Dysmenorrhea is one of the most prevalent causes of pelvic pain among women (1). The World Health Organization categorized it as a primary and non-specific condition in the Tenth Revision of the International Statistical Classification of Diseases and Related Health Problems in 1992 (2). Dysmenorrhea manifests in two forms: primary and secondary, with primary dysmenorrhea being the more common. It is characterized by lower abdominal pain occurring just before or during menstruation, without any evident pelvic pathology, typically emerging 6–12 months or 1–2 years following menarche (3, 4). Secondary dysmenorrhea accounts for about 10% of dysmenorrhea cases, and the most common cause is endometriosis (5). The pain associated with dysmenorrhea can range from moderate to severe and significantly impairs quality of life, affecting approximately 72.8% of women (2).

The etiology of primary dysmenorrhea primarily involves prostaglandins (6). Currently, the most widely used pharmacological treatments for dysmenorrhea are non-steroidal anti-inflammatory drugs (NSAIDs) (7), which inhibit prostaglandin synthesis via cyclooxygenase inhibition (8). Another common treatment is oral contraceptives, which suppress ovulation and reduce endometrial thickness, thereby alleviating menstrual cramps and pain (9, 10). However, pharmacological treatments can lead to gastrointestinal side effects, impact the central nervous system, affect metabolism, have diminished long-term effectiveness, and may lead to drug resistance (11). Alternative treatments for menstrual cramps include: (a) transcutaneous electrical nerve stimulation, which modifies the body’s pain perception (12), (b) acupuncture, which increases the release of norepinephrine and β-endorphins into the bloodstream and cerebrospinal fluid, reducing pain (13), and (c) surgical interventions like laparoscopic uterosacral nerve ablation. Each method offers benefits but also carries potential side effects. Currently, about 70% of women with menstrual cramps engage in self-management (14, 15). Factors such as an unhealthy lifestyle, lack of self-care awareness, and chronic repetitive menstrual pain can exacerbate symptoms by inducing menstruation-related fear or anxiety.

Given the severity of symptoms during dysmenorrhea episodes, which often prevents timely medical consultation, and the challenges patients face in mastering effective pain management techniques, there is a significant practical need for an effective, patient-administered physical therapy. Numerous studies have demonstrated the efficacy of acupressure in alleviating dysmenorrhea (16–18). Acupressure is a non-invasive method that involves applying pressure to specific acupoints using fingers or thumbs to relieve pain. Wrist-ankle acupuncture (WAA), a specific modality within the broader acupuncture framework, also shows promising analgesic effects (19–21). Our research team has developed the Acupressure Wrist-Ankle Strap (AWA) based on WAA principles. This innovative, portable device (22) aims to replace traditional acupuncture needles, allowing patients to self-administer treatment and achieve pain relief. However, its effectiveness in treating primary dysmenorrhea had not been previously verified. To support and validate the clinical efficacy of this novel therapy, we designed a single-blind randomized controlled trial (RCT) to assess the effectiveness of the AWA and to explore potential factors influencing its efficacy.

The objective of this study was to assess the clinical efficacy of the AWA in alleviating primary dysmenorrhea through a single-blind RCT. We recorded the VAS scores, the onset time for “obvious relief” of dysmenorrhea pain, and changes in pain threshold at SP9 to evaluate the immediate analgesic effects of AWA on dysmenorrhea.

The findings demonstrated a significant reduction in VAS scores within the AWA group, with marked differences between the scores at 5, 10 and 30 min after intervention compared to baseline, which were statistically significant. The most substantial decline in VAS scores occurred from 10 to 30 min post-intervention. This reduction can be attributed to: (1) the lengthier measurement interval during this phase, enhancing the visibility of the strap’s efficacy; (2) the progressive increase in acupressure effects over the duration of the intervention. In contrast, the VAS scores in the NAWA group exhibited only a marginal decrease at 5 min post-intervention, lacking statistical significance, which suggests a possible placebo effect associated with NAWA.

Regarding the onset time for “obvious relief” of dysmenorrhea pain, 16 out of the 39 participants in the AWA group reported significant pain relief, with onset times ranging from 8 to 27 min and an average of 21.50 ± 3.65 min. The remaining 23 participants did not report “obvious relief,” possibly due to a more gradual alleviation of their pain. As indicated in Table 3, the VAS scores decreased from an initial 5.72 ± 1.75 to 2.82 ± 2.01 after 30 min of intervention, signifying that some participants continued to experience discomfort post-intervention.

The pressure pain threshold is a credible metric for validating the mechanisms of acupuncture, recognized as an effective and precise indicator for assessing pain (29).

In the AWA group, the pain threshold at SP9 on both sides exhibited a downward trend. Conversely, in the NAWA group, the pain threshold at the right SP9 displayed an upward trend, though no statistically significant changes were noted at the left SP9. Some studies have found that women with dysmenorrhea exhibit reduced sensitivity to subcutaneous and muscular electrical stimulation during menstruation (30–34), and the occurrence of dysmenorrhea appears to lower the pain threshold at skin tenderness sites (31, 32, 35, 36). Key reasons for the discrepancies between the results of this study and those of previously published studies (30–35) include: (1) women with dysmenorrhea exhibit heightened pain sensitivity compared to healthy individuals (31, 32, 34); (2) pain intensity during menstruation was measured in these studies without any intervention (30–35); (3) variations in the selection of experimental pain stimuli, such as the location and depth of application. These methodological differences complicate the drawing of linear conclusions due to the diverse range of painful stimuli, neglect of anatomical variations in pain areas, and the absence of dysmenorrhea as the “background” pain when testing pain thresholds outside the menstrual period. Some studies have suggested that dysmenorrhea may be associated only with somatic hyperalgesia of deep tissues, while central sensitization of skin pain is less evident (35). The pain experienced by individuals with dysmenorrhea is complex, subjective, and multidimensional, with significant interindividual variability in pain perception, further complicating the derivation of reliable conclusions.

We also monitored temperature changes at CV4 to explore the potential mechanisms of action of AWA. The results indicated no statistically significant differences in temperature at CV4, either pre- and post-intervention or between groups (p > 0.05). Previous research by Slater et al. (36) demonstrated that acupuncture at Sanyinjiao (SP6, corresponding to the Lower 2 compression point in this study) can enhance uterine artery blood flow, thereby alleviating dysmenorrhea pain. Other studies reported significant increases in skin temperature at CV4 following acupuncture at SP6 (37). In our study, the absence of temperature changes at CV4 might be attributed to the limited duration of acupoint pressure (30 min) and the timing of temperature measurements post-intervention. Nonetheless, these findings suggest that the immediate analgesic effects of AWA do not derive from increased temperature at CV4 through improved uterine artery blood flow as induced by needling stimulation at SP6.

In this trial, the ETCS questionnaire was employed to assess patients’ expectations and satisfaction with the intervention’s efficacy. The results indicated that the AWA group reported a significantly higher degree of satisfaction with the intervention’s efficacy compared to the NAWA group, suggesting that AWA was substantially more effective than the sham control.

AWA represents a physical therapy approach that is effective, non-toxic, and devoid of side effects. It is simple to administer and can be used repeatedly. Further research should explore the effectiveness of AWA for other conditions.

This study is subject to several limitations. Firstly, the investigation was confined to observing the effects of a single 30-min treatment session, specifically focusing on three time points during the intervention. The primary aim was to assess the immediate analgesic effects. Future research is necessary to explore the long-term efficacy of this device and to ascertain its safety and acceptability for frequent use over extended periods. Secondly, the recruitment of participants was limited to students from a university with a high proportion of female students in order to secure a sufficient sample size within a specific timeframe and to ensure participant compliance. This selection criterion may affect the external validity of the findings. Future studies should aim to include a more diverse participant pool to verify the efficacy of the AWA more broadly. Thirdly, the potential impact of the treatment may have been overestimated due to the lack of follow-up assessments. Fourthly, the VAS of the control group exhibited a decrease at the 5th minute which could be attributed to a placebo effect. To further investigate this phenomenon, it is recommended to increase the number of blank controls and trials in subsequent experiments.

This trial substantiated our hypothesis that the AWA provides immediate analgesic effects for patients suffering from primary dysmenorrhea. The AWA represents a safe and efficacious intervention for alleviating abdominal pain associated with this condition. As a non-invasive physical therapy, it offers a self-administered, non-pharmacological option for pain relief in patients with primary dysmenorrhea. The clinical relevance of AWA could be further enhanced by extensive research to validate its effectiveness for additional medical conditions.

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding authors.

The studies involving humans were approved by China Ethics Committee of Registering Clinical Trials (ethics reference: ChiECRCT20190037). The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.

SZ: Data curation, Supervision, Writing – original draft, Writing – review & editing. CW: Data curation, Software, Supervision, Writing – review & editing. YR: Data curation, Formal analysis, Methodology, Supervision, Writing – review & editing. YL: Writing – review & editing, Conceptualization, Resources, Validation. RM: Resources, Data curation, Writing – review & editing. FF: Funding acquisition, Resources, Validation, Writing – review & editing. QZ: Methodology, Supervision, Writing – review & editing.