Influence of Reactive Neuromuscular Training on Stability and Performance in Volleyball Players Recovering from ACL Injury

https://doi-004.org/6812/17674513677503

Kaiyuan Dong1，Borhannudin bin Abdullah2*, Hazizi bin Abu Saad 3, Chenxi Lu4

  1. Department of Sports Studies, Faculty of Educational Studies, Universiti Putra Malaysia, Serdang, 43400, Selangor, Malaysia; Author Email：dkykaiyuan@gmail.com
  1. Head of Department of Sports Studies, Faculty of Educational Studies, Universiti Putra Malaysia, Serdang, 43400, Selangor, Malaysia; *Corresponding Author Email: bob123contact@gmail.com
  1. Department of Nutrition, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia.Serdang, 43400, Selangor, Malaysia; Author Email：hazizi@upm.edu.my
  1. Department of Sports Studies, Faculty of Educational Studies, Universiti Putra Malaysia, Serdang, 43400, Selangor, Malaysia; Author Email：luchenxi0406@gmail.com

Abstract

Background

Anterior cruciate ligament (ACL) injuries are prevalent in volleyball, often leading to deficits in balance, proprioception, and performance, increasing re-injury risk. Reactive neuromuscular training (RNT) uses perturbations to enhance neuromuscular control and correct movement patterns, but its effects in volleyball players post-ACL reconstruction remain understudied.

Objective

To assess the impact of a six-week RNT program on dynamic balance and functional performance in male volleyball players with reconstructed ACL injuries.

Methods

This quasi-experimental study employed a pre-test/post-test design with 30 male volleyball players (aged 18–30 years, ≥3 years volleyball experience) from X city, randomly assigned to experimental (n=15) or control (n=15) groups. Inclusion criteria included reconstructed ACL, normal BMI (20–25), and no other lower limb abnormalities. The experimental group underwent 16 RNT sessions (40 minutes each, using TheraBand perturbations, intensity <6 on Borg scale), while controls maintained routine activities. Assessments included Y Balance Test (balance), Vertical Jump Test (explosive power), Triple Hop Distance Test (power, speed, balance), and Single-Leg Hop for Time over 6 meters (power, speed, balance, time). Data were analyzed using paired t-tests (within-group) and ANCOVA (between-group), with p ≤ 0.05.

Results

The experimental group showed significant improvements: balance (96.15 ± 1.46 to 98.74 ± 1.86, p=0.0001), triple hop distance (414.29 ± 53.42 cm to 439.24 ± 26.19 cm, p=0.022), single-leg hop time (3.08 ± 0.24 s to 2.79 ± 0.29 s, p=0.015), and vertical jump (39.66 ± 3.49 cm to 44.13 ± 4.58 cm, p=0.014). Controls exhibited no significant changes (p>0.05). Between-group differences were significant for all measures (p<0.05, effect sizes 0.174–0.243).

Conclusions

Six weeks of RNT significantly enhances balance and performance in volleyball players post-ACL reconstruction, supporting its integration into rehabilitation protocols to optimize recovery and reduce re-injury risk.

Keywords: Anterior cruciate ligament, volleyball players, reactive neuromuscular training, dynamic balance, functional performance, rehabilitation

 

 

  1. Introduction

Anterior cruciate ligament (ACL) injuries represent one of the most common and debilitating knee injuries in sports, particularly in high-demand activities involving rapid changes in direction, jumping, and landing (1). In volleyball, a sport characterized by repetitive explosive movements such as spiking, blocking, and diving, ACL tears are prevalent, accounting for a significant proportion of lower extremity injuries (2). Studies indicate that the incidence of ACL injuries in volleyball players ranges from 0.1 to 0.9 per 1000 athlete-exposures, with non-contact mechanisms predominating in up to 70-80% of cases (3,4). These injuries often occur during landing phases, where improper biomechanics like knee valgus collapse or reduced knee flexion increase vulnerability (5). Female athletes are disproportionately affected, experiencing ACL injury rates 2-8 times higher than males, attributed to factors such as anatomical differences (e.g., wider pelvis, increased Q-angle), hormonal influences, and neuromuscular imbalances (6,7).

The consequences of ACL injuries extend beyond immediate pain and instability, leading to long-term deficits in balance, proprioception, and functional performance, which heighten the risk of re-injury upon return to sport (8). Post-reconstruction, athletes frequently exhibit persistent neuromuscular control issues, including asymmetrical loading, reduced explosive power, and impaired dynamic stability, which can compromise athletic performance and quality of life (9). Volleyball players, reliant on vertical jumps, quick lateral movements, and single-leg stability, are particularly susceptible to these impairments, potentially delaying return-to-play and increasing secondary injury rates (10).

Rehabilitation strategies emphasizing neuromuscular training have emerged as effective interventions to address these deficits. Reactive neuromuscular training (RNT), a specialized approach, utilizes perturbations (e.g., resistance bands) to enhance proprioceptive feedback, correct movement patterns, and promote dynamic muscular stabilization during functional activities (11). Evidence suggests that RNT can improve knee kinematics, reduce valgus moments, and enhance balance and performance metrics such as jump height and hop distance in post-ACL reconstruction athletes (12,13). For instance, studies have shown significant gains in dynamic balance and lower limb power following 4-8 weeks of neuromuscular protocols, with reduced re-injury risks (14,15). However, limited research has specifically examined RNT’s effects in volleyball players, a population with unique biomechanical demands.

This study aims to evaluate the impact of a six-week RNT program on balance and performance in male volleyball players with reconstructed ACL injuries. Using a quasi-experimental design with pre- and post-test assessments, we hypothesize that RNT will yield significant improvements in dynamic balance (Y Balance Test), explosive power (Vertical Jump Test), and functional performance (Triple Hop Distance and Single-Leg Hop for Time) compared to controls. These findings could inform tailored rehabilitation protocols to optimize recovery and prevent re-injury in this athletic cohort.

 

  1. Methods and material

2.1. Define Research Type and Design

The study employed a quasi-experimental pre-test/post-test design with two groups—an experimental group and a control group. This design was selected to incorporate an intervention variable while purposefully recruiting participants according to defined inclusion and exclusion criteria. To reduce bias and control potential confounding factors, participants were randomly assigned to the respective groups.

2.2. Identify Study Population:

The population consisted of male volleyball players from X city, who were the focus of the study due to their relevance to the research objectives.

2.3. Determine Sample Size and Selection

Based on calculations from sample size determination formulas and preliminary findings from a pilot study, the final sample was set at 30 individuals. To maintain equal representation, participants were randomly allocated into two groups, with 15 assigned to the experimental group and 15 to the control group.

2.4. Obtain Informed Consent

Prior to enrollment, all participants provided written informed consent. They received comprehensive explanations regarding the study’s aims and procedures to ensure their participation was fully informed and voluntary.

2.5. Collect Background Data

Information on participants’ personal, medical, and athletic backgrounds was obtained through structured questionnaires and interviews. Furthermore, anatomical and anthropometric assessments were conducted to document baseline characteristics.

2.6. Establish Inclusion Criteria

Eligibility criteria required participants to have a reconstructed anterior cruciate ligament (ACL) injury, be between 18 and 30 years of age, possess a minimum of three years of consistent volleyball experience (averaging three sessions per week), and maintain a normal body mass index (BMI) ranging from 20 to 25. Additional requirements included the absence of noticeable lower limb deformities (such as femoral anteversion, genu varum, genu valgum, tibial torsion, or flat feet), no prior surgeries involving the trunk or upper limbs, no ongoing lower limb pathologies (including degenerative joint conditions or ankle instability), and active enrollment in an ACL injury prevention training program.

2.7. Define Exclusion Criteria

Participants were excluded if they failed to cooperate during the study, missed two consecutive training sessions, or experienced pain during training activities.

2.8. Assign Participants to Groups

Participants were randomly allocated to one of two groups: the experimental group, which participated in the designated training intervention, or the control group, which maintained their usual daily routines without engaging in targeted training or being informed about the activities undertaken by the experimental group.

2.9. Conduct Pre-Test Measurements

At the scheduled time, participants reported to the designated testing site. Following a 10-minute warm-up and orientation to the testing procedures, baseline data were collected through three valid trials for each of four assessments: the Y Balance Test to evaluate dynamic balance, the Vertical Jump Test to measure explosive power, the Triple Hop Distance Test to assess power, speed, and balance, and the Single-Leg Hop for Time over 6 meters to examine power, speed, balance, and timing.

2.10. Implement Y Balance Test

For the Y Balance Test, participants stood on their dominant leg at the center of a Y-shaped apparatus and pushed a movable component as far as possible in three specific directions—anterior, posteromedial, and posterolateral—at angles of 135°, 135°, and 90°, respectively, while avoiding errors such as shifting the stance foot or losing balance. The reach distance in each direction was recorded, normalized to leg length, and expressed as a percentage. A composite score was then determined by averaging the three directional percentages. Reported reliability coefficients ranged from 0.85 to 0.91 for inter-rater measurements, 0.99 to 1.00 for intra-rater measurements in individual directions, and 0.91 to 0.99 for the composite score.

2.11. Perform Vertical Jump Test

In the Vertical Jump Test, participants stood with their feet shoulder-width apart and used chalk-covered fingers to mark their standing reach height (zero point). They then performed a maximal vertical jump, marking the highest point reached. The jump height was calculated as the difference between the standing reach and the peak jump mark, and the average of three trials was recorded as the final score.

2.11. Execute Triple Hop Distance Test

For the Triple Hop Distance Test, participants stood behind a starting line on their dominant leg and executed three consecutive maximal hops in a straight line while keeping their hands on their hips. The distance from the starting line to the heel at the landing of the third hop was measured, and the mean of three trials was calculated as the final score. This test demonstrated a reliability coefficient of 0.98.

2.12. Conduct Single-Leg Hop for Time Test

Participants performed a rapid hop over a distance of 6 meters using their dominant leg, keeping their hands positioned behind their back. They began from a designated starting line and ended upon crossing a marked finish line. Each participant completed three trials, with the fastest time among these recorded. The test demonstrated high reliability, with consistency coefficients ranging from 0.82 to 0.92.

2.13. Implement Training Program

The experimental group underwent 16 sessions of Reactive Neuromuscular Training (RNT), aimed at enhancing movement patterns by promoting active error detection and providing feedback. During training, TheraBand resistance bands generated perturbing forces, with the intensity carefully maintained below 6 on the Borg scale to avoid fatigue. Each session began with a 10-minute warm-up, followed by 40 minutes of RNT focused on deliberately increasing knee valgus under professional supervision. Additionally, one session served as a rest day to act as a control condition.

2.14. Monitor Control Group

The control group maintained their regular daily activities without any intervention, while monitoring and reporting any changes in their routines to ensure consistency throughout the study.

2.15. Conduct Post-Test Measurements

Following the completion of the 16-session intervention, both groups performed the same four assessments Y Balance, Vertical Jump, Triple Hop Distance, and Single-Leg Hop for Time under identical conditions to the pre-test. For each test, three valid attempts were recorded.

2.16. Analyze Data

Raw data were processed using SPSS version 22. Descriptive statistics summarized the data, while inferential statistics, including independent-samples t-tests (for between-group comparisons) and paired-samples t-tests (for within-group pre-test/post-test changes), were used to analyze differences. The significance level was set at p ≤ 0.05.

 

 

  1. Result

3.1. Descriptive Findings:

Table 1 presents a detailed summary of the descriptive statistics for key demographic characteristics of the participants, including age, height, and weight, separately for the experimental and control groups. The data are expressed as means accompanied by their corresponding standard deviations, offering insight into the variability within each group. Specifically, the experimental group consisted of 15 individuals with an average age of 25.86 years, showing a moderate spread around this mean with a standard deviation of 3.35 years. Their average height was measured at 177.53 centimeters, with variability indicated by a standard deviation of 5.69 cm. Similarly, the mean weight for this group was 71.73 kilograms, accompanied by a standard deviation of 5.81 kg, reflecting individual differences in body mass. In comparison, the control group, also comprising 15 participants, was slightly younger on average, with a mean age of 23.06 years and a somewhat wider age range reflected in a standard deviation of 3.67 years. Their mean height was 178.80 cm, with a standard deviation of 7.02 cm, indicating marginally greater height variability than the experimental group. The control group’s average weight was 69.86 kilograms, with a standard deviation of 5.20 kg, suggesting a slightly narrower distribution in body weight. These demographic data provide a comprehensive baseline overview, highlighting that both groups are relatively comparable in terms of physical characteristics, although minor differences exist in age and anthropometric measures.

Table 1. Mean and Standard Deviation of Age, Height, and Weight of Participants.

Variable Group Number Mean Standard Deviation
Age Experimental 15 25.86 3.35
Control 15 23.06 3.67
Height Experimental 15 177.53 5.69
Control 15 178.80 7.02
Weight Experimental 15 71.73 5.81
Control 15 69.86 5.20

Table 2 provides a comprehensive overview of the statistical measures for key performance variables balance, triple hop distance, single-leg hop time over 6 meters, and vertical jump—for both the experimental and control groups during the pre-test and post-test assessments. In terms of balance, the experimental group demonstrated a noticeable improvement, with the mean score increasing from 96.15 (SD = 1.46) before the intervention to 98.74 (SD = 1.86) afterward. In contrast, the control group showed a marginal change, with a slight increase from 97.04 (SD = 0.97) at baseline to 97.14 (SD = 1.51) post-test, indicating relatively stable performance. Regarding the triple hop distance, the experimental group exhibited a marked enhancement, increasing their average distance from 414.29 cm (SD = 53.42) pre-intervention to 439.24 cm (SD = 26.19) post-intervention. Conversely, the control group experienced a decline, with their mean distance decreasing from 423.35 cm (SD = 33.05) to 411.36 cm (SD = 33.88). For the single-leg hop time over a 6-meter distance, the experimental group showed a significant improvement, reducing their mean time from 3.08 seconds (SD = 0.24) before the sessions to 2.79 seconds (SD = 0.29) after the intervention. Meanwhile, the control group’s performance slightly deteriorated, with their average time increasing from 2.97 seconds (SD = 0.27) to 3.05 seconds (SD = 0.22). Lastly, vertical jump height also improved in the experimental group, rising from a mean of 39.66 cm (SD = 3.49) at pre-test to 44.13 cm (SD = 4.58) post-test. The control group, however, experienced a slight reduction, with mean jump height decreasing from 39.40 cm (SD = 3.08) to 39.20 cm (SD = 3.36). Overall, these results suggest that the experimental intervention had a positive effect on all measured physical performance variables, while the control group generally maintained or slightly declined in performance across the same metrics.

Table 2. Statistical Indices for Research Variables.

Variable Group Pre-Test Mean ± SD Post-Test Mean ± SD
Balance Experimental 96.15 ± 1.46 98.74 ± 1.86
Control 97.04 ± 0.97 97.14 ± 1.51
Triple Hop Distance (cm) Experimental 414.29 ± 53.42 439.24 ± 26.19
Control 423.35 ± 33.05 411.36 ± 33.88
Single-Leg Hop Time (6m, sec) Experimental 3.08 ± 0.24 2.79 ± 0.29
Control 2.97 ± 0.27 3.05 ± 0.22
Vertical Jump (cm) Experimental 39.66 ± 3.49 44.13 ± 4.58
Control 39.40 ± 3.08 39.20 3.36

3.2. Inferential Findings

This section first examines the assumptions required for statistical analysis, followed by the testing of the research hypotheses using appropriate statistical tests.

3.3. Examination of Research Assumptions

The initial assumption assessed was whether the data followed a normal distribution, which was evaluated using the Shapiro-Wilk test, as detailed in Table 3. The findings reveal that for all measured variables—including balance, triple hop distance, single-leg hop time, and vertical jump—across both the experimental and control groups and during both pre-test and post-test phases, the p-values exceeded the 0.05 threshold. This outcome confirms that the data met the assumption of normality (p > 0.05) for all conditions examined.

Table 3. Shapiro-Wilk Test Results.

Variable Group Phase Statistic p-value
Balance Experimental Pre-Test 0.92 0.19
Post-Test 0.91 0.14
Control Pre-Test 0.96 0.81
Post-Test 0.93 0.28
Triple Hop Distance Experimental Pre-Test 0.88 0.06
Post-Test 0.94 0.41
Control Pre-Test 0.91 0.18
Post-Test 0.88 0.06
Single-Leg Hop Time (6m) Experimental Pre-Test 0.98 0.97
Post-Test 0.90 0.12
Control Pre-Test 0.90 0.13
Post-Test 0.97 0.87
Vertical Jump Experimental Pre-Test 0.89 0.07
Post-Test 0.91 0.16
Control Pre-Test 0.91 0.15
Post-Test 0.93 0.34

The second assumption tested was the homogeneity of variances using Levene’s test, as presented in Table 4. The p-values for all variables were greater than 0.05, indicating that the assumption of equal variances was met (p > 0.05).

Table 4. Levene’s Test Results

Variable Test Statistic p-value
Balance 2.24 0.14
Triple Hop Distance 0.19 0.66
Single-Leg Hop Time (6m) 2.29 0.14
Vertical Jump 3.60 0.06

The third assumption was the homogeneity of regression slopes, evaluated in Table 4-5. The p-values for all variables were greater than 0.05, confirming that the assumption of homogeneous regression slopes was satisfied (p > 0.05).

Table 5. Homogeneity of Regression Slopes Results

Variable Test Statistic p-value
Balance 1.87 0.18
Triple Hop Distance 0.04 0.83
Single-Leg Hop Time (6m) 2.33 0.13
Vertical Jump 0.01 0.89

3.4. Testing the First Hypothesis

The first hypothesis investigated whether a six-week course of reactive neuromuscular training (RNT) produces a significant improvement in the balance of volleyball players who have undergone anterior cruciate ligament (ACL) reconstruction. The null hypothesis (H0) asserted that RNT would have no meaningful impact on balance, whereas the alternative hypothesis (H1) proposed that RNT would lead to a significant enhancement. To evaluate changes within each group between the pre-test and post-test, paired-samples t-tests were performed, with the outcomes presented in Tables 4 through 6. The experimental group demonstrated a statistically significant improvement in balance, with the mean score rising from 96.15 (SD = 1.46) at baseline to 98.74 (SD = 1.86) post-intervention (t = -5.92, degrees of freedom = 14, p = 0.0001). Conversely, the control group exhibited no significant difference, with mean balance scores of 97.04 (SD = 0.97) pre-test and 97.14 (SD = 1.51) post-test (t = -1.22, df = 14, p = 0.240). These findings are visually depicted in Figure 4-1, which clearly illustrates the substantial increase in mean balance for the experimental group compared to the relatively stable performance in the control group.

Table 6. Paired-Samples t-Test Results for Within-Group Balance Comparison.

Group Pre-Test Mean ± SD Post-Test Mean ± SD df t p-value
Experimental 96.15 ± 1.46 98.74 ± 1.86 14 -5.92 0.0001
Control 97.04 ± 0.97 97.14 ± 1.51 14 -1.22 0.240

Figure 1. Changes in the average balance of groups during the pre-test and post-test phases.

An analysis of covariance (ANCOVA) was conducted to compare balance outcomes between the experimental and control groups while controlling for baseline (pre-test) scores, as detailed in Table 7. The analysis revealed a statistically significant difference between groups (F = 8.66, df = 1, p = 0.007), with a moderate effect size of 0.243. After adjusting for initial balance levels, the experimental group showed a significantly higher mean balance score (adjusted mean = 17.73) compared to the control group. These findings support the hypothesis that six weeks of reactive neuromuscular training (RNT) leads to a meaningful improvement in balance among volleyball players recovering from ACL injuries.

Table 7. ANCOVA Results for Between-Group Balance Comparison.

Source Sum of Squares df Mean Square F p-value Effect Size
Group 17.73 1 17.73 8.66 0.007 0.243

3.5. Testing the Second Hypothesis

The second hypothesis investigated whether six weeks of RNT significantly affects the performance (measured via triple hop distance, single-leg hop time over 6 meters, and vertical jump) of volleyball players with reconstructed ACL injuries. The null hypothesis (H0) stated no significant effect, while the alternative hypothesis (H1) posited a significant effect. Paired-samples t-tests were used to evaluate within-group changes, with results presented in Table 8. For triple hop distance, the experimental group improved significantly from 414.29 cm (SD=53.42) to 439.24 cm (SD=26.19) (t=-2.58, df=14, p=0.022), while the control group showed no significant change (423.35 cm to 411.36 cm, t=0.89, df=14, p=0.384). For single-leg hop time, the experimental group improved from 3.08 seconds (SD=0.24) to 2.79 seconds (SD=0.29) (t=2.76, df=14, p=0.015), while the control group showed no significant change (2.97 seconds to 3.05 seconds, t=-1.34, df=14, p=0.200). For vertical jump, the experimental group improved from 39.66 cm (SD=3.49) to 44.13 cm (SD=4.58) (t=-2.79, df=14, p=0.014), while the control group showed no significant change (39.40 cm to 39.20 cm, t=-0.63, df=14, p=0.535). Figures 2, 3, and 4 illustrate these changes, showing improvements in the experimental group for triple hop distance, single-leg hop time, and vertical jump, respectively, compared to minimal or no changes in the control group.

Figure 2. Changes in the average balance of groups during the pre-test and post-test phases.

Figure 3. Changes in the average time of single-leg jump at a distance of six meters in the groups during the pre-test and post-test phases

Figure 4. Changes in the average vertical jump of the groups during the pre-test and post-test phases.

 

Table 8. Paired-Samples t-Test Results for Within-Group Performance Comparison.

Variable Group Pre-Test Mean ± SD Post-Test Mean ± SD df T p-value
Triple Hop Distance (cm) Experimental 414.29 ± 53.42 439.24 ± 26.19 14 -2.58 0.022
Control 423.35 ± 33.05 411.36 ± 33.88 14 0.89 0.384
Single-Leg Hop Time (6m, sec) Experimental 3.08 ± 0.24 2.79 ± 0.29 14 2.76 0.015
Control 2.97 ± 0.27 3.05 ± 0.22 14 -1.34 0.200
Vertical Jump (cm) Experimental 39.66 ± 3.49 44.13 ± 4.58 14 -2.79 0.014
Control 39.40 ± 3.08 39.20 ± 3.36 14 -0.63 0.535

Between-group comparisons were performed using ANCOVA with pre-test scores as covariates, as summarized in Table 9. The analysis revealed significant differences favoring the experimental group across multiple performance metrics: triple hop distance (F = 5.67, df = 1, p = 0.024, effect size = 0.174), single-leg hop time (F = 8.24, df = 1, p = 0.008, effect size = 0.234), and vertical jump height (F = 7.26, df = 1, p = 0.012, effect size = 0.212). These results demonstrate that participants who underwent six weeks of reactive neuromuscular training (RNT) significantly outperformed the control group in all evaluated measures of physical performance, thereby confirming the study hypothesis.

Table 9. ANCOVA Results for Between-Group Performance Comparison.

Variable Source Sum of Squares df Mean Square F p-value Effect Size
Triple Hop Distance Group 5728.67 1 5728.67 5.67 0.024 0.174
Single-Leg Hop Time (6m) Group 0.57 1 0.57 8.24 0.008 0.234
Vertical Jump Group 118.76 1 118.76 7.26 0.012 0.212

 

 

  1. Discussion

This chapter synthesizes the findings of the study, comparing them with previous research to contextualize the results and draw meaningful conclusions. The study, a quasi-experimental design with a pre-test/post-test structure, involved 30 male volleyball players from X city, aged 18–30 years, with at least three years of regular volleyball participation. These participants, selected based on specific inclusion and exclusion criteria, were randomly assigned to experimental and control groups (15 participants each). The experimental group underwent a four-week reactive neuromuscular training (RNT) program, while the control group continued their routine activities. Measurements included balance (Y Balance Test), triple hop distance, single-leg hop time over 6 meters, and vertical jump, assessed before and after the intervention. Statistical analyses, conducted using SPSS version 22, utilized paired-samples t-tests and ANCOVA, with a significance level of p ≤ 0.05. Notably, the document incorrectly states that data were not normally distributed; however, the results from Chapter 4 (Table 4-3) confirm normality (p > 0.05), suggesting the use of parametric tests was appropriate.

The knee joint’s position in the middle of the lower limb kinematic chain makes it particularly vulnerable to excessive forces during weight-bearing sports activities, such as volleyball, where loads from the upper body are transmitted through the hip to the foot. The contraction of thigh muscles significantly influences knee loading, as noted in prior studies (16). Research indicates that lower limb injuries, particularly anterior cruciate ligament (ACL) injuries, are prevalent in volleyball, with ACL injuries being the most common in both genders, especially among athletes aged 15–25 years (17–20). Non-contact ACL injuries, occurring without direct contact with an object or player, are more frequent than contact injuries and are often associated with movements involving deceleration, jump-landing, and repetitive pivoting, common in sports like volleyball and handball (21–24). Women are reported to be 2–8 times more susceptible to ACL injuries than men, potentially due to anatomical and structural differences (25–28).

The first hypothesis tested whether six weeks of RNT significantly improves balance in volleyball players with reconstructed ACL injuries. The paired-samples t-test results (Table 4-6) demonstrated a significant improvement in the experimental group’s balance, from a mean of 96.15 (SD=1.46) to 98.74 (SD=1.86) (t=-5.92, p=0.0001), while the control group showed no significant change (97.04 to 97.14, t=-1.22, p=0.240). ANCOVA results (Table 4-7) confirmed a significant between-group difference (F=8.66, p=0.007, effect size=0.243), indicating that RNT significantly enhanced balance compared to the control group. These findings align with several studies. Saki et al. (2018) investigated plyometric training in 26 women with dynamic knee valgus, finding significant improvements in knee valgus angle after eight weeks, though no significant change in pelvic drop angle was observed (p > 0.05). Mohammadi et al. (2018) examined corrective exercises in 32 basketball players with dynamic knee valgus, reporting significant improvements in range of motion, strength, and performance, suggesting potential for injury prevention (29). Janot et al. (2013) found that TRX training significantly improved muscular fitness indices in both young and older adults, enhancing core and muscular endurance (30). Kim et al. (2013) demonstrated that neurofeedback suspension training improved postural balance and muscle activation patterns in individuals with chronic low back pain (31). These studies collectively support the efficacy of training interventions, including RNT, in improving balance by enhancing neuromuscular coordination and muscle activation, particularly in stabilizing muscles.

The second hypothesis evaluated whether six weeks of RNT significantly improves performance (measured via triple hop distance, single-leg hop time over 6 meters, and vertical jump) in volleyball players with reconstructed ACL injuries. Paired-samples t-test results (Table 4-8) showed significant improvements in the experimental group: triple hop distance increased from 414.29 cm (SD=53.42) to 439.24 cm (SD=26.19) (t=-2.58, p=0.022), single-leg hop time improved from 3.08 seconds (SD=0.24) to 2.79 seconds (SD=0.29) (t=2.76, p=0.015), and vertical jump height rose from 39.66 cm (SD=3.49) to 44.13 cm (SD=4.58) (t=-2.79, p=0.014). The control group showed no significant changes (p > 0.05 for all measures). ANCOVA results (Table 4-9) confirmed significant between-group differences for triple hop distance (F=5.67, p=0.024, effect size=0.174), single-leg hop time (F=8.24, p=0.008, effect size=0.234), and vertical jump (F=7.26, p=0.012, effect size=0.212), indicating superior performance in the experimental group. These findings are consistent with prior research. Mohammadi et al. (2018) reported that corrective exercises improved strength, range of motion, and performance in basketball players, aiding injury prevention (29). Rajasekar et al. (2018) found that kinesiotaping significantly reduced dynamic knee valgus immediately after application, with sustained improvements in gluteus medius strength, supporting neuromuscular control enhancements (32). Nagano et al. (2011) demonstrated that five weeks of jumping and balance training improved knee flexion and hamstring activity during single-leg landings in female basketball players (33). Asalani et al. (2018) showed that TRX and hopping exercises equally improved static and dynamic balance, stability limits, and performance in male athletes (34). These studies corroborate the current findings, highlighting the role of targeted training in enhancing lower limb performance and reducing biomechanical risk factors for ACL injuries.

The effectiveness of RNT in this study is likely due to its focus on improving movement patterns through active error detection and feedback, as described. By engaging stabilizing muscles, particularly core and lower limb muscles, RNT enhances proprioceptive feedback and motor control, correcting deviations such as dynamic knee valgus. This aligns with the observed improvements in balance and performance, which are critical for rehabilitation and injury prevention in athletes with reconstructed ACLs. The study’s results suggest that RNT can play a significant role in re-educating movement patterns, enhancing muscle synergy, and reducing injury risk by addressing modifiable biomechanical factors.

In conclusion, the study confirms that six weeks of RNT significantly improves both balance and performance in male volleyball players with reconstructed ACL injuries. These findings are supported by a robust body of literature demonstrating the efficacy of neuromuscular and corrective training in enhancing joint stability, muscle strength, and functional performance. The implications for practice include the integration of RNT into rehabilitation and training programs for athletes with ACL injuries to optimize recovery and prevent re-injury. Future research could explore longer intervention durations, diverse athlete populations, or comparisons with other training modalities to further validate and expand these findings.

 

 

  1. Conclusion

The study confirms that six weeks of RNT significantly improves both balance and performance in male volleyball players with reconstructed ACL injuries. These findings are supported by a robust body of literature demonstrating the efficacy of neuromuscular and corrective training in enhancing joint stability, muscle strength, and functional performance. The implications for practice include the integration of RNT into rehabilitation and training programs for athletes with ACL injuries to optimize recovery and prevent re-injury. Future research could explore longer intervention durations, diverse athlete populations, or comparisons with other training modalities to further validate and expand these findings.

 

 

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Influence of Reactive Neuromuscular Training on Stability and Performance in Volleyball Players Recovering from ACL Injury

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