Once qi has arrived, clips are attached to the needle handles and a small current is passed between pairs of points. Continuous wave gives steady stimulation, dense-disperse alternates between two frequencies and is used for pain, and interrupted wave produces a rhythmic on-off pattern used for paralysis and muscular weakness.
Electroacupuncture gives a consistent stimulus that does not tire the practitioner, and its parameters can be standardised for research, which is why most clinical trials use it. It is avoided in patients with cardiac pacemakers, over the chest, and in areas where muscle spasm would be dangerous.