Although meridians—defined as channels that transport life energy—form the foundation of Traditional Chinese Medicine (TCM), there is no evidence of their physical presence. In other words, no physical tubes can be found with a scalpel. Yet, there is a growing body of research that supports the efficacy of meridians.
While meridians are not hollow tubes, extensive research has been conducted into the role of the fascia network (connective tissue).
Fascia as a conductor: Scientists such as Dr. Helene Langevin have demonstrated that acupuncture points often coincide with areas where connective tissue planes meet. - Helene M Langevin 1, Jason A Yandow, Relationship of acupuncture points and meridians to connective tissue planes. Anat Rec. 2002 Dec 15;269(6):257-65. In this study, researchers used ultrasound imaging of the arm to show that more than 80% of acupuncture points and half of the meridians in the arm coincide with the boundaries of intermuscular or intramuscular connective tissue planes. - Helene M Langevin 1, David L Churchill, Junru Wu, Gary J Badger, Jason A Yandow, James R Fox, Martin H Krag, Evidence of connective tissue involvement in acupuncture. FASEB Journal. 2002 Jun;16(8): 872-4. This research showed that when an acupuncture needle is rotated, the underlying connective tissue (fascia) wraps around the needle. This causes a mechanical deformation of the cells (mechanotransduction), explaining why acupuncture has an effect on the entire body rather than just the site of insertion. The principles of mechanical stimulation (pressure and stretching, as used in acupressure and Do-In stretches) are comparable to the mechanical stimulus Langevin describes in this study.
Mechanotransduction: By applying stretch (as in Do-In) or pressure (acupressure) to the connective tissue, signals are sent to the cells that influence physiology. This supports the idea that meridians are paths of "least resistance" within the connective tissue. - Mingzhu Huo, Qingxiang Zhang, Yuxin Si, Youlin Zhang, Hongen Chang, Mengmeng Zhou, Di Zhang, Yuxin Fang, The role of purinergic signaling in acupuncture-mediated relief of neuropathic and inflammatory pain. Purinergic Signal. 2024 Feb 2;21(4):873–891. This research indicates that mechanical stimulation leads to the release of ATP from cells. This ATP binds to purinergic receptors, triggering a cascade of reactions that dampen pain. - Lisbeth Berrueta, Igla Muskaj, Sara Olenich, Taylor Butler, Gary J Badger, Romain A Colas, Matthew Spite, Charles N Serhan, Helene M Langevin, Stretching impacts inflammation resolution in connective tissue. J Cell Physiol. 2015 Dec 10;231(7):1621–1627. Studies with rats showed that daily stretching (similar to the meridian stretches in Do-In) prompts fibroblasts to release pro-resolution mediators, which aid in the recovery from chronic inflammation.
The most widely accepted scientific basis for meridian work lies within the nervous system:
Stimulus Transmission: Pressure on specific points stimulates nerve endings that send signals to the spinal cord and brain.
- Kathleen KS Hui, Jing Liu, Nikos Makris, Randy L Gollub, Anthony JW Chen, Christopher I Moore, David N Kennedy, Bruce R Rosen, Kenneth K Kwong, Acupuncture modulates the limbic system and subcortical gray structures of the human brain: Evidence from fMRI studies in normal subjects. Hum Brain Mapp. 2000 Feb 16;9(1):13–25.
Modern technology allows researchers to directly observe what happens in the brain when a meridian point is stimulated. These studies show that stimulating specific points (such as the Large Intestine meridian on the hand, point LI4, which we often include in a Do-In series) directly corresponds with activity in areas like the thalamus and the limbic cortex.
- Nanna Goldman, Michael Chen, Takumi Fujita, Qiwu Xu, Weiguo Peng, Wei Liu, Tina K Jensen, Yong Pei, Fushun Wang, Xiaoning Han, Jiang-Fan Chen, Jurgen Schnermann, Takahiro Takano, Lane Bekar, Kim Tieu, Maiken Nedergaard, Adenosine A1 receptors mediate local anti-nociceptive effects of acupuncture. Nat Neurosci. 2010 Jul;13(7):883-8.
A more recent breakthrough focuses on the release of ATP (adenosine triphosphate) in the tissue surrounding meridian points. When a point is stimulated, adenosine is released, acting as a local "anesthetic" on the surrounding nerve endings. This research explains the direct, local communication between the connective tissue and the peripheral nervous system.
Endorphins: It has been proven that acupuncture and acupressure stimulate the production of the body's own painkillers (endorphins and enkephalins). - Ji-Sheng Han, Acupuncture: neuropeptide release produced by electrical stimulation of different frequencies. Trends Neurosci. 2003 Jan;26(1):17-22. This study demonstrated that different frequencies of stimulation release different types of neuropeptides. - - Andrew J Vickers, Emily A Vertosick, George Lewith, Hugh MacPherson, Nadine E Foster, Karen J Sherman, Dominik Irnich, Claudia M Witt, Klaus Linde; Acupuncture for Chronic Pain: Update of an Individual Patient Data Meta-Analysis. J Pain. 2018 May;19(5):455-474. The conclusion of this research is that acupuncture is effective for treating chronic pain (back, neck, osteoarthritis, and headaches) and that the effect is greater than a placebo effect alone, indicating a physiological response (such as endorphin production).
Autonomic Nervous System: Do-In exercises help the body shift from 'fight-or-flight' mode (sympathetic) to 'rest-and-digest' mode (parasympathetic). This explains the deep relaxation clients experience. - Qian-Qian Li, Guang-Xia Shi, Qian Xu, Jing Wang, Cun-Zhi Liu 1, Lin-Peng Wang, Acupuncture Effect and Central Autonomic Regulation, Evid Based Complement Alternat Med. 2013 May 26;2013:267959. The most common method to measure the activity of the parasympathetic nervous system is through Heart Rate Variability (HRV). Research into techniques similar to Do-In (such as acupressure and yoga) consistently shows an increase in HRV. The mechanism: Stimulating specific points (such as on the Pericardium or Heart meridian) activates the Vagus Nerve. This is the "main highway" of the parasympathetic system. - Dawson Church, Garret Yount, Audrey J Brooks, The effect of emotional freedom techniques on stress biochemistry: a randomized controlled trial. J Nerv Ment Dis. 2012 Oct;200(10):891-6. This study showed a significant decrease in cortisol levels (up to 24%) after stimulating meridian points, compared to a control group that received only talk therapy. - - Hyun Jin Song, Hyun-Ju Seo, Heeyoung Lee, Heejeong Son, Sun Mi Choi, Sanghun Lee; Effect of self-acupressure for symptom management: a systematic review. Complement Ther Med. 2015 Feb;23(1):68-78. This systematic review concludes that self-administered acupressure is a promising and safe method for relieving various health complaints, including allergies, cancer-related nausea, respiratory conditions, menstrual pain, stress, and sleep problems. The researchers hope more studies will be conducted to strengthen these conclusions.
The WHO recognizes acupuncture and related techniques as effective for a wide range of complaints, including: - Chronic pain (back, neck, knee) - Nausea and digestive issues - Stress-related conditions
While the WHO does not directly confirm the existence of "Ki" (Japanese) or "Qi" (Chinese for energy), they acknowledge that interventions on the meridians produce clinically relevant results.
The effect is proven: For many complaints (pain, stress, circulation), there is solid evidence that meridian-based therapies work.
The mechanism, however, remains partly a mystery: We know that it works, but science is still debating why. Is it purely the nervous system, is it the connective tissue, or is it a bio-electromagnetic field?