Researchers lead by Harvard Medical School in the US, have been studying the mechanisms behind acupuncture’s ability to relieve pain. A total of 79 patients aged 18 to 60, with chronic lower back pain were randomly assigned to four weeks of either real or sham acupuncture. Six treatments were given in total per patient. Resting state functional MRI scans were performed prior to the first treatment and after the last treatment.
Fifty patients completed the study. Reductions in the extent to which patients were troubled by their pain, were observed in both treatment groups, with significantly greater pain relief occurring in the real acupuncture group. Real acupuncture was found though to increase connectivity between the periaqueductal gray and ventral tegmental areas of the brain, with the amygdala.
The authors conclude that acupuncture may simultaneously modulate connectivity between key brain regions, linked via the amygdala, to block pain signals. The amygdala is not only involved in pain signal processing, but it also plays a role in negative emotion management. The authors also point out that the pain relief observed is consistent with findings from systematic reviews testing the efficacy of acupuncture for chronic lower back pain. These reviews found that although differences between real and sham acupuncture are relatively modest, acupuncture is superior to both a non-acupuncture control and sham acupuncture for the treatment of chronic pain.
(Acupuncture Treatment Modulates the Connectivity of Key Regions of the Descending Pain Modulation and Reward Systems in Patients with Chronic Low Back Pain. Journal of Clinical Medicine, 3 June 2020.)
Brazilian university researchers studying acupuncture for spinal pain, have found that ear acupuncture reduces the degree of disability in sufferers. In a clinical trial, 110 people aged 18 to 80 were randomised into three groups: true acupuncture, placebo acupuncture and a no-treatment control group. Both treatment groups received five sessions, over six weeks. 
A large matched cohort study undertaken in Korea, suggests that having acupuncture treatment for lower back pain is associated with less likelihood of eventually needing lower back surgery. Using a nationwide insurance database, researchers identified all newly-diagnosed cases of lower back pain over a six year period, and separated out the subset who had had a course of acupuncture. After matching, over 130 000 patients were included in each of an acupuncture and non-acupuncture group. The lumbar surgery rate in the two years following a first acupuncture session was calculated.
Authors of a study in Japan looking at acupuncture for spinal stenosis of the lumbar region, have concluded that it is more effective than either medication or physical exercise. A total of 109 patients with L5 root radiculopathy associated with lumbar spinal stenosis, visiting Iwai Orthopaedic Medical Hospital for surgical treatment, were assigned to receive either paracetamol (900mg three times a day), exercise therapy, or acupuncture (five sessions) over a period of four weeks. All groups were permitted to use additional non-steroidal anti-inflammatory drugs as required for pain control. 
Clinicians in Berlin, Germany have shown that cupping for lower back pain, combined with analgesics, is more effective than analgesics alone. In the four week study they performed, 110 patients aged 18 to 65 were randomised to receive either eight sessions of cupping, plus paracetamol as required, or low suction cupping plus paracetamol as required, or paracetamol alone as required.