The immediate effects of local and adjacent acupuncture on the tibialis anterior muscle: a human study

Abstract

Background: This study compares the immediate effects of local and adjacent acupuncture on the tibialis anterior muscle and the amount of force generated or strength in Kilogram Force (KGF) evaluated by a surface electromyography.

Methods: The study consisted of a single blinded trial of 30 subjects assigned to two groups: local acupoint (ST36) and adjacent acupoint (SP9). Bipolar surface electrodes were placed on the tibialis anterior muscle, while a force transducer was attached to the foot of the subject and to the floor. An electromyograph (EMG) connected to a computer registered the KGF and root mean square (RMS) before and after acupuncture at maximum isometric contraction. The RMS values and surface electrodes were analyzed with Student's t-test.

Results: Thirty subjects were selected from a total of 56 volunteers according to specific inclusion and exclusion criteria and were assigned to one of the two groups for acupuncture. A significant decrease in the RMS values was observed in both ST36 (t = -3.80, P = 0,001) and SP9 (t = 6.24, P = 0.001) groups after acupuncture. There was a decrease in force in the ST36 group after acupuncture (t = -2.98, P = 0.006). The RMS values did not have a significant difference (t = 0.36, P = 0.71); however, there was a significant decrease in strength after acupuncture in the ST36 group compared to the SP9 group (t = 2.51, P = 0.01). No adverse events were found.

Conclusion: Acupuncture at the local acupoint ST36 or adjacent acupoints SP9 reduced the tibialis anterior electromyography muscle activity. However, acupuncture at SP9 did not decrease muscle strength while acupuncture at ST36 did.

Figure 1

Flow diagram of the local and adjacent acupuncture. The diagram also includes the number of volunteers who were excluded from the trial.

Figure 2

Electromyography activities in root mean square (RMS) percentage for the SP9 (A) and ST36 (B) groups before and after acupuncture. Data were reported as mean ± SD. *Statistically significant differences, in comparison to the pre- and post-SP9 or ST36 treatment values, according to paired t-test (P = 0.001) in A and (P = 0.002) in B. N = 15 for each group, Pre: local and adjacent point groups before acupuncture, Post ST36 treatment: local point group after acupuncture, Post SP9 treatment: adjacent point group after acupuncture.

Figure 3

Electromyography (EMG) of a single subject in the local point ST36 group. A = EMG acupuncture. B = EMG after acupuncture. In the x axis the duration is 5 seconds. In the y axis the amplitude scale is 308 μV in A and 102 μV in B.

Figure 4

Electromyography (EMG) of a single subject in the adjacent point SP9 group. A = EMG before acupuncture. B = EMG after acupuncture. In the x axis the duration is 5 seconds. In the y axis the amplitude scale is 33 μV in A and 25 μV in B.

Figure 5

Muscle strength (KGF) results of the SP9 (A) and ST36 (B) groups before and after acupuncture. Data are reported as mean ± SD. * The values between the two groups after acupuncture are statistically different (P = 0.01). N = 15 for each group, Pre: local and adjacent point groups before acupuncture, Post ST36 treatment: local point group after acupuncture, Post SP9 treatment: adjacent point group after acupuncture.

Figure 6

Electromyography activities in root mean square (RMS) percentage (A) and muscle strength (KGF) (B) in the SP9 and ST36 groups before acupuncture. Data are reported as mean ± SD. * The values between the two groups after acupuncture are statistically different (P = 0.01). N = 15 for each group, Pre: local and adjacent point groups before acupuncture, Post ST36 treatment: local point group after acupuncture, Post SP9 treatment: adjacent point group after acupuncture.