Document Type : Original Articles

Authors

1 Corrective Exercises and Sport Injuries, Faculty of Sport Sciences, Shahid Rajaee Teacher Training University, Tehran, Iran.

2 Master of Sports Injuries and Corrective Exercises, Faculty of Physical Education, Hakim Nezami Higher Education Institute, Quchan, Iran

3 corrective exercise and sport injury, Alborz campus, university of Tehran, Tehran, Iran

Abstract

Background: The present study aimed to evaluate the effectiveness of Dynamic Neuromuscular Stabilization (DNS) training on movement patterns and postural control in female athletes with lower cross syndrome (LCS).
Method: This research employed a quasi-experimental, pre-and post-test design. Thirty healthy female athletes with an average age of 24.98 ± 2.26 years and diagnosed with LCS were randomly divided into an experimental group (15 subjects) and a control group (15 subjects). Participants in the experimental group completed the DNS training protocol, which consisted of three sessions per week for eight weeks. Postural control and functional movements were assessed using the Y-balance test and Functional Movement Screening (FMS) before and after the intervention. Statistical analysis included paired t-tests, ANCOVA, and the Wilcoxon test.
Results: ANCOVA revealed a significant difference in the Y-balance test and FMS scores between the experimental and control groups for participants with LCS. Within-group analysis indicated that the post-test mean scores of the experimental group were significantly improved compared to pre-test scores following DNS training (P<0.05).
Conclusion: The results indicate that eight weeks of DNS training significantly improved functional movement screening and Y-balance test scores in female athletes with LCS. Therefore, DNS exercises may be recommended to athletes to enhance balance and lower limb performance.
 
 

Keywords

Introduction

Prolonged inappropriate posture can lead to widespread adverse adaptations in joints and soft tissues over time, including muscle shortening and stiffening on one side, elongation, and weakness on the opposite side, resulting in abnormalities and muscle imbalance [ 1 , 2 ]. According to the muscle imbalance theory, derived from Janda’s approach, three main patterns of imbalance are classified: upper cross syndrome (UCS), lower cross syndrome (LCS), and layer syndrome (LS). LCS is a muscle imbalance pattern characterized by a cross-imbalance in the lumbar and hip muscle segments; it involves stiffness in the lumbar extensors and hip flexors, along with weakness in the hip extensors and trunk flexors. This syndrome contributes to significant issues such as joint function disorder, anterior pelvic tilt, increased lumbar lordosis curve, tibial lateral rotation, and knee hyperextension in the affected individual’s posture [ 3 ]. Muscle imbalances can sometimes impair postural control and contribute to structural abnormalities. Vladimir Janda highlighted the interconnection between the nervous, muscular, and skeletal systems, suggesting that defects in any joint or muscle group can affect the function and quality of other muscles and joints [ 2 , 4 ]. Changes or disorders in one area’s muscles and joints can trigger chain reactions impacting other body parts. According to scientific literature, these chain reactions in posture occur across three systems—articular, muscular, and neural. These systems interact closely, and changes in one chain can disrupt another and vice versa [ 5 , 6 ].

Training programs that integrate all body segments and enhance their coordinated function are essential for addressing musculoskeletal abnormalities. Furthermore, the effect of these abnormalities on an individual’s motor function and balance should not be underestimated. Among such holistic training methods, the dynamic neuromuscular stabilization (DNS) technique has gained recognition in sports rehabilitation. DNS emphasizes not only muscular strength but also the involvement of the nervous system, offering a comprehensive approach to rehabilitation [ 7 ].

Dynamic Neuromuscular Stabilization (DNS) therapy accurately assesses the quality of stability or movement restoration through a spine integration system incorporating specific exercises based on the ideal musculoskeletal position. These exercises follow Janda’s chain reaction principles, inspired by the neuromuscular development observed in healthy infants. They aim to re-stimulate neuromuscular growth and enhance balance and motor function, which can benefit athletes.

The fundamental techniques in DNS therapy include core stabilization and control training, limb pattern training (both with and against limb movement for forward motion and support), evolutionary postural movement models for positional stabilization, and attention to muscle chain involvement. Additionally, DNS emphasizes postural function alignment with movement force, stability training alongside breathing techniques, maintaining spinal stability, and advancing movements from simple to complex without pathological patterns. Exercises begin after patients receive awareness training from healthcare providers [ 7 ].

Yi Lin Lim investigated the effects of DNS training on postural control and lumbar spine flexion in individuals with nonspecific chronic low back pain. The findings indicated that DNS exercises improved patients’ balance, highlighting the need for further studies on DNS applications in physiotherapy settings [ 8 ].

Movement screening tests are valuable for evaluating general performance and various motor and functional capabilities. These tests serve three main objectives: (1) dynamic evaluation of the kinematic chain, (2) detection of body alignment, and (3) identification of weak movement patterns [ 9 ]. Movement screening tests assess an individual’s susceptibility to injury, inefficiencies, and weaknesses within the kinematic chain. This, in turn, allows for developing effective exercise programs to enhance motor abilities. The Functional Movement Screening (FMS) test specifically challenges an individual’s capacity to perform movement patterns that involve proprioception, coordination, range of motion, muscle strength, balance, and flexibility [ 10 , 11 ].

Based on the principles underlying DNS exercises and their potential effectiveness for Lower Cross Syndrome (LCS), neuromuscular training appears to be a promising intervention for patients with this disorder. However, no studies to date have examined the impact of this type of neuromuscular training on postural control and movement function, specifically in athletes with LCS. Therefore, this study aimed to evaluate whether DNS training could improve postural control and motor function as measured by the Functional Movement Screening (FMS) test in female athletes with LCS.

Methods

This quasi-experimental study employed a pre-test and post-test design. The sample comprised 30 female athletes aged 20–30 years with Lower Cross Syndrome (LCS) from Mashhad, who were purposefully and randomly divided into control and experimental groups based on inclusion and exclusion criteria. Ethical considerations were followed per the Ethics Committee guidelines of Shahroud University (IR.SHAHROODUT. REC.1402.032). Postural control was evaluated using the Y-balance test, and functional movement was assessed through the Functional Movement Screening (FMS) test. Inclusion criteria included: diagnosis of LCS syndrome, lumbar lordosis above 46.92 degrees, anterior pelvic tilt above 5 degrees, a minimum of three years of exercise experience, regular exercise (1-4 days per week) in both groups, voluntary participation, completion of an individual consent form, and adherence to health protocols for COVID-19 prevention [ 12 , 13 ]. Exclusion criteria encompassed experiencing pain in the lower back or lower limbs, presence of a lumbar disc condition, pain during exercises, failure to complete the training program, irregular attendance, and failure to maintain the required time interval for sessions due to COVID-19 concerns.

Tools

Evaluating LCS: The selected indices for assessing LCS complications were lumbar hyperlordosis angle and anterior pelvic tilt. A flexible ruler [ 14 ] measured the lordosis angle, while a tilt gauge [ 15 ] assessed the pelvic tilt angle. For lordosis measurement, participants positioned themselves in the designated area for spinal arch assessment. The evaluator identified and marked the T12 and S2 spinous processes using palpation. The flexible ruler was placed between these marked points, with uniform pressure applied to ensure no space between the ruler and the skin. Without altering the arc, the evaluator transferred the ruler’s curvature onto A3 paper by tracing the marked points. A straight line (labeled “I”) was drawn connecting these points, and a perpendicular line from the deepest part of the arc was measured as the width (H). The lumbar curvature angle (Ө) was calculated using the formula: Ө=4Arctan(2H/L) [ 14 , 16 ].

For pelvic angle measurement, participants stood on a flat surface, placing one hand on the posterior superior iliac spine (PSIS) and the other on the anterior superior iliac spine (ASIS). Once aligned, the degree was read directly (Figure 1) [ 15 , 17 ].

Figure 1. Y-balance test (left) and scoring method (right)

Y-Balance Test: This test was used to evaluate dynamic balance. Participants stood barefoot, positioning one foot at the center of the Y-board with the other foot adjacent to it. Maintaining balance on one foot, participants extended the free foot forward and diagonally backward in both the internal and external directions (Figure 3.3). The reach distance from the center was measured in centimeters. Each direction was tested three times. Before starting, the lower limb length was measured [ 18 ]. The balance test score in each direction was calculated individually using the following formula:

Functional Movement Screening (FMS) tests: The FMS test results are categorized into three scoring levels:

1. Score of 3: The task is performed correctly without errors or compensatory movements.

2. Score of 2: The task is performed correctly but with compensatory movements.

3. Score of 1: The task is completed with difficulty

and requires compensatory movements.

If the subject experiences pain during any task or clearing test, no points are awarded for that movement. Consequently, a subject could receive a final score of zero if pain is reported in each movement test or a maximum score of 21 if they achieve a score of three on every movement test [ 11 , 19 ].

Procedure

After visiting sports clubs in Mashhad, athletes with visible signs of anterior pelvic tilt and increased lumbar lordosis were identified. Those meeting the selection criteria who volunteered to participate were informed about the research process. Following confirmation of eligibility for Lower Crossed Syndrome (LCS) and other criteria, participants received a detailed explanation of the study’s purpose and the DNS training protocol. They were then asked to complete a consent form confirming their willingness to participate, which allowed the research process to begin as scheduled.

Initial assessments were performed using a flexible ruler and tilt gauge, and participants meeting the criteria for lordosis and anterior pelvic tilt were designated as research subjects. Participants completed a personal information questionnaire detailing age, height, weight, lower limb length, and sports activity history. Thirty athletes were randomly assigned to either the control or experimental group. Before implementing the training protocol, Y-balance and FMS tests were administered to both groups to establish baseline (pre-test) data.

The experimental group then completed an eight-week training protocol with three sessions per week, held either at participating clubs or at home for those who could not attend in person. This study occurred in Mashhad in the summer of 2020, during the COVID-19 pandemic, and health precautions were implemented to minimize virus transmission during tests and training sessions. Each session allowed up to four participants to train over a two- and-a-half-hour period. After the eight-week program, the Y-balance and FMS tests were re-administered as a post-test, with the results recorded.

Statistical Method

Data were analyzed using SPSS version 22. Descriptive and inferential statistical analyses were conducted. The Shapiro-Wilk test was used to test data normality. Assuming a normal distribution, a paired t-test assessed within-group effects, while ANCOVA evaluated between- group effects. For non-normally distributed data, the Wilcoxon test was applied (P ≤ 0.05).

Results

This section details the demographic and physical characteristics of the subjects, including height, weight, age, lordosis angle, anterior pelvic tilt, body mass index (BMI), and leg length. Table 1 summarizes these characteristics along with the results of the group homogeneity analysis.

Variable Groups No. Mean and standard deviation t value Significance level
Age (years) Experimental 15 25.13±2.99 0.276 0.784
Control 15 24.84±2.23
Weight (kg) Experimental 15 67±3.87 -0.689 0.496
Control 15 68.06±4.57
Height (cm) Experimental 15 167.20±4.14 0.314 0.756
Control 15 166.73±3.99
BMI Experimental 15 20.62±1.59 -1.144 0.262
Control 15 21.33±1.76
Lower limb length Experimental 15 79.06±3.53 0.456 0.652
Control 15 78.53±2.82
Lordosis angle Experimental 15 47.60±5.51 -0.665 0.512
Control 15 48.80±4.29
Anterior pelvic tilt Experimental 15 9.93±2.31 -0.467 0.644
Control 15 10.33±2.38
BMI: Body mass index
Table 1. Demographic information of samples (mean±standard deviation)

The Shapiro-Wilk test indicated that the FMS test subscales exhibited a non-normal distribution (P<0.05). Consequently, the Wilcoxon test, with a 95% significance level and P≤0.05, was applied to assess the impact of DNS training on FMS subscales. The test confirmed normal distribution for the FMS test’s total score and the anterior, internal posterior, external posterior, and total Y-balance test scores (P<0.05). To examine the effect of DNS exercises on the Y-balance variable between the two groups (control and experimental), ANCOVA was conducted, and a paired t-test was used within each group at a 95% significance level (P≤0.05).

According to the Wilcoxon test results shown in Table 2, there was a statistically significant difference in the mean test scores for Deep Squat (P=0.014), Shoulder Mobility (P=0.003), In-line Lunge (P=0.039), Hurdle Step (P=0.008), Trunk Stability Push-Up (P=0.033), and Rotary Stability (P=0.002) in the experimental group between the pre-test and post-test (P<0.05). In contrast, no statistically significant differences were found in the control group for the mean scores of Hurdle Step, In-line Lunge, Deep Squat, Active Straight Leg Raise, Rotary Stability, Shoulder Mobility, and Trunk Stability Push- Up between pre-test and post-test (P<0.05). Furthermore, no significant difference was observed between the two groups regarding the Active Straight Leg Raise variable. The ANCOVA test was employed to compare the total FMS score and posture control test variable (across the three indices of anterior, internal posterior, external posterior, and total Y-balance score) between the control and experimental groups. The analysis of covariance revealed a significant difference between the control and experimental groups for the total FMS score and the posture control test variable in athletes with LCS (P=0.001), as determined by examining the mean scores (Table 3).

Variable Groups Score Mean Score Test statistics
Positive score Negative score Equal score Positive score Negative score z sig
Deep squat Experimental 0 6 9 0 3.5 -2.449 *0.014
Control 2 3 10 3 3 -0.447 0.655
Hurdle step Experimental 0 7 8 0 4 -2.646 *0.008
Control 1 1 11 2.5 2.5 -1 0.317
In-line lunge Experimental 3 10 2 6 7.30 -2.066 *0.039
Control 4 4 7 5 4 -0.302 0.763
Shoulder mobility Experimental 0 9 6 0 5 -3 *0.003
Control 2 2 11 3 2 -0.378 0.705
Active straight leg raise Experimental 2 6 7 4 4.67 -1.508 0.132
Control 3 4 8 4.17 3.88 -0.264 0.792
Trunk stability push-up and Experimental 1 7 7 3.5 4.64 -2.126 *0.033
Control 3 4 8 4.5 3.63 -0.090 0.928
Rotary stability Experimental 0 10 5 0 5.5 -3.051 *0.002
Control 2 1 12 2 2 -0.577 0.564
*Significance level P<0.05
Table 2. Wilcoxon test results comparing the mean score of the FMS subscales in the experimental and control groups
Variable Groups Mean F Df P Eta Squared
Total FMS test score Experimental 17.73±1.90 15.002 1 0.001 0.462
Control 14.20±0.86
Anterior Experimental 92.52±6.50 18.818 1 0.001 0.420
Control 80.14±8.27
Medial posterior Experimental 102.29±5.51 40.294 1 0.001 0.608
Control 88.49±5.37
Lateral posterior Experimental 97.23±5.14 30.514 1 0.001 0.540
Control 84.77±4.40
The total score of Y Experimental 97.34±4.55 10.184 1 0.004 0.281
Control 83.99±4.65
FMS: Functional Movement Screen
Table 3. Results of the analysis of covariance: the effect of the independent and predictor variable on the post-test

Table 4 summarizes the paired t-test results comparing the total scores of the FMS and Y-balance tests between the pre-test and post-test.

Variable Experimental group Control group
M±SD M±SD
Pre-test Post-test P value Pre-test Post-test P value
Total FMS score 14.10±0.84 17.73±1.90 0.001 14.06±0.86 14.20±0.86 0.701
Anterior 79.98±7.90 92.52±6.50 0.001 79.37±9.11 80.14±8.27 0.117
Medial posterior 88.64±7.52 102.29±5.51 0.001 87.89±6.74 88.49±5.37 0.403
Lateral posterior 83.27±6.09 97.23±5.14 0.001 84.23±5.54 84.77±4.40 0.481
The total score of Y 83.97±4.39 97.34±4.55 0.001 83.83±5.48 83.99±4.65 0.751
FMS: Functional Movement Screen
Table 4. The mean difference of the total variable of the Functional Movement Screen (FMS( test in the subjects before and after the training protocols

The mean total score of the FMS test in the experimental group increased from 14.10±0.84 before DNS exercises to 17.73±1.90 after participation. The paired t-test results indicated that this increase of 3.63 was statistically significant (P=0.001). Similarly, the mean total score of the Y-balance test in the experimental group rose from

83.97±4.39 to 97.34±4.55 following DNS exercises. The paired t-test confirmed that this increase of 13.37 in the Y-balance test score was also statistically significant (P=0.001).

Discussion

The current study investigated the impact of an 8-week DNS training protocol on motor function and postural control in 20–30-year-old female athletes with LCS. Results indicated a significant improvement in the FMS test scores of athletes in the experimental group. In contrast, the control group showed no statistically significant change between pre-and post-test scores. These findings align with previous research, including studies by Arazzadeh (2018) [ 20 ], Daneshjoo (2019)

Conclusion

DNS training is a rehabilitation technique that has recently gained traction in studies that facilitate the neuromuscular system. The results showed that 8 weeks of DNS training significantly improved FMS and Y-balance test scores in female athletes with LCS. This exercise regimen enhances strength, agility, flexibility, balance, and core stability and can be conveniently performed at home or elsewhere without substantial costs. Therefore, DNS exercises are recommended for athletes with LCS to improve balance and lower limb function. These exercises may also have the potential to reduce the incidence of LCS. Experts in the field are encouraged to incorporate these exercises to mitigate the disorder. Further research is suggested to evaluate the extent of reduction in lumbar lordosis and anterior pelvic tilt in patients with LCS following these exercises.

Conflict of Interest

None declared.

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