Background Acupuncture is used clinically to treat muscle spasticity and flaccidity. Claims have been made that acupuncture can affect muscle EMG activity, though there is some doubt about the reliability of these studies. This study’s aim was to examine the immediate effects of acupuncture on the EMG activity of the common wrist extensor muscles.
Methods Thirty five right-handed healthy volunteers, 17 male and 18 female, aged 18-70 years were recruited from a convenience sample. Five subjects provided reliability data, and the remaining 30 took part in the main study. The study was a crossover, within-subject design, with the interventions counterbalanced. The three conditions were genuine acupuncture to LI4 (Hegu) and LI10 (Shousanli) for 20 minutes, with de qi; inappropriate acupuncture to PC3 (Quze) and PC6 (Neiguan) for 20 minutes; and 20 minutes of a no intervention control. All participants received each condition in random order.
The outcome measure was surface EMG activity recorded over the common wrist extensor muscles during a 10 second, sub-maximal, isometric contraction. The average of three readings was used. The reliability of the outcome measurement was assessed in five volunteers selected at random who received repeated EMG recordings without acupuncture.
Results The reliability tests showed the EMG procedure was highly reliable, with an intraclass correlation coefficient (ICC 2,1) of 0.9996 and a standard error of measurement of 0.014mV. In the main study, paired t tests for the effect of the order of the first two interventions showed no detectable carry-over effect. Freidman analysis of variance found no difference between the three conditions (P=0.573).
Conclusion No meaningful change was detected in EMG activity following acupuncture interventions, but this study provides a sound protocol and normative values on which to plan future research.
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