==== Front
J Transl Med
J Transl Med
Journal of Translational Medicine
1479-5876
BioMed Central London

4250
10.1186/s12967-023-04250-z
Research
Dose–effect of long-snake-like moxibustion for chronic fatigue syndrome: a randomized controlled trial
Luo Hong 1
Gong Rui 1
Zheng Rui 1
Tan Jing 2
Chen Ruixue 1
Wu Jie 3
http://orcid.org/0000-0002-2571-1808
Ma Tingting matingting@cdutcm.edu.cn

3
1 grid.411304.3 0000 0001 0376 205X College of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075 China
2 grid.412901.f 0000 0004 1770 1022 Center of Chinese Evidence-Based Medicine, Sichuan University West China Hospital, Chengdu, 610041 China
3 grid.415440.0 Center of Preventive Medicine, Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, 610075 China
3 7 2023
3 7 2023
2023
21 4304 4 2023
6 6 2023
© The Author(s) 2023
https://creativecommons.org/licenses/by/4.0/ Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
Background

The dose–effect relationship of Long-snake-like moxibustion for chronic fatigue syndrome (CFS) remains poorly understood. In order to address this gap, we designed this trial to assess the association between different treatment duration of Long-snake-like moxibustion and its effects on CFS based on the combination measurements of the subjective patient-reported scales with objective medical infrared imaging technology─Thermal Texture Maps (TTM).

Methods

From December 2020 to January 2022, 60 female CFS patients were recruited and equally allocated to two groups: Group A, receiving 60-min Long-snake-like moxibustion per treatment, and Group B, receiving 30-min Long-snake-like moxibustion per treatment. The treatment was administered 3 times per week for a total of 4 weeks. The primary outcome was defined as the improvement of symptoms measured by the Fatigue scale-14 (FS-14), and secondary outcomes were designated as the improvement in Symptoms Scale of Spleen-Kidney Yang Deficiency, Self-rating depression scale, and Self-rating anxiety scale. TTM scanning was employed twice for CFS patients (before and after 4-week treatment) and once for Healthy control subjects (HCs).

Results

At week 4, the scores of FS-14 and Symptoms Scale of Spleen-Kidney Yang Deficiency in Group A were significantly lower than those in Group B (physical fatigue: 5.00 vs. 6.00, with 95%CI − 2.00 to 0.00, p = 0.003; FS-14 total score: 8.00 vs. 9.00, with 95%CI − 3.00 to 0.00, p = 0.012; total score of Symptoms Scale of Spleen-Kidney Yang Deficiency: 9.80 vs. 13.07, with 95%CI − 5.78 to − 0.76, P = 0.012). All thermal radiation values of the two groups increased, and statistical differences in ΔTs between Group A and HCs were not obtained. More significant correlations between symptoms improvements and ΔT changes were observed in Group A, and its ΔT changes in Upper Jiao, Shenque (CV8), Zhongwan (CV12), Danzhong (CV17), Zhiyang (GV9), Dazhui (GV14), upper arm, thoracic segments, lumbar segments, renal region, popliteal fossa strongly correlated with the improvement of Spleen-Kidney Yang Deficiency symptoms.

Conclusions

In the same course of treatment, the positive dose–effect relationship was found between the treatment duration of Long-snake-like moxibustion and CFS effect assessment. 60-min Long-snake-like moxibustion per treatment were associated with optimal clinical response and TTM improvement.

Trial registration

Chinese Clinical Trail Registry (No. ChiCTR2000041000, date of registration: 16 December 2020), http://www.chictr.org.cn/showproj.aspx?proj=62488

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-023-04250-z.

Keywords

Chronic fatigue syndrome
Long-snake-like moxibustion
Dose–effect relationship
Randomized controlled trial
Science & Technology Department of Sichuan ProvinceNo. 2020YFS0378 Ma Tingting issue-copyright-statement© BioMed Central Ltd., part of Springer Nature 2023
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pmcBackground

Chronic fatigue syndrome (CFS) is a condition characterized by persistent and debilitating fatigue lasting for at least 6 months, which is not relieved by rest [1]. The fatigue and its accompanied symptoms, including sleep disturbance, pain, sore throat, impaired short-term memory and concentration, greatly affect patients’ quality of life and ability to work. CFS has a global prevalence of 40% and is more prevalent in women than in men [2]. Despite its widespread occurrence, the medical cause of CFS is still unclear, resulting in a lack of specific pharmacological treatment recommendations. However, several promising approaches, including acupuncture [3], moxibustion [4], yoga [5], cognitive behavioral therapy), and graded exercise therapy [6–8] have shown potential for treating CFS.

According to the theory of traditional Chinese Medicine (TCM), fatigue is the result of Yang deficiency. Yang, or Yang-qi, an important concept in TCM, represents the vital energy of life. Yang deficiency refers to a pathological state characterized by a deficiency of Yang qi, representing the impaired functions of warming and promotion. Consequently, when organ function declines, the symptoms such as decreased vitality, listlessness, aversion to cold and preference for warmth, and reduced metabolism will manifest. The most typical affected Zang and Fu of Yang deficiency is Spleen-Kidney Yang. Moxibustion has the ability to produce Yang-warming effect and improve deficient Yang for Zang and Fu. Although the precise mechanism by which moxibustion treats CFS is not fully explained, moxibustion therapy has been shown to be effective in relieving symptoms [9, 10]. Long-snake-like moxibustion, also known as Du moxibustion, involves applying a large range of moxa cones or sticks over herbs or ginger on the Governor Vessel from GV14 to GV2 to generate a powerful warming stimulation. Compared to general moxibustion therapies, Long-snake-like moxibustion has a wider treatment area and utilizes the medicinal properties of moxa wool and ginger. It has a greater effect of warming yang, supplementing qi, promoting the circulation of qi and blood, and harmonizing yin and yang. Currently, there are a variety of Long-snake-like moxibustion applications. It has been applied to rheumatic immune diseases [11], osteoarthropathy [12], digestive disorders [13], etc. The mechanisms behind the therapeutic effects of Long-snake-like moxibustion on these diseases may involve the regulation of immune imbalance, reduction of immune response, acceleration of blood circulation, alleviation of tissue edema, and reduction of gastrointestinal burden. In our previous study [14], we improved the Long-snake-like moxibustion technique through applying moxa boxes placed over ginger slices on the back from GV14 to GV2, as well as on the same level of the first lateral line of Bladder Meridian. This modification enhanced clinical operability and improved the therapeutic effect.

We searched several databases (PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure Database, Wanfang Database, China Science and Technology Journal Database, etc.) from their respective inception dates to January 31, 2020. The search was performed using keywords such as ‘moxibustion’, ‘moxibustion therapy’, ‘moxibustion treatment’, ‘dose’, ‘moxibustion dose’, ‘dose–effect relationship’, ‘moxibustion effect’, etc. The searching results found that moxibustion is influenced by various factors that affect its therapeutic efficacy, such as moxibustion dose, which includes moxibustion duration, treatment frequency, moxibustion amount-size, and the number of moxa cones used [15–18]. Therefore, we conducted this trial to investigate the relationship between the duration of Long-snake-like moxibustion and its effect on CFS by using both subjective scales and objective measurements for assessment.

So far, CFS trials evaluating the efficacy and safety of therapies have employed self-reported subjective measurements, including the Chalder Fatigue Scale, Short Form 36 Health Survey Questionnaire, Anxiety and Depression Scale, and Visual Analogue Pain Rating Scale, to evaluate improvements in physical function, anxiety, depression, and pain [19]. In addition, biological markers and imaging techniques, such as MRI, have also been used to support clinical diagnosis and evaluate treatment effects [20, 21]. In this trial, we used Thermal Texture Maps (TTM), a thermography technique that evaluates thermal signatures of the body through a holistic interpretation of infrared images, to aid in CFS diagnosis and moxibustion dose–effect assessment.

Methods

Design

The single-center, randomized, controlled trial was conducted at the Center of Preventive Medicine, Hospital of Chengdu University of TCM. This trial strictly adhered to the rules of the Declaration of Helsinki and the Good Clinical Practice Guidelines, and it was registered with a unique registration number (ChiCTR2000041000) at http://www.chictr.org.cn. The protocol received approval from the Ethics Committee of Affiliated Hospital of Chengdu University of TCM in 2020 (No.2020KL-046). Written informed consent was obtained from all participants, which included 60 female patients with CFS and 30 healthy control subjects (HCs).

The CFS patients were randomly allocated to either the 60-min Long-snake-like moxibustion group (Group A) or the 30-min Long-snake-like moxibustion group (Group B) in a 1:1 ratio, with a treatment period of 4 weeks consisting of 3 times per week, every other day.

Subjects

Patients were recruited from multiple sources, including the hospital as well as electronic posters on WeChat and physical posters displayed in hospitals and communities. Face-to-face interviews were conducted by the clinical trial coordinator to ensure that all patients met the inclusion criteria. The inclusion and exclusion criteria for patients and HCs are shown in Table 1.

Table 1 The inclusion and exclusion criteria for patients and HCs

Patients with CFS	
 Inclusion criteria	
  1. Females aged 18 to 60 years old;	
  2. Chronic fatigue is lasting and can’t be explained by illness;	
  3. Debilitating fatigue predates and is accompanied by at least 4 out of the 8 designated symptoms: post-exertional malaise lasting more than 24 h; unrefreshing sleep; impaired short-term memory or concentration severe enough to cause substantial reduction in previous levels of occupational, educational, social, or personal activities; headaches of a new type, pattern, or severity; muscle pain; multi-joint pain without swelling or redness; sore throat; and tender cervical/axillary lymph nodes. Accompanying symptoms must have persisted or recurred during 6 or more consecutive months of illness.	
Patients should also meet the inclusion criteria of the pattern of Spleen-Kidney Yang deficiency, which include	
  1. Presence of at least 3 out of the 5 main symptoms: fear of cold and cold extremities, lassitude and lack of strength, shortness of breath and laziness to speak, reduced food intake, soreness and weakness of waist and knees;	
  2. Presence of at least 2 out of the 6 accompanied symptoms: lumbar cold pain, abdominal fullness and distention, loose stool, cold, more urine volume during night, teeth-mark tongue and a deep, weak pulse.	
Exclusion criteria	
  1. Pregnancy or lactation;	
  2. Presence of diseases that definitely influence TTM results, such as scoliosis or limb deformity, etc.;	
  3. Poor understanding or expression;	
  4. Presence of obviously damaged, scarred skin, or sensitivity to ginger.	
HCs	
Inclusion criteria:	
  1. Females aged 18 to 60 years old;	
  2. No disorder in physical examination in the preceding one year, and in good physical and mental health during the study period;	
  3. No family history of mental or nervous system disorders;	
  4. No spinal diseases that definitely influence TTM results, such as scoliosis, limb deformity, etc.	
Exclusion criteria	
  1. Pregnant or lactating;	
  2. Presence of obvious damage or scarring on the skin;	
  3. Long term smoking, alcoholism, or adverse drug use;	
  4. Participation in another concurrent research study.	

Randomization and blinding

Eligible CFS patients were randomly allocated to either Group A or Group B. Random numbers were generated by Statistics Analysis System, and then placed in opaque envelopes. A research assistant, who was uninvolved in the assessment or treatment, was responsible for keeping the original random allocation sequences, printing serial numbers on the outside of the envelopes, and sealing the envelopes. All envelopes were put into a plastic container in numerical order. Once patients were assessed to meet the inclusion criteria and provided informed consent, investigators opened the envelopes in turn. To ensure blinding, the outcome assessors and statistical analysts were blinded to the intervention assignments throughout the trial.

Intervention

Practitioners: Certified acupuncturists with TCM license and more than 2-year clinical experience were trained to administer Long-snake-like moxibustion. The training focused on the correct manipulation of the moxibustion technique.

Group A: 60-min Long-snake-like moxibustion. Patients were positioned prone with their entire back exposed and received ginger-indirect moxibustion on the Governor Vessel and Bladder Meridian. Ginger slices, 2 mm in thickness, were placed on the back from GV14 to GV2, covering the area of the Governor Vessel and the first lateral line of the Bladder Meridian (Fig. 1). Five or six 3-hole moxa boxes (depending on the patient’s height, Fig. 2) were then placed on top of the ginger slices, with a distance of 4.8 cm between the centers of the nearby holes to ensure the moxa sticks’ temperature (pure-mugwort moxa stick; 20 cm in length and 18 mm in diameter; Hwato, Suzhou, China, PRC) covered the Governor Vessel and the first lateral line of the Bladder Meridian. The depth of moxa sticks was regulated every 5 min during 60-min treatment to maintain full combustion and obtain equal warm stimulation. Patients received 12 sessions of moxibustion treatment over a 4-week period (1 session per day, 3 sessions per week, every other day).Fig. 1 Ginger slices were placed on the back from GV14 to GV2

Fig. 2 Five or six 3-hole moxa boxes were put on the participants of two groups

Group B: 30-min Long-snake-like moxibustion. The treatment process was the same as in Group A, with a moxibustion duration of 30 min.

Outcome measures

Primary outcome: In this trial, the improvement in fatigue severity assessed by Fatigue scale-14 (FS-14) was set as the primary outcome. FS-14 is a standardized questionnaire reflecting physical and mental fatigue and comprises 14 questions. Each question has two options (yes or no) and a score of 0 to 1 (0 = no, 1 = yes), resulting in a total score ranging from 0 to 14 [22, 23]. Higher scores indicate a higher level of chronic fatigue. The assessment using FS-14 was conducted at baseline and at the end of the 4-week treatment period (week 4).

Secondary outcome: The secondary outcome measures included the scores of the Symptoms Scale of Spleen-Kidney Yang Deficiency, the Self-rating depression scale (SDS), and the Self-rating anxiety scale (SAS). The Symptoms Scale of Spleen-Kidney Yang Deficiency is a 4-rate scale designed to evaluate symptoms based on TCM syndrome differentiation. It consists of primary symptoms with scores ranging from 0 to 6, including fear of cold and cold extremities, lassitude and lack of strength, shortness of breath and laziness to speak, reduced food intake, soreness and weakness of waist and knees. It also includes secondary symptoms with scores ranging from 0 to 3, including lumbar cold pain, abdominal fullness and distention, loose stool, cold and more urine volume during night. Higher scores indicate a higher level of Spleen-Kidney Yang Deficiency. Both the SDS and SAS are 20-item scales designed to measure depression/anxiety with scores ranging from 20 to 80. Higher scores indicate a higher level of depression and anxiety. All secondary outcomes were assessed at baseline and at the end of the 4-week treatment period (week 4).

TTM scanning: 90 eligible participants (30 female CFS patients in Group A, 30 female CFS patients in Group B, and 30 HCs) received TTM (Digital Medical Infrared Imaging System, MTI-ex pro-2013, Chongqing, China) scanning at baseline, and only patients in Groups A and B received a second TTM scanning after the 4-week treatment period. To weaken the influence of external thermo-source on the moxibustion effect assessment, the second TTM scanning was employed 5 days after the end of treatment. To minimize the impact of outside temperature, all the scanning was executed in the morning at the health examination center of the Affiliated Hospital of Chengdu university of TCM. The scanning room was maintained at a controlled temperature of 21℃ ± 2℃ and a humidity level of 50% ± 10%. The subjects were positioned in an environment with no direct ventilation, sunlight, or infrared radiation source [24, 25]. The TTM scanning process and relevant precautions are detailed in Table 2, and the image area definitions based on the Three-Jiao theory in TCM (Upper Jiao, Middle Jiao, and Lower Jiao) are shown in Table 3 [26, 27].

Table 2 The process and relevant precautions of TTM

The process was listed below:	
   1. Fill the personal health information form before scanning, which contained the medical history and the state of body condition in all organs;	
   2. Remove the ornaments, loosen the bra, and relax hair in advance. Have a rest of 30 min at rest room before scanning;	
   3. Prior to the scanning, patients were asked to take all clothing off and expose the body in a temperature-controlled room for 10–15 min. Then images were taken from the front vs. back, and left vs. right to assess overall topological features of the whole body.	
All participants were asked to adhere to the following precautions	
   1. Fasting for at least 2 h before the scanning;	
   2. Before the examination, alcohol should be stopped for at least 24 h, the usage of medications (i.e., vasodilator, vasoconstrictors) should be stopped for at least 4 h, vigorous exercise should be forbidden for at least 4 h, other stimulants should be stopped for at least 2 h and hand washing should be avoided for at least 30 min;	
   3. Skin conditioning such as use of cosmetics and perfume had to be avoided, and a dress of looser clothing is advised;	
   4. No scanning during menstruation.	

Table 3 The definition of Three-Jiao in TTM image

Areas	Border	
Upper Jiao	Upper border: the line of clavicles	
Lower border: the line of the 5th intercostal spaces	
Two sides: the anterior axillary lines	
Middle Jiao	Upper border: the line of the 5th intercostal spaces	
Lower border: level with the umbilicus	
Two sides: the anterior axillary lines	
Lower Jiao	Upper border: level with the umbilicus	
Lower border: level with the pubic symphysis	

Sample size

Based on our preliminary study [28], which demonstrated an improvement of 2.45 in the FS-14 score following 60 min of Long-snake-like moxibustion therapy, we expected a mean improvement difference of 0.4 in the FS-14 score. With a desired power of 0.9 and a significance of 0.05, the estimated sample size required was 27 participants per group. Considering a dropout rate of 10%, the total number of patients was 60, while the total number of HCs was 30.

Statistical methods

The data was analyzed by an independent statistician. Quantitative data were described by mean with standard deviation (SD) or median with percentile (Q1, Q3). All the statistical analyses were performed with SPSS software version 25.0 (SPSS Inc, IBM Corporation, Chicago, Illinois, USA). The correlation analysis and visualization were performed with R language version 4.2.0 (R Development Core Team, Vienna, Austria). A two-sided test was applied for all available data, and a P-value < 0.05 was considered statistically significant.

The main analysis was based on an intention-to-treat population, and missing data at random were replaced by the multiple imputation method. The primary outcome of FS-14 score was analyzed by Mann-Whitney U-test. For secondary outcomes, including the score of Symptoms Scale of Spleen-Kidney Yang Deficiency, SDS score and SAS score, we conducted independent sample T test or Mann-Whitney U test (used in non-normally distributed variables) to compare the scores after 4 -week treatment between Groups A and B.

TTM analysis: Disease-related areas, specific regions or acupoints were acquired through comparing HCs with CFS patients in the whole-body thermal map. The relative thermal radiation value difference was defined as the temperature difference between the local temperature and the average temperature of the front or back of the trunk. It was automatically detected by TTM. Median differences and 95% confidence intervals of the temperature difference (ΔT) comparison between Group A or B and HCs at the end of 4-week treatment in the above area or acupoints were calculated by Hodges-Lehmann method.

Attrition analyses: Considering the possible effect from visit lost on results, we added 10% more sample size for each group in recruitment to hedge against expected attrition. For incomplete outcome data, we used multiple imputation method to replace random missing data. Sensitivity analysis using the per protocol set was performed and compared with the intention-to-treat analysis results.

Data collection and quality control

The original data were recorded in paper case report form (CRF) and then filled in a spreadsheet. An independent investigator checked the original data to ensure the consistency of CRF and spreadsheet. Only the principal investigators and clinical investigators were qualified to review the data. Before the start of trial, all involved researchers underwent training to guarantee the full understanding of study protocol, research process and CRF-filling. Additionally, once the eligible participants were enrolled, full communication about possible benefits and risks were made and a comfortable treatment environment was provided to ensure participants’ compliance. For participants with poor compliance, investigators contacted them by phone to acquire the outcome data, inquire about possible reasons for non-compliance, and encourage them to complete the study.

Results

Patient characteristics

From December 2020 to January 2022, a total of 101 patients were screened, and 60 patients were included with a median age of 30.50 (Q1, Q3: 24.00, 40.75) years and a median CFS duration of 31.00 (Q1, Q3: 12.00, 60.00) months. The study flowchart is shown in Fig. 3. There were no significant differences between the two groups with respect to baseline demographic and clinical characteristics (P > 0.05). These results suggested that the two groups were comparable (Table 4).Fig. 3 Patient flowchart. ITT intention-to-treat

Table 4 Baseline characteristics of patients

Characteristics	Group A (n = 30)	Group B (n = 30)	
Age (years), Median (Q1, Q3)	31.50 (24.00, 47.50)	29.50 (24.00, 38.50)	
Course of disease (month), Median (Q1, Q3)	36.00 (24.00, 72.00)	24.00 (12.00, 48.00)	
BMI (kg/m2), Median (Q1, Q3)	21.16 (19.64, 22.52)	21.12 (19.30, 22.85)	
FS-14 at baseline, Median (Q1, Q3)			
 Physical fatigue	7.50 (6.00, 8.00)	7.00 (7.00, 8.00)	
 Mental fatigue	4.00 (3.00, 5.00)	4.00 (3.00, 5.00)	
 Total score	11.00 (9.00, 12.00)	11.00 (10.00, 13.00)	
Symptoms scale of spleen-kidney Yang deficiency at baseline, Median (Q1, Q3)			
 Fear of cold and cold extremities	4.00 (4.00, 6.00)	4.00 (4.00, 4.00)	
 Lassitude and lack of strength	3.00 (2.00, 4.00)	2.00 (2.00, 4.00)	
 Shortness of breath and laziness to speak	2.00 (2.00, 4.00)	2.00 (2.00,4.00)	
 Reduced food intake	2.00 (0.00, 4.00)	2.00 (0.00, 2.00)	
 Soreness and weakness of waist and knees	2.00 (0.00, 4.00)	2.00 (0.00, 3.00)	
 Lumbar cold pain	1.00 (1.00, 2.00)	1.00 (0.00, 2.00)	
 Abdominal fullness and distention	1.00 (1.00, 2.00)	1.00 (1.00, 2.00)	
 Loose stool	1.00 (0.00, 1.00)	1.00 (0.00,2.00)	
 Cold and more urine volume during night	0.00 (0.00, 1.00)	0.00 (0.00, 1.00)	
 Total score, Mean (SD)	18.03 (6.39)	16.57 (3.86)	
 SDS at baseline, Mean (SD)	52.77 (11.76)	49.83 (10.22)	
 SAS at baseline, Mean (SD)	47.37 (11.83)	43.67 (9.09)	
Group A: Long-snake-like moxibustion for 60 min; Group B: Long-snake-like moxibustion for 30 min; Data were presented as mean ± standard deviation (SD) and Median (Q1, Q3); Q: quarter; Q1: 25th percentile; Q3: 75th percentile

BMI Body Mass Index; FS-14 Fatigue Scale-14; SDS Self-rating Depression Scale; SAS Self-Rating Anxiety Scale

Primary outcome

After 12 treatment sessions within 4 weeks, physical fatigue score and FS-14 total score decreased in both groups compared to baseline (Fig. 4). Group A showed significantly lower scores at the end of treatment (physical fatigue: 5.00 vs. 6.00, 95%CI − 2.00 to 0.00, p = 0.003; FS-14 total score: 8.00 vs. 9.00, 95%CI − 3.00 to 0.00, p = 0.012) (Table 5).

Table 5 Scores of FS-14 in the end of treatment

Items	Group A (n = 30)	Group B (n = 30)	Median (95% CI)	P-value	
Physical fatigue	5.00 (3.75, 6.00)	6.00 (5.00, 6.25)	− 1.00 (− 2.00, 0.00)	0.003*	
Mental fatigue	3.00 (2.00, 3.00)	3.00 (1.75, 4.00)	0.00 (− 1.00, 0.00)	0.542	
Total score	8.00 (5.00, 9.00)	9.00 (7.00, 10.00)	− 1.00 (− 3.00, 0.00)	0.012*	
Mann-Whitney U test was used for comparing differences between groups to obtain P-values. Hodges-Lehmann method was used to calculate median differences and their 95% confidence intervals. Group A: Long-snake-like moxibustion for 60 min; Group B: Long-snake-like moxibustion for 30 min; Data were presented as Median (Q1, Q3); Q: quarter; Q1: 25th percentile; Q3: 75th percentile; 95% CI95% Confidence Interval

* p < 0.05

Secondary outcomes

Symptoms scale of spleen-kidney Yang Deficiency

The scores of Symptoms Scale of Spleen-Kidney Yang Deficiency decreased after 4-week treatment (Fig. 4). Compared with Group B, Group A showed significantly lower scores in fear of cold and cold extremities (2.00 vs. 4.00, 95%CI − 2.00 to 0.00, P = 0.034), shortness of breath and laziness to speak (2.00 vs. 2.00, 95%CI − 1.00 to 0.00, P = 0.045), soreness and weakness of waist and knees (0.00 vs. 2.00, 95%CI − 2.00 to 0.00, P = 0.033), lumbar cold pain (1.00 vs. 1.00, 95%CI − 1.00 to 0.00, P = 0.028), loose stool (0.00 vs. 1.00, 95%CI − 1.00 to 0.00, P = 0.028), cold and more urine volume during night(0.00 vs. 0.00, 95%CI 0.00 to 0.00, P = 0.046) and total score (9.80 vs. 13.07, 95%CI − 5.78 to − 0.76, P = 0.012) (Table 6).Fig. 4 Effects of Long-snake-like moxibustion at baseline and week 4. Data in a, b, c were shown by the median with interquartile range and data in d, e, f were shown by mean with error bar represented standard deviation; a Physical fatigue score at baseline and week 4; b Mental fatigue score at baseline and week 4; c Total score of FS-14 at baseline and week 4; d Symptoms scale score of spleen-kidney Yang deficiency at baseline and week 4; e SDS score at baseline and week 4; f SAS score at baseline and week 4

Table 6 Scores of symptoms scale of spleen-kidney Yang deficiency in the end of treatment

Items	Group A (n = 30)	Group B (n = 30)	Median/MD (95%CI)	P-value	
Fear of cold and cold extremities	2.00 (1.50, 4.00)	4.00 (2.00, 4.00)	0.00 (− 2.00, 0.00)	0.034*	
Lassitude and lack of strength	2.00 (2.00, 2.50)	2.00 (2.00, 2.00)	0.00 (0.00, 0.00)	0.290	
Shortness of breath and laziness to speak	2.00 (0.00, 2.00)	2.00 (2.00, 2.00)	0.00 (− 1.00, 0.00)	0.045*	
Reduced food intake	0.00 (0.00, 1.25)	0.00 (0.00, 2.00)	0.00 (− 1.00, 0.00)	0.072	
Soreness and weakness of waist and knees	0.00 (0.00, 2.00)	2.00 (0.00, 2.00)	0.00 (− 2.00, 0.00)	0.033*	
Lumbar cold pain	1.00 (0.00, 1.00)	1.00 (0.00, 2.00)	0.00 (− 1.00, 0.00)	0.028*	
Abdominal fullness and distention	1.00 (0.00, 1.00)	1.00 (1.00, 1.00)	0.00 (− 1.00, 0.00)	0.173	
Loose stool	0.00 (0.00, 1.00)	1.00 (0.00, 1.00)	0.00 (− 1.00, 0.00)	0.028*	
Cold and more urine volume during night	0.00 (0.00, 1.00)	0.00 (0.00, 0.00)	0.00 (0.00, 0.00)	0.046*	
Total score	9.80 (4.37)	13.07 (5.29)	− 3.27 (− 5.78, − 0.76)	0.012*	
Independent sample T test (for total score) and Mann-Whitney U test (for non-normally distributed items) were used for comparing differences between groups to obtain P-values; Hodges-Lehmann method was used to calculate median differences and their 95% confidence intervals. Group A: Long-snake-like moxibustion for 60 min; Group B: Long-snake-like moxibustion for 30 min; Data were presented as mean ± standard deviation (SD) and Median (Q1, Q3); Q: quarter; Q1: 25th percentile; Q3: 75th percentile

MD mean difference; 95%CI 95% Confidence Interval

* p < 0.05

SDS and SAS

SDS and SAS scores of both groups decreased after treatment (Fig. 4), and there were no statistical differences between groups (Table 7).

Table 7 Scores of SDS and SAS in the end of treatment

Scales	Group A (n = 30)	Group B (n = 30)	MD (95%CI)	P-value	
SDS	43.20 (12.64)	41.87 (11.16)	1.33 (− 4.83, 7.50)	0.667	
SAS	39.47 (10.85)	38.00 (9.59)	1.47 (− 3.83, 6.76)	0.581	
Independent sample T test was used for comparing differences between groups to obtain P-values. Group A: Long-snake-like moxibustion for 60 min; Group B: Long-snake-like moxibustion for 30 min; Data were presented as Mean (SD)

SD standard deviation; MD mean difference; 95% CI 95% Confidence Interval; SDS Self-rating Depression Scale; SAS Self-Rating Anxiety Scale

TTM outcome

When comparing with HCs, statistical differences in ΔT of Groups A and B were obtained at baseline in Middle Jiao (Group A vs. HCs − 0.22 vs. 0.07, 95%CI 0.10 to 0.64; Group B vs. HCs − 0.33 vs. 0.07, 95%CI 0.15 to 0.79), Lower Jiao (Group A vs. HCs − 0.67 vs. − 0.38, 95%CI 0.06 to 0.76; Group B vs. HCs − 0.81 vs. − 0.38, 95%CI 0.18 to 0.82), Shenque (CV8) (Group A vs. HCs 0.57 vs. 1.17, 95%CI 0.34 to 1.13; Group B vs. HCs 0.57 vs. 1.17, 95%CI 0.31 to 1.11), neck (Group A vs. HCs 0.68 vs. 1.41, 95%CI 0.29 to 1.46; Group B vs. HCs 0.41 vs. 1.41, 95%CI 0.66 to 1.56), upper arm (Group A vs. HCs − 0.42 vs. 0.24, 95%CI 0.04 to 0.93; Group B vs. HCs − 0.42 vs. 0.24, 95%CI 0.20 to 1.00), thoracic segments (Group A vs. HCs 0.33 vs. 0.76, 95%CI 0.17 to 0.77; Group B vs. HCs 0.31 vs. 0.76, 95%CI 0.31 to 0.93).

After 4-week treatment, statistical differences in ΔT between Group A and HCs were not obtained at the aforementioned sites, while statistical differences in ΔT between Group B and HCs were still obtained in neck (0.85 vs. 1.41, 95%CI 0.09 to 0.88), upper arm (− 0.25 vs. 0.24, 95%CI 0.01 to 0.85) (Table 8).

Table 8 Comparison of ΔT between Group A or B and HCs

Sites	Time /ΔT	Group A
(n = 30)	Group B
(n = 30)	HCs
(n = 30)	Median (CI)*	Median (CI)**	
Upper Jiao	Baseline	0.32 (− 0.01, 0.56)	0.36 (0.05, 0.54)	0.35 (0.19, 0.58)	0.05 (− 0.18, 0.25)	0.07 (− 0.19, 0.22)	
Week 4	0.43 (0.26, 0.69)	0.43 (0.07, 0.57)	0.35 (0.19, 0.58)	− 0.08 (− 0.25, 0.09)	− 0.02 (− 0.19, 0.21)	
Middle Jiao	Baseline	− 0.22 (− 0.71, 0.14)	− 0.33 (− 0.99, 0.09)	0.07 (− 0.11, 0.25)	0.35 (0.10, 0.64)	0.44 (0.15, 0.79)	
Week 4	0.06 (− 0.02, 0.26)	0.00 (− 0.06, 0.24)	0.07 (− 0.11, 0.25)	0.00 (− 0.18, 0.10)	0.10 (− 0.15, 0.14)	
Lower Jiao	Baseline	− 0.67 (− 1.37, − 0.29)	− 0.81 (− 1.89, − 0.41)	− 0.38 (− 0.64, − 0.12)	0.37 (0.06, 0.76)	0.44 (0.18, 0.82)	
Week 4	− 0.47 (− 0.66, − 0.05)	− 0.57 (− 0.70, − 0.39)	− 0.38 (− 0.64, − 0.12)	0.03 (− 0.21, 0.25)	0.17 (− 0.01, 0.33)	
Shenque

(CV8)

	Baseline	0.57 (− 0.06, 0.91)	0.57 (0.06, 1.17)	1.17 (0.73, 1.78)	0.74 (0.34, 1.13)	0.68 (0.31, 1.11)	
Week 4	1.29 (0.85, 2.07)	1.12 (0.95, 1.42)	1.17 (0.73, 1.78)	− 0.12 (− 0.54, 0.27)	0.00 (− 0.29, 0.30)	
Zhongwan

(CV12)

	Baseline	− 0.84 (− 1.43, − 0.17)	− 0.91 (− 2.07, − 0.16)	− 0.15 (− 1.19, 0.19)	0.47 (− 0.07, 1.00)	0.65 (0.10, 1.12)	
Week 4	− 0.50 (− 0.92, − 0.11)	− 0.53 (− 0.92, − 0.23)	− 0.15 (− 1.19, 0.19)	0.14 (− 0.47, 0.59)	0.17 (− 0.34, 0.64)	
Danzhong

(CV17)

	Baseline	0.45 (− 0.11, 1.08)	0.35 (− 0.06, 0.80)	0.65 (0.40, 1.11)	0.19 (− 0.16, 0.53)	0.34 (0.05, 0.64)	
Week 4	0.53 (0.10, 0.80)	0.53 (0.08, 0.82)	0.65 (0.40, 1.11)	0.19 (− 0.08. 0.45)	0.26 (− 0.08, 0.54)	
Governor vessel	Baseline	0.58 (0.36, 0.91)	0.53 (− 0.01, 0.79)	0.74 (0.40, 1.13)	0.10 (− 0.17, 0.36)	0.31 (0.00, 0.61)	
Week 4	0.60 (0.41, 1.00)	0.68 (0.44, 0.88)	0.74 (0.40, 1.13)	0.08 (− 0.16, 0.32)	0.04 (− 0.17, 0.31)	
Pishu

(BL20)

	Baseline	0.39 (0.09, 0.73)	0.15 (− 0.55, 0.36)	0.40 (0.14, 0.70)	0.02 (− 0.22, 0.30)	0.37 (0.08, 0.74)	
Week 4	0.40 (0.27, 0.74)	0.31 (0.18, 0.42)	0.40 (0.14, 0.70)	− 0.06 (− 0.30, 0.10)	0.08 (− 1.00, 0.30)	
Shenshu

(BL23)

	Baseline	0.45 (0.21, 0.92)	0.16 (− 0.22, 0.54)	0.51 (0.14, 0.97)	0.06 (− 0.24, 0.36)	0.42 (0.13, 0.69)	
Week 4	0.56 (0.51, 0.87)	0.52 (0.25, 0.60)	0.51 (0.14, 0.97)	− 0.11 (− 0.38, 0.16)	0.06 (-0.16, 0.34)	
Neck	Baseline	0.68 (− 0.40, 1.48)	0.41 (− 0.08, 0.89)	1.41 (0.74, 1.99)	0.84 (0.29, 1.46)	1.13 (0.66, 1.56)	
Week 4	0.89 (0.82, 1.79)	0.85 (0.72, 1.31)	1.41 (0.74, 1.99)	0.28 (− 0.17, 0.78)	0.42 (0.09, 0.88)	
 Upper arm	Baseline	− 0.42 (− 1.07, 0.15)	− 0.42 (− 0.81, − 0.18)	0.24 (− 0.42, 0.66)	0.48 (0.04, 0.93)	0.64 (0.20, 1.00)	
Week 4	− 0.20 (− 0.98, 0.45)	− 0.25 (− 0.98, 0.17)	0.24 (− 0.42, 0.66)	0.34 (− 0.34, 0.82)	0.50 (0.01, 0.85)	
Thoracic segments	Baseline	0.33 (− 0.24, 0.85)	0.31 (− 0.41, 0.64)	0.76 (0.53, 1.07)	0.44 (0.17, 0.77)	0.60 (0.31, 0.93)	
Week 4	0.66 (0.54, 1.02)	0.66 (0.51, 0.86)	0.76 (0.53, 1.07)	0.06 (− 0.13, 0.29)	0.11 (− 0.40, 0.33)	
Lumbar segments	Baseline	0.35 (− 0.06, 0.82)	0.21 (− 0.12, 0.54)	0.49 (0.22, 0.83)	0.18 (− 0.08, 0.43)	0.35 (0.13, 0.58)	
Week 4	0.63 (0.57, 0.93)	0.59 (0.43, 0.72)	0.49 (0.22, 0.83)	− 0.15 (− 0.37, 0.04)	− 0.09 (− 0.23, 0.11)	
Renal region	Baseline	− 0.08 (− 0.77, 0.30)	− 0.32 (− 1.12, 0.03)	0.07 (− 0.13, 0.35)	0.22 (− 0.04, 0.52)	0.49 (0.21, 0.82)	
Week 4	0.11 (− 0.02, 0.41)	0.04 (− 0.20, 0.12)	0.07 (− 0.13, 0.35)	− 0.06 (− 0.26, 0.14)	0.08 (− 0.11, 0.23)	
Group A: Long-snake-like moxibustion for 60 min; Group B: Long-snake-like moxibustion for 30 min. Bold data represented statistical differences in ΔT of Groups A and B compared to HCs.  Data were presented as Median (Q1, Q3); Q: quarter; Q1: 25th percentile; Q3: 75th percentile. 

HCs Healthy control subjects; 95%CI 95% Confidence Interval

* Group A vs. HCs, ** Group B vs. HCs. Hodges-Lehmann method was used to calculate median differences and their 95% confidence intervals

Correlation with symptoms and TTM

The two groups had significant correlations between score changes and ΔT changes in TTM (Fig. 5). In Group A, the score change of fear of cold and cold extremities was negatively correlated with ΔT changes of upper arm (r = − 0.43, p = 0.019), thoracic segments (r = − 0.43, p = 0.019), lumbar segments (r = − 0.46, p = 0.010), renal region (r = − 0.44, p = 0.016), popliteal fossa (r = − 0.46, p = 0.011); the score change of lassitude and lack of strength was negatively correlated with ΔT changes of Upper Jiao (r = − 0.42, p = 0.022), Danzhong (CV17) (r = − 0.49, p = 0.006), Zhiyang (GV9) ( r = − 0.44, p = 0.016), Dazhui (GV14) (r = − 0.42, p = 0.023); the score change of shortness of breath and laziness to speak was negatively correlated with ΔT change of Zhongwan (CV12) (r = − 0.46, p = 0.011); the score change of lumbar cold pain was negatively correlated with ΔT change of thoracic segments (r = − 0.38, p = 0.041); the score change of abdominal fullness and distention was negatively correlated with ΔT changes of Shenque (CV8) (r = − 0.42, p = 0.022), thoracic segments (r = − 0.37, p = 0.047); the total score change of Spleen-Kidney Yang Deficiency Symptoms Scale was negatively correlated with ΔT change of thoracic segments (r = − 0.44, p = 0.016). In Group B, only the score change of fear of cold and cold extremities was negatively correlated with ΔT change of Zhiyang (GV9) (r = − 0.41, p = 0.024).Fig. 5 Correlations with score changes and ΔT changes. Score change = week 4-baseline;ΔT change = week 4-baseline; ΔT: temperature difference; a Correlations in Group A; b Correlations in Group B; Spearman’s correlation was calculated and displayed as corrplot graphs using R package “corrplot”. r ranges between − 1 and 1, where − 1 ≤ r < 0 means negative correlation, r = 0 means no correlation, and 0 < r ≤ 1 means positive correlation. Blue circles represent positive correlation and red circles represent negative correlation. The darker the color and the larger the circle, the stronger is the correlation

Sensitivity analysis

Sensitivity analysis performed by the per protocol set showed similar results as the intention-to-treat analysis (Additional file 1).

Discussion

Due to the non-organic pathophysiology, CFS is associated with suboptimal health status [29]. The present treatment of CFS is given based on limited or even contradictory evidence from clinical studies [30–32]. CFS is named as fatigue syndrome in TCM theory and its main reason is believed to be Yang-qi deficiency. Especially Spleen and Kidney Yang are thought to be the vital motivity, and organs will become hypofunctional once Yang qi decreases. Therefore, Spleen-Kidney Yang Deficiency Syndrome is a commonly used visceral pattern in clinical diagnosis of CFS [33, 34]. Moxibustion therapy has been applied in Yang deficiency patients for thousands of years in China and it is used widely to relieve fatigue symptoms [35]. A systematic review has suggested that moxibustion has more advantages than acupuncture and drugs in relieving fatigue symptoms and improving clinical efficacy [36]. As a unique traditional moxibustion therapy, Long-snake-like moxibustion has shown to be a safe and effective therapy for relieving fatigue and improving Yang deficiency constitution [14, 37].

The dose–effect relationship is a crucial issue in the moxibustion research, with key factors such as treatment duration, frequency, extent, and amount of moxa cones/sticks determining the moxibustion dose. However, the relationship between the dose of moxibustion stimulation and the resulting therapeutic efficacy has not yet been established. Previous studies have shown that the above dose factors affect efficacy to varying degrees in different diseases. For instance, in the study of treating diarrhea-predominant irritable bowel syndrome, aconite cake-separated moxibustion with a treatment regimen of 3 sessions per week and 1 cone per session appeared to produce better therapeutic effects compared to a regimen of 6 sessions per week and 2 cones per session [18]. Another study on suspended moxibustion for focal cerebral ischemia/reperfusion injury found that 35-min moxibustion indicated a greater anti-apoptotic effect than 15-min moxibustion [17]. In the treatment of depression-like behavior disorder in rats, prolonged duration of moxibustion under optimal extent could increase the level of 5-HT [16]. Furthermore, in the treatment of chronic neck pain using direct moxibustion with small moxa cones, there was a trend of improved effectiveness with an increase in the amount of moxa cones when the other dose factors were constant [15].

The duration of Long-snake-like moxibustion is a key factor in optimizing efficacy, but the treatment duration for CFS varies [38, 39]. In our 4-week trial with 3 treatments per week, we compared the dose–effect relationship of the therapy using treatment durations of 30 and 60 min. Our findings suggest that 60-min Long-snake-like moxibustion is more effective in relieving fatigue and improving symptoms of Spleen-Kidney Yang Deficiency compared to 30-min Long-snake-like moxibustion. Specifically, the fatigue was relieved primarily by improving physical fatigue rather than improving mental fatigue, and the TCM pattern was improved primarily by alleviating main symptoms (such as fear of cold and cold extremities, soreness and weakness of waist and knees, lumbar cold pain, etc.), suggesting that 60-min Long-snake-like moxibustion therapy has a better ability to tonify Yang qi and improve the fatigue state. However, there was no statistically significant between-group difference in lassitude and lack of strength in the Symptoms Scale of Spleen-Kidney Yang Deficiency, which was different from the result obtained with FS-14. This discrepancy may be due to the fact that fatigue is a multidimensional and subjective sense of physical, mental, or emotional tiredness [40]. Lassitude and lack of strength is only a component item in the Symptoms Scale of Spleen-Kidney Yang Deficiency and it is relatively simple and unidimensional. In contrast, FS-14 is an internationally recognized measurement tool for evaluating fatigue symptoms in clinics, providing a more comprehensive reflection of fatigue severity [22, 41]. It could measure fatigue across multiple dimensions with better reliability and validity, offering a clearer understanding of the type of fatigue experienced and improved assessment precision compared to single-item measures [42]. Besides, statistically significant between-group differences in SDS and SAS were not observed, which may be associated with the relatively short course of treatment and no follow-up period. The moxibustion effects on mental fatigue and mental distress require further study.

A large body of evidence has showed that diseases or deviation from normal functioning are accompanied by temperature changes in the body, which, in turn, affect the temperature of the skin. Infrared imaging (IR) has proven to be a useful method for diagnosing signs of certain diseases by measuring the local skin temperature. As a new medical IR technology, TTM enables contactless and non-invasive identification of abnormal heat sources within the human body by analyzing thermographic data and surface temperature distribution [43]. Since its invention, TTM has been applied in disease diagnosis such as oncology (breast, skin, etc.), vascular disorders (diabetes, deep venous thrombosis), and monitoring the efficacy of therapeutic drugs, etc. [44–48]. Therefore, we combined measurements of the subjective patient-reported scales with objective TTM technology in this trail. Unlike previous study that only used objective technique to quantify muscle fatigue [49], our trial took a comprehensive approach. We not only employed subjective scales to evaluate fatigue levels and Spleen-Kidney Yang Deficiency symptoms before and after treatment but also utilized objective technique (TTM) to assess thermal energy metabolism changes in CFS patients and compared them with those of HCs. The aim of this trial was to quantify the therapeutic effect of Long-snake-like moxibustion, evaluate the thermal energy metabolism under different physiological/pathological conditions and different durations of moxibustion, and obtain the optimal dose–effect of Long-snake-like moxibustion.

According to the results, most thermal radiation values in CFS patients were obviously lower than those in HCs at baseline, and the ΔTs in CFS patients were statistically different from those of HCs in Middle Jiao, Lower Jiao, Shenque (CV8), neck, upper arm, thoracic segments. Some studies have shown that irregularities in energy metabolism [50], impaired cell metabolism [51], activated immune system [52], viral infection [53], impaired functioning in the hypothalamic-pituitary-adrenal axis and neuroendocrine dysregulation [54] have been considered possible causes of CFS. An animal experiment indicated that fatigued rats would have a deterioration in energy metabolism [55]. Since TTM images present the level of energy metabolism by displaying the thermal radiation value distribution [56], we found that most CFS patients were in a state of low energy metabolism. After 4-week Long-snake-like moxibustion, thermal radiation values increased at both directly and indirectly stimulated sites by moxibustion, indicating that Long-snake-like moxibustion could transfer and penetrate heat to far and deep sites, increase metabolic heat in different sites and regions of the body, and improve the low energy metabolism state. This heat energy transfer may be the underlying mechanism of moxibustion therapy [57]. Moreover, at the end of 4-week treatment, there were no statistically significant differences in ΔTs between the 60-min Long-snake-like moxibustion group and HCs in the above sites, whereas the ΔTs in neck and upper arm still showed statistically significant differences between the 30-min Long-snake-like moxibustion group and HCs. This suggests that 60-min Long-snake-like moxibustion has a more pronounced ability to increase thermal radiation values and demonstrates a closer trend to that of HCs. The TTM results were consistent with the subjective scales results, suggesting that 60-min Long-snake-like moxibustion had a more significant effect than 30-min moxibustion.

It is worth mentioning that ΔT changes were negatively correlated with the score changes, indicating that the more thermal radiation values increased, the better the CFS symptoms improved. This suggests that the increase in thermal radiation values may be an indirect reflection of warming and tonifying Yang. ΔT changes in Upper Jiao, Shenque (CV8), Zhongwan (CV12), Danzhong (CV17), Zhiyang (GV9), Dazhui (GV14), upper arm, thoracic segments, lumbar segments, renal region, popliteal fossa strongly correlated with the improvement of Spleen-Kidney Yang Deficiency symptoms. This suggests that Zhiyang (GV19), Dazhui (GV14), thoracic segments, lumbar segments, renal region on the Governor vessel are key acupoints and regions with the Yang-tonifying effect. Other randomized controlled trials have also shown that moxibustion on the Governor vessel has good therapeutic effects on Yang deficiency diseases [13, 58]. The improvement of Yang deficiency symptoms is also related to the fact that Long-snake-like moxibustion stimulates Yang of the whole body to a greater extent by transferring heat to the extremities and penetrating heat to Upper Jiao and acupoints on the Conception vessel. This heat transfer and penetration of moxibustion are considered manifestations of Deqi [59, 60], which is believed to be an important parameter in acupuncture and moxibustion treatment [61]. The number of correlations was significantly greater in the 60-min Long-snake-like moxibustion group than in the 30-min Long-snake-like moxibustion group. Specifically, there were correlations between Upper Jiao, Shenque (CV8), Zhongwan (CV12), Danzhong (CV17), Zhiyang (GV9), Dazhui (GV14), upper arm, thoracic segments, lumbar segments, renal region, popliteal fossa and fear of cold and cold extremities, lassitude and lack of strength, shortness of breath and laziness to speak, lumbar cold pain, abdominal fullness and distention, symptoms total score in the 60-min Long-snake-like moxibustion group. However, there was only one correlation between Zhiyang (GV9) and fear of cold and cold extremities in the 30-min Long-snake-like moxibustion group. This result suggests that the longer the duration of moxibustion, the greater the dose of heat stimulation. As the heat transfers further and penetrates deeper, more acupoints and regions are mobilized to tonify Yang. In the same course of treatment, 60-min duration generates a greater dose of moxibustion and a stronger effect on tonifying Yang.

One of the limitations of our trial is the small sample size. Considering the pathogenesis characteristic of CFS [2], only female subjects were recruited and examined. Further trials could enlarge the sample size or recruit male subjects to reduce the selection bias. Another limitation is that there were only two time points for TTM scanning in this trial. Increasing the course of treatment and adding additional scanning time points in further trials may be beneficial for analyzing the dynamic changes of dose–effect of Long-snake-like moxibustion and helping deeply explore the saturated dose rule of Long-snake-like moxibustion.

Conclusions

This trial evaluated the effect difference of Long-snake-like moxibustion with different dose of 60-m and 30-m duration, measured by subjective traditional scales and objective medical infrared imaging technology. In the same treatment course, 60-min Long-snake-like moxibustion is superior to 30-min Long-snake-like moxibustion in relieving physical fatigue and overall fatigue status, improving Spleen-Kidney Yang Deficiency symptoms, and raising the low heat state to the level of healthy people. This trial provides evidence for selecting the appropriate treatment duration for Long-snake-like moxibustion in treating CFS, and enriches the content of dose–effect research on moxibustion therapy.

Supplementary Information

Additional file 1: Sensitivity analysis.

Abbreviations

CFS Chronic fatigue syndrome

TCM Traditional Chinese medicine

GV Governor Vessel

TTM Thermal texture maps

HCs Healthy control subject

FS-14 Fatigue scale-14

SDS Self-rating depression scale

SAS Self-rating anxiety scale

SD Standard deviation

Q1 25th percentile

Q3 75th percentile

CI Certificate interval

CRF Case report form

ITT Intention-to-treat

BMI Body mass index

CV Conception vessel

T Thermal radiation value

Acknowledgements

The authors would like to thank all the patients who agreed to participate in this trial. They also thank all the participants and staff who conducted and assisted in this trial.

Author contributions

TM conceptualized and designed the study, provided study materials/patients, participated in the writing of the original draft and its review and editing. JW worked on the conceptualization and administrative support. RG and RZ worked on collection and assembly of data. JT worked on data analysis and interpretation. HL worked on the formal analysis, visualization, drafting/revision of the manuscript, reviewing, and editing. All authors read and approved the final manuscript.

Funding

This trial was externally supported by the government funding—Science and Technology Support Program of Science & Technology Department of Sichuan Province (No. 2020YFS0378).

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The trial was conducted in accordance with the Declaration of Helsinki (as revised in 2013). Research ethics approval was attained from the Ethics Committee of Teaching Hospital of Chengdu University of TCM (No.2020KL-046). Informed consent was obtained from each patient.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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References

1. Reeves WC Lloyd A Vernon SD Identification of ambiguities in the 1994 chronic fatigue syndrome research case definition and recommendations for resolution BMC Health Serv Res 2003 3 1 25 33 10.1186/1472-6963-3-25 14702202
2. Capelli E Zola R Lorusso L Chronic fatigue syndrome/myalgic encephalomyelitis: an update Int J Immunopathol Pharmacol 2010 23 4 981 9 10.1177/039463201002300402 21244747
3. Ng SM Yiu YM Acupuncture for chronic fatigue syndrome: a randomized, sham-controlled trial with single-blinded design Altern Ther Health Med 2013 19 4 21 6 23981369
4. Tingting M Jie W Lijie Y Ginger-indirect moxibustion plus acupuncture versus acupuncture alone for chronic fatigue syndrome: a randomized controlled trial J Tradit Chin Med 2022 42 2 242 9 10.19852/j.cnki.jtcm.20211214.003 35473345
5. Oka T Tanahashi T Chijiwa T Isometric yoga improves the fatigue and pain of patients with chronic fatigue syndrome who are resistant to conventional therapy: a randomized, controlled trial Biopsychosoc Med 2014 8 1 27 35 10.1186/s13030-014-0027-8 25525457
6. Price JR Mitchell E Tidy E Cognitive behaviour therapy for chronic fatigue syndrome in adults Cochrane Database Syst Rev 2008 2008 3 CD001027 10.1002/14651858 18646067
7. White PD Goldsmith KA Johnson AL Comparison of adaptive pacing therapy, cognitive behaviour therapy, graded exercise therapy, and specialist medical care for chronic fatigue syndrome (PACE): a randomised trial Lancet 2011 377 9768 823 36 10.1016/S0140-6736(11)60096-2 21334061
8. Van Cauwenbergh D De Kooning M Ickmans K How to exercise people with chronic fatigue syndrome: evidence-based practice guidelines Eur J Clin Invest 2012 42 10 1136 44 10.1111/j.1365-2362.2012.02701.x 22725992
9. Kim HG Yoo SR Park HJ Indirect moxibustion (CV4 and CV8) ameliorates chronic fatigue: a randomized, double-blind, controlled study J Altern Complement Med 2013 19 2 134 40 10.1089/acm.2011.0503 22757691
10. Shu Q Wang H Litscher D Acupuncture and moxibustion have different Effects on fatigue by regulating the autonomic nervous system: a pilot controlled clinical trial Sci Rep 2016 6 37846 10.1038/srep37846 27886247
11. Zuo Z Liu Z Yuan K Effects and mechanism of the long-snake moxibustion on ankylosing spondylitis based on Th17/Treg/Th1 immune imbalance Zhongguo Zhen Jiu 2018 38 10 1053 7 10.13703/j.0255-2930.2018.10.006 30672234
12. Zhang W Chen M Hu J Long-snake moxibustion for rheumatoid arthritis: a randomized controlled trial Zhongguo Zhen Jiu 2016 36 7 694 8 10.13703/j.0255-2930.2016.07.005 29231407
13. Xuan YC Liu J Huang YY Therapeutic effect of long-snake moxibustion combined with western medication on diarrhea type irritable bowel syndrome of spleen and kidney yang deficiency Zhongguo Zhen Jiu 2021 41 2 133 6 10.13703/j.0255-2930.20191225-k0003 33788459
14. Huang LR Treating chronic fatigue syndrome with modified long snake moxibustion combined with acupuncture, a randomized controlled clinical study [D] 2018 Chengdu Chengdu University of Traditional Chinese Medicine
15. Lu L Fu JM Feng FY Dose–effect relationship in treatment of chronic neck pain with the direct moxibustion of small moxa cone Zhongguo Zhen Jiu 2019 39 7 734 8 10.13703/j.0255-2930.2019.07.015 31286736
16. Li H Sang L Xia X Therapeutic duration and extent affect the effect of moxibustion on depression-like behaviour in rats via regulating the brain tryptophan transport and metabolism Evid Based Complement Alternat Med 2019 2019 7592124 10.1155/2019/7592124 31534466
17. Xiao AJ He L Ouyang X Comparison of the anti-apoptotic effects of 15- and 35-minute suspended moxibustion after focal cerebral ischemia/reperfusion injury Neural Regen Res 2018 13 2 257 64 10.4103/1673-5374.226396 29557375
18. Zhao JM Wu LY Liu HR Factorial study of moxibustion in treatment of diarrhea-predominant irritable bowel syndrome World J Gastroenterol 2014 20 37 13563 72 10.3748/wjg.v20.i37.13563 25309087
19. Hives L Bradley A Richards J Can physical assessment techniques aid diagnosis in people with chronic fatigue syndrome/myalgic encephalomyelitis? A diagnostic accuracy study BMJ Open 2017 7 11 e017521 10.1136/bmjopen-2017-017521 29133321
20. Twisk FN The status of and future research into myalgic encephalomyelitis and chronic fatigue syndrome: the need of accurate diagnosis, objective assessment, and acknowledging biological and clinical subgroups Front Physiol 2014 5 109 10.3389/fphys.2014.00109 24734022
21. Almutairi B Langley C Crawley E Using structural and functional MRI as a neuroimaging technique to investigate chronic fatigue syndrome/myalgic encephalopathy: a systematic review BMJ Open 2020 10 8 e031672 10.1136/bmjopen-2019-031672 32868345
22. Chalder T Berelowitz G Pawlikowska T Development of a fatigue scale J Psychosom Res 1993 37 2 147 53 10.1016/0022-3999(93)90081-p 8463991
23. Jing MJ Lin WQ Wang Q Reliability and construct validity of two versions of chalder fatigue scale among the general population in Mainland China Int J Environ Res Public Health 2016 13 1 147 10.3390/ijerph13010147 26805863
24. Fernández-Cuevas I Bouzas-Marins JC Arnáiz-Lastras J Classification of factors influencing the use of infrared thermography in humans: a review Infrared Phys Technol. 2015 71 28 55 10.1016/j.infrared.2015.02.007
25. Thermography Guidelines (TG)., Standards and protocols in clinical thermographic imaging. 2002. http://www.iact-org.org/professionals/thermog-guidelines.html.
26. Sun D Study on infrared thermography characterization of liver qi stagnation syndrome population surface partition attachment: overview of medical infrared thermal imaging technology [D] 2017 Chengdu Chengdu University of Traditional Chinese Medicine
27. Chen ZJ Preliminary study on infrared thermography characteristics of Wagner grade 0 diabetic foot patients from the perspective of traditional chinese medicine[D] 2021 Beijing Beijing University of Traditional Chinese Medicine
28. Ding GJ The study on the correlation between moxibustion sensation and curative effect in treating chronic fatigue syndrome by needling LU7, KI6 combined with modified long snake moxibustion [D] 2019 Chengdu Chengdu University of Traditional Chinese Medicine
29. Wang W Russell A Yan Y Global Health Epidemiology Reference Group (GHERG) Traditional Chinese medicine and new concepts of predictive, preventive and personalized medicine in diagnosis and treatment of suboptimal health EPMA J 2014 5 1 4 10.1186/1878-5085-5-4 24521056
30. National Collaborating Centre for Primary Care (UK). Chronic fatigue syndrome/myalgic encephalomyelitis (or encephalopathy): diagnosis and management of chronic fatigue syndrome/myalgic encephalomyelitis (or encephalopathy) in adults and children. London: Royal College of General Practitioners (UK); 2007.
31. Yancey JR Thomas SM Chronic fatigue syndrome: diagnosis and treatment Am Fam Physician 2012 86 8 741 6 23062157
32. Vink M Vink-Niese A Cognitive behavioural therapy for myalgic encephalomyelitis/chronic fatigue syndrome is not effective. Re-analysis of a cochrane review Health Psychol Open 2019 6 1 2055102919840614 10.1177/2055102919840614 31080632
33. Son CG Analysis of patients visiting an oriental hospital with idiopathic chronic fatigue or chronic fatigue syndrome J Korean Med 2013 34 119 25 10.13048/jkm.13017
34. Kwak KK Cho JH Son CG Study on chronic fatigue syndrome from oriental medicine point of view Korean J Orient Int Med 2008 29 962 9
35. Wang T Xu C Pan K Acupuncture and moxibustion for chronic fatigue syndrome in traditional chinese medicine: a systematic review and meta-analysis BMC Complement Altern Med 2017 17 1 163 10.1186/s12906-017-1647-x 28335756
36. You J Ye J Li H Moxibustion for chronic fatigue syndrome: a systematic review and meta-analysis Evid Based Complement Alternat Med 2021 2021 6418217 10.1155/2021/6418217 34804182
37. Hu XW Deng CY Tang LM Ginger-separated snake moxibustion improves Yang deficiency constitution by up-regulating serum adrenocorticotropic hormone and cortisol levels in Yang deficiency constitution volunteers Zhen Ci Yan Jiu 2018 43 12 773 6 10.13702/j.1000-0607.180513 30585454
38. Huang P Deng CY Jiang XM Observation on the clinical effect of long snake-like moxibustion in treating chronic fatigue syndrome of deficiency of heart and spleen Guangming J Chin Med 2020 35 13 2028 31
39. Zheng SH Zheng SZ Wu YJ Clinical efficacy of long snake moxibustion on chronic fatigue syndrome with spleen and kidney deficiency type and its effect on cytokines Chin Arch Tradit Chin Med 2013 31 11 2555 7 10.13193/j.issn.1673-7717.2013.11.036
40. Billones RR Kumar S Saligan LN Disentangling fatigue from anhedonia: a scoping review Transl Psychiatry 2020 10 1 273 10.1038/s41398-020-00960-w 32769967
41. Schwartz JE Jandorf L Krupp LB The measurement of fatigue: a new instrument J Psychosom Res 1993 37 7 753 62 10.1016/0022-3999(93)90104-n 8229906
42. Başoğlu F Öncü J Kuran B The reliability and validity of the turkish version of multidimensional fatigue Inventory-20 for the evaluation of different dimensions of fatigue in patients with fibromyalgia Turk J Phys Med Rehabil 2020 66 4 436 43 10.5606/tftrd.2021.5781 33364564
43. Shang Z Jiang G Fundamental theoretic research of thermal texture maps Isimulation and analysis of the relation between the depth of inner heat source and surface temperature distribution in isotropy tissue Conf Proc IEEE Eng Med Biol Soc 2004 2004 5271 3 10.1109/IEMBS.2004.1404471 17271528
44. Huth TK Eaton-Fitch N Staines D A systematic review of metabolomic dysregulation in chronic fatigue syndrome/myalgic encephalomyelitis/systemic exertion intolerance disease (CFS/ME/SEID) J Transl Med 2020 18 1 198 10.1186/s12967-020-02356-2 32404171
45. Cortes Rivera M Mastronardi C Silva-Aldana CT Myalgic encephalomyelitis/chronic fatigue syndrome: a comprehensive review Diagnostics (Basel) 2019 9 3 91 10.3390/diagnostics9030091 31394725
46. Herman C Cetingul MP Quantitative visualization and detection of skin cancer using dynamic thermal imaging J Vis Exp 2011 51 2679 10.3791/2679
47. Bauer J Hoq MN Mulcahy J Implementation of artificial intelligence and non-contact infrared thermography for prediction and personalized automatic identification of different stages of cellulite EPMA J 2020 11 1 17 29 10.1007/s13167-020-00199-x 32140183
48. Murthy JN van Jaarsveld J Fei J Thermal infrared imaging: a novel method to monitor airflow during polysomnography Sleep 2009 32 11 1521 7 10.1093/sleep/32.11.1521 19928392
49. Guguvcevski L Muscle fatigue in temporomandibuar disorder patients evaluated by electromyography Adv Biology Earth Sci 2017 2 1 117 21
50. Armstrong CW McGregor NR Butt HL Metabolism in chronic fatigue syndrome Adv Clin Chem 2014 66 121 72 10.1016/b978-0-12-801401-1.00005-0 25344988
51. Mandarano AH Maya J Giloteaux L Myalgic encephalomyelitis/chronic fatigue syndrome patients exhibit altered T cell metabolism and cytokine associate-ons J Clin Invest 2020 130 3 1491 505 10.1172/JCI132185 31830003
52. Sotzny F Blanco J Capelli E Myalgic encephalomyelitis/chronic fatigue syndrome-evidence for an autoimmune disease Autoimmun Rev. 2018 17 6 601 9 10.1016/j.autrev.2018.01.009 29635081
53. Bansal AS Bradley AS Bishop KN Chronic fatigue syndrome, the immune system and viral infection Brain Behav Immun 2012 26 1 24 31 10.1016/j.bbi.2011.06.016 21756995
54. Klimas NG Broderick G Fletcher MA Biomarkers for chronic fatigue Brain Behav Immun 2012 26 8 1202 10 10.1016/j.bbi.2012.06.006 22732129
55. Kume S Yamato M Tamura Y Potential biomarkers of fatigue identified by plasma metabolome analysis in rats PLoS ONE 2015 10 3 e0120106 10.1371/journal.pone.0120106 25793974
56. Lin C Sa ZY Zhong XL Effect of deqi induced by needling sanyinjiao (SP6) on energy metabolism indicators in patients with primary dysmenorrhea in cold and dampness stagnation pattern Fujian J Tradit Chin Med 2021 52 11 10 4 10.13260/j.cnki.jfjtcm.012360
57. Li Y Sun C Kuang J An invitro and numerical study of moxibustion therapy on biological tissue IEEE Trans Biomed Eng 2018 65 4 779 88 10.1109/TBME.2017.2719633 28650805
58. Hong XE Zhang LY Lin W Governor vessel moxibustion combined with warming acupuncture for knee osteoarthritis with yang deficiency and cold congelation based on the supporting-yang theory Zhongguo Zhen Jiu 2022 42 12 1357 62 10.13703/j.0255-2930.20220617-k0002 36484187
59. Chen R Chen M Xiong J Comparative effectiveness of the deqi sensation and non-deqi by moxibustion stimulation: a multicenter prospective cohort study in the treatment of knee osteoarthritis Evid Based Complement Alternat Med 2013 2013 906947 10.1155/2013/906947 24027596
60. Xie D Liu Z Hou X Heat sensitisation in suspended moxibustion: features and clinical relevance Acupunct Med 2013 31 4 422 4 10.1136/acupmed-2013-010409 24008013
61. Lv Z Liu Z Huang D The characterization of deqi during moxibustion in stroke rats Evid Based Complement Alternat Med 2013 2013 140581 10.1155/2013/140581 24194777