Study design

A parallel-group randomized controlled trial was used in this study. The trial has been registered with the Chinese Clinical Trial Registry since June 20, 2023 (ChiCTR2300072669). It was also approved ethically by the Ethical Review Committee of Biomedical Research, Fujian Medical University [(2023) Fuyi Ethics Review No. (102)]. The Helsinki Declaration was followed in all aspects of the experiments. The study’s reporting adhered to the rigor CONSORT guidelines.

Participants

We recruited 74 students from Fujian Medical University diagnosed with UCS. These students were recruited between Sep 1 and Oct 5, 2023, through posters published by the investigators. If a participant met the following requirements, they were eligible to participate.

(1)

They were full-time college students of age 18–26 years;

(2)

Their condition satisfied the diagnostic criteria raised by the Asian Fitness Society for UCS, i.e., (i) The corner of the eye and the upper corner of the ear are not in the same horizontal plane; (ii) The two earlobes lines are in front of the two acromion lines; (iii) The left and right acromium are not equidistant from the midline of the human body. (iv) The distance between the scapula and the spinous process of the spine exceeds the width of the four fingers of the body finger; and (v) The cervical C7-posterior occipital carina curvature gap was larger than the four-finger width of the body finger;

(3)

They provided the informed consent.

With regard to exclusion criteria, individuals were considered ineligible if they engaged in additional exercise in two weeks, which was likely to affect the results of the research. Individuals with a history of spine, shoulder fractures, surgery, or other disease, or having severe cardia-cerebrovascular disease were also excluded.

Dropout criteria were considered if three consecutive interventions were unsuccessful, the participant was unable to complete follow-up testing, or other factors were present that could influence the study results.

Randomization

Block randomization in a 1:1 ratio was generated using the SPSS 27.0 program, and the sequence of randomization was managed by an investigator who was not involved in the recruitment, evaluation, and intervention phases. Allocation concealment was accomplished by opening sequentially numbered opaque sealed envelopes. The CG or the IG group to which the subject was randomly allocated was specified on a card inside. During the experiment, outcome assessors were kept unaware of the groups they were assigned to. Figure 1 depicts the flowchart for the study.

Fig. 1Intervention

All the IG participants received instructions from two professional trainers to conduct the cervical and thoracic “Daoyin” training. The time (Monday to Saturday at 5:00–5:45 p.m. or 9:00–9:45 p.m.) and location (a classroom of Fujian Medical University) of exercise were consistent and fixed. The training was conducted five times a week for two months.

The cervical and thoracic “Daoyin” training, by mimicking the movements and postures of natural animals such as turtles, swans, rocs, and tigers, aims to improve issues like rounded shoulders, hunched back, and forward head posture, thereby preventing and treating neck and shoulder pain. It consisted of the following five movements in this study: (1) Dantian Gong (2) Turtle shrinking its neck (3) Roc spreading its wings (4) White goose stretching its neck (5) Tiger lying. The interval of each movement was 30–60 s, and the duration was 45 min. For the specific diagrams and detailed instructions on the cervical and thoracic “Daoyin” training, please refer to Additional file 1 (Figure S1 and Table S1).

The CG participants were instructed to maintain daily activities and not partake in any further sports. Health education was given to all participants before the start of the experiment. The contents included UCS-related concepts, etiology, hazards, mitigation methods, and precautions.

Outcomes

At baseline, the following demographic characteristics (age, weight, height, BMI) were assessed. Three researchers who were not involved in the group allocation process collected data and variables immediately prior to group allocation and following the intervention. Primary outcome measures included FHA and FSA, pain score, and cervical spine function assessment. Secondary outcome measures included a pulmonary function test, cervical range of motion measurement, and emotional state assessment.

Forward head and shoulder angles

The PA200LE body monitoring and analysis system (The Big Sports Co. Ltd, Japan) was used to evaluate the Forward Head Angle (FHA) and Forward Shoulder Angle (FSA). In a separate room, participants stood on the plantar platen with the camera positioned 2.4 m in front of the plate, and the camera’s Red Cross was calibrated to coincide with the white cross on the plantar platen before evaluation began. During the postural assessment, participants wore tight fitting-clothing and red marker points for photo image analysis were attached to the spinous process of the C-7 spinous, right tragus, and acromion. Participants stood with their feet 10 cm apart on the plantar platen on the side, with the fifth metatarsal eminence of their feet al.igned with the white line in the sagittal direction of the plantar platen, looking forward with their hands naturally hanging at their sides. A straight line was made perpendicular to the ground through the C-7 spinous process, and then the tragus and acromion were connected with the C-7 spinous process, respectively. ∠1 was FHA, and ∠2 was FSA (Fig. 2). The Angle Meter software was downloaded on the mobile phone, and the pictures were put into the software for analysis, the angles of FHA and FSA were calculated, and the final data were obtained [20].

Fig. 2

Static neck and shoulder posture measurement diagram.∠1 FHA, forward head angle; ∠2 FSA, forward shoulder angle

Pain score

Using the VAS, which consists of a 10 cm straight line, the degree of pain was assessed, with 0 on one end meaning “painless” and 10 on the other meaning “probably the most intense pain.” Patients marked their pain on this straight line, with higher scores indicating more pain [11, 21].

Cervical spine function assessment

The NDI was used to evaluate the cervical spine’s functionality. It is a self-rated questionnaire, most commonly used in clinical studies related to neck pain. The evaluation took into account how neck discomfort affected a person’s capacity to do activities of daily life [22]. The NDI scale consists of 10 items, each of which is scored from 0 to 5. More dysfunction is indicated by a higher score.

Pulmonary function test

BTL-08 Spiro (BTL, United Kingdom) was used to measure lung function. Calibration was performed before measurement, and the error was within 3%. At the same time, we ensured that the test was carried out in a relatively non-interference state. Before the test, 74 participants were uniformly trained on relevant test methods, and the formal test could only be started after they had mastered the correct test methods. The parameters of lung function test included forced vital capacity (FVC), forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC), and maximal voluntary ventilation (MVV) measured value as a percentage of estimated value (real/predicted). We tested each parameter thrice and took the mean value each time.

Cervical range of motion measurement

The active range of motion of the cervical spine was measured using a medical human joint protractor (BWP-JDC, China), which consisted of a fixed arm, a movable arm, and an axis [23]. Before measurement, the osseous markers of the cervical spine were required to be determined. The axis of the protractor was aligned with the joint axis. The fixed arm was parallel to the shaft of the proximal bone of the joint, and the movable arm was parallel to the shaft of the distal bone. Each of the six primary cervical spine movements was measured, including forward flexion (FF) and backward extension (BE) in the coronal plane, left lateral flexion (LLF) and right lateral flexion (RLF) in the sagittal plane, as well as left rotation (LR) and right rotation (RR) in the transverse plane.

Emotional state assessment

Emotional states were evaluated with the Self-Rating Anxiety Scale (SAS), a self-assessment tool for anxiety symptoms, which can reflect the subjective feelings of adults with anxiety tendencies. There are 20 questions on this scale, including 15 forward scores and five reverse scores. We multiplied the total assessed score by 1.25 to give the final score. Higher scores indicate higher anxiety [24].

Sample size calculation

Based on the results of an earlier study of upper crossed syndrome [25], the FSA was 44.60 ± 7.54 and 38.95 ± 4.81 degrees in the CG and the IG, respectively, at the end of the intervention. Using the GPower3.1 software, the trial required 74 participants (37 in each group) to be able to perform a statistical test with the assumption of a type I error of 5% (α = 0.05), 95% power (β = 0.05), and the allowance of a dropout rate of 10%.

Statistical analysis

All statistical analyses were performed using SPSS 27.0 software. Means and standard deviations were used to describe results for continuous variables, while frequencies and percentages were used to provide results for categorical variables. P < 0.05 and P < 0.01 were used to determine if the results were statistically different and significantly different. The Shapiro - Wilk test test and histogram were used to determine if the data distribution was normal. The statistical analysis entailed the utilization of the change value between the baseline and the 8-week intervention measurements. Continuous variables were analyzed using the independent-samples t-test (normal data distribution) and Mann–Whitney U test (skewed distribution) in order to compare differences between groups. Categorical variables were analyzed using Chi-square test. Cohen’s d was used to calculate the between-group effect sizes, with effect sizes of 0.2, 0.5, and 0.8 regarded as small, medium, and large, respectively.