You may not know the definition of a trigger point, but most people have experienced the ache or stab of pain that occurs when these locations on the body are touched or pressed. Simply put, a trigger point is a discrete, hyperirritable nodule (like a “knot”) that is palpable in a taut band of muscle—and it can produce pain in a particular spot or in another part of the body.

Recently, trigger points have been implicated in various conditions including myofascial pain syndrome (a chronic disorder involving the muscles and the surrounding connective tissue); tension-type headaches (particularly in women); migraine headaches; chronic neck pain; and low back pain. While the formal term “myofascial trigger point” was coined in the 1950s, research investigating the underlying causes and effective treatments is relatively new.

That’s a positive development because trigger points are common—“85 percent of people will have myofascial pain at some point in their lives and often it involves trigger points,” says Shana Margolis, a physical medicine and rehabilitation physician at Northwestern Medicine in the Chicago area. “Myofascial pain syndrome is kind of a big black box of pain disorders,” says Kiran Rajneesh, a neurologist and pain medicine physician at The Ohio State University Medical Center in Columbus. “There may be more to it than just a muscle issue. There could be underlying joint inflammation.”