Effects of Dynamic Neuromuscular Stabilization Training on the Core Muscle Contractility and Standing Postural Control in Patients with Chronic Low Back Pain: A Randomized Controlled Trial

Effects of Dynamic Neuromuscular Stabilization Training on the Core Muscle Contractility and Standing Postural Control in Patients with Chronic Low Back Pain: A Randomized Controlled Trial | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effects of Dynamic Neuromuscular Stabilization Training on the Core Muscle Contractility and Standing Postural Control in Patients with Chronic Low Back Pain: A Randomized Controlled Trial Huanjie Huang, Haoyu Xie, Guifang Zhang, Wenwu Xiao, Le Ge, Songbin Chen, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5146743/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Mar, 2025 Read the published version in BMC Musculoskeletal Disorders → Version 1 posted 4 You are reading this latest preprint version Abstract Background Patients with chronic low back pain (cLBP) usually demonstrated poor postural control due to impaired core muscle function. Dynamic neuromuscular stabilization (DNS) is based on developmental kinesiology principles, utilizing infant motor patterns to treat motor disorders. DNS has been shown to improve postural control in cerebral palsy patients by activating core muscle. Conventional core exercises were able to enhance core muscle contractility and postural control in cLBP patients. However, whether the DNS approach is superior for enhancing core muscle contractility and postural control in cLBP patients still remains unclear. Objectives This study aimed to investigate the effects of DNS on core muscle contractility and standing postural control in cLBP patients. Methods Sixty cLBP patients were randomly assigned to a DNS group or a control group. Participants in the DNS group received DNS training, while those in the control group completed conventional core exercises. Both groups completed 12 sessions over 4 weeks (3 sessions/week, 50 minutes/session). Pre- and post-intervention evaluations included diagnostic musculoskeletal ultrasound to assess change rate of core muscles (transversus abdominis (TrA), lumbar multifidus, and diaphragm), using a balance assessment system to evaluate postural control performance (center of pressure displacement (COP)) in an upright standing position, and clinical questionnaires (Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Roland-Morris Disability Questionnaire (RDQ)) for the pain intensity and disability. Results After 4 weeks, comparisons between both groups revealed significant statistical differences in the interaction effects of time*group. These differences were observed in the change rates of the left and right TrA (F 1,58 =4.820 and 3.964, p = 0.032 and 0.041), diaphragm change rate (F 1,58 =11.945, p = 0.001), as well as COP velocity (F 1,58 =5.283, p = 0.025), variability (F 1,58 =13.189, p = 0.001) in the anterior-posterior (AP) direction, COP path length (F 1,58 =6.395, p = 0.014), and COP area (F 1,58 =5.038, p = 0.029) in the eye-close condition. DNS participants showed significantly greater muscle change rates and reduced COP ( p < 0.05). The scores of VAS (F 1,58 =173.929, p = 0.001), ODI (F 1,58 =60.871, p = 0.001), and RDQ (F 1,58 =60.015, p = 0.001) decreased significantly over time, although no differences in the interaction effects of time*group were found between both groups ( p > 0.05). Conclusions DNS is superior to conventional core exercises in enhancing core muscle contractility and standing postural control in cLBP patients, showing potential to reduce pain and improve disability. Its mechanism may involve the enhancement of proprioceptive feedback, particularly when visual feedback is blocked. Trial registration This study was registered in the Chinese Clinical Trial Registry (ChiCTR) with the registration number ChiCTR2300074595 on 10 August 2023. Chronic low back pain Dynamic neuromuscular stabilization Core muscle Postural control Pain intensity Disability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Background Chronic low back pain (cLBP) is one of the most common musculoskeletal disorder with the lifetime prevalence of 13.1–20.3%, according to the latest epidemiological survey [ 1 ]. Since 1990, the worldwide number of patients with cLBP has dramatically increased from 0.37 billion to 0.57 billion, leading to an increase in years lived with disability (YLDs) for people [ 2 ]. cLBP has a profound impact on patients' lives, families, and work [ 3 ]. Moderate medical evidence suggests that core stability exercises may be an effective treatment for cLBP compared to no treatment, usual care, or placebo for pain [ 4 , 5 ]. Although there have been some advances in the assessment and treatment of cLBP in recent years, the clinical efficacy are still unsatisfactory [ 6 , 7 ]. The major symptom of cLBP is persistent, intractable pain located at lumbosacral area. Patients with cLBP commonly exhibit atrophy of the core muscle and increased fat infiltration [ 8 – 10 ]. In response to pain, they may alter the activation sequence of trunk muscles and the excitability of the motor cortex [ 9 , 11 ]. Prolonged compensatory mechanisms may eventually lead to core muscle atrophy. Additionally, patients with cLBP often suffer from impaired postural control, significantly impacting their activities of daily living [ 12 ]. In the clinical setting, posturography, a non-invasive specialized clinical assessment technique, is widely used to assess the postural control performance, which addresses the lack of reliable clinical tests for assessing posture or balance-related disorders [ 13 ]. Postural control is usually quantified by recording the trajectory of the center of pressure (COP) using force platforms when humans maintain an upright, quiet standing position. The COP trajectory tracks the point of application of ground reaction forces resultant under the feet. Based on the COP trajectory, multiple variables, such as COP displacement speed and area, can be obtained to analyze its one-dimensional variations in the anterior-posterior (AP) and medial-lateral (ML) directions [ 14 ]. The measurement of COP-related variables has been identified as a quantitative, objective method to accurately evaluate the postural control of patients with cLBP in comparison to traditional balance tests or questionnaires [ 15 ]. According to published studies, patients with cLBP usually demonstrate a significantly increased COP sway and larger displacement compared to healthy populations, especially in the AP direction, indicating a poor postural control [ 15 ]. Wang et al. [ 16 ] assess the postural control performance and the thickness of core muscles (bilateral transversus abdominis (TrA) and lumbar multifidus (MF)) in patients with cLBP and healthy controls. Their results show that the existence of cLBP leads to the significantly decreased thickness of TrA, larger path length and sway area of COP trajectory [ 16 ]. Therefore, the impaired postural control in patients with cLBP might be related to the contractility of core muscles. Panjabi proposes that the postural control impairment is attributed to a deficiency in core stability, which is defined as the ability to maintain a stable spinal position via the co-contraction of core muscles [ 17 ]. Multiple studies suggest that conventional core exercise is able to specifically intensify the contractility of core muscles and improve postural control of patients with cLBP [ 12 , 18 , 19 ]. However, a common limitation in above-mentioned studies is the neglect of the diaphragm, which serves as one of the core muscles and the most vital respiratory muscle. A published review indicates that the normal contraction of diaphragm also plays a significant role in the core stability of patients with cLBP [ 20 ]. Another study evaluates the dynamics of diaphragm in patients with cLBP via magnetic resonance imaging. It reveals significantly smaller diaphragm excursions in a postural control task, suggesting a decreased coordination capacity of diaphragm in patients with cLBP [ 21 ]. However, current conventional core exercise do not prioritize the maintenance of a rhythmic breathing pattern, leading to inadequate training of the diaphragm for optimal contribution to core stability [ 20 ]. Hence, an updated exercise protocol that specifically targets the diaphragm might be superior to improve the postural control of patients with cLBP. Dynamic neuromuscular stabilization (DNS) is a novel functional approach based on the developmental kinesiological models. This method treat motor-related disorders by utilizing infant motor development process [ 22 ]. The DNS training achieves optimal, global body function in a neutral alignment of head and spine via integrating postural awareness, precise breathing pattern, and motor control [ 23 ]. The DNS training emphasizes the coordination of all body segments to maintain a functionally centered position and perform precise muscle contraction simultaneously for breathing and postural control. Therefore, the ultimate objective of the DNS training is to activate appropriate respiratory and postural muscles (core muscles) to maintain core stability in any positions or during all locomotor tasks [ 22 ]. In comparison to conventional core exercises, the DNS training has been proven as effective in improving the breathing pattern, increasing lumbar stability and intra-abdominal pressure [ 24 ]. The application of DNS training on patients with cLBP is still limited. A recent randomized controlled trail conducts a 6-week DNS training in obsess postpartum females with cLBP and finds that the DNS training demonstrates a better effect on improving pain intensity, the LBP-related disability, and respiratory function based on the evaluation of multiple clinical questionnaires [ 25 ]. However, the effects of DNS training on the contractility of core muscles and postural control in patients with cLBP still remains unclear when evaluated using quantitative assessment methods. Therefore, the present study aimed to investigate the effects of the DNS training on the contractility of core muscles, the postural control performance, pain intensity, and the LBP-related disability in patients with cLBP. We hypothesized that in comparison to conventional core exercises, the DNS training was superior to improve the above-mentioned indictors in patients with cLBP. This study may provide new ideas and evidence for the treatment for cLBP and the clinical application of the DNS training as updated rehabilitation protocols. Methods Study Design This was a randomized controlled trial with single-blinded parallel groups of patients with cLBP. The details of the recruiting process were illustrated in Fig. 1 . A specific research responsible for the clinical assessment of participants and experienced physical therapists who assisted participants to complete the intervention were blinded to the allocation of each participant. A series of random numbers was generated using the statistical software (IBM SPSS 25.0) to randomly assign participants to either the DNS group or control group. This study was carried out under the regulation of and upon approval by the Institutional Ethics Committee of the First Affiliated Hospital of Sun Yat-sen University (IRB# [2023] 324). The written informed consent was obtained from each participant at the day of inclusion, and detailed information about this study was also provided. Participants were free to withdraw from the study at any time without providing a reason. The Declaration of Helsinki was strictly followed throughout the course of the study. Participants and Sample Size Calculation Patients with cLBP were recruited between May 2023 and February 2024 from the Department of Rehabilitation Medicine, the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China. At the day of recruitment, each participant was subjected to a clinical evaluation by an experienced physician, and their medical history was reviewed in detail. The inclusion criteria were as follow: 1) diagnosed as non-specific LBP with pain persisting for more than 3 months according to the diagnostic guidelines from the American College of Physicians and the American Pain Society [ 26 ]; 2) aged between 18 and 60 years; 3) visual analog scale (VAS) ≥ 3cm; 4) body mass index ≤ 28kg/m 2 ; 5) intact psychological and cognitive function to complete the experiment. Participants were excluded if they had any of the following: 1) previous back surgery, spinal tumors, deformities or infections; 2) LBP of traumatic or structural origins or LBP with neurological symptoms (e.g., radiating pain or numbness in the lower extremities); 3) previous neurological and/or cardiopulmonary diseases that severely affected locomotor performance (e.g., stroke, Parkinson’s disease, and chronic obstructive pulmonary disease); 4) pregnancy. The determination of sample size was based on a previous publication [ 18 ] via the computation of power analysis through G*power ( http://www.gpower.hhu.de/ ). Based on their study, recruitment of 34 participants would generate a power of 80% and a level of significance of 5% (two-sided) for detecting a true difference. According to the Partial Eta Squared method, the η 2 = 0.138 as the large effect size was used to calculate the effect size f [ 27 ]. Therefore, with the calculated effect size f as 0.4 and the potential drop-out rate of 15%, recruiting 57 patients with cLBP should be statistically sufficient for identifying the true difference in outcomes of interest. Interventions In this study, participants in DNS and control groups were treated with a 4-week intervention. Following the health education about cLBP prior to the intervention period, there were a total of 12 training sessions for each participant (3 sessions per week). Each session lasted 50 minutes. Two experienced physical therapists assisted participants to complete the intervention. The study personnel were trained to implement study protocols in an effort to ensure standardization within and cross sites. When there was any intolerable increased pain or symptoms, the intervention would be terminated immediately and participants would be provided with sufficient rest or medical care if necessary. During the intervention, appropriate breaks were provided for participants to avoid excessive muscle fatigue. Participants were also allowed to request more rest according to their individual status and needs. If any participants did not accomplish the intervention, they would be treated as dropouts and be excluded in data analysis. Intervention protocols for participants in DNS and control groups were shown as follows. For participants in the DNS group, follow the stretching of muscles, there were 6 difference exercises in the DNS training, including the supine diaphragmatic breathing, the dead-bug exercise, the side-lying rolling, the bear-crawl exercise, high side plank and the kneeling-sitting transfer (Fig. 2 ) [ 25 ]. According to the DNS approach, participants in the DNS groups were guided by oral feedback from an experienced physical therapist to follow three basic DNS principles, so as to assure a high quality of training [ 22 ]. Firstly, learning the abdominal respiration skills to maintain an appropriate intra-abdominal pressure during the DNS training. Secondly, maintaining the spinal stability in the sagittal plane to achieve good spinal alignment and curve. Thirdly, inducing the co-contraction of agonists and antagonists by specific positioning of joints. Each exercise was designed as 2 sets with 10 repetitions per set. A mandatory 2-minute break was assigned to every participant between each exercises. Participants in the control group received conventional core exercises for cLBP, consisting of the stretching, single/double leg-bridge, side bridge, crunch, prone plank and the bird-dog exercises (Fig. 3 ) [ 28 ]. Participants were required to control their movements slow and steady, as well as keeping a natural, rhythmic breath to avoid the Valsalva maneuver. Each exercise was designed as 2 sets with 10 repetitions per set. A mandatory 2-minute break was assigned to every participant between each exercises. Outcome Measures In the present study, each participant was evaluated by a specific researcher who was a professionally-trained physician blinded to the allocation of each participant before and after the 4-week intervention. Outcomes of interest included following three parts. (1) The Percent Change of Core Muscles Thickness In this study, a diagnostic musculoskeletal ultrasound (SONIMAGE HS1, Konica Minolta Inc., Japan) with a linear transducer at 18.0MHz and a curvilinear transducer at 4.0MHz was used to measure the morphologic changes of core muscles (bilateral TrA and lumbar MF, and diaphragm) for each participant before and after the intervention. For each core muscle, thickness was measured at rest and during maximum voluntary isometric contraction (MVIC), with each measurement repeated three times. A 1-minute break was provided for participants among measurements of muscle thickness at MVIC state to avoid muscle fatigue. Considering the impact of different demographic characteristics (sex, age, weight, and height), the percent change of muscle thickness was used to measure the contractility of core muscles and ensure the comparability among different participants. The calculation of percent change of muscle thickness was based on the following formula [ 29 ], $$\:Percent\:cℎange=\frac{Tℎickness\:\left(MVIC\right)-Tℎickness\:\left(Rest\right)}{Tℎickness\:\left(Rest\right)}\times\:100\%$$ Then, the average values of percent change of muscle thickness at different states for a participant were regarded as the final outcome to be used in data analysis. Figure 4 demonstrated an example of core muscle ultrasound image from a participant. To measure unilateral TrA, participants were instructed to hold a supine hook-lying position with both arms crossing over their chest and knee flexing to 90 degrees. The linear transducer with B-mode was placed on the ipsilateral mid-axillary line at the level of umbilicus (just above the iliac crest). Following a deep inspiration and then a forced expiration, participants was required to keep breathing out and voluntarily relax their abdomen to record the thickness of TrA at the rest state, and the image of TrA was taken at the end of exhalation. Then, they were guided to perform the abdominal draw-in maneuver to measure the thickness of TrA at MVIC state [ 9 ]. To more accurately measure it, participants were allowed to practice this maneuver before the data collection to correctly contract the TrA. To measure the diaphragm, participants were required to keep the above-mentioned supine hook-lying position. The linear transducer with B-mode was placed on the intersection between the right anterior axillary line and the 7th or 8th intercostal space (depending on participants’ body size) to record the longitudinal image of diaphragm [ 30 , 31 ]. Assessor adjusted the angle of transducer until obtaining the clear image of diaphragm and held this angle during the measurement. Participants were required to exhale as far as possible to reach maximum exhalation and record the thickness of diaphragm at the rest state. Then, they were instructed to inhale to reach total lung capacity and hold their breath to measure the thickness of diaphragm at MVIC state. The measurement of unilateral MF followed the procedure as follow. Firstly, participants kept a prone position on a therapy table with a pillow placed under their abdomen to flatten the lumbosacral curve. To measure lumbar MF at the L5/S1 level, the curvilinear transducer with B-mode was longitudinally positioned about 2cm lateral to the midline of the L5 spinal process, and medially angled to obtain the image of the ipsilateral L5/S1 zygapophyseal joint and MF at the rest state. Then, the thickness of MF at MVIC state was measured by participants lifting their contralateral arms 5cm off the table and holding at shoulder abduction of 120 degrees and elbow flexion of 90 degrees [ 18 ]. Assessor would also apply a downward force to the lifted elbow to better contract the target MF. (2) Postural Control Performance A balance evaluation system (PRO-KIN Version, PK252P, TecnoBody, Italy) was used in this study to assess the postural control performance of participants with cLBP in an upright standing position. The sample frequency was set at 50Hz. Prior to the data collection, the detailed information about the evaluation of balance was provided for participants and any questions were answered. An individual account was established for each participant to enter the information about age, height, and weight, so as to calibrate the system for standardization. Participants were instructed to stand barefoot on the firm, stable surface of the balance system, with their arms naturally placed at either sides of the body. There were several orientation lines to guide each participant to place their feet at an angle of approximately 30 degrees to the sagittal plane, and their heels were kept apart with shoulder width. Then, participants were required to stand within the system for 1 minute for familiarization. After the familiarization, a 1-minute mandatory rest was provided for each participant. There were two different standing tasks (double-leg stance with eye-open (EO) and eye-close (EC)), and each task was repeated for three times to decrease measuring error. Hence, a total of six standing trials were randomly assigned to each participants. Each standing trial lasted 30 seconds. During an EO trial, participants were instructed to maintain standing balance with their eyes looking forward horizontally after receiving a signal from the examiner. For the EC trial, participants were required to maintain an upright standing posture but keeping their eyes closed during the data collection. A 1-minute mandatory rest was provided between two trials to wash out the learning effect [ 32 ]. The details of the evaluation process referred to our previous publication [ 16 ]. A safety lanyard connected with the balance system was used for participants’ safety. Participants were allowed to open their eyes or hold the handrail if they felt unstable during a trial. In the present study, outcomes of interest for postural control performance included the average displacement velocity of COP in the anterior-posterior (AP) and medial-lateral (ML) directions, the variability (standard deviation) of COP displacement in the AP and ML directions, the displacement area of COP, and the path length of COP (the total length of COP trajectory during the 30-second trial) [ 14 ]. The man values of repeated measurements were used for data analysis. (3) Questionnaire Assessment In this study, to understand alterations in the pain intensity and LBP-related disability, participants in two groups were assisted to complete the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Roland-Morris Disability Questionnaire (RDQ) before and after the 4-week intervention. VAS was a commonly-used clinical tool to measure the self-reported pain intensity, which required participants to place a marker on a 10-cm-long straight line to represent the intensity of pain they felt [ 33 ]. In this straight line, the left ending (0cm) indicated no pain and the right ending (10cm) indicated the worst pain. In this study, the LBP-related disability was evaluated by ODI and RDQ. ODI included 10 items in total, and each item was measured by a 6-level ordinal scale ranging from the best (scored as 0) to worst scenario (scored as 5) [ 34 , 35 ]. ODI covered activities of daily living (ADL) that may be disrupted by LBP and had been proven as an appropriate instrument with good reliability and validity for the assessment of functional status of patients with cLBP [ 34 , 35 ]. Also, RDQ was a self-rated assessment of ADL function for patients with LBP. There were 24 Yes/No questions to evaluate the ADL-related disability due to LBP [ 36 , 37 ]. In comparison to ODI, RDQ had the advantages of ease of use and follow-up [ 36 ]. For all three questionnaires, a higher score indicated a greater level of pain intensity and LBP-related disability due to LBP. Statistical Analysis Statistical analysis was performed using SPSS 25.0 (IBM Corporation, Armond, NY, USA). Continuous data were presented as the mean ± standard deviation according to normal distribution. The Shapiro-Wilk normality test and Levene test were used to measure the normality and homogeneity of variance of each dependent variable respectively. If the p -value was greater than 0.05, independent-sample t- test was applied to identify any significant differences between participants with cLBP in two groups before the intervention. Two-way repeated measures ANOVA was applied to investigate the interaction between the effect of DNS training and the time effect. If the p -value was less than 0.05, the Mann-Whitney U -test and the Friedmann's test were performed. Chi-square test was used to compare the sex distribution of two groups. The significance level was set at 0.05. Results Demographic Characteristics of Participants A total of 60 patients with cLBP were recruited in this study and randomly allocated to DNS group (n = 30) and control group (n = 30). Participants in each group accomplished the DNS training or conventional core exercises for 4 weeks. There was no participant in two groups dropped out during the entire intervention period. Demographic characteristics of all participants were illustrated in Table 1 . There was no statistical difference between participants in two groups regarding sex ( p = 0.766), age ( p = 0.383), height ( p = 0.170), weight ( p = 0.749), and body mass index ( p = 0.165). At baseline, the outcomes of interest from participants in both groups showed no significant difference ( p > 0.05). Table 1 Demographic information for participants with chronic low back pain (mean ± standard deviation) DNS group (n = 30) Control group (n = 30) t / χ 2 p -value Gender (male/female) 8/22 7/23 0.089 0.766 Age (years) 39.23 ± 8.44 37.43 ± 7.38 0.880 0.383 Height (cm) 165.25 ± 9.02 162.43 ± 6.50 1.338 0.170 Weight (kg) 60.45 ± 10.47 61.30 ± 9.97 -0.322 0.749 Body mass index (kg/m 2 ) 22.19 ± 2.59 23.13 ± 2.59 -1.406 0.165 DNS = dynamic neuromuscular stabilization. Differences in the Percent Change of Core Muscles of Participants in DNS and Control Groups As shown in Fig. 5 , significant interactions between the effect of DNS training and the time effect were observed in left TrA (F 1,58 =4.820, p = 0.032), right TrA (F 1,58 =3.964, p = 0.041), and diaphragm (F 1,58 =11.945, p = 0.001). Post hoc comparisons indicated that after the intervention period, patients with cLBP in the DNS group demonstrated significantly higher percent change of left TrA ( p = 0.001), right TrA ( p = 0.031), and diaphragm ( p = 0.002) than those who received 4-week conventional core exercises. No significant difference appeared on the percent change of left and right MF ( p > 0.05). Differences in the Postural Control Performance of Participants in DNS and Control Groups In the eye-open condition, there was no significant interaction between the effect of DNS training and the time effect observed in all COP variables ( p > 0.05) (Fig. 6 ). Patients with cLBP in two groups demonstrated no significant difference on all COP variables before and after the intervention ( p > 0.05). However, significant time effects were observed in COP velocity in the AP direction ( p = 0.038 for DNS group; p = 0.042 for control group), COP variability in the AP direction ( p = 0.033 for DNS group), and COP path length ( p = 0.040 for DNS group; p = 0.045 for control group). As shown in Fig. 7 , in the eye-close condition, significant interaction between the effect of DNS training and the time effect was observed in COP velocity (F 1,58 =5.283, p = 0.025) and variability (F 1,58 =13.189, p = 0.001) in the AP direction, COP path length (F 1,58 =6.395, p = 0.014), and COP area (F 1,58 =5.038, p = 0.029). After the 4-week intervention, patients with cLBP in the DNS group showed significantly lower COP velocity in the AP direction ( p = 0.025), COP variability in the AP direction ( p = 0.004), COP path length ( p = 0.005), and COP area ( p = 0.001) than those in the control group. However, there was no significant interaction observed in COP velocity and variability in the ML direction ( p > 0.05). Differences in the Questionnaire Evaluation of Participants in DNS and Control Groups As shown in Fig. 8 , no significant interaction between the effect of DNS training and the time effect was observed in scores of VAS, RDQ, and ODI ( p > 0.05). Patients with cLBP in two groups demonstrated no significant difference on scores of all three questionnaires before and after the intervention ( p > 0.05). However, significant time effect was observed that the scores of VAS, RDQ, and ODI significantly decreased after 4-week intervention in both DNS and control groups ( p < 0.05). Discussion The present study investigated the effectiveness of the DNS training on the contractility of core muscles, postural control performance, pain intensity and the LBP-related disability in patients with cLBP after the 4-week intervention. The results partially agreed with our hypotheses that the DNS training significantly increased the percent change of TrA and diaphragm, and decreased the COP displacement in the eye-close condition compared to conventional core exercises. However, the DNS training demonstrated the similar effect on decreasing pain intensity and the LBP-related disability as conventional core exercises. The DNS training further enhanced the contractility of TrA and diaphragm than conventional core exercises In the present study, participants with cLBP in both DNS and control groups demonstrated significantly increased percent change of TrA after 4-week intervention, and there were significant differences on the percent change of TrA between two groups post-intervention. Our results indicated that in comparison to conventional core exercises, the DNS training demonstrated a better effect on increasing the contractility of TrA of patients with cLBP, which was consistent with previous studies [ 12 , 18 ]. According to previously published studies, TrA played an important role in maintaining the core stability and the proprioceptive perception of lumbar area [ 12 ]. The effective contraction of TrA managed the intra-abdominal pressure and the spinal stability during an upright standing position [ 38 ]. A potential mechanism about cLBP suggested that the progression of cLBP might be due to the lack of core stability, which further induced the impaired postural control [ 17 ]. Hence, based on our results, it was effective to apply the 4-week DNS training to enhance the contractility of TrA in patients with cLBP, so as to improve their postural control performance. However, it should be mentioned that this conclusion could be controversial. Park et al. [ 39 ] found that there was no significant difference on the thickness of TrA in young patients with cLBP after the 4-week conventional core exercises. A possible explanation involved that a short-term conventional core exercises might be insufficient to induce significant changes in the morphology of TrA. The improvement of core stability after the 4-week intervention should attribute to the enhancement of contractility of TrA. Therefore, we speculated that the DNS training may promote the recruitment of muscle fibers of TrA during maintaining a standing posture. In other words, the 4-week DNS training improved the efficiency of TrA, so that TrA could effectively contract to provide necessary core stability when maintaining a standing position. Also, the measurement of percent change might be a better indicator than the assessment of muscle thickness to evaluate the short-term effect of the DNS training on core muscles. Furthermore, the present study also evaluated the contractility of diaphragm of patients with cLBP in two groups before and after the 4-week intervention. However, previous clinical trials involving patients with cLBP did not pay much attention to the measurement of diaphragm [ 12 , 18 , 38 ]. As diaphragm was one of important core muscles that maintained core stability during standing tasks, investigating how exercise intervention affected the contractility of diaphragm was necessary to comprehensively evaluate the alterations of core stability and postural control performance in patients with cLBP. Our results showed that patients in the DNS group demonstrated significantly higher percent change of diaphragm than those in the control group, indicating that the DNS training could further improve the contractility of diaphragm compared to conventional core exercises. Increased contractility of diaphragm might attribute to the first DNS principle that participants were instructed to utilize the abdominal respiration to maintain an appropriate intra-abdominal pressure during the DNS training, which further enhanced the participation of diaphragm than conventional core exercises [ 22 ]. Therefore, in comparison to conventional core exercises, the DNS training could demonstrate a better effect on promoting diaphragm [ 40 ]. To our best knowledge, the present study was the first one that investigated the effectiveness of the DNS training on the diaphragmatic function in patients with cLBP. A previous study from Son et al. [ 41 ] applied the DNS training on patients with cerebral palsy and found that the 4-week DNS training significantly improved the activation of diaphragm and its movement, as well as the postural control performance in a standing position. Combined with results of the present study, the DNS training was promising, effective intervention for facilitating the contractility of core muscles, thereby enhancing the core stability in patients with cLBP. The DNS training improved the standing postural control of patients with cLBP in the eye-close condition According to the results of this study, after the 4-week intervention, significant difference on COP-related variables between two groups was observed only in the eye-close condition. Our results indicated that the DNS training significantly improved the standing postural control of patients with cLBP via decreasing COP sway, especially in the AP direction, than conventional core exercises when there was a lack of visual feedback. The non-significant difference in the eye-open condition could be interpreted as the compensatory effects of vision via the sensory reweighting theory [ 42 ]. The availability and accuracy of sensory inputs from proprioceptive, visual, and vestibular systems play important roles in maintaining postural control [ 43 ]. When one source of sensory inputs was impaired, other intact sensory systems would be more weighted to compensate for the reduced sensory inputs [ 42 ]. Thereby, the maintenance of postural control in a standing position depended on the level of reliability of each sensory system. In this study, although the proprioceptive perception of patients with cLBP was impaired, the intact visual feedback could compensate for the decreased proprioceptive feedback to maintain a good standing posture in the eye-open condition [ 12 ]. In other words, the eye-open condition might be not a good method to distinguish the effect of different interventions on the proprioceptive perception in patients with cLBP because of the compensatory effect of vision. However, when visual inputs were blocked (the eye-close condition), participants with cLBP had no choice but relying on the proprioceptive feedback more to maintain postural control as their brain automatically allocated fewer sensory weights to the visual system. Therefore, the significantly smaller COP sway of participants in the DNS group after the 4-week intervention suggested that the DNS training may demonstrate a better effect on improving the standing postural control of patients with cLBP than conventional core exercises by further facilitating the proprioceptive perception of lumbar area [ 18 ]. Furthermore, a previous study showed that patients with cLBP prioritized postural stability in the AP direction to maintain balance [ 44 ]. In this study, significantly decreased COP velocity and variability in the AP direction but not ML direction indicated that the DNS training improved the standing postural control of patients with cLBP in the AP direction by promoting the spinal stability in the sagittal plane (the second DNS principle) [ 22 ]. In summary, the DNS training might be a better approach than conventional core exercises to facilitate the standing postural control of patients with cLBP in the clinical practice for musculoskeletal rehabilitation. The DNS training demonstrated similar effects on pain intensity and LBP-related disability to conventional core exercises In the present study, although there was no significant difference on the results of clinical questionnaires between two groups, participants in two groups demonstrated significantly decreased scores of VAS, ODI, and RDQ after the 4-week intervention. Our results were consistent with previous studies, indicating that the DNS training demonstrated similar effects on decreasing pain intensity and LBP-related disability to conventional core exercises [ 18 , 19 , 45 ]. Non-significant difference between the DNS training and conventional core exercises might involve following two explanations. On one hand, the 4-week intervention may be not long enough to induce the superior effect of the DNS training on the pain intensity and LBP-related disability of patients with cLBP. We suggested that a longer intervention period plus a follow-up period would be better to investigate the long-term effectiveness of the DNS training on patients with cLBP in the future study. On the other hand, participants recruited in the present study were young and middle-aged patients with mild-to-moderate pain and LBP-related disability. Thus, there might be the ceiling effect when participants in two groups were evaluated by the above-mentioned questionnaires, which had been verified by Sandal et al. [ 46 ]. Another study from Ge et al. [ 12 ] which recruited older patients with cLBP showed a significant difference on scores of VAS and ODI between two groups after the intervention. It was worth noting that participants with cLBP demonstrated higher scores of VAS and ODI (moderate-to-severe pain and LBP-related disability) before the intervention in their study [ 12 ]. According to the results of this study, the DNS training demonstrated similar effects on pain intensity and LBP-related disability of patients with cLBP to conventional core exercises. Limitations Several limitations should be taken into consideration in the present study. Firstly, only 60 patients with cLBP were enrolled in this randomized controlled trial. Nevertheless, based on the Partial Eta Squared method, the effect size of this study was moderate to large and the power could reach 80%, suggesting the practical significance of our findings. Secondly, there was a lack of follow-up period in this study. It still remained unknown about the long-term effect of the DNS training on patients with cLBP. Thirdly, this study only included young and middle-aged patients with cLBP. Whether the DNS training also demonstrated the positive effect on older patients with cLBP needed further research. Our team will attempt to investigate these important research questions in the near future. Conclusion The DNS training was a novel, effective treatment for patients with cLBP to enhance the percent change of TrA and diaphragm and reduce the body sway in standing. It also effectively reduces pain intensity and LBP-related disability of patients with cLBP. The potential mechanism of the DNS training might involve the improvement of contractility of core muscles and proprioceptive perception of lumbar area, so as to facilitate the postural control performance in an upright standing position. The DNS training might be a better choice as the exercise intervention for patients with cLBP in the clinical practice. Abbreviations cLBP Chronic low back pain YLDs Years lived with disability TrA Transversus abdominis MF Multifidus COP Center of pressure AP Anterior-posterior ML Medial-lateral DNS Dynamic neuromuscular stabilization VAS Visual analog scale ODI Oswestry Disability Index RDQ Roland-Morris Disability Questionnaire EO Eye-open EC Eye-close MVIC Maximum voluntary isometric contraction ADL Activities of daily living Declarations Acknowledgement We would like to thank all participants for their contribution to the study. We would like to sincerely thank the generosity of faculties at the Department of Rehabilitation Medicine at the First Affiliated Hospital, Sun Yat-sen University for supporting this research project. Consort This clinical trial adheres to the CONSORT guidelines. Authors’ Contributions H.J.H., G.F.Z. and H.L. conceived this study. W.W.X. and L.G. performed data collection and statistical analysis. H.J.H. and H.Y.X.drafted the manuscript. S.B.C., Y.K.Z. and C.H.W. revised the manuscript. All authors read and approved the final manuscript. Funding Statement The authors declare that the study was supported by the Shenzhen Science and Technology Program (JCYJ20210324134401004), Shenzhen Medical Research Fund (B2302002) and National Natural Science Foundation of China (82172532). Availability of data and materials The data used to support the findings of this study are available from the corresponding author upon reasonable request (Corresponding email; Hai Li, lihai2018 @smu. edu. cn). Ethical Approval The studies involving human participants were reviewed and approved by the Institutional Ethics Committee of the First Affiliated Hospital of Sun Yat-sen University (Ethical #: [2023] 324). All participants and respective guardians provided their written informed consent to participate in this study. Consent for publication All authors gave consent for publication. Competing interests The authors reported no conflicts of interest. Author details a Neurorehabilitation Laboratory, Department of Rehabilitation Medicine, Shenzhen Hospital, Southern Medical University, Shenzhen 518101, China. b Department of Rehabilitation Medicine, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China. c Department of Rehabilitation Medicine, Guangzhou First People’s Hospital, School of Medicine, South China University of Technology, Guangzhou 510080, China. d Department of Rehabilitation Medicine, Shenzhen University General Hospital, Shenzhen 518101, China. 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The effect of horse simulator riding on visual analogue scale, body composition and trunk strength in the patients with chronic low back pain. Int J Clin Pract. 2014;68(8):941–9. Koc M, Bayar B, Bayar K. A comparison of back pain functional scale with Roland Morris disability questionnaire, Oswestry disability index, and short form 36-health survey. Spine (Phila Pa 1976). 2018;43(12):877–82. Edelen MO, Rodriguez A, Herman P, et al. Crosswalking the Patient-Reported Outcomes Measurement Information System Physical Function, Pain Interference, and Pain Intensity Scores to the Roland-Morris Disability Questionnaire and the Oswestry Disability Index. Arch Phys Med Rehabil. 2021;102(7):1317–23. Roland M, Fairbank J. The Roland-Morris disability questionnaire and the Oswestry disability questionnaire. Spine (Phila Pa 1976). 2000;25(24):3115–24. Yamato TP, Maher CG, Saragiotto BT, et al. The Roland-Morris disability questionnaire: one or more dimensions? Eur Spine J. 2017;26(2):301–8. Kong YS, Lee WJ, Park S, et al. The effects of prone bridge exercise on trunk muscle thickness in chronic low back pain patients. J Phys Ther Sci. 2015;27(7):2073–6. Park SD, Yu SH. The effects of abdominal draw-in maneuver and core exercise on abdominal muscle thickness and Oswestry disability index in subjects with chronic low back pain. J Exerc Rehabil. 2013;9(2):286–91. Nezhad FF, Daryabor A, Abedi M, et al. Effect of dynamic neuromuscular stabilization and Vojta therapy on respiratory complications in neuromuscular diseases: A literature review. J Chiropr Med. 2023;22(3):212–21. Son MS, Jung DH, You J, et al. Effects of dynamic neuromuscular stabilization on diaphragm movement, postural control, balance and gait performance in cerebral palsy. NeuroRehabilitation. 2017;41(4):739–46. Xie H, Song H, Schmidt C, et al. The effect of mechanical vibration-based stimulation on dynamic balance control and gait characteristics in healthy young and older adults: A systematic review of cross-sectional study. Gait Posture. 2023;102:18–38. Peterka RJ. Sensorimotor integration in human postural control. J Neurophysiol. 2002;88(3):1097–118. Porter S, Nantel J. Older adults prioritize postural stability in the anterior-posterior direction to regain balance following volitional lateral step. Gait Posture. 2015;41(2):666–9. Hlaing SS, Puntumetakul R, Khine EE, et al. Effects of core stabilization exercise and strengthening exercise on proprioception, balance, muscle thickness and pain-related outcomes in patients with subacute nonspecific low back pain: A randomized controlled trial. BMC Musculoskelet Disord. 2021;22(1):998. Sandal D, Jindal R, Gupta S, et al. Reliability and validity of Punjabi version of Oswestry disability index in patients with mechanical low back pain. J Clin Orthop Trauma. 2021;13:163–8. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 01 Mar, 2025 Read the published version in BMC Musculoskeletal Disorders → Version 1 posted Editorial decision: Revision requested 30 Sep, 2024 Editor assigned by journal 28 Sep, 2024 Submission checks completed at journal 28 Sep, 2024 First submitted to journal 24 Sep, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5146743","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":360456254,"identity":"65860448-cd3d-48f8-bd6f-070a17bab468","order_by":0,"name":"Huanjie Huang","email":"","orcid":"","institution":"Neurorehabilitation Laboratory, Department of Rehabilitation Medicine, Shenzhen Hospital, Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Huanjie","middleName":"","lastName":"Huang","suffix":""},{"id":360456255,"identity":"1181345e-5c14-4c8e-829e-c5fcd500c645","order_by":1,"name":"Haoyu 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16:38:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5146743/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5146743/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12891-025-08417-1","type":"published","date":"2025-03-01T15:56:59+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":72415672,"identity":"16c18930-ec68-4251-afdb-53ed5703f4e9","added_by":"auto","created_at":"2024-12-26 20:29:20","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":46495,"visible":true,"origin":"","legend":"\u003cp\u003eCONSORT flow diagram for this study.\u003c/p\u003e","description":"","filename":"OnlineFigure1.png","url":"https://assets-eu.researchsquare.com/files/rs-5146743/v1/09b3e309bcd4a22a4951e881.png"},{"id":72415674,"identity":"d90e95a1-07dd-4941-a784-3c819a5a267d","added_by":"auto","created_at":"2024-12-26 20:29:20","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1038749,"visible":true,"origin":"","legend":"\u003cp\u003eDiagram of the dynamic neuromuscular stabilization (DNS) training. (A): supine diaphragmatic breathing; (B): the dead-bug exercise; (C): side-lying rolling; (D): the bear-crawl exercise; (E): high side plank; (F): the kneeling-sitting transfer.\u003c/p\u003e","description":"","filename":"Figure23.png","url":"https://assets-eu.researchsquare.com/files/rs-5146743/v1/b4fbcadfab7e5857294c040a.png"},{"id":72416399,"identity":"e34bc9e6-e90f-4bc1-b73a-a8059c271c60","added_by":"auto","created_at":"2024-12-26 20:45:20","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1029338,"visible":true,"origin":"","legend":"\u003cp\u003eDiagram of the general exercise training for chronic low back pain (cLBP). (A): single leg-bridge; (B): double leg-bridge; (C): side bridge; (D): crunch; (E): prone plank; (F): the bird-dog exercise.\u003c/p\u003e","description":"","filename":"Figure34.png","url":"https://assets-eu.researchsquare.com/files/rs-5146743/v1/fb78c8f25822ef09b6ba9cc7.png"},{"id":72415673,"identity":"01add7e8-abe7-4a6d-a353-7bece157cafd","added_by":"auto","created_at":"2024-12-26 20:29:20","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":237493,"visible":true,"origin":"","legend":"\u003cp\u003eAn example of ultrasound images of core muscles at the rest and the maximum voluntary isometric contraction (MVIC) states.(A): transversus abdominis (TrA); (B): diaphragm; (C): lumbar multifidus (MF).\u003c/p\u003e","description":"","filename":"OnlineFigure4.png","url":"https://assets-eu.researchsquare.com/files/rs-5146743/v1/05c10bc6390c5ea117b63ad8.png"},{"id":72416100,"identity":"4907e4ba-1b27-4bc3-a0ac-0a0f06bd1691","added_by":"auto","created_at":"2024-12-26 20:37:20","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":438832,"visible":true,"origin":"","legend":"\u003cp\u003eThe percentage change of core muscles before and after interventions for patients with chronic low back pain in dynamic neuromuscular stabilization (DNS) and control groups. * indicates the significant difference between DNS and control groups after the intervention (p\u0026lt;0.05). TrA , transversus abdominis; MF, multifidus.\u003c/p\u003e","description":"","filename":"OnlineFigure5.png","url":"https://assets-eu.researchsquare.com/files/rs-5146743/v1/db3cca5cdb3442ce0dd7a1c4.png"},{"id":72415677,"identity":"c2c6e253-9b06-4190-a7cf-bbdbad11cf3a","added_by":"auto","created_at":"2024-12-26 20:29:20","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":509348,"visible":true,"origin":"","legend":"\u003cp\u003ePostural control performance in the eye-open condition before and after interventions for patients with chronic low back pain in dynamic neuromuscular stabilization (DNS) and control groups. No significant difference was observed between DNS and control groups before and after the intervention (p\u0026lt;0.05). AP, \u0026nbsp;anterior-posterior direction; COP, center of pressure; ML, medial-lateral direction.\u003c/p\u003e","description":"","filename":"OnlineFigure6.png","url":"https://assets-eu.researchsquare.com/files/rs-5146743/v1/55dad65a37acd35b19af4c4f.png"},{"id":72416548,"identity":"6e003602-7c3b-48bc-be3e-eea3f51564b9","added_by":"auto","created_at":"2024-12-26 20:53:20","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":536538,"visible":true,"origin":"","legend":"\u003cp\u003ePostural control performance in the eye-close condition before and after interventions for patients with chronic low back pain in dynamic neuromuscular stabilization (DNS) and control groups. * indicates the significant difference between DNS and control groups after the intervention (p\u0026lt;0.05). AP, anterior-posterior direction; COP, center of pressure; ML, medial-lateral direction.\u003c/p\u003e","description":"","filename":"OnlineFigure7.png","url":"https://assets-eu.researchsquare.com/files/rs-5146743/v1/cb41106934af3acb4e93dae7.png"},{"id":72416102,"identity":"fd8fe718-5d76-4c67-a519-89e7ee1bbddb","added_by":"auto","created_at":"2024-12-26 20:37:20","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":270028,"visible":true,"origin":"","legend":"\u003cp\u003eResults of clinical questionnaires for patients with chronic low back pain in dynamic neuromuscular stabilization (DNS) and control groups. No significant difference was observed between DNS and control groups before and after the intervention (p\u0026gt;0.05). VAS, Visual Analogue Scale; RDQ, Roland Morris Disability Questionnaire; ODI, Oswestry Disability Index.\u003c/p\u003e","description":"","filename":"OnlineFigure8.png","url":"https://assets-eu.researchsquare.com/files/rs-5146743/v1/07f0328480a84814bce9ca07.png"},{"id":77622430,"identity":"3a8ae5be-f44e-4fe2-9381-ad0ba6b1ae16","added_by":"auto","created_at":"2025-03-03 16:06:28","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6803354,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5146743/v1/2e423598-c4a7-45eb-82d5-f3370204f479.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effects of Dynamic Neuromuscular Stabilization Training on the Core Muscle Contractility and Standing Postural Control in Patients with Chronic Low Back Pain: A Randomized Controlled Trial","fulltext":[{"header":"Background","content":"\u003cp\u003eChronic low back pain (cLBP) is one of the most common musculoskeletal disorder with the lifetime prevalence of 13.1\u0026ndash;20.3%, according to the latest epidemiological survey [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Since 1990, the worldwide number of patients with cLBP has dramatically increased from 0.37\u0026nbsp;billion to 0.57\u0026nbsp;billion, leading to an increase in years lived with disability (YLDs) for people [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. cLBP has a profound impact on patients' lives, families, and work [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Moderate medical evidence suggests that core stability exercises may be an effective treatment for cLBP compared to no treatment, usual care, or placebo for pain [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Although there have been some advances in the assessment and treatment of cLBP in recent years, the clinical efficacy are still unsatisfactory [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The major symptom of cLBP is persistent, intractable pain located at lumbosacral area. Patients with cLBP commonly exhibit atrophy of the core muscle and increased fat infiltration [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. In response to pain, they may alter the activation sequence of trunk muscles and the excitability of the motor cortex [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Prolonged compensatory mechanisms may eventually lead to core muscle atrophy. Additionally, patients with cLBP often suffer from impaired postural control, significantly impacting their activities of daily living [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the clinical setting, posturography, a non-invasive specialized clinical assessment technique, is widely used to assess the postural control performance, which addresses the lack of reliable clinical tests for assessing posture or balance-related disorders [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Postural control is usually quantified by recording the trajectory of the center of pressure (COP) using force platforms when humans maintain an upright, quiet standing position. The COP trajectory tracks the point of application of ground reaction forces resultant under the feet. Based on the COP trajectory, multiple variables, such as COP displacement speed and area, can be obtained to analyze its one-dimensional variations in the anterior-posterior (AP) and medial-lateral (ML) directions [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The measurement of COP-related variables has been identified as a quantitative, objective method to accurately evaluate the postural control of patients with cLBP in comparison to traditional balance tests or questionnaires [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. According to published studies, patients with cLBP usually demonstrate a significantly increased COP sway and larger displacement compared to healthy populations, especially in the AP direction, indicating a poor postural control [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Wang et al. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] assess the postural control performance and the thickness of core muscles (bilateral transversus abdominis (TrA) and lumbar multifidus (MF)) in patients with cLBP and healthy controls. Their results show that the existence of cLBP leads to the significantly decreased thickness of TrA, larger path length and sway area of COP trajectory [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Therefore, the impaired postural control in patients with cLBP might be related to the contractility of core muscles. Panjabi proposes that the postural control impairment is attributed to a deficiency in core stability, which is defined as the ability to maintain a stable spinal position via the co-contraction of core muscles [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Multiple studies suggest that conventional core exercise is able to specifically intensify the contractility of core muscles and improve postural control of patients with cLBP [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. However, a common limitation in above-mentioned studies is the neglect of the diaphragm, which serves as one of the core muscles and the most vital respiratory muscle. A published review indicates that the normal contraction of diaphragm also plays a significant role in the core stability of patients with cLBP [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Another study evaluates the dynamics of diaphragm in patients with cLBP via magnetic resonance imaging. It reveals significantly smaller diaphragm excursions in a postural control task, suggesting a decreased coordination capacity of diaphragm in patients with cLBP [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. However, current conventional core exercise do not prioritize the maintenance of a rhythmic breathing pattern, leading to inadequate training of the diaphragm for optimal contribution to core stability [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Hence, an updated exercise protocol that specifically targets the diaphragm might be superior to improve the postural control of patients with cLBP.\u003c/p\u003e \u003cp\u003eDynamic neuromuscular stabilization (DNS) is a novel functional approach based on the developmental kinesiological models. This method treat motor-related disorders by utilizing infant motor development process [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The DNS training achieves optimal, global body function in a neutral alignment of head and spine via integrating postural awareness, precise breathing pattern, and motor control [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The DNS training emphasizes the coordination of all body segments to maintain a functionally centered position and perform precise muscle contraction simultaneously for breathing and postural control. Therefore, the ultimate objective of the DNS training is to activate appropriate respiratory and postural muscles (core muscles) to maintain core stability in any positions or during all locomotor tasks [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. In comparison to conventional core exercises, the DNS training has been proven as effective in improving the breathing pattern, increasing lumbar stability and intra-abdominal pressure [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The application of DNS training on patients with cLBP is still limited. A recent randomized controlled trail conducts a 6-week DNS training in obsess postpartum females with cLBP and finds that the DNS training demonstrates a better effect on improving pain intensity, the LBP-related disability, and respiratory function based on the evaluation of multiple clinical questionnaires [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. However, the effects of DNS training on the contractility of core muscles and postural control in patients with cLBP still remains unclear when evaluated using quantitative assessment methods.\u003c/p\u003e \u003cp\u003eTherefore, the present study aimed to investigate the effects of the DNS training on the contractility of core muscles, the postural control performance, pain intensity, and the LBP-related disability in patients with cLBP. We hypothesized that in comparison to conventional core exercises, the DNS training was superior to improve the above-mentioned indictors in patients with cLBP. This study may provide new ideas and evidence for the treatment for cLBP and the clinical application of the DNS training as updated rehabilitation protocols.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design\u003c/h2\u003e \u003cp\u003eThis was a randomized controlled trial with single-blinded parallel groups of patients with cLBP. The details of the recruiting process were illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. A specific research responsible for the clinical assessment of participants and experienced physical therapists who assisted participants to complete the intervention were blinded to the allocation of each participant. A series of random numbers was generated using the statistical software (IBM SPSS 25.0) to randomly assign participants to either the DNS group or control group.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e This study was carried out under the regulation of and upon approval by the Institutional Ethics Committee of the First Affiliated Hospital of Sun Yat-sen University (IRB# [2023] 324). The written informed consent was obtained from each participant at the day of inclusion, and detailed information about this study was also provided. Participants were free to withdraw from the study at any time without providing a reason. The Declaration of Helsinki was strictly followed throughout the course of the study.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eParticipants and Sample Size Calculation\u003c/h3\u003e\n\u003cp\u003ePatients with cLBP were recruited between May 2023 and February 2024 from the Department of Rehabilitation Medicine, the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China. At the day of recruitment, each participant was subjected to a clinical evaluation by an experienced physician, and their medical history was reviewed in detail.\u003c/p\u003e \u003cp\u003eThe inclusion criteria were as follow: 1) diagnosed as non-specific LBP with pain persisting for more than 3 months according to the diagnostic guidelines from the American College of Physicians and the American Pain Society [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]; 2) aged between 18 and 60 years; 3) visual analog scale (VAS)\u0026thinsp;\u0026ge;\u0026thinsp;3cm; 4) body mass index\u0026thinsp;\u0026le;\u0026thinsp;28kg/m\u003csup\u003e2\u003c/sup\u003e; 5) intact psychological and cognitive function to complete the experiment. Participants were excluded if they had any of the following: 1) previous back surgery, spinal tumors, deformities or infections; 2) LBP of traumatic or structural origins or LBP with neurological symptoms (e.g., radiating pain or numbness in the lower extremities); 3) previous neurological and/or cardiopulmonary diseases that severely affected locomotor performance (e.g., stroke, Parkinson\u0026rsquo;s disease, and chronic obstructive pulmonary disease); 4) pregnancy.\u003c/p\u003e \u003cp\u003eThe determination of sample size was based on a previous publication [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] via the computation of power analysis through G*power (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://www.gpower.hhu.de/\u003c/span\u003e\u003cspan address=\"http://www.gpower.hhu.de/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). Based on their study, recruitment of 34 participants would generate a power of 80% and a level of significance of 5% (two-sided) for detecting a true difference. According to the Partial Eta Squared method, the η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.138 as the large effect size was used to calculate the effect size \u003cem\u003ef\u003c/em\u003e [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Therefore, with the calculated effect size \u003cem\u003ef\u003c/em\u003e as 0.4 and the potential drop-out rate of 15%, recruiting 57 patients with cLBP should be statistically sufficient for identifying the true difference in outcomes of interest.\u003c/p\u003e\n\u003ch3\u003eInterventions\u003c/h3\u003e\n\u003cp\u003eIn this study, participants in DNS and control groups were treated with a 4-week intervention. Following the health education about cLBP prior to the intervention period, there were a total of 12 training sessions for each participant (3 sessions per week). Each session lasted 50 minutes. Two experienced physical therapists assisted participants to complete the intervention. The study personnel were trained to implement study protocols in an effort to ensure standardization within and cross sites. When there was any intolerable increased pain or symptoms, the intervention would be terminated immediately and participants would be provided with sufficient rest or medical care if necessary. During the intervention, appropriate breaks were provided for participants to avoid excessive muscle fatigue. Participants were also allowed to request more rest according to their individual status and needs. If any participants did not accomplish the intervention, they would be treated as dropouts and be excluded in data analysis. Intervention protocols for participants in DNS and control groups were shown as follows.\u003c/p\u003e \u003cp\u003eFor participants in the DNS group, follow the stretching of muscles, there were 6 difference exercises in the DNS training, including the supine diaphragmatic breathing, the dead-bug exercise, the side-lying rolling, the bear-crawl exercise, high side plank and the kneeling-sitting transfer (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. According to the DNS approach, participants in the DNS groups were guided by oral feedback from an experienced physical therapist to follow three basic DNS principles, so as to assure a high quality of training [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Firstly, learning the abdominal respiration skills to maintain an appropriate intra-abdominal pressure during the DNS training. Secondly, maintaining the spinal stability in the sagittal plane to achieve good spinal alignment and curve. Thirdly, inducing the co-contraction of agonists and antagonists by specific positioning of joints. Each exercise was designed as 2 sets with 10 repetitions per set. A mandatory 2-minute break was assigned to every participant between each exercises.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eParticipants in the control group received conventional core exercises for cLBP, consisting of the stretching, single/double leg-bridge, side bridge, crunch, prone plank and the bird-dog exercises (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Participants were required to control their movements slow and steady, as well as keeping a natural, rhythmic breath to avoid the Valsalva maneuver. Each exercise was designed as 2 sets with 10 repetitions per set. A mandatory 2-minute break was assigned to every participant between each exercises.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eOutcome Measures\u003c/h3\u003e\n\u003cp\u003eIn the present study, each participant was evaluated by a specific researcher who was a professionally-trained physician blinded to the allocation of each participant before and after the 4-week intervention. Outcomes of interest included following three parts.\u003c/p\u003e\n\u003ch3\u003e(1) The Percent Change of Core Muscles Thickness\u003c/h3\u003e\n\u003cp\u003eIn this study, a diagnostic musculoskeletal ultrasound (SONIMAGE HS1, Konica Minolta Inc., Japan) with a linear transducer at 18.0MHz and a curvilinear transducer at 4.0MHz was used to measure the morphologic changes of core muscles (bilateral TrA and lumbar MF, and diaphragm) for each participant before and after the intervention. For each core muscle, thickness was measured at rest and during maximum voluntary isometric contraction (MVIC), with each measurement repeated three times. A 1-minute break was provided for participants among measurements of muscle thickness at MVIC state to avoid muscle fatigue. Considering the impact of different demographic characteristics (sex, age, weight, and height), the percent change of muscle thickness was used to measure the contractility of core muscles and ensure the comparability among different participants. The calculation of percent change of muscle thickness was based on the following formula [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e],\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:Percent\\:cℎange=\\frac{Tℎickness\\:\\left(MVIC\\right)-Tℎickness\\:\\left(Rest\\right)}{Tℎickness\\:\\left(Rest\\right)}\\times\\:100\\%$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThen, the average values of percent change of muscle thickness at different states for a participant were regarded as the final outcome to be used in data analysis. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e demonstrated an example of core muscle ultrasound image from a participant.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo measure unilateral TrA, participants were instructed to hold a supine hook-lying position with both arms crossing over their chest and knee flexing to 90 degrees. The linear transducer with B-mode was placed on the ipsilateral mid-axillary line at the level of umbilicus (just above the iliac crest). Following a deep inspiration and then a forced expiration, participants was required to keep breathing out and voluntarily relax their abdomen to record the thickness of TrA at the rest state, and the image of TrA was taken at the end of exhalation. Then, they were guided to perform the abdominal draw-in maneuver to measure the thickness of TrA at MVIC state [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. To more accurately measure it, participants were allowed to practice this maneuver before the data collection to correctly contract the TrA.\u003c/p\u003e \u003cp\u003e To measure the diaphragm, participants were required to keep the above-mentioned supine hook-lying position. The linear transducer with B-mode was placed on the intersection between the right anterior axillary line and the 7th or 8th intercostal space (depending on participants\u0026rsquo; body size) to record the longitudinal image of diaphragm [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Assessor adjusted the angle of transducer until obtaining the clear image of diaphragm and held this angle during the measurement. Participants were required to exhale as far as possible to reach maximum exhalation and record the thickness of diaphragm at the rest state. Then, they were instructed to inhale to reach total lung capacity and hold their breath to measure the thickness of diaphragm at MVIC state.\u003c/p\u003e \u003cp\u003eThe measurement of unilateral MF followed the procedure as follow. Firstly, participants kept a prone position on a therapy table with a pillow placed under their abdomen to flatten the lumbosacral curve. To measure lumbar MF at the L5/S1 level, the curvilinear transducer with B-mode was longitudinally positioned about 2cm lateral to the midline of the L5 spinal process, and medially angled to obtain the image of the ipsilateral L5/S1 zygapophyseal joint and MF at the rest state. Then, the thickness of MF at MVIC state was measured by participants lifting their contralateral arms 5cm off the table and holding at shoulder abduction of 120 degrees and elbow flexion of 90 degrees [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Assessor would also apply a downward force to the lifted elbow to better contract the target MF.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e(2) Postural Control Performance\u003c/h2\u003e \u003cp\u003eA balance evaluation system (PRO-KIN Version, PK252P, TecnoBody, Italy) was used in this study to assess the postural control performance of participants with cLBP in an upright standing position. The sample frequency was set at 50Hz. Prior to the data collection, the detailed information about the evaluation of balance was provided for participants and any questions were answered. An individual account was established for each participant to enter the information about age, height, and weight, so as to calibrate the system for standardization. Participants were instructed to stand barefoot on the firm, stable surface of the balance system, with their arms naturally placed at either sides of the body. There were several orientation lines to guide each participant to place their feet at an angle of approximately 30 degrees to the sagittal plane, and their heels were kept apart with shoulder width. Then, participants were required to stand within the system for 1 minute for familiarization. After the familiarization, a 1-minute mandatory rest was provided for each participant. There were two different standing tasks (double-leg stance with eye-open (EO) and eye-close (EC)), and each task was repeated for three times to decrease measuring error. Hence, a total of six standing trials were randomly assigned to each participants. Each standing trial lasted 30 seconds. During an EO trial, participants were instructed to maintain standing balance with their eyes looking forward horizontally after receiving a signal from the examiner. For the EC trial, participants were required to maintain an upright standing posture but keeping their eyes closed during the data collection. A 1-minute mandatory rest was provided between two trials to wash out the learning effect [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. The details of the evaluation process referred to our previous publication [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. A safety lanyard connected with the balance system was used for participants\u0026rsquo; safety. Participants were allowed to open their eyes or hold the handrail if they felt unstable during a trial.\u003c/p\u003e \u003cp\u003eIn the present study, outcomes of interest for postural control performance included the average displacement velocity of COP in the anterior-posterior (AP) and medial-lateral (ML) directions, the variability (standard deviation) of COP displacement in the AP and ML directions, the displacement area of COP, and the path length of COP (the total length of COP trajectory during the 30-second trial) [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The man values of repeated measurements were used for data analysis.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003e(3) Questionnaire Assessment\u003c/h3\u003e\n\u003cp\u003eIn this study, to understand alterations in the pain intensity and LBP-related disability, participants in two groups were assisted to complete the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Roland-Morris Disability Questionnaire (RDQ) before and after the 4-week intervention. VAS was a commonly-used clinical tool to measure the self-reported pain intensity, which required participants to place a marker on a 10-cm-long straight line to represent the intensity of pain they felt [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. In this straight line, the left ending (0cm) indicated no pain and the right ending (10cm) indicated the worst pain. In this study, the LBP-related disability was evaluated by ODI and RDQ. ODI included 10 items in total, and each item was measured by a 6-level ordinal scale ranging from the best (scored as 0) to worst scenario (scored as 5) [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. ODI covered activities of daily living (ADL) that may be disrupted by LBP and had been proven as an appropriate instrument with good reliability and validity for the assessment of functional status of patients with cLBP [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Also, RDQ was a self-rated assessment of ADL function for patients with LBP. There were 24 Yes/No questions to evaluate the ADL-related disability due to LBP [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. In comparison to ODI, RDQ had the advantages of ease of use and follow-up [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. For all three questionnaires, a higher score indicated a greater level of pain intensity and LBP-related disability due to LBP.\u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eStatistical analysis was performed using SPSS 25.0 (IBM Corporation, Armond, NY, USA). Continuous data were presented as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation according to normal distribution. The Shapiro-Wilk normality test and Levene test were used to measure the normality and homogeneity of variance of each dependent variable respectively. If the \u003cem\u003ep\u003c/em\u003e-value was greater than 0.05, independent-sample \u003cem\u003et-\u003c/em\u003etest was applied to identify any significant differences between participants with cLBP in two groups before the intervention. Two-way repeated measures ANOVA was applied to investigate the interaction between the effect of DNS training and the time effect. If the \u003cem\u003ep\u003c/em\u003e-value was less than 0.05, the Mann-Whitney \u003cem\u003eU\u003c/em\u003e-test and the Friedmann's test were performed. Chi-square test was used to compare the sex distribution of two groups. The significance level was set at 0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eDemographic Characteristics of Participants\u003c/h2\u003e \u003cp\u003eA total of 60 patients with cLBP were recruited in this study and randomly allocated to DNS group (n\u0026thinsp;=\u0026thinsp;30) and control group (n\u0026thinsp;=\u0026thinsp;30). Participants in each group accomplished the DNS training or conventional core exercises for 4 weeks. There was no participant in two groups dropped out during the entire intervention period. Demographic characteristics of all participants were illustrated in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There was no statistical difference between participants in two groups regarding sex (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.766), age (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.383), height (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.170), weight (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.749), and body mass index (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.165). At baseline, the outcomes of interest from participants in both groups showed no significant difference (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic information for participants with chronic low back pain (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDNS group\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eControl group\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et / χ\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender (male/female)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8/22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7/23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.089\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.766\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39.23\u0026thinsp;\u0026plusmn;\u0026thinsp;8.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.43\u0026thinsp;\u0026plusmn;\u0026thinsp;7.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.880\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.383\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e165.25\u0026thinsp;\u0026plusmn;\u0026thinsp;9.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e162.43\u0026thinsp;\u0026plusmn;\u0026thinsp;6.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.338\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.170\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight (kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60.45\u0026thinsp;\u0026plusmn;\u0026thinsp;10.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e61.30\u0026thinsp;\u0026plusmn;\u0026thinsp;9.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.322\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.749\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBody mass index (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22.19\u0026thinsp;\u0026plusmn;\u0026thinsp;2.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.13\u0026thinsp;\u0026plusmn;\u0026thinsp;2.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.406\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.165\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eDNS\u0026thinsp;=\u0026thinsp;dynamic neuromuscular stabilization.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eDifferences in the Percent Change of Core Muscles of Participants in DNS and Control Groups\u003c/h2\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, significant interactions between the effect of DNS training and the time effect were observed in left TrA (F\u003csub\u003e1,58\u003c/sub\u003e=4.820, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032), right TrA (F\u003csub\u003e1,58\u003c/sub\u003e=3.964, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.041), and diaphragm (F\u003csub\u003e1,58\u003c/sub\u003e=11.945, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001). \u003cem\u003ePost hoc\u003c/em\u003e comparisons indicated that after the intervention period, patients with cLBP in the DNS group demonstrated significantly higher percent change of left TrA (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001), right TrA (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.031), and diaphragm (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002) than those who received 4-week conventional core exercises. No significant difference appeared on the percent change of left and right MF (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eDifferences in the Postural Control Performance of Participants in DNS and Control Groups\u003c/h2\u003e \u003cp\u003eIn the eye-open condition, there was no significant interaction between the effect of DNS training and the time effect observed in all COP variables (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Patients with cLBP in two groups demonstrated no significant difference on all COP variables before and after the intervention (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, significant time effects were observed in COP velocity in the AP direction (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.038 for DNS group; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.042 for control group), COP variability in the AP direction (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.033 for DNS group), and COP path length (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.040 for DNS group; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.045 for control group).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, in the eye-close condition, significant interaction between the effect of DNS training and the time effect was observed in COP velocity (F\u003csub\u003e1,58\u003c/sub\u003e=5.283, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.025) and variability (F\u003csub\u003e1,58\u003c/sub\u003e=13.189, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001) in the AP direction, COP path length (F\u003csub\u003e1,58\u003c/sub\u003e=6.395, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014), and COP area (F\u003csub\u003e1,58\u003c/sub\u003e=5.038, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.029). After the 4-week intervention, patients with cLBP in the DNS group showed significantly lower COP velocity in the AP direction (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.025), COP variability in the AP direction (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004), COP path length (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005), and COP area (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001) than those in the control group. However, there was no significant interaction observed in COP velocity and variability in the ML direction (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eDifferences in the Questionnaire Evaluation of Participants in DNS and Control Groups\u003c/h2\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, no significant interaction between the effect of DNS training and the time effect was observed in scores of VAS, RDQ, and ODI (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Patients with cLBP in two groups demonstrated no significant difference on scores of all three questionnaires before and after the intervention (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, significant time effect was observed that the scores of VAS, RDQ, and ODI significantly decreased after 4-week intervention in both DNS and control groups (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe present study investigated the effectiveness of the DNS training on the contractility of core muscles, postural control performance, pain intensity and the LBP-related disability in patients with cLBP after the 4-week intervention. The results partially agreed with our hypotheses that the DNS training significantly increased the percent change of TrA and diaphragm, and decreased the COP displacement in the eye-close condition compared to conventional core exercises. However, the DNS training demonstrated the similar effect on decreasing pain intensity and the LBP-related disability as conventional core exercises.\u003c/p\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eThe DNS training further enhanced the contractility of TrA and diaphragm than conventional core exercises\u003c/h2\u003e \u003cp\u003eIn the present study, participants with cLBP in both DNS and control groups demonstrated significantly increased percent change of TrA after 4-week intervention, and there were significant differences on the percent change of TrA between two groups post-intervention. Our results indicated that in comparison to conventional core exercises, the DNS training demonstrated a better effect on increasing the contractility of TrA of patients with cLBP, which was consistent with previous studies [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. According to previously published studies, TrA played an important role in maintaining the core stability and the proprioceptive perception of lumbar area [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The effective contraction of TrA managed the intra-abdominal pressure and the spinal stability during an upright standing position [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. A potential mechanism about cLBP suggested that the progression of cLBP might be due to the lack of core stability, which further induced the impaired postural control [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Hence, based on our results, it was effective to apply the 4-week DNS training to enhance the contractility of TrA in patients with cLBP, so as to improve their postural control performance. However, it should be mentioned that this conclusion could be controversial. Park et al. [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e] found that there was no significant difference on the thickness of TrA in young patients with cLBP after the 4-week conventional core exercises. A possible explanation involved that a short-term conventional core exercises might be insufficient to induce significant changes in the morphology of TrA. The improvement of core stability after the 4-week intervention should attribute to the enhancement of contractility of TrA. Therefore, we speculated that the DNS training may promote the recruitment of muscle fibers of TrA during maintaining a standing posture. In other words, the 4-week DNS training improved the efficiency of TrA, so that TrA could effectively contract to provide necessary core stability when maintaining a standing position. Also, the measurement of percent change might be a better indicator than the assessment of muscle thickness to evaluate the short-term effect of the DNS training on core muscles.\u003c/p\u003e \u003cp\u003eFurthermore, the present study also evaluated the contractility of diaphragm of patients with cLBP in two groups before and after the 4-week intervention. However, previous clinical trials involving patients with cLBP did not pay much attention to the measurement of diaphragm [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. As diaphragm was one of important core muscles that maintained core stability during standing tasks, investigating how exercise intervention affected the contractility of diaphragm was necessary to comprehensively evaluate the alterations of core stability and postural control performance in patients with cLBP. Our results showed that patients in the DNS group demonstrated significantly higher percent change of diaphragm than those in the control group, indicating that the DNS training could further improve the contractility of diaphragm compared to conventional core exercises. Increased contractility of diaphragm might attribute to the first DNS principle that participants were instructed to utilize the abdominal respiration to maintain an appropriate intra-abdominal pressure during the DNS training, which further enhanced the participation of diaphragm than conventional core exercises [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Therefore, in comparison to conventional core exercises, the DNS training could demonstrate a better effect on promoting diaphragm [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. To our best knowledge, the present study was the first one that investigated the effectiveness of the DNS training on the diaphragmatic function in patients with cLBP. A previous study from Son et al. [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e] applied the DNS training on patients with cerebral palsy and found that the 4-week DNS training significantly improved the activation of diaphragm and its movement, as well as the postural control performance in a standing position. Combined with results of the present study, the DNS training was promising, effective intervention for facilitating the contractility of core muscles, thereby enhancing the core stability in patients with cLBP.\u003c/p\u003e \u003cp\u003e \u003cb\u003eThe DNS training improved the standing postural control of patients with cLBP in the eye-close condition\u003c/b\u003e \u003c/p\u003e \u003cp\u003eAccording to the results of this study, after the 4-week intervention, significant difference on COP-related variables between two groups was observed only in the eye-close condition. Our results indicated that the DNS training significantly improved the standing postural control of patients with cLBP via decreasing COP sway, especially in the AP direction, than conventional core exercises when there was a lack of visual feedback. The non-significant difference in the eye-open condition could be interpreted as the compensatory effects of vision via the sensory reweighting theory [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. The availability and accuracy of sensory inputs from proprioceptive, visual, and vestibular systems play important roles in maintaining postural control [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. When one source of sensory inputs was impaired, other intact sensory systems would be more weighted to compensate for the reduced sensory inputs [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. Thereby, the maintenance of postural control in a standing position depended on the level of reliability of each sensory system. In this study, although the proprioceptive perception of patients with cLBP was impaired, the intact visual feedback could compensate for the decreased proprioceptive feedback to maintain a good standing posture in the eye-open condition [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In other words, the eye-open condition might be not a good method to distinguish the effect of different interventions on the proprioceptive perception in patients with cLBP because of the compensatory effect of vision. However, when visual inputs were blocked (the eye-close condition), participants with cLBP had no choice but relying on the proprioceptive feedback more to maintain postural control as their brain automatically allocated fewer sensory weights to the visual system. Therefore, the significantly smaller COP sway of participants in the DNS group after the 4-week intervention suggested that the DNS training may demonstrate a better effect on improving the standing postural control of patients with cLBP than conventional core exercises by further facilitating the proprioceptive perception of lumbar area [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Furthermore, a previous study showed that patients with cLBP prioritized postural stability in the AP direction to maintain balance [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. In this study, significantly decreased COP velocity and variability in the AP direction but not ML direction indicated that the DNS training improved the standing postural control of patients with cLBP in the AP direction by promoting the spinal stability in the sagittal plane (the second DNS principle) [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. In summary, the DNS training might be a better approach than conventional core exercises to facilitate the standing postural control of patients with cLBP in the clinical practice for musculoskeletal rehabilitation.\u003c/p\u003e \u003cp\u003e \u003cb\u003eThe DNS training demonstrated similar effects on pain intensity and LBP-related disability to conventional core exercises\u003c/b\u003e \u003c/p\u003e \u003cp\u003eIn the present study, although there was no significant difference on the results of clinical questionnaires between two groups, participants in two groups demonstrated significantly decreased scores of VAS, ODI, and RDQ after the 4-week intervention. Our results were consistent with previous studies, indicating that the DNS training demonstrated similar effects on decreasing pain intensity and LBP-related disability to conventional core exercises [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. Non-significant difference between the DNS training and conventional core exercises might involve following two explanations. On one hand, the 4-week intervention may be not long enough to induce the superior effect of the DNS training on the pain intensity and LBP-related disability of patients with cLBP. We suggested that a longer intervention period plus a follow-up period would be better to investigate the long-term effectiveness of the DNS training on patients with cLBP in the future study. On the other hand, participants recruited in the present study were young and middle-aged patients with mild-to-moderate pain and LBP-related disability. Thus, there might be the ceiling effect when participants in two groups were evaluated by the above-mentioned questionnaires, which had been verified by Sandal et al. [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]. Another study from Ge et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] which recruited older patients with cLBP showed a significant difference on scores of VAS and ODI between two groups after the intervention. It was worth noting that participants with cLBP demonstrated higher scores of VAS and ODI (moderate-to-severe pain and LBP-related disability) before the intervention in their study [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. According to the results of this study, the DNS training demonstrated similar effects on pain intensity and LBP-related disability of patients with cLBP to conventional core exercises.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eSeveral limitations should be taken into consideration in the present study. Firstly, only 60 patients with cLBP were enrolled in this randomized controlled trial. Nevertheless, based on the Partial Eta Squared method, the effect size of this study was moderate to large and the power could reach 80%, suggesting the practical significance of our findings. Secondly, there was a lack of follow-up period in this study. It still remained unknown about the long-term effect of the DNS training on patients with cLBP. Thirdly, this study only included young and middle-aged patients with cLBP. Whether the DNS training also demonstrated the positive effect on older patients with cLBP needed further research. Our team will attempt to investigate these important research questions in the near future.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe DNS training was a novel, effective treatment for patients with cLBP to enhance the percent change of TrA and diaphragm and reduce the body sway in standing. It also effectively reduces pain intensity and LBP-related disability of patients with cLBP. The potential mechanism of the DNS training might involve the improvement of contractility of core muscles and proprioceptive perception of lumbar area, so as to facilitate the postural control performance in an upright standing position. The DNS training might be a better choice as the exercise intervention for patients with cLBP in the clinical practice.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003ecLBP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eChronic low back pain\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eYLDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eYears lived with disability\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eTrA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eTransversus abdominis\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eMF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eMultifidus\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eCOP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eCenter of pressure\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eAP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eAnterior-posterior\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eML\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eMedial-lateral\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eDNS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eDynamic neuromuscular stabilization\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eVAS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eVisual analog scale\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eODI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eOswestry Disability Index\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eRDQ\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eRoland-Morris Disability Questionnaire\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eEO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eEye-open\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eEC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eEye-close\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eMVIC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eMaximum voluntary isometric contraction\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003eADL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 315px;\"\u003e\n \u003cp\u003eActivities of daily living\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank all participants for their contribution to the study. We would like to sincerely thank the generosity of faculties at the Department of Rehabilitation Medicine at the First Affiliated Hospital, Sun Yat-sen University for supporting this research project.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsort\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis clinical trial adheres to the CONSORT guidelines.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eH.J.H., G.F.Z. and H.L. conceived this study. W.W.X. and L.G. performed data collection and statistical analysis. H.J.H. and H.Y.X.drafted the manuscript. S.B.C., Y.K.Z. and C.H.W. revised the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Statement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that the study was supported by the Shenzhen Science and Technology Program (JCYJ20210324134401004), Shenzhen Medical Research Fund (B2302002) and National Natural Science Foundation of China (82172532).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data used to support the findings of this study are available from the corresponding author upon reasonable request (Corresponding email; Hai Li, lihai2018 @smu. edu. cn).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe studies involving human participants were reviewed and approved by the Institutional Ethics Committee of the First Affiliated Hospital of Sun Yat-sen University (Ethical #: [2023] 324). All participants and respective guardians provided their written informed consent to participate in this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors gave consent for publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors reported no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor details\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003ea\u0026nbsp;\u003c/sup\u003eNeurorehabilitation Laboratory, Department of Rehabilitation Medicine, Shenzhen Hospital, Southern Medical University, Shenzhen 518101, China.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003eb\u0026nbsp;\u003c/sup\u003eDepartment of Rehabilitation Medicine, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003ec\u0026nbsp;\u003c/sup\u003eDepartment of Rehabilitation Medicine, Guangzhou First People\u0026rsquo;s Hospital, School of Medicine, South China University of Technology, Guangzhou 510080, China.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003ed\u0026nbsp;\u003c/sup\u003eDepartment of Rehabilitation Medicine, Shenzhen University General Hospital, Shenzhen 518101, China.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMaher C, Underwood M, Buchbinder R. 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The effect of mechanical vibration-based stimulation on dynamic balance control and gait characteristics in healthy young and older adults: A systematic review of cross-sectional study. Gait Posture. 2023;102:18\u0026ndash;38.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeterka RJ. Sensorimotor integration in human postural control. J Neurophysiol. 2002;88(3):1097\u0026ndash;118.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePorter S, Nantel J. Older adults prioritize postural stability in the anterior-posterior direction to regain balance following volitional lateral step. Gait Posture. 2015;41(2):666\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHlaing SS, Puntumetakul R, Khine EE, et al. Effects of core stabilization exercise and strengthening exercise on proprioception, balance, muscle thickness and pain-related outcomes in patients with subacute nonspecific low back pain: A randomized controlled trial. BMC Musculoskelet Disord. 2021;22(1):998.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSandal D, Jindal R, Gupta S, et al. Reliability and validity of Punjabi version of Oswestry disability index in patients with mechanical low back pain. J Clin Orthop Trauma. 2021;13:163\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Chronic low back pain, Dynamic neuromuscular stabilization, Core muscle, Postural control, Pain intensity, Disability","lastPublishedDoi":"10.21203/rs.3.rs-5146743/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5146743/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePatients with chronic low back pain (cLBP) usually demonstrated poor postural control due to impaired core muscle function. Dynamic neuromuscular stabilization (DNS) is based on developmental kinesiology principles, utilizing infant motor patterns to treat motor disorders. DNS has been shown to improve postural control in cerebral palsy patients by activating core muscle. Conventional core exercises were able to enhance core muscle contractility and postural control in cLBP patients. However, whether the DNS approach is superior for enhancing core muscle contractility and postural control in cLBP patients still remains unclear.\u003c/p\u003e\u003ch2\u003eObjectives\u003c/h2\u003e \u003cp\u003eThis study aimed to investigate the effects of DNS on core muscle contractility and standing postural control in cLBP patients.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eSixty cLBP patients were randomly assigned to a DNS group or a control group. Participants in the DNS group received DNS training, while those in the control group completed conventional core exercises. Both groups completed 12 sessions over 4 weeks (3 sessions/week, 50 minutes/session). Pre- and post-intervention evaluations included diagnostic musculoskeletal ultrasound to assess change rate of core muscles (transversus abdominis (TrA), lumbar multifidus, and diaphragm), using a balance assessment system to evaluate postural control performance (center of pressure displacement (COP)) in an upright standing position, and clinical questionnaires (Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Roland-Morris Disability Questionnaire (RDQ)) for the pain intensity and disability.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAfter 4 weeks, comparisons between both groups revealed significant statistical differences in the interaction effects of time*group. These differences were observed in the change rates of the left and right TrA (F\u003csub\u003e1,58\u003c/sub\u003e=4.820 and 3.964, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032 and 0.041), diaphragm change rate (F\u003csub\u003e1,58\u003c/sub\u003e=11.945, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001), as well as COP velocity (F\u003csub\u003e1,58\u003c/sub\u003e=5.283, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.025), variability (F\u003csub\u003e1,58\u003c/sub\u003e=13.189, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001) in the anterior-posterior (AP) direction, COP path length (F\u003csub\u003e1,58\u003c/sub\u003e=6.395, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014), and COP area (F\u003csub\u003e1,58\u003c/sub\u003e=5.038, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.029) in the eye-close condition. DNS participants showed significantly greater muscle change rates and reduced COP (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The scores of VAS (F\u003csub\u003e1,58\u003c/sub\u003e=173.929, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001), ODI (F\u003csub\u003e1,58\u003c/sub\u003e=60.871, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001), and RDQ (F\u003csub\u003e1,58\u003c/sub\u003e=60.015, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001) decreased significantly over time, although no differences in the interaction effects of time*group were found between both groups (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eDNS is superior to conventional core exercises in enhancing core muscle contractility and standing postural control in cLBP patients, showing potential to reduce pain and improve disability. Its mechanism may involve the enhancement of proprioceptive feedback, particularly when visual feedback is blocked.\u003c/p\u003e\u003ch2\u003eTrial registration\u003c/h2\u003e \u003cp\u003eThis study was registered in the Chinese Clinical Trial Registry (ChiCTR) with the registration number ChiCTR2300074595 on 10 August 2023.\u003c/p\u003e","manuscriptTitle":"Effects of Dynamic Neuromuscular Stabilization Training on the Core Muscle Contractility and Standing Postural Control in Patients with Chronic Low Back Pain: A Randomized Controlled Trial","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-26 20:29:15","doi":"10.21203/rs.3.rs-5146743/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-09-30T06:47:00+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-09-28T11:15:04+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-09-28T11:14:51+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2024-09-24T16:35:21+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"0e8634e2-3d87-483e-b9ab-3f8e239f35d7","owner":[],"postedDate":"December 26th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-03-03T16:00:27+00:00","versionOfRecord":{"articleIdentity":"rs-5146743","link":"https://doi.org/10.1186/s12891-025-08417-1","journal":{"identity":"bmc-musculoskeletal-disorders","isVorOnly":false,"title":"BMC Musculoskeletal Disorders"},"publishedOn":"2025-03-01 15:56:59","publishedOnDateReadable":"March 1st, 2025"},"versionCreatedAt":"2024-12-26 20:29:15","video":"","vorDoi":"10.1186/s12891-025-08417-1","vorDoiUrl":"https://doi.org/10.1186/s12891-025-08417-1","workflowStages":[]},"version":"v1","identity":"rs-5146743","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5146743","identity":"rs-5146743","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}