Temporal divergence of changes in pain and pain-free grip strength after manual acupuncture or electroacupuncture: an experimental study in people with lateral epicondylalgia

Abstract

Background: The objective of this study was to examine, in individuals with lateral epicondylalgia (LE), the acute time course of acupuncture-induced hypoalgesia and change in pain-free grip strength (PFGS).

Methods: This was an experimental study, conducted at a single research center in Vancouver, BC. Twenty-one participants with unilateral LE lasting more than 6 weeks duration were enrolled. Participants received a single treatment of acupuncture (either electroacupuncture, 10-30 Hz, or manual acupuncture, assigned randomly). The primary outcome measure was pain level (0-10) during tendon loading (while making a fist) immediately after treatment, and over a 72 h follow-up period. Secondary outcome measures included pain-free grip strength (N).

Results: There was a small but statistically significant reduction in participants' perceived pain level immediately after acupuncture (mean improvement of 1.2, 95% CI 0.45-1.9). This change in pain was not accompanied by a change in PFGS. No difference was observed between the two types of acupuncture at any time point.

Conclusions: The use of acupuncture or electroacupuncture, as administered in the current study, is unlikely to acutely enhance the ability of people with LE to engage in pain-free rehabilitation exercise. Trial registration Registered February 25, 2015. ISRCTN14667535, http://www.isrctn.com/ISRCTN14667535.

Keywords: Acupuncture; Musculoskeletal; Tendinitis; Tendinopathy; Tendon.

Fig. 1

Flow of participants

Fig. 2

Changes in LE pain over time. a Participant-reported pain level before (pre) and after (post) treatment with manual acupuncture (dotted line) or electroacupuncture (solid line). There was a consistent trend for pain to lessen immediately after treatment, regardless of type of acupuncture. b The change in pain from baseline is indicated, with negative numbers indicating a lessening of pain. Asterisks indicate statistically significant improvements in pain compared to baseline. NRS numeric rating scale. N = 21, 20 and 20 for the three time points shown. Error bars represent 95% CI. c The pain diary measures demonstrated that, unexpectedly and for unknown reasons, pain levels continued to decline during the 72-h follow-up period. Changes are shown relative to day 1 midday, which was the first diary entry following acupuncture treatment, which took place in the morning of day 1. NRS: Numeric rating scale. N = 20 for all time points shown. Error bars represent 95% CI

Fig. 3

Changes in pain free grip strength (PFGS) over time. a The sensory threshold at which point participants report the onset of pain during gripping, before (pre) and after (post) treatment with manual acupuncture (dotted line) or electroacupuncture (solid line). There was no consistent trend observed for either type of acupuncture, and no difference between the two treatment groups. b The change in PFGS from baseline is indicated for all participants (both treatment groups), with positive numbers indicating an improved (raised) pain threshold. Unexpectedly and for unknown reasons, PFGS improved during the 72-h follow-up period. Asterisk indicates a statistically significant improvement in PFGS compared to baseline, but this occurred too late in the experiment to be confidently attributed to the effects of acupuncture. N = 21, 20 and 20 for the three time points shown. Error bars represent 95% CI