Unilateral intramuscular needling can improve ankle dorsiflexor strength and muscle activation in both legs

Abstract

Background/objective: The aim of this study was to determine whether unilateral manual needling at nonacupoints could result in bilateral strength gain similar to that found in electroacupuncture at specific acupoints.

Methods: Fifty healthy male volunteers with an age range of 19-27 years were recruited and randomly allocated into five groups: (1) manual acupuncture and (2) electroacupuncture at two acupoints (ST-36 and ST-39); (3) manual acupuncture and (4) electroacupuncture at two nonacupoints on the tibialis anterior muscle; and (5) control group. The intervention groups received needling in each session on the right leg for 15 minutes in Week 1, 20 minutes in Week 2, and 30 minutes in Weeks 3-8, three sessions per week. The maximal isometric ankle dorsiflexion strength and muscle activation (as determined by twitch interpolation) of both legs were assessed pre, post, 2 weeks post, and 3 weeks post the experimental period.

Results: Mixed models (linear) with repeated-measures analysis identified significant strength gains (p < 0.01) after the intervention period in both limbs, while no significant differences were detected between the intervention groups and between the two legs, and no change was found in the control group. A significant improvement in muscle activation (p < 0.01) was also observed in both legs in the intervention groups.

Conclusion: It was concluded that both unilateral manual and electric needling caused significant bilateral strength gain, and this effect was not specific to the selected acupoints or electric stimulation. The strength gain was sustained for at least 3 weeks after the 8-week intervention.

Keywords: Acupuncture; Detraining; Muscle activation; Muscle strength.

Figure 1

Locations of the acupoints ST-36 and ST-39, and sham points on the tibialis anterior muscle. Cun is a unit for relative length used in traditional Chinese medicine. The breadth of participant's index, middle, ring, and little fingers, at the level of proximal interphalangeal joint at the dorsum of the middle finger, is 3 cun. Sham points are located at the top one-third and lower one-third on the muscle belly of the tibialis anterior muscle, and 3 cm lateral to the anterior crest of the tibia. Note. The figure is reproduced with permission.

Figure 2

Effects of 8 weeks of unilateral acupuncture at acupoints or needling at sham points on the right leg on ankle dorsiflexion force of both legs. The larger dots and thick lines represent the group means, and the smaller dots and thin lines represent individual data in each group. *p < 0.05, post > pre. EAcu = electroacupuncture on acupoints; ESham = electroacupuncture on sham points; MAcu = manual acupuncture on acupoints; MSham = manual acupuncture on sham points.

Figure 3

Effects of 8 weeks of unilateral acupuncture at acupoints or needling at sham points on muscle activation (mean ± SD), as determined by twitch interpolation technique. *p < 0.05, post > pre. EAcu = electroacupuncture on acupoints; ESham = electroacupuncture on sham points; MAcu = manual acupuncture on acupoints; MSham = manual acupuncture on sham points; SD = standard deviation.