor — the frequencies themselves are far older than the modern method. They trace back to a device built in 1922, from an era when thousands of physicians were experimenting with frequency-based therapies, an approach that later fell out of use and was largely forgotten. In 1946, a British osteopath named Harry Van Gelder bought a practice in Vancouver, uncovered that 1922 machine along with its handwritten list of frequencies, and began using them with remarkable results. Decades later, in 1983, the chiropractor Dr. George Douglas studied with Van Gelder and carried the list home to Portland — where it sat in a desk drawer until Dr. Carolyn McMakin joined his practice in 1995 and rediscovered it.
McMakin is the one who turned that inherited list into the method we know today. From 1995 she began applying the frequencies with a modern, FDA-approved two-channel microcurrent device, taught the first FSM course in 1997, and built the clinical protocols, research, and training that practitioners now use around the world. So the frequencies were recorded long ago; what McMakin developed was a careful, teachable, evidence-minded way to use them. What I appreciate about it as a physiotherapist is that it isn't mystical — it's an evolving clinical method, and it pairs naturally with the hands-on structural work I already do.
What a session feels like
You rest comfortably and fully clothed while soft contacts — often warm, damp cloths or graphite gloves — are placed on the body, so the current can flow gently between them. A session usually lasts somewhere between twenty minutes and an hour. Most people feel nothing more than a faint warmth, a soft tingle, or occasionally a slight metallic taste; many simply find it deeply relaxing and drift off to sleep. There's nothing to "do" — your only job is to let your body receive it.
One small but important detail: the current travels far better through a well-hydrated body, so I'll usually ask you to drink water before and after. Some people feel a little tired afterwards — much like the rest-and-repair tiredness I've written about before. That's a sign the body has shifted into recovery mode, not a cause for worry.
What it may help with
In the right context, FSM can be supportive for recovering from acute injuries and sprains, calming inflammation and swelling, soothing nerve-related pain, softening old scar tissue and adhesions, and easing the deep muscle soreness that follows heavy activity. Because the frequencies can be matched to so many different tissues, it's a flexible tool — but it works best when it's pointed at the right target, which is exactly why assessment always comes first.
Where it fits
In my practice, FSM is one part of a holistic plan rather than a standalone fix. I often weave it in alongside structural therapy and acupuncture — for example, releasing a restriction with my hands, then using microcurrent to help the tissue settle and repair. It can be especially supportive for recovering from acute injury, for keeping progress moving between deeper sessions, and for those times when your body and energy simply need a recharge. How many sessions help depends entirely on you and what we're working with: acute issues sometimes respond quickly, while long-standing patterns ask for a little more patience.
Is it for everyone?
FSM is gentle and very well tolerated, but it isn't right for every situation. As a precaution, I avoid using it over a pacemaker or other implanted electrical device, during pregnancy, and directly over an active cancer unless it's part of a plan agreed with your doctor. If any of these apply to you, just let me know — there's almost always another gentle path we can take together.
Healing is rarely about forcing the body. More often it's about giving it the right conditions — and sometimes, a gentle reminder, in the body's own electrical language, that it is safe to begin repairing again.
References & further reading
- McMakin CR. Frequency-Specific Microcurrent in Pain Management. Edinburgh: Churchill Livingstone / Elsevier; 2011.
- McMakin CR. The Resonance Effect: How Frequency Specific Microcurrent Is Changing Medicine. Berkeley: North Atlantic Books; 2017.
- McMakin CR, Gregory WM, Phillips TM. Cytokine changes with microcurrent treatment of fibromyalgia associated with cervical spine trauma. Journal of Bodywork and Movement Therapies. 2005;9(3):169–176.
- Cheng N, Van Hoof H, Bockx E, et al. The effects of electric currents on ATP generation, protein synthesis, and membrane transport in rat skin. Clinical Orthopaedics and Related Research. 1982;(171):264–272.
- Frequency Specific Seminars. History of the FSM Process. frequencyspecific.com.
For education only, and not medical advice. FSM is not a cure-all, individual responses vary, and the research is still growing. It is used as a complement to — not a replacement for — appropriate medical care.