A new study establishes a link between needle manipulation and biomechanical effects
Bethesda, MD -- Western medical experts have been inherently skeptical of acupuncture's therapeutic value for the treatment of pain and other medical conditions. One reason is that it seems very unlikely that the simple act of inserting fine needles into tissue could elicit any effect at all, let alone wide-ranging and long-lasting therapeutic effects. Acupuncture needles are of a finer gauge than even the finest hypodermic needles (not considered therapeutic); acupuncture rarely results in a single drop of blood being discharged.
What skeptics are not aware of is that acupuncture typically involves manual needle manipulation after needle insertion. Manual needle manipulation consists of rapidly rotating (back-and-forth or one direction) and/or pistoning (up-and-down motion) of the needle. The manipulation can be brief (a few seconds), prolonged (several minutes), or intermittent depending on the clinical situation. Manipulation occurs even when electrical stimulation is used (a relatively recent development in the history of acupuncture).
Traditionally, manipulation is performed to elicit the characteristic reaction to acupuncture needling known as "de qi." De qi has a sensory component, known as "needle grasp," which is perceived by the patient as an ache or heaviness in the area surrounding the needle and a simultaneously occurring biomechanical component that can be perceived by the acupuncturist. During needle grasp, the acupuncturist feels as if the tissue is grasping the needle such that there is increased resistance to further motion of the manipulated needle. This "tug" on the needle is classically described as "like a fish biting on a fishing line."
Needle grasp can range from subtle to very strong, with pulling back on the needle resulting in visible tenting of the skin. During acupuncture treatments, needle manipulation is used to elicit and enhance de qi, and de qi is used as feedback to confirm that the proper amount of needle stimulation has been used.
De qi is widely viewed as essential to acupuncture's therapeutic effectiveness. Needle manipulation, de qi, and needle grasp, therefore, are potentially important components of acupuncture's therapeutic effect, yet the mechanisms underlying de qi and needle grasp are unknown. As a first step toward understanding the physiological and therapeutic significance of de qi, researchers quantified needle grasp by measuring the force necessary to pull an inserted acupuncture needle out of the tissues (pullout force). They also hypothesized that:
- Pullout force is greater with two different types of needle manipulation commonly used in acupuncture practice [bidirectional (BI) and unidirectional (UNI) needle rotation] than with needle insertion with no manipulation (NO). If proven true, this will demonstrate that needle manipulation has measurable biomechanical effects.
- These measurable effects could suggest that needle manipulation may indeed play an important role in acupuncture therapy as de qi is traditionally believed to be greater at "acupuncture points."
- Pullout force is greater at classically defined acupuncture points than at nonacupuncture control points.
To test these hypotheses, an experiment was performed in which normal human subjects received different types of acupuncture needle manipulation at eight acupuncture points and eight corresponding control points.
The authors of the research study, "Biomechanical Response to Acupuncture Needling in Humans," are Helene M. Langevin, David L. Churchill, James R. Fox, Gary J. Badger, Brian S. Garra, and Martin H. Krag, all from the University of Vermont College of Medicine, Burlington, Vermont. Their findings are published in the December 2001 edition of the Journal of Applied Physiology.
Healthy volunteers, ages 18-55, were invited to participate. Exclusion criteria were a history of diabetes, neuromuscular disease, bleeding disorder, collagen vascular disease, acute or chronic corticosteroid therapy, and extensive scarring or dermatological abnormalities in the areas tested. Volunteers taking anti-inflammatory or antihistamine medications were asked to discontinue their use three days before testing. Female volunteers were excluded if they were pregnant. Testing was not scheduled during menstruation to avoid possible discomfort due to cessation of anti-inflammatory medication.
Thirty-eight women and 22 men completed the testing protocol. The mean age and body mass index of the participants was 37.1 ± 10.2 years and 26.5 ± 5.3 kg/m2, respectively. There were no significant differences with respect to these subject characteristics between the groups of subjects randomized to the three needle-manipulation types.
Eight traditional acupuncture point locations were investigated. For each location, pairs of corresponding acupuncture points on the right and left sides of the body were identified and marked with a skin marker (16 acupuncture points total). Acupuncture points were identified according to traditional methods. Approximate position was determined in relation to anatomic landmarks (e.g., bones, tendons) and proportional measurements (e.g., fraction of the distance between wrist and elbow creases). Palpation, feeling for a slight depression or yielding of tissues determined the precise position of each acupuncture point. For each location, right and left sides of the body were then randomly selected for acupuncture point and control point. On the side selected for control point, a disk-shaped template was centered on the acupuncture point.
Throughout testing, subjects were neither told nor able to see or hear any indication of which side was used for each point (acupuncture and control) and which needle manipulation type (NO, BI, or UNI) was being performed. All needling procedures (insertion, manipulation, pullout, and pullout-force measurement) were performed by a computer-controlled acupuncture needling system. This ensured consistent experimental conditions and eliminated many potential sources of investigator bias.
The measurements of pullout force are the first quantification of needle grasp, a biomechanical aspect of the characteristic de qi reaction widely viewed as essential to the therapeutic effect of acupuncture. The research found 167 and 52 percent increases in pullout force with UNI and BI, respectively, compared with NO. Needle manipulation increased pullout force at both acupuncture points and control points. Although 18 percent difference in mean pullout force between acupuncture points and control points existed, the magnitude of this difference was much smaller than the difference caused by manipulation of the needle. Together, these results indicate that needle grasp is strongly influenced by needle manipulation and that this effect is not unique to acupuncture points.
Needle grasp has been described in acupuncture textbooks for over 2,000 years. This study constitutes a first step toward determining the biological and clinical significance of this phenomenon. For the first time, a link has been demonstrated between acupuncture needle manipulation and biomechanical events in the tissue. These biomechanical events are potentially associated with long-lasting cellular and extracellular effects. Developing an understanding of these effects in future studies may eventually lead to insights into acupuncture's therapeutic mechanisms. In the shorter term, these same effects may also provide important biological markers that can be used in clinical trials of acupuncture.
December 2001 edition of the Journal of Applied Physiology.
The American Physiological Society (APS) was founded in 1887 to foster basic and applied science, much of it relating to human health. The Bethesda, MD-based Society has more than 10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals every year.