The Effect of Neuromuscular Training on Functional Movement Screen Scores in Injury-Prone Military Athletes

Pre-participation examinations are the standard approach for assessing poor movement quality that would increase musculoskeletal injury risk. On the other hand, the neuromuscular control plays a significant role in the prevention of injury and rehabilitation. The main purpose of this study was to determine the effect of an 8-week neuromuscular training on functional movement screen (FMS) in injury-prone military athletes. In the present quasi-experimental study, forty injury-prone male military athlete were identified by functional movement Screen. Functional Movement screen were assessed before and after the 8-week program. Participants were placed into 1 of the 2 groups: intervention (n = 20) and control (n = 20). The intervention group was required to complete a neuromuscular training program that met 3 times per week for 8-week. Data analysis was done using the independent t-test and analysis of covariance at the significant level of p < 0.05. The comparison of total FMS score indicated a significant difference (P < 0.05 and effect size = 0.83) between intervention (17.75 ± 1.55) and control (11 ± 1.55) groups. A significant improvement in mobility (p < 0.05 and effect size = 0.39), stability (p < 0.05 and effect size = 0.77) and advanced movement (p < 0.05 and effect size = 0.75) were also found.


Abstract Background
Pre-participation examinations are the standard approach for assessing poor movement quality that would increase musculoskeletal injury risk. On the other hand, the neuromuscular control plays a significant role in the prevention of injury and rehabilitation. The main purpose of this study was to determine the effect of an 8-week neuromuscular training on functional movement screen (FMS) in injury-prone military athletes.

Methods
In the present quasi-experimental study, forty injury-prone male military athlete were identified by functional movement Screen. Functional Movement screen were assessed before and after the 8-week program. Participants were placed into 1 of the 2 groups: intervention (n = 20) and control (n = 20). The intervention group was required to complete a neuromuscular training program that met 3 times per week for 8-week. Data analysis was done using the independent t-test and analysis of covariance at the significant level of p < 0.05.

Results
The comparison of total FMS score indicated a significant difference (P < 0.05 and effect size = 0.83) between intervention (17.75 ± 1.55) and control (11 ± 1.55) groups. A significant improvement in mobility (p < 0.05 and effect size = 0.39), stability (p < 0.05 and effect size = 0.77) and advanced movement (p < 0.05 and effect size = 0.75) were also found.

Conclusion
An 8-week neuromuscular training program enhances functional movement screen in military athletes. It seems that this training program can minimize injury risk in injury-prone individuals. Background Individuals in the armed forces of all countries and military personnel are largely different from the ordinary individuals due to some physical fitness and characteristics [1]. There are jobs with high levels of stress, including military jobs. Numerous studies on the high vulnerability of military forces in various groups confirm this issue [2,3]. This is especially important in military organizations that have trained personnel in specialized fields and spend a great deal of time and money on their training as their damage can lead to economic losses to the organization, affect their function and ultimately reduce military strength and readiness [3].
Due to the risk of injury after participation in sports activities and the importance of identifying injured military athletes, screening is significantly important before participation in sports activities.
Risk factors and their association with injury also need further evaluation. A number of these evaluation methods have primarily focused on distinct factors such as power or range of motion.
Since a combination of different factors is effective in causing injury, researchers have thus focused on evaluating comprehensive movement patterns for injury prevention [4]. Functional Movement Screen (FMS) is a method that can detect motor dysfunctions using translational motion that can identify high-risk individuals in addition to evaluating quality of implementation of functional movement patterns [4].

Cook et al. introduced Functional Motion Screen by considering pre-season screening and
performance-related factors. The Functional Movement Screen was developed to evaluate movement performance during 7 movement patterns [4]. Scores from each movement are summed for a maximal composite score of 21 and a composite score of ≤ 14 is suggestive of increased injury risk in male football players [5], female collegiate athletes [6], and male military candidates [7].
The applied tests in the FMS such as the deep squat, the hurdle step and lunge challenge factors such as coordination, limb mobility, postural control, balance, pelvic and core stability [4]. These tests are designed to interact between motor chain mobility and the necessary stability to implement functional movement patterns and simply measure the state of neuromuscular coordination, especially core stability and balance [4]. The reduced individual stability and mobility decreases the FMS score and puts the individuals at a greater risk of injury. A great number of studies indicate that people with lower scores in the FMS test are forced to use compensatory movement patterns for optimal performance while exercising and this can also exert extra force on some body structures, thereby increasing the likelihood of injury [7].
Risk factors, which are common in most injuries among athletes include agonist and antagonist muscle involvement in strength, endurance and abnormal skeletal muscle structure, neuromuscular control, core muscle weakness, and bilateral imbalance or lack of muscle symmetry [8]. Given the above risk factors, various exercise activities are performed to reduce the likelihood of injury, including neuromuscular exercises that are performed to increase joint stability, improve proprioception, and develop protective reflexes to prevent injury because neuromuscular control dysfunctions play important roles in the likelihood of injury [9]. There is some evidence that proprioception is involved in maintaining the balance and proper functions of lower extremities and reducing the likelihood of injury; and it has been found that neuromuscular training programs are more effective than strength training in improving the muscle reaction [10]. Therefore, neuromuscular exercises aim to develop neuromuscular control, thereby increasing the joint stability that may reduce the likelihood of injury. These types of programs include strength, stretching, plyometric, balance and stability exercises [11]. The balance and core stability exercises can prevent or reduce the severity of lower extremity injury in male and female athletes [12]. They also cause better interaction of neuromuscular system and can improve functions of feet and lower extremities [13].
Military research has found that preventive injury training programs, which focus on strengthening muscles of core stability (trunk control), agility and balance and do not use any additional equipment such as balance balls or wobble board, decrease the incidence of injury by 20-30% [14,15].
As the prevalence of injury increases, it is important to prevent them and identify factors that make people prone to injuries. Given the high prevalence and cost of treatment as well as long duration of musculoskeletal injuries, the sensitivity and importance of preventing these injuries seem essential among military personnel. Therefore, the purpose of this study was to determine the effect of an 8week neuromuscular training on functional movement screen in injury-prone military athletes.

Materials And Methods Participants
This quasi-experimental study consisted of forty physically active male military athletes prone to injury (with a score of ≤ 14 in the FMS) between the ages of 24 and 33 that volunteered for this study.
Military athletes (martial arts = 10, wrestling = 8, futsal = 12, volleyball = 10) were defined as militaries who participated in military sport teams, were currently in their off-season, and that were training at least 3 times per week (> 1.5 h/week). All participants were currently free from any kind of musculoskeletal injury, had not sustained any kind of musculoskeletal injury within the past 6 weeks, and had never undergone surgery for a musculoskeletal condition. For this purpose, the individuals were entered into the study with the approval of a physician and reviewing medical records.
Participants were selected by availability and purposive sampling that were assigned to either the training group (20 male: age = 27.45 ± 2.3 years, height = 176.72 ± 5.1 cm, weight = 75.02 ± 3.5 kg) or the control group (20 male: age = 27.20 ± 2.4 years, height = 176.42 ± 5.5 cm, weight = 74.05 ± 3.6 kg) based on their availability to participate in training. All participants completed all phases of the investigation and gave written informed consent before any data collection.

Procedures
All testing and training was done in the School of Sports Sciences health Center. This study was comprised of three phases: 1) pre-testing, 2) a supervised neuromuscular training three times per week for 8 weeks, and 3) post-testing. Prior to pre-testing, participants were familiarized to all aspects of the study protocol and performed practice trials of all assessments. During pre-and post-testing, all testers utilized the same verbal instructions. Once assigned, the intervention group was required to complete neuromuscular training 3 times per week in addition to their usual training routine. The Control group received no intervention. They were instructed to maintain usual daily activities for the duration of the 8-week intervention. All participants were in the off season of their respective sports and none of the athlete's off season training programs included neuromuscular training. Post-testing was conducted in a manner identical to pre-testing. All sessions were supervised by the one of researchers, who has qualifications as a personal trainer. The neuromuscular training program was designed to enhance movement control and, as well as to increase the stability of the trunk, knee and ankle. The focus of all of the exercises was on the use of proper technique, such as good posture, maintenance of core stability or positioning of the hips, knees and ankles, especially "knee over toe" position. The neuromuscular training program included 9 exercises: 1) One-leg standing with a stick, 2) Squat exercises with a stick using, respectively, two legs or one leg, 3) Horizontal side support, 4) Jumping from side to side, 5) Modified pushups, 6) Stretching exercise for hip flexor muscles, 7) Hamstring exercise on the knees, 8) Stretching exercise with a stick for hamstring muscles and 9) Upper-body rotation while lying on one's side; a "yoga stretch". Participants were instructed to maintain a neutral position of the spine while holding the correct exercise position. The intensity and volume of each neuromuscular exercise were progressed gradually at a standard rate as previously described and shown in the Supplemental file [16].

Measures
The Functional Movement Screen (FMS) is composed of the following seven tasks: 1) Deep squat (DS); 2) Hurdle step (HS); 3) In-line lunge (ILL); 4) Shoulder mobility (SM); 5) Active straight leg raise (SLR); 6) Trunk stability push-up (PU); 7) Rotary stability (RS) (Fig. 1). "Clearing" tests (impingement, press up, and posterior rocking) are also included with the SM, PU and RS to expose other painful movements that may be overlooked while performing the primary FMS tasks. Additional details of each task have been published previously [4,17,18]. Each task is scored, and a 4-point scale (0-3) and on tests where left and right sides are measured, the lowest score is used, giving a total score out of 21 [4,17,18]. A score of 3 was assigned if the participant performed a functional movement pattern with no movement compensation. A score of 2 was assigned if the participant performed a functional movement pattern, with some degree of compensation. A score of 1 was assigned if the participant was unable to perform or complete a functional movement pattern according to published guidelines, and a score of 0 was reserved for participants who had pain with the movement or presented with pain while performing a clearing test [4]. Screens were performed in a convenience order, and participants were given adequate rest to account for fatigue. FMS has internal reliability and high router (ICC = .98) between experienced and novice experimenters [19,20]. Before starting the study, the examiners conducted a preliminary study of 14 participants to obtain the reliability of the interrater in proportion to the previously published values.
Scores were reported and analyzed in several ways to determine the efficacy of the neuromuscular training program. First, a composite score was calculated for the 7 tests by summing the final score for each assessment. Second, individual FMS tests were subcategorized into one of the following 3 categories: 1) Mobility, 2) Stability, and 3) Advanced movements. Mobility tests included the active straight leg raise and shoulder mobility assessment. Stability tests included the trunk stability push-up and the rotary stability assessment. Advanced movements included the deep squat, hurdle step, and inline lunge. Final scores for each category were summed to determine a composite score for that category [21].

Analyses
Data were analyzed using SPSS statistical software 22 (IBM, Armonk, NY, USA). ). Independent t-test was used to compare the mean of Participants' descriptive characteristics between intervention and control groups. Analysis of covariance test was performed to determine statistically significant differences between-FMS scores between the two groups. Significance level was set a priori at p < 0.05. Table 1 presents participants' personal characteristics. Based on results of the independent t-test, there was no significant difference between personal characteristics of the two groups.

Results
Descriptive statistics are presented in Tables 2, 3. A significant improvement in total FMS score was found following the 8-week neuromuscular program (p = 0.001, effect size = 0.83). A significant difference was found between all three stability (effect size = 0.77, F = 115.33, P < 0.05), and advanced movements (effect size = 0.75, F = 100.34, P < 0.05) and mobility (effect size = 0.39, F = 23.12, P < 0.05).    [23], Finch et al. [24], Bodden et al. [25] and Kiesel et al. [26]. In a study on the effectiveness of a personalized corrective training program on the active firefighters' scores of functional movement screening test, Stanek et al. [21] classified tests into three categories: mobility, stability, and advanced movement tests. They reported that total FMS scores and the stability and advanced movement tests significantly improved due to the corrective training program, but mobility scores were not statistically significant despite their increase. In the present study, scores of all three categories of mobility, stability and advanced movement tests were also significantly improved, while effect sizes of three categories showed lower improved scores of mobility test than other two categories. Bagherian et al. [23] examined the impact of core stability training on the functional movement pattern in college athletes and indicated that eight weeks of core stability training resulted in improved functional movement and dynamic postural control in athletes. Finch et al. [24] also examined the effect of neuromuscular training program on injury prevention in football players. They suggested that neuromuscular exercises might help reduce the likelihood of injury in football players.

Discussion
Bodden et al. [25] and Kiesel et al. [26] also used a training algorithm by designed Cook in their separate training programs. This algorithm uses specific corrective exercises that are performed for four sessions per week and target movement pattern restrictions associated with seven tests of FMS [25,26]. A program by Bodden et al. [25] focused on weak or asymmetric scores for 8 weeks with an initial emphasis on mobility patterns and then stability patterns. Kiesel et al. [26] [27]. Wright et al. [28] also stated that four weeks of exercise using body weight or elastic bands, which emphasizes performance quality, would have little effect on the functional movement screening scores of physically active students. They mentioned the short duration of study as its reason and stated that exercises might only affect components in isolation and not affect movement patterns over a short period. Based on the results of above-mentioned studies, intervention programs, which directly involve specific movement patterns in adult athletes, may affect FMS scores [25,26]. On the contrary, intervention programs, which focus on the coordination and control of the whole body or maximization of performance and fitness, may not be successful in improving movement patterns [27]. Results of a research by Siamaki et al. [29] were in contrast to this issue. They found that basic movement patterns were improved using the FMS after 10 weeks of functional training in young male soccer players. Principles of training, especially the principle of specificity and selection of appropriate training variables were provided in their program. Siamaki et al. [29] believed that despite non-direct