Trigger point dry needling is a technique based on neurophysiology. (Sam Edwards/Getty Images)

When an old Achilles tendon injury flared up and prevented me from running, I tried all my previous tricks — ice, rehab exercises, rest. At my wits’ end, I sought advice from a physical therapist, who suggested “trigger point dry needling,” a technique in which thin needles are inserted through the skin and into so-called trigger points in the muscle.

Desperate for relief, I was soon facedown on the exam table with needles going into my calves. The procedure didn’t last long, but it felt like electric-charged spikes jabbing my nerves. My calf muscles reacted by twitching and seizing into a prolonged cramp. The next day, they were so sore I could barely walk. A few weeks later, my Achilles problem had healed enough that I could run again. Did the needling help? I have no idea.

The experts aren’t certain, either. On a scale of zero to 10, with 10 being absolute certainty about its effectiveness and zero being no supporting evidence at all, “I’d say it’s probably in the 6 range,” says Edo Zylstra, a physical therapist and owner of Kinetacore in Brighton, Colo., which trains medical professionals in the technique. “The evidence on it is improving all the time — every month there are new studies.”

One recent study randomly assigned people undergoing total knee replacement to receive either trigger point dry needling or a placebo treatment while under anesthesia (neither patients nor their health-care providers knew who was in each group) and found that people who had been needled reported less pain than the controls during the first month after the surgery. A 2005 review published by the Cochrane Collaboration concluded that dry needling may be useful when added to other therapies for chronic low-back pain.

Although it uses the same needles as acupuncture, trigger point dry needling is an entirely different technique based on neurophysiology, says Jan Dommerholt, a physical therapist at Bethesda Physiocare who teaches seminars on the technique. “We share a tool, but that’s it,” he says. “Trigger point dry needling has nothing to do with Asian medicine or meridians and energy flow.” Where acupuncture needles remain close to the skin’s surface, dry needling pushes the them farther into the muscle and thus requires an intricate understanding of anatomy.

The technique arose from observations of muscle injections made as far back as the 1940s. There seemed to be trigger points where injections provided pain relief, regardless of what was in the needle, Dommerholt says. “That suggested that it’s not what you inject, but the mechanical stimulation of the needle that does the trick.” Since then, the technique has been widely studied, but “we still don’t really know how dry needling works,” he says.

Trigger points are like knots in the muscle; when you inject a needle into them, it sparks a change in chemistry inside the muscle. “The environment in these trigger points is extremely acidic, and because of the acidity, there are lots of chemicals released in the muscle that don’t belong there,” Dommerholt says. “We know that within minutes of needling, these chemicals are gone — that’s been shown in humans and rabbits — but we still don’t know why dry needling does that.”

Dry needling is akin to rebooting your computer when it’s trapped in the spinning ball of doom, says Charlie Merrill, my physical therapist at Merrill Performance in Boulder, Colo. “You’re causing micro-trauma in that part of the muscle,” he says, which triggers increased circulation, an inflammatory response and biochemical changes (like the ones Dommerholt mentioned) that help the muscle heal. “When it comes back online, things are working more normally again,” he says.

Needling is not a fix-all solution, Merrill says. “It’s usually only a piece of the puzzle, and often a very small piece.” He says he almost never gives a patient dry needling alone. Instead, it’s one tool in a larger treatment plan that might also include exercises, range-of-motion drills and stretching.

Dry needling is most often done by physical therapists, but doctors, nurses, chiropractors and acupuncturists who have been trained can also do it. If you try it, look for a practitioner who has had specific training in the technique (typically a weekend class), and be sure that your clinic keeps needles sterile.

While the American Physical Therapy Association does not have an official position on dry needling, it recognizes that the technique “is within the professional scope of practice for physical therapists,” says Erin Wendel, the association’s senior media relations specialist.

When done by a physical therapist, dry needling is considered a regular part of physical therapy so patients (and insurers) aren’t charged added fees for it and practitioners don’t have the lure of extra income tempting them to use the technique inappropriately. However, in Idaho, New York, South Dakota and Tennessee, concerns raised by acupuncture advocates about which health-care professionals should be allowed to use needles have led to prohibitions on physical therapists providing dry needling. If you live in one of those states, you’ll have to seek the treatment from a physician.

When I told Merrill how much pain I’d had the day after the treatment, he wasn’t surprised. “It’s not like massage, where you’re going to feel good today,” he says. “It’s a feel-worse-today-to-feel-better-in-a-week-or-two sort of thing.” Dry needling is most painful in the calves and the glutes, Merrill says. When I received the treatment for hip pain on another occasion, it didn’t hurt a bit. But I’m still wondering whether it helped.

The problem I have assessing an intervention such as this is that I can’t know how my injury would have done without the procedure. If it was going to resolve itself on its own over those same few weeks, perhaps its greatest benefit was that it gave me a distraction — and a new pain to deal with, temporarily, and the feeling that I’d done something proactive — while nature ran its course.