Effects of Self-Myofascial Release and Dynamic Neuromuscular Stabilization Exercises on Pain, Balance, Muscle Function, and the Autonomic Nervous System in Women with Chronic Low Back Pain

Introduction

Low back pain is one of the most common musculoskeletal disorders in modern society, affecting 60–80% of the population in their lifetime. Chronic low back pain, the most common type of low back pain, lasts >3 months, interferes with daily activities, and is responsible for some of the greatest healthcare and lost productivity costs worldwide [1]. About 90% of chronic low back pain is nonspecific (ie, unknown cause) or lacks evident structural defects rather than structural deformity or direct lumbar spine factors [2]. Chronic low back pain is caused by deterioration of muscles and ligaments in the lower back surrounding the vertebrae, resulting in decreased joint range of motion, which limits athletic performance owing to decreased flexibility, strength, and endurance [3]. In addition, patients with chronic low back pain experience changes in the length of the muscles, tendons, ligaments, joint pockets, and other tissues around the joints because of repetitive overuse, as well as weakness of the deep muscles, resulting in decreased proprioception and deficits in neuromuscular coordination, leading to spinal segmental instability [4], which is loss of the ability to maintain displacement patterns under physiologic loading [5]. Pain due to spinal instability results in decreased spinal motion and increased tone in surrounding muscles, restricting functional movement [6]. Chronic back pain affects an individual’s life, causes pain and dysfunction, and affects both physical and psychological factors [7]. Therefore, although several methods can address chronic back pain, the best treatment remains uncertain, and prevention and solutions are needed. Chronic low back pain (CLBP) is a heterogeneous condition with multifactorial etiologies, encompassing biomechanical dysfunctions (eg, muscular imbalances, joint restrictions), neuropathic mechanisms (eg, central sensitization, altered pain processing), and psychosocial contributors (eg, anxiety, fear-avoidance behavior, and depression). This complexity underscores the need for individualized and multimodal treatment strategies that address not only physical impairments but also the broader functional and psychological dimensions of pain. Therefore, interventions that simultaneously target structural mobility and neuromuscular coordination may offer more comprehensive relief for diverse CLBP populations.

Several movement therapy treatments for chronic low back pain have recently emerged, including self-stretching, muscle energy techniques, myofascial trigger point therapy, and self-myofascial release (SMR) technique. SMR for treating low back pain involves direct relaxation of the tense fascial tissue causing pain [8]. Myofascial release techniques promote localized scar tissue repair and increase muscle strength, blood flow, skin temperature, and cell activation [9]. The SMR technique is used to treat soft-tissue adhesions caused by microdamage and inflammation due to overuse and repetitive movement of small tools [10]. SMR techniques use tool pressure to reduce pain and improve proprioception, lymphatic circulation, joint positioning, and flexibility [11]. It is also effective in improving athletic performance by reducing muscle tension and improving muscle function and activation [9].

BALLance® is an SMR technique designed by German scientist Dr. Tanja Kühne that uses slow rolling, spinning, and pressure-based movements in sync with breathing to help relax fascia, increase spinal mobility, reduce pain, and increase movement [12]. One study has reported that SMR using the BALLance® technique improves pain avoidance, reduces pain, and decreases the autonomic nervous system stress index in patients with chronic low back pain [13]. Myofascial release applied to the erector spinae muscles of the spine reduces low back pain and improves range of motion and stress tolerance [14].

Dynamic neuromuscular stabilization (DNS) exercises are an alternative treatment for chronic low back pain. They are based on the principles of child developmental kinesiology and aim to provide dynamic stabilization of the spine by strengthening the deep muscles around the lumbar spine and optimizing neuromuscular coordination and the motor system [15]. In particular, the exercises are based on the developmental patterns of lying down, lying prone, sitting, rolling, walking, and standing up from a seated position with breathing control [16]. DNS exercises are effective in learning functional movement, joint positioning, and neuromuscular control [15]. In addition, such exercises for patients with chronic low back pain are effective in improving spinal stability, pain reduction, and balance by activating intra-abdominal pressure and the surrounding muscles through the cooperative action of the core muscles [16]. Core exercises using DNS can retrain trunk muscle function and increase the accuracy of the sensory integration processes for spinal stability in patients with chronic low back pain [17]. Moreover, hamstring shortening reduces lower back flexibility, which is associated with low back pain, and combining core stability with contraction-relaxation exercises can further increase hamstring flexibility [18].

SMR techniques and DNS exercises have been widely studied and are currently used in clinical practice for treating patients with chronic low back pain. However, the effectiveness of DNS exercises combined with SMR remains unclear. Notably, the combination of SMR and DNS can produce synergistic effects by sequentially targeting both passive and active components of the musculoskeletal system. SMR helps to reduce fascial tension and muscle tone, thereby increasing soft-tissue compliance and enhancing joint mobility. This preparatory effect can optimize the neuromuscular responsiveness and motor pattern acquisition facilitated by subsequent DNS exercises. DNS, in turn, activates the deep stabilizing muscles of the spine and improves postural control through breathing and core coordination. By integrating these approaches, the intervention can address both mechanical restrictions and motor control deficits more effectively than either modality alone. Such synergy is particularly beneficial for individuals with chronic low back pain, where multifactorial impairments involving tissue stiffness, motor dysfunction, and autonomic imbalance coexist. The hypothesis of this study was that rather than applying DNS exercises directly to patients with low back pain, SMR should be used to relax the hypertonic myofascial tissue to improve athletic performance, and then applying DNS exercises will have a positive effect on physical and functional changes. Therefore, this study aimed to investigate the effects of applying a combination of the SMR technique and DNS exercises using the BALLance® method on pain, balance, muscle function, and daily living function in patients with chronic low back pain.

Material and Methods

PATIENTS:

This study recruited 40 women in their 30s and 40s who visited the H Exercise Center in Seongnam City. Participants were eligible if they voluntarily agreed to participate, met the inclusion criteria, and were capable of understanding the study procedures necessary for providing informed consent. To minimize bias, participants were not informed about the specific differences in intervention content between groups (eg, the inclusion of SMR in the experimental group) during recruitment or data collection. Twenty participants were randomly assigned to the experimental group, which was instructed to perform SMR combined with DNS exercises, and 20 to the control group, which performed DNS exercises only. Randomization was performed using a computer-generated allocation program (Random Allocation Software for Windows 2.0; Isfahan University of Medical Sciences, Iran). To minimize bias, a single-blind design was used in which the participants were unaware of their group assignments.

Sample size was calculated using G*Power 3.1.9.7 (Heinrich Heine University, Düsseldorf, Germany), based on an effect size of 0.25, significance level (α) of 0.05, and power (1-β) of 0.80. The required minimum number of participants was 34, and 40 participants were recruited to account for possible dropouts.

The inclusion criteria were: (1) chronic low back pain lasting >3 months; (2) Korean version of the Oswestry Disability Index (KODI) score between 20% and 40%; (3) ability to perform all assessments and interventions; and (4) willingness to comply with the study protocol. The exclusion criteria were: (1) acute disc herniation; (2) spinal surgery within the past 6 months; (3) current pregnancy or childbirth within the past year; and (4) structural abnormalities, such as fractures or neurological impairments.

All participants provided written informed consent prior to enrollment. This study was approved by the Institutional Review Board of Sahmyook University (SYU 2024-06-023). The study followed CONSORT guidelines for randomized controlled trials, and the study was registered with the Clinical Research Information Service(CRIS) (KCT0010401).

PAIN: Pain was assessed using the VAS, a validated tool that provides a numerical quantification of perceived pain intensity. The VAS consists of a 100-mm horizontal line labeled “no pain” at the left end and “extreme pain” at the right end. Participants marked a point on the line corresponding to their current pain level, and the distance from the left end was measured in millimeters. This method reflects the continuum of pain perception from none to severe and has demonstrated high interrater reliability (ICC=0.97) [19]. The pre- and post-intervention assessments were conducted in the same quiet and independent setting to ensure consistency and participant concentration.

STATIC BALANCE: Static balance was assessed using the FRT. The participants stood with their feet shoulder-width apart and extended 1 arm forward 90° to the shoulder. The distance from the starting point to the farthest reach, without losing balance, was measured using a tape measure fixed to the wall. A reach of <15–17.5 cm indicates limited functional balance. The test demonstrated high test–retest reliability (r=.92) and interrater reliability (r=.98) [20]. The best results of 3 trials were recorded.

DYNAMIC BALANCE: The YBT, a standardized modification of the Star excursion balance test, was used to evaluate dynamic balance, proprioception, and lower-extremity function. After the practice trials, the participants performed 3 tests in the anterior, posteromedial, and posterolateral directions. The maximum distance reached (cm) in each direction was recorded and standardized using the leg length measured from the ASIS to the medial malleolus. The YBT has excellent intra-rater reliability (ICC=0.98–1.00) [21].

MUSCLE ENDURANCE (SBT): Participants lifted the pelvis in a supine position until the shoulders, hips, and knees formed a straight line. The duration (in seconds) for which the position was held was measured 3 times and averaged. This test has good interrater reliability (ICC=0.836) [22].

FLEXIBILITY (SRT): Using a standardized flexibility meter (T.K.K. 5403), the participants sat with their knees straight and reached forward with their arms extended. The furthest distance reached (cm) was measured over 3 trials and averaged. The SRT had an interrater reliability of ICC=0.76 [23].

MUSCLE TONE AND STIFFNESS (MYOTON PRO): Muscle tone and stiffness of the rectus abdominis and erector spinae muscles were assessed using the Myoton PRO (Myoton AS, Estonia), which employs a 3-axis accelerometer for contact-based soft-tissue evaluation. Measurements were obtained at standardized anatomical landmarks with the probe held perpendicular to the skin. Each site was measured thrice and averaged. Higher values indicate increased tension and stiffness. The rectus abdominis was measured 2 cm lateral to the midline between the umbilicus and xiphoid process, and the erector spinae were measured bilaterally at the L4–L5 level [24].

PROCEDURES:

Participants were randomly assigned to either the experimental group (n=20), which performed SMR followed by DNS exercises, or the control group (n=20), which performed DNS exercises only. A single-blind design was employed to reduce bias, and the participants were unaware of their group allocation.

Before the intervention, baseline measurements were obtained for all participants. Pain was assessed using the visual analog scale (VAS), static balance with the functional reach test (FRT), and dynamic balance with the Y-balance test (YBT). Muscle function assessments included muscle endurance using the supine bridge test (SBT), flexibility via the sit-and-reach test (SRT), and muscle tension and stiffness using Myoton PRO (Myoton AS, Estonia), a contact-based tissue assessment device with a 3-axis digital accelerometer. Functional disability due to low back pain was evaluated using the KODI. Autonomic nervous system activity was measured using an SA-3000new device (Medicore, South Korea), with standard deviation of the normal-to-normal interval (SDNN) used as an index of stress resistance.

The intervention was performed twice a week over a 6-week period. The experimental group performed 20 minutes of SMR using foam rollers or massage tools, followed by 30 minutes of DNS exercises. The control group performed the DNS exercises for only 30 minutes. Upon completion of the 6-week intervention, all outcome measures were reassessed using the same procedures as in the pre-test (Figure 1). Although this study used a double-blind design by concealing group allocation from the participants and blinding outcome assessors, complete double-blinding was not feasible due to the nature of the intervention. The intervention was delivered by a licensed physical therapist certified in DNS, who was not involved in the study design, data collection, or statistical analysis. Given that the therapist had to deliver different protocols (SMR+DNS vs DNS alone), they were necessarily aware of the intervention type. Therefore, this trial more accurately reflects a single-blind design. We acknowledge this as a methodological limitation and recommend that future studies explore alternative methods to further minimize performance bias.

SELF-MYOFASCIAL RELEASE (SMR) EXERCISE PROGRAM: The SMR program used in this study was adapted from the BALLance Exercise Guide and implemented using the BALLance ball, a specialized myofascial release tool. The program consisted of a sequence of inhalation, exhalation, rolling, and rubbing movements performed twice weekly for 6 weeks, with each session lasting approximately 20 minutes [13].

SMR exercises were standardized using a metronome set at 60 beats per minute to control the rolling speed. Participants were instructed to roll the ball in one direction for 2 beats, resulting in approximately 15 rolling movements per minute [27]. The equipment consisted of 2 spring-connected bolster balls of different sizes: a large ball (11 cm diameter, 360 g) and a small ball (9 cm diameter, 270 g). These tools were designed to selectively target myofascial areas while avoiding direct pressure on the spinous processes, allowing for the safe and effective release of tension and facilitation of mobility.

Before the intervention, the participants performed a brief warm-up and were instructed on exercise posture, breathing, and precautions to ensure safety and proper techniques, especially for those unfamiliar with the exercises (Table 1).

DYNAMIC NEUROMUSCULAR STABILIZATION (DNS) EXERCISE PROGRAM: DNS exercises were performed under the supervision of a licensed physical therapist trained in DNS techniques. The therapist provided verbal explanations and visual demonstrations before each session. During the exercises, the therapist offered continuous verbal guidance and passive corrections to help the participants acquire optimal alignment of the pelvis, spine, pectoralis major, and scapula, while stabilizing the trunk in various postural positions. Given the precise nature of DNS movements, the therapist closely supervised each step to ensure accurate execution [15].

Exercise intensity was regulated using the rating of perceived exertion (RPE) scale. In weeks 1–4, the focus was on learning and mastering correct postural control and movement patterns with exercises performed at an RPE of 11–12. During weeks 5 and 6, the intensity gradually increased to an RPE of 13–14 to enhance neuromuscular control and trunk stability [15] (Table 1).

STATISTICAL ANALYSIS:

All statistical analyses were performed using SPSS software (version 24.0; IBM Corp., Armonk, NY, USA). The Shapiro-Wilk test was used to assess data normality, and all variables were normally distributed. Accordingly, the data are expressed as means and standard deviations.

Descriptive statistics were used to summarize participants’ general characteristics. Prior to the intervention, homogeneity tests were conducted on the dependent variables to confirm baseline equivalence between the groups.

Paired t-tests were used to analyze the within-group differences between the pre- and post-intervention measurements of pain, static balance, dynamic balance, muscular endurance, flexibility, muscle tension, stiffness, functional disability, and autonomic nervous system function. To evaluate between-group differences over time, 2-way repeated-measures analysis of variance [2 (group: experimental, control)×2 (time: pre-test, post-test)] were conducted, with time as the within-subjects factor and group as the between-subjects factor.

Statistical significance was set at p<0.05. When significant interaction effects were observed.

Given the number of outcome measures analyzed, we acknowledge the risk of Type I error due to multiple statistical comparisons. As this study was exploratory in nature and aimed to provide a comprehensive assessment of the intervention’s impact across multiple physiological and functional domains, no formal corrections (eg, Bonferroni adjustment) were applied. However, to improve clarity and interpretation, the Korean version of the Oswestry Disability Index (KODI) was defined as the primary outcome measure, given its clinical relevance in assessing disability due to chronic low back pain. Other variables were treated as secondary outcomes. Future confirmatory trials should apply statistical correction methods or employ multivariate models to further control for the inflation of false-positive results.

Results

VAS:

The experimental and control groups showed significant within-group differences in improvements as assessed by VAS (p<0.001). Significant differences in the group-by-time interaction for the VAS were also observed (p<0.05) (Table 2).

STATIC BALANCE (FRT):

The experimental and control groups showed significant within-group differences in improvements in static balance (p<0.001). Significant differences in the group-by-time interaction for the FRT were also observed (p<0.05) (Table 3).

1) CHANGE IN DYNAMIC BALANCE OF THE RIGHT LEG BEFORE AND AFTER THE INTERVENTION: The experimental and control groups showed significant within-group differences in improvements in the dynamic balance of the right leg (p<0.001). Significant differences in the group-by-time interaction for the dynamic balance of the right leg were also observed (p<0.05) (Table 3).

2) CHANGE IN DYNAMIC BALANCE OF THE LEFT LEG BEFORE AND AFTER THE INTERVENTION: The experimental and control groups showed significant within-group differences in improvements in the dynamic balance of the left leg (p<0.001). Significant differences in the group-by-time interaction for the dynamic balance of the left leg were also observed (p<0.05) (Table 3).

MUSCULAR ENDURANCE (SBT):

The experimental and control groups showed significant within-group differences in improvements in the SBT (p<0.001). Significant differences in the group-by-time interaction for the SBT were also observed (p<0.05) (Table 4).

MUSCLE FLEXIBILITY (SRT):

The experimental and control groups showed significant within-group differences in improvements in the SRT (p<0.001). Significant differences in the group-by-time interaction for the SRT were also observed (p<0.05) (Table 4).

1) RIGHT RECTUS ABDOMINIS, LEFT RECTUS ABDOMINIS, AND RIGHT AND LEFT SPINAL ERECTORS: The experimental and control groups showed significant within-group improvements in muscle tone (p<0.001). Significant differences in the group-by-time interaction for muscle tone were also observed (p<0.05) (Table 5).

1) RIGHT RECTUS ABDOMINIS, LEFT RECTUS ABDOMINIS, AND RIGHT AND LEFT SPINAL ERECTORS: The experimental and control groups showed significant within-group improvements in muscle stiffness (p<0.001). Significant differences in the group-by-time interaction for muscle stiffness were also observed (p<0.05) (Table 6).

BACK PAIN DISABILITY INDEX (KODI):

The experimental and control groups showed significant within-group improvements in the KODI (p<0.001). Significant differences in the group-by-time interaction for the KODI were also observed (p<0.05) (Table 7).

1) SDNN: The experimental and control groups showed significant within-group improvements in the SDNN (p<0.001). Significant differences in the group-by-time interaction for the SDNN were also observed (p<0.05) (Table 8).

Discussion

A total of 40 adult women who met the inclusion criteria participated in the study and were randomized into the experimental group comprising 20 women who performed SMR+DNS exercises and the control group comprising 20 women who performed DNS exercises only.

Considering VAS changes from pre- to post-intervention assessments in this study, the within-group difference between the experimental and control groups was significantly reduced (p<0.001). The change in VAS scores between the groups was also significantly lower in the experimental group than in the control group (p<0.05). The SMR exercise improved flexibility and reduced pain by releasing spinal fascial trigger points, thereby enhancing range of motion and performance [28]. Similarly, DNS exercises effectively reduced pain and activated motor control by engaging the cerebral cortex [29]. These exercises improve pain control by increasing spinal stability and activating core muscles, thereby addressing the instability that often causes back pain [30].

When examining pre- to post-intervention changes in static balance, the experimental and control groups demonstrated significant within-group improvements (p<0.001). Between-group static balance changes were also significantly better in the experimental group than in the control group (p<0.05). In addition, considering the changes in the dynamic balance of the right and left legs from pre- to post-intervention assessments, the experimental and control groups showed significant improvements (p<0.001). The change in dynamic balance was also significantly better in the experimental group than in the control group (p<0.05). Thus, SMR with a BALLance reduced muscle stiffness in the lumbar extensors, relaxed the hip flexors, and improved balance control through enhanced interbody stability via DNS exercises[30]. Additionally, using a BALLance tool for SMR reduces pain and improves proprioception, contributing to better balance [11]. Previous studies have indicated that exercise with BALLance improves balance, functional performance, and gait [31]. In a study of 30 healthy older participants who performed 8 weeks of DNS exercises, static and dynamic balance both improved, and walking time decreased, helping prevent falls [32]. These improvements in balance may result from the development of the local muscular system, which enhances the spinal segment safety and functional movement [32].

When examining the change in muscular endurance (SBT) from pre- to post-intervention assessments, the within-group difference between the experimental and control groups was significant (p<0.001). The change in muscle endurance was also significantly greater in the experimental group than in the control group (p<0.05). Autologous fascia improves muscle endurance and activity by relaxing key back muscles and optimizing abdominal pressure during stabilization exercises [12,15]. Previous studies have confirmed that SMR and Pilates Reformer exercises help reduce pain and improve muscle function in women with chronic low back pain [12]. DNS exercises involving coordinated contractions of key muscles are effective in treating low back pain [15,33]. Muscular endurance improvement is attributable to the optimization of the movement system, which adjusts the postural stabilization cylinder belt and muscles, such as the transverse abdominis, latissimus dorsi, pelvic floor, and pectoralis major to create optimal intra-abdominal pressure [15].

Examining the changes in flexibility (SRT) from pre- to post-intervention assessments, the experimental and control groups demonstrated significant within-group differences (p<0.001). The improvement in flexibility between the groups was also significantly greater in the experimental group than in the control group (p<0.05). Thus, pressure from the SMR tool can be effective in reducing pain and improving proprioception, lymphatic circulation, joint positioning, and flexibility [11]. Consistent with these findings, previous studies have reported that Pilates SMR and combined Pilates exercises positively impact strength and flexibility; SMR also helps relieve muscle tension and increases flexibility [12]. Additionally, DNS exercises are effective in enhancing joint positioning and neuromuscular efficiency, which improves functional movement by optimizing stability [15].

In terms of the changes in muscle tone of the right and left rectus abdominis and right and left spinal erector spinae muscles from pre- to post-intervention assessments, the within-group difference between the experimental and control groups was significantly reduced (p<0.001). The between-group muscle tone was also significantly reduced in the experimental group compared to that in the control group (p<0.05). Autologous myofascial release effectively reduces muscle tone by increasing the joint range of motion, improving flexibility, and relieving stiffness and pain [34]. Moreover, SMR and Pilates Reformer exercises help reduce pain, improve quality of life, and decrease muscle tone in women with chronic low back pain [12]. The reduction in muscle tone is attributed to improved spinal stability and activation of subcortical brain areas, enhancing core stabilization and neuromotor control for optimal movement [9].

In terms of the changes in stiffness of the right and left rectus abdominis and right and left spinal erector spinae muscles from pre- to post-intervention assessments in this study, the within-group difference between the 2 groups was significantly reduced (p<0.001). The change in muscle stiffness was also significantly lower in the experimental group than in the control group (p<0.05). SMR using small tools effectively reduces muscle stiffness by relaxing soft-tissue adhesions caused by muscle microdamage and inflammation caused by repetitive motion [10]. Moreover, it decreases muscle tone, increases pain threshold, and improves muscle function and athletic performance [12]. Muscle stiffness reduction is likely attributable to improved core muscle imbalances, which enhance interbody safety through muscle activation [35].

In the KODI before and after the intervention, the within-group difference between the 2 groups significantly reduced (p<0.001). The changes in KODI between the groups were also significantly lower in the experimental group than in the control group (p<0.05). Autogenous myofascial release by targeting the sacrolumbar fascia and erector spinae with ball pressure and breathing movements reduces muscle tone, alleviates pain, and improves walking, sitting, and sleeping components of the low back pain disability index [12]. Moreover, therapeutic exercises reduce back pain and enhance daily functioning [36]. A study on DNS exercises showed a significant KODI reduction in 40 postpartum women with low back pain after a 6-week intervention [37]. This reduction is attributed to activation of the lower back and core muscles, improved neuromuscular response and blood flow, and reduced functional limitations [37].

Considering the changes in autonomic nervous system SDNN from pre- to post-intervention assessments in this study, the within-group SDNN change was significantly greater in the experimental group than in the control group (p<0.001). Between-group SDNN changes were also significantly greater in the experimental group than in the control group (p<0.05). The SMR therapy in this study effectively reduced physical stress and cortisol levels, improving the autonomic nervous system SDNN [38]. Previous studies have indicated that SMR relieves stress and enhances vasodilation, muscle contraction, and joint range of motion [39,40]. The BALLance method of SMR effectively reduces pain and stress in patients with chronic low back pain, and bladder neck massage can reduce stress and anxiety by lowering cortisol levels [41]. Stimulation of the bladder meridian can regulate high-mobility group box 1 protein, suppress inflammation, balance the autonomic nervous system, and alleviate anxiety and stress [42]. The bladder meridians are Zhishi (BL52), Shenshu (BL23), Qihaishu (BL24), and Dachangshu (BL25) of the spine-centered Taiyang Bladder meridians [43]. The selection of the BALLance Trainer® over standard foam rollers was based on its distinct structural design, which facilitates symmetrical and controlled rolling along the spine while minimizing direct vertebral pressure. These characteristics enable safer and more reproducible fascial stimulation in populations with chronic low back pain. Prior studies have reported that the BALLance method enhances spinal mobility, reduces pain, and supports autonomic regulation. Although conventional rollers are more commonly used, the BALLance Trainer® offered advantages in terms of standardization and user safety, which were critical in the context of a clinical trial. The authors declare that no financial relationships, sponsorships, or conflicts of interest exist with the manufacturer of the BALLance Trainer®, and its use in this study was guided exclusively by clinical and methodological considerations.

This study has some limitations. First, the myofascial release techniques were performed using a bolster ball. Although a bolster ball was used as a myofascial release technique, many other methods exist (eg, strain counter strain, myofascial trigger point therapy, and muscle energy techniques) [44]. The effectiveness of each method may vary, and further research is required to compare them. Second, information on the optimal intensity, duration, and number of sets with rest periods for the bounce ball technique is limited, possibly influencing the results. Third, all participants were women, which limits the generalizability of the findings to males or more diverse populations. Sex-based differences in musculoskeletal structure and neuromuscular control may influence intervention outcomes. Fourth, recruitment from a single exercise center in Seongnam City may not capture regional or cultural variability, further restricting external validity. Future studies should include more heterogeneous samples, encompassing both sexes and multiple recruitment sites, to enhance the generalizability and applicability of the findings. Fifth, Although the total intervention duration differed between groups (50 minutes in the experimental group vs 30 minutes in the control group), this design reflects a common approach in physical therapy research, where additional interventions are layered onto a shared baseline treatment to assess their additive effects. Furthermore, although the 6-week intervention period was sufficient to detect short-term improvements in pain, function, and autonomic regulation, it was too brief to evaluate the long-term sustainability of these effects. Future studies should include extended follow-up assessments to determine whether the observed benefits are maintained over time. Nevertheless, it is acknowledged that the longer session time in the experimental group may confound the attribution of outcomes specifically to the SMR technique. To strengthen internal validity, future studies should consider matching total treatment duration across groups or including an SMR-only group to better isolate its individual contribution. Finally, this study was limited by a small sample size and a single-site design. Although the 6-week intervention period was sufficient to detect short-term effects, it may be inadequate to assess the long-term sustainability and retention of the observed benefits. Additionally, the absence of interim assessments during the intervention period hindered the ability to precisely monitor the progression of changes and the timing of effect onset. Therefore, future research should incorporate longer follow-up durations, a more diverse participant pool, and varied methodological approaches. Including interim evaluations would allow for a more detailed examination of the temporal dynamics of intervention effects, thereby verifying their long-term maintenance and strengthening the clinical evidence base. Furthermore, the interpretation of this study’s findings may be limited by the lack of consideration for alternative explanatory factors, such as the longer intervention duration in the experimental group (50 minutes vs 30 minutes) and potential placebo effects stemming from the perception of receiving an additional treatment. These variables may have contributed to the observed improvements in the experimental group, making it difficult to attribute the outcomes solely to the intervention itself and potentially compromising internal validity. Future research should adopt more rigorous study designs – such as equalizing intervention durations or including a placebo-controlled group – to control for these confounding factors and more accurately isolate the effects of the intervention.

Conclusions

This study investigating the synergistic effects of SMR and DNS exercises on pain, balance, muscle function (muscle endurance, flexibility, tension, and stiffness), KODI, and the autonomic nervous system in 40 women identified significant differences in group interactions for pain, balance, muscle function, KODI, and autonomic nervous system SDNN (p<0.05).

In this study, we investigated the effects of SMR and DNS exercises on women with chronic low back pain, the most common type of low back pain, which is characterized by functional movement limitations and rigid posture, resulting in difficulties with balance and daily function. The combination of SMR and DNS exercises exhibited a significant improvement in pain relief, balance, muscle function (muscle endurance, flexibility, tone, and stiffness), KODI and autonomic nervous system stress reduction to the extent that the combination of SMR and DNS exercises could be considered an effective intervention method. The combination of SMR and DNS exercises was more effective than DNS exercises alone.