The Chinese explanation of how this ancient needling treatment works fits uncomfortably in the western psyche.
The traditional explanation is that bodily health depends on the smooth flow of vital energy ('qi') around the body, the qi flowing along 14 narrow channels or meridiens.
A blockage in the flow of qi, it is explained, can cause dysfunction or disease, and 'needling' a small hole through the skin on a meridien line can release the blockage, allowing the restoration of natural flow - with consequent healing.
Traditional acupuncturists describe particular points along the meridiens where needling has particularly enhanced effect. Each of these special points have their own names and numbers (eg Large Intestine Meridien, point #4 of 20; L14, Hegu).
Twiddling a needle in these special points helps to identify the right spot, as a trained acupuncturist feels a tiny responsive tug on the needle. Correctly placed, the needles cause a sensation of tingling or heaviness rather than pain.
A recent experiment [ref] with a computerised needle showed that it was indeed measurably harder to pull the needles out of these known meridien points than other parts of the body! Twiddling the needle enhanced the measured effect.
So how do we translate the acupuncture effect into something the western mind is comfortable with?
Well, it seems that these particularly sensitive points release neurotransmitters when needled, chemicals well known to western science and which assist the transmission of nerve impulses. One of them, 'substance P', is known to have a particular effect on pain. Natural opiates ('endorphins') are also released during acpuncture.
Another phenomenon confusing to the western mind is that the needles are frequently placed in places remote to the problem - like the webspace between finger and thumb might be used to treat constipation. Or the therapist might be needling the problem area - but on the other side of the body!
The former makes reasonable sense to the western doctor who knows that many nerve pathways have been shown to cross over to the other side of the body. For example, a stroke on the left hand side of the brain often impairs function in the right hand. And the latter reminds me of 'referred pain' - well known in western medicine - eg. arthritis of the hip can present with pain in the knee, or appendicitis with pain in the bellybutton!
Cross-over of knowledge and understanding is also beginning to occur - traditional acupuncturists are taking cognisance of western publications, and westerners are learning technique from traditionalists. Acupuncture is becoming part of the rehab armamentarium of physiotherapy departments around the world.