Muscle Asymmetry Research Articles

Evaluating pelvic rotator strength: Investigating asymmetry and its correlation with pelvic rotation angle during active straight leg raise

Background Although lumbopelvic rotation control muscle is important to maintain pelvic neutral alignment during active straight leg raise (ASLR), pelvic rotator strength has not been evaluated. Thus, a novel method is needed to measure pelvic rotator strength and to determine whether pelvic rotator muscle asymmetry is related to side difference in transverse plane pelvic rotation angle (TrPRA) during ASLR. Objective To find average pelvic rotator strength, verify the reliability of pelvic rotator strength measurement method, and identify the correlation between pelvic rotator strength asymmetry and side difference in TrPRA during ASLR. Methods Forty healthy participants were enrolled. Pelvic rotator strength was measured using a hand-held dynamometer. TrPRA was measured using a smart KEMA motion sensor. Reliability was analyzed using intraclass correlation coefficient (ICC). The correlation between pelvic rotator strength asymmetry and side difference in TrPRA during ASLR was analyzed using Pearson's correlation coefficient. Results The average pelvic rotator strength was 120.3 N (72.9–202.2) for males and 94.4 N (58–125.8) for females. The reliability of pelvic rotator strength measurement demonstrated good to excellent intra- (ICC = 0.87–0.97) and inter-rater (ICC = 0.93–0.98) values. A significant moderate relationship existed between pelvic rotator strength asymmetry and side difference in TrPRA during ASLR (r = 0.39, p < 0.05). Conclusion The pelvic rotator muscle strength measurement method can be clinically used with good to excellent intra- and inter-rater reliability. Pelvic rotator strength asymmetry should be considered to evaluate and manage the pelvic rotation control during ASLR.

Functional and Lateral Asymmetry of the Knee Joint Muscles Measured Using Tensiomyography (TMG) in Professional Football Players of Different Playing Positions.

Background/Objectives: The aim of this study is to determine whether different playing positions in football influence muscle asymmetry, which is a common cause of injuries in football. This study aimed to determine the difference in the functional and lateral asymmetry of the knee joint muscles measured using tensiomyography (TMG) between football players of different playing positions. Methods: This study included 52 professional football players (25.1 ± 4.7 years) divided into three groups according to their playing position: defenders-DF (N = 18), midfielders-MF (N = 15), and forwards-FW (N = 19). Functional and lateral symmetry were investigated by applying TMG on the knee joint muscles Rectus femoris, Vastus medialis, Vastus lateralis, Biceps femoris, and Semitendinosus of the right and left leg, and using the algorithm proposed by the manufacturer and previous studies. Results: The results of one and two-way ANOVA revealed no significant differences in functional (F = 0.596, p = 0.555, on average) and lateral asymmetry (F = 0.888, p = 0.497, on average) from the aspect of muscle contraction velocity and muscle stiffness between football players of different playing positions. Conclusions: The study results show that the specificity of the playing position in football does not influence the functional and lateral asymmetry of the knee joint muscles. However, it has been shown that there is a high percentage of players with lateral (n = 14.5, 39.6%, on average) and specifically functional asymmetry (n = 27, 51.9%, on average).

TREATMENT OF PERIPHERAL FACIAL PARALYSIS AS PART OF MOTOR NEUROREHABILITATION

The disease of the facial nerve (n.facialis) is in the first place among peripheral neuritis, both in terms of frequency and significance of functional dysfunctions and post-paralytic facial synkinesis can develop in any paralysis of the face and is associated with significant functional and psychosocial consequences for sick patients. The type and severity of nerve injury determine the degree of pathologic change, capacity for regeneration and prognosis for recovery. In the case of facial nerve neuritis, the greatest emphasis is placed on early detection, correct diagnosis of the damage and starting rehabilitation as soon as possible. In addition to drug therapy in the rehabilitation of facial nerve paralysis, the application of physiotherapeutic means, as well as acupressure, a technique from traditional Chinese medicine, has a significant place. Both basic concepts are holistic, with a comprehensive approach to the patient and the determination of treatments based on the differentiation of symptoms. The aim of the research is to analyze the impact of physiotherapeutic means combined with acupressure - a technique from traditional Chinese medicine, in patients with peripheral paralysis of the n.facialis with a moderate degree of functional disorder. Material and methods: Six patients (3 women and 3 men) diagnosed with peripheral paralysis of the facial nerve (4 left side / 2 right side) with a moderate degree of functional impairment are included in the study. For the purposes of the research, the following physiotherapeutic means were applied: thermotherapy, light therapy, electrotherapy - electrophoresis with Novocain and electrostimulation, therapeutic exercises and acupressure on the following points: Zanzhu (BL2), Yangbai (GB14), Taiyang (EX-HN5), Zygoma (SL18), Xiaguan (ST7), Yingxiang (LI20) and Yifeng (TE17). For the purposes of the research, a functional examination with a manual muscle test (MMT) for facial muscles and a test for the subjective feeling of pain is applied to all subjects at the beginning, during the therapies and at the end of the overall motor neurorehabilitation. Results: From the processed results, the influence of physiotherapeutic means in combination with acupressure in patients with peripheral paralysis of n.facialis with a moderate degree of functional disorder on muscle strength and pain intensity is observed and is most pronounced in the first month from the beginning of treatment. Discussion and conclusion: This is a complex research on physiotherapeutic possibilities combined with acupressure as part of modern motor neurorehabilitation to overcome muscle weakness, pain and asymmetry in patients with unilateral peripheral n.facialis. The presence of a positive change in the examined functional parameters is observed after the application of the combination of physiotherapy and acupressure and is most significant in the first month after the beginning of the treatments.

Corrigendum: Assessment of trunk and shoulder muscle asymmetries during two-armed kettlebell swings: implications for training optimization and injury prevention

Corrigendum: Assessment of trunk and shoulder muscle asymmetries during two-armed kettlebell swings: implications for training optimization and injury prevention

Symmetrical analysis of paravertebral muscles during superman exercise in patients with adolescent idiopathic scoliosis

BackgroundTo investigate the asymmetry of paravertebral muscles during the superman exercise in patients with adolescent idiopathic scoliosis, and to analyze the applicability of this exercise for the rehabilitation of these patients from the perspective of muscle electromyographic activity. Methods37 patients with adolescent idiopathic scoliosis are selected for this study. Surface electromyography signals of the bilateral paravertebral muscles during the daily sitting and the superman exercise are recorded. The differences in Surface electromyography of the bilateral paravertebral muscles are analyzed using the root mean square method and the paraspinal muscle symmetry index. FindingsThe results show that there is no significant difference in the paraspinal muscle symmetry index between the two states. Specifically, 29 patients exhibit the same paraspinal muscle symmetry index, 2 patients have similar indices, and 6 patients display different indices. The root mean square of the convex side paravertebral muscles is generally higher than that of the concave side. InterpretationIn this study, the activation level of paravertebral muscles during the superman exercise is similar to that during the daily sitting, with the activation level on the convex side being higher than that on the concave side. This indicates that the superman exercise is not suitable for the rehabilitation of patients with adolescent idiopathic scoliosis and may even exacerbate the condition.

Assessment of trunk and shoulder muscle asymmetries during two-armed kettlebell swings: implications for training optimization and injury prevention.

Greater side-to-side asymmetry can indicate impaired skill, reduced power production, and an increased risk of injury. Bilateral differences highlight the presence of asymmetries that should be assessed to understand their impact on both injury risk and performance enhancement. This study aimed to assessment muscle activation and bilateral asymmetry in major trunk and shoulder muscles during a two-armed kettlebell swing exercise. Twenty-seven participants (age: 24.2 ± 2.6 years; body mass: 82.9 ± 7.7 kg; height: 176.9 ± 7.0 cm) were included in the study. Electromyographic (EMG) data were collected bilaterally from twelve muscles (six muscles per side: anterior deltoid [AD], posterior deltoid [PD], erector spinae longissimus [ESL], erector spinae iliocostalis [ESI], external oblique [EO], and rectus abdominis [RA]). Results indicated that asymmetry indices for the AD, ESL, ESI, and RA muscles during the upward propulsion phase fell within the determined threshold of 15%. However, the asymmetry indices for the PD and EO muscles exceeded this threshold by 3.36% and 2.62%, respectively. The findings suggest that trunk muscle asymmetries during the kettlebell swing are generally less pronounced than those of the shoulder muscles, particularly during the float phase. These results provide valuable insights into bilateral muscle asymmetry during a two-armed kettlebell swing, which can inform the development of targeted training programs. The methods and findings of this study may further contribute to understanding the effects of muscle balance, symmetry, and injury mechanisms in dynamic movements.

Suspension training improves bilateral isometric strength asymmetry of knee muscles in people with multiple sclerosis

IntroductionMost people with multiple sclerosis are diagnosed with bilateral strength asymmetry in the lower limbs. Strength asymmetry increases muscle metabolic cost, muscle fatigability, postural instability, gait disturbance, imbalance, and risk of falling, and negatively affects the quality of life in PwMS. So far, the effects of rehabilitation exercises on reducing the asymmetric index in this population has not been studied convincingly. The purpose of this study was to investigate the effect of suspension exercise on bilateral isometric strength asymmetry of knee muscles in patients with multiple sclerosis. Materials & methodsIn this randomized controlled trial, twenty-seven female patients were purposively selected as the statistical sample and randomly divided into the control (n = 13, age: 34.72 ± 5.01 years) and exercise (n = 14, age: 37.62 ± 4.58 years) groups. The control group received routine care while the exercise group received the suspension exercise protocol. Isometric muscle strength and bilateral asymmetry were measured at baseline and after 8 weeks. The Biodex isokinetic dynamometer was used to measure the maximal voluntary isometric contraction of the flexor and extensor muscles of the knee. The analysis of covariance was used to analyze the data. ResultsThe isometric strength of the knee extensor muscles in the weak leg at the angle of 20° and in both legs at the angle of 70° in the exercise group improved significantly. Furthermore, the strength of the knee flexor muscles in the exercise group was increased. The amount of bilateral strength asymmetry in the knee flexor and extensor muscles at the angle of 70° significantly decreased in the exercise group. Discussions & conclusionsThese data suggest that suspension training is a practical approach to manage bilateral asymmetry in knee flexor and extensor muscle strength in patients with an EDSS of less than four.

Changes in 3-Dimensional Measurements of Masseter Muscle After Orthognathic Surgery in Patients with Facial Asymmetry

ObjectiveThe aim of this study was to quantitatively evaluate morphological and volumetric changes in the masseter muscle using 3-dimensional analysis of facial asymmetry patients and to identify factors influencing these changes before and after orthognathic surgery.Methods[Reviewer1 (2)]A single-center retrospective cohort study was conducted on twenty-two patients with deviation of the chin > 4 mm. Masseter muscle volume and morphology were measured at different periods during long-term follow-up (mean 15 ± 3.2 months). Factors related to changes in masseter muscle cross-sectional area and volume analyzed were also analyzed.Results[Reviewer1 (2) and (9)]The volume and cross-sectional area of the masseter muscle on the non-deviated side reduced by 13.5% (P < 0.05) and 16.4% (P < 0.05), respectively, after orthognathic surgery. The length of the masseter muscle increased by 13.9% on the deviated side (P < .05) but decreased by 11.7% on the non-deviated side (P < 0.05). The width decreased on the deviated side from T1 to T2 (13.51 ± 2.09 mm vs. 12.04 ± 1.39 mm), but the non-deviated side showed an opposite tendency (10.81 ± 1.31 mm vs. 12.69 ± 2.37 mm). The difference in masseter muscle length and width between the two sides significantly reduced after surgery (P < 0.05). There was a noticeable decrease in the asymmetry in the muscle in proportion to the degree of the occlusal plane angle.ConclusionMasseter muscle asymmetry exists in patients with facial asymmetry, but it could be improved with maxilla-mandible correction. Atrophy of the masseter muscle after orthognathic surgery was greater in patients with a large inclined occlusal plane angle due to improved dental compensation.Level of Evidence IVThis journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Anisometropic Patient and Current Bioelectrical Activity in the Masticatory and Cervical Muscles

(1) Background: This study aims to analyze the bioelectrical activity of the masticatory and cervical muscles in a subject with anisometropia. (2) Methods: A female patient aged 23 years with a best-corrected visual acuity of 1.0 in the right eye and 0.1 in the left eye, a refractive error of −2.25 Dsph in the right eye and +4.25 Dsph in the left eye, and astigmatism of −1.75 Dcyl axis 24° was examined. A comprehensive ophthalmological examination and the study of the bioelectrical activity of the muscles were carried out. During the ophthalmological examination, best-corrected visual acuity was determined, refractive error (spherical equivalent) was assessed, and additionally, retinal thickness, choroidal thickness, axial length, and intraocular pressure were measured. (3) Results: It was demonstrated that higher tension in the resting mandibular position and pain-free maximum unassisted opening were observed on the right side (myopia). Conversely, higher tension during maximum voluntary clenching in the intercuspal position and maximum voluntary clenching on dental cotton rolls in the intercuspal position was observed on the left side (hyperopia and astigmatism). (4) Conclusions: In the case study, muscle asymmetry was demonstrated, which is likely associated with anisometropia. This phenomenon requires further investigation.

Magnitude and direction of shoulder torque asymmetries between different angular velocities in competitive swimmers

ABSTRACT Asymmetries in swimming can be the result of poor technique or coordination between limbs, reducing the ability to produce propulsive force and increasing resistive drag. Therefore, this study aimed to compare the magnitude and determine the consistency of isokinetic peak torque asymmetries between the angular velocities of in the shoulder joint movements of internal and external rotation, flexion, and extension. Twenty-one competitive swimmers performed concentric actions at 60°/s (3 repetitions) and 180°/s (20 repetitions) in the movements of internal and external rotation, flexion, and extension of the shoulders using an isokinetic dynamometer, with the peak torque and asymmetry index being common metrics across the tests. The results showed a greater magnitude of asymmetry in internal rotation (16.86 vs. 9.86; p = 0.007) and flexion (12.06 vs. 7.35; p = 0.008) at 60 vs. 180°/s, respectively. The agreement levels of the direction of asymmetries between angular velocities were fair to substantial (Kappa: 0.40 to 0.69). Evaluating isokinetic torque in different movements and angular velocities resulted in different levels of asymmetry. Muscle force asymmetries can impact propulsion efficiency and movement coordination during swimming. Understanding muscle asymmetries allows the development of targeted and individualised training programmes to correct strength imbalances.

Role of Sling Tuina Exercise Technique in Improving Paraspinal Muscle Asymmetry in Patients with Adolescent Idiopathic Scoliosis

Role of Sling Tuina Exercise Technique in Improving Paraspinal Muscle Asymmetry in Patients with Adolescent Idiopathic Scoliosis

Transcriptome Analysis of Left Versus Right Intrinsic Laryngeal Muscles Associated with Innervation.

Recurrent laryngeal nerve injury diagnosed as idiopathic or due to short-term surgery-related intubation exhibits a higher incidence of left-sided paralysis. While this is often attributed to nerve length, it is hypothesized there are asymmetric differences in the expression of genes related to neuromuscular function that may impact reinnervation and contribute to this laterality phenomenon. To test this hypothesis, this study analyzes the transcriptome profiles of the intrinsic laryngeal muscles (ILMs), comparing gene expression in the left versus right, with particular attention to genetic pathways associated with neuromuscular function. Laboratory experiment. RNA was extracted from the left and right sides of the rat posterior cricoarytenoid (PCA), lateral thyroarytenoid (LTA), and medial thyroarytenoid (MTA), respectively. After high-throughput RNA-Sequencing, 88 samples were organized into 12 datasets according to their age (P15/adult), sex (male/female), and muscle type (PCA/LTA/MTA). A comprehensive bioinformatics analysis was conducted to compare the left-right ILMs across different conditions. A total of 774 differentially expressed genes were identified across the 12 experimental groups, revealing age, sex, and muscle-specific differences between the left versus right ILMs. Enrichment analysis of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways implicated several genes with a left-right laryngeal muscle asymmetry. These genes are associated with neuronal and muscular physiology, immune/inflammatory response, and hormone control. Bioinformatics analysis confirmed divergent transcriptome profiles between the left-right ILMs. This preliminary study identifies putative gene targets that will characterize ILM laterality. N/A Laryngoscope, 134:3741-3753, 2024.

Quantitative analysis of paravertebral muscle asymmetry and its correlation with spinal deformity in patients with degenerative lumbar scoliosis: a retrospective case-control study.

The degeneration and functional decline of paravertebral muscles (PVMs) are reported to be closely linked to the incidence of degenerative lumbar scoliosis (DLS), a spinal deformity of the mature skeleton. However, the functional role and degeneration of PVMs and their relationship to the development of spinal deformities remain controversial. Therefore, the present study analyzed the morphological changes in the PVMs of patients with DLS, and explored the relationship between PVM degeneration and spinal osseous parameters. In this retrospective case-control study, we evaluated the PVM parameters of patients with DLS (n=120) and compared them with patients free of DLS (control group, n=120). The cross-sectional area (CSA) and computed tomography (CT) values of the PVM at the lumbar vertebra 1-5 levels were measured. Further, the lumbar scoliosis Cobb, lumbar lordotic, and apical vertebral rotation angles were measured on CT and radiographs in the DLS group, and the relationship between PVM changes and these factors was analyzed. In the control group, the PVM CSA and CT values differed insignificantly between the bilateral sides at all levels (P>0.05). In the DLS group, the CSAs of the multifidus (MF) and erector spinae (ES) were larger on the convex side than the concave side (P>0.05), whereas that of the psoas major (PM) was smaller on the convex side than the concave side (P<0.05). The CT value of the PVM was lower on the convex side at all levels (P<0.05). The CSA and CT values on both sides of the patients were lower in the DLS group than the control group at all levels (P<0.05). Further, the degree of PVM asymmetry at the apical vertebral level was positively correlated with the lumbar scoliosis (P<0.01) and apical vertebral rotation angles (P<0.05), but negatively correlated with the lumbar lordotic angle (P<0.05). Asymmetric degeneration of the PVM was observed bilaterally in DLS patients, and the degeneration was more pronounced on the concave side than the convex side. This asymmetrical degeneration was closely associated with the severity of lumbar scoliosis, vertebral rotation, and loss of lumbar lordosis, and a stronger correlation was observed with the MF and ES than with the PM.

The intra- and inter-rater reliability of measuring trunk coronal asymmetry by adjusting positioning variability: A prospective study.

Chronic low back pain (LBP) can lead to muscle spasms, limited range of motion, and abnormal posture, resulting in trunk muscle asymmetry. This study aimed to assess the intra- and inter-rater reliability of a quantitative measurement of trunk coronal asymmetry in patients with chronic LBP, minimizing unnecessary gravity and friction force using a manual table in the prone position. This prospective study was conducted at a single center, targeting patients with chronic LBP to measure trunk coronal asymmetry on a manual table in the prone position. The intra-class correlation coefficient (ICC) was calculated using one-way random-effects and two-way mixed-effects models. Fifty-eight patients who had LBP for more than three months were enrolled from May 1, 2021, to December 31, 2021. The intra- and inter-rater reliabilities of the two examiners' measurements were 0.872 and 0.899, and 0.852, respectively. Based on pain severity, the participants were classified into mild and severe groups, with ICCs of 0.823 and 0.889, and 0.936 and 0.918, respectively. Measurement of trunk coronal asymmetry in the prone position using a manual table demonstrates high intra- and inter-rater reliability. In addition, the reliability increases with greater pain severity.

Effect of a Ten-week Sensorimotor Exercise Program on the Side-to-Side LAM Asymmetry of Adolescent Football Players: A Randomized Control Trial.

In this study we, evaluated the effects of a 10-week sensorimotor exercise program on the thickness and side-to-side asymmetry of the lateral abdominal muscles in adolescent soccer players. From among 120 initially recruited participants, we included 90 athletes (aged 10-17 years old) in our final analysis. Healthy athletes who met our inclusion criteria were randomly divided into comparative experimental and control groups. Sensorimotor exercises were conducted twice weekly for 10-weeks in the experimental group, and the control group received no intervention. We took ultrasound measurements when participants were in supine and standing rest positions. In the supine position, the experimental group (a) reduced the asymmetry of the internal oblique (IO) muscle by 0.4mm (MD: 0.7; 95% CI 0.6-1.1); (b) increased the thickness of the external oblique (EO) muscle on the right by 0.7mm (MD: 0.2; 95% CI 0.1-0.6) and on the left by 0.9mm (MD: 0.2, 95% CI 0.2-0.7); and (c) increased the muscle on the IO right by 0.8mm (MD: 0.3; 95% CI 0.2-0.9) and on the, left by 1.2mm (MD: 0.4 95% CI 0.3-1.1). In a standing position the experimental group increased the thickness of the EO on the right by 1.5mm (MD: 0.6; 95% CI 0.03-1.2) and on the left by 2.1mm (MD: 0.6; 95% CI 0.1-1.3) and increased the IO on the right by 1.2mm (MD: 0.7; 95% CI 0.2-1.7) and on the left by 1.1mm (MD: 0.9; 95%CI 0.1-2.0). Thus, this 10-week program of additional sensorimotor exercises reduced the (side-to-side) asymmetry of the internal oblique muscle and increased the thickness of the EO and IO muscles in young football players.

A systematic approach to increase confidence in the diagnosis of muscle asymmetry

Asymmetry is one of the most widespread pathologies of the neuromuscular system. Depending on the composition of the same body from different types of muscles, as well as the fact that it does not seem so dangerous in the initial phases, the asymmetry is determined in clinical conditions, especially in severe phases. This requires long-term and sometimes painful treatment. The goal of the research is to detect the mentioned pathological condition at the initial stages. For this purpose, is designed a system that allows decision-making by applying several methods used to determine asymmetry.

Comparison of Obliques Muscles Strength Between Left and Right Side in Normal Young Adults Using Handheld Dynamometer - A Pilot Study

Background: Asymmetry of abdominal muscles is a potential cause for lowback pain. Most studies assume therotational strength towards non dominant side to be more but no studies have been conducted to objectivelymeasure the asymmetry. In subjects with spinal deformity like scoliosis which has a rotational component to it,it can be presumed that there could be asymmetry between the oblique force couplehowever this study aims tofind out whether this asymmetry exists in normal healthy individuals. By using manual muscle testing for assessingoblique muscle strength only gross asymmetry can be detected. Therefore there is a need for more objectivemeasure to detect subtle discrepancies within strength of both sides.Objective: The objective of this study is to measure the strength of external and internal oblique on both sideusing handheld dynamometer and to compare the strength on both sides.Methodology:30 healthy young individuals in the age group of 18-30 years were selected to participate in thestudy. All subjects were right hand dominant.External oblique and internal oblique muscle strength was measuredin KGs using a Jamar type of hydraulichand held dynamometer.Results: There was a significant difference between the strength of external obliques on right and left side withstrength on right side being more whereas there was no significant difference between strength of internaloblique between right and left side.

Acute effects of muscle mechanical properties after 2000-m rowing in young male rowers.

The mechanical properties of muscles, such as changes in muscle tone and stiffness, are related to sports performance and injuries. Rowers are at increased risk of muscle fatigue and injury during high-repetition and heavy-load cyclic muscle actions. In view of this, the aim of the present study was to investigate the acute effect on muscle tone and stiffness, as well as bilateral muscle asymmetry, in high school rowers after a 2000-meter rowing ergometer test. Twelve young male rowers (age = 17.1 ± 0.9 years, body weight = 73.5 ± 9.7 kg) were included in the study. The data of muscle tone (frequency) and stiffness of the posterior deltoids (PD), latissimus dorsi (LD), and rectus femoris (RF) (dominant and non-dominant side) before and after a 2000-m rowing ergometer test were collected using a handheld MyotonPRO device. After the rowing ergometer test, the muscle tone of dominant side PD, LD, and RF were significantly increased (p < 0.05). On the other hand, the muscle stiffness of the non-dominant side LD and RF, as well as the dominant side PD, LD, and RF were significantly increased after the rowing ergometer test (p < 0.05). The muscle tone and stiffness results showed that the dominant side PD, LD, and RF were all significantly higher than the non-dominant side after the rowing ergometer test (p < 0.05), where bilateral PD and RF exhibits moderate asymmetry (5% < symmetry index < 10%). After a high-intensity and high-load 2000-m rowing ergometer test, PD, LD, and RF showed increases in muscle tone and stiffness, as well as changes in the symmetry of bilateral muscle mechanical properties.

Asymmetry of muscles in women engaged in pole acrobatics: study results using myography

Asymmetry of muscles in women engaged in pole acrobatics: study results using myography

Effects of an 8-week pre-season targeted training on sprinting performance, agility and lower limb muscular asymmetries in elite soccer players.

The purpose of this study was to determine the effects of an 8 week targeted training program on speed, agility, and muscle asymmetries in soccer players. 32 elite soccer players were recruited for the study. Their age, body mass, and body height were 25.8 ± 7.3 years, 77.4 ± 11.1 kg, and 177.5 ± 9.8 cm, respectively. After the warm-up, participants performed two maximum 30 m sprints with a 5-minute rest interval between trials. After the linear sprint test, performed two repetitions of the COD randomized ZigZag test. The tests were performed at the beginning and at the end of the pre-season, which lasted for 8 weeks. EMG was measured bilaterally from the quadriceps, hamstrings, and gluteal muscles with shorts made of knitted fabric similar to elastic clothes. Athletes in the experimental group performed sport-specific targeted strength training based on movement patterns 4 times per week (Monday, Tuesday, Thursday, and Friday). The training included 6 bodyweight exercises (Bird Dog, Single-Leg Glute Bridge, Dead Bug, Side Plank, Reverse Lunge, and Clamshell), performed unilaterally in 5 sets of 10 repetitions of each exercise. The load progression included an additional set in each successive week of the experiment. The data analysis showed significant improvement in 5 m and 30 m sprints after applying the 8-week targeted training protocol. A statistically significant improvement in performance was also observed after the 8-week training period in case of COD, while the speed deficit also decreased significantly. The greatest improvements were observed during the COD test. As a result of repeated COD training over a period of 8 weeks, its technique was improved. Implementation of training methods, which target specific aspects of soccer in the pre-season training routines can improve key motor abilities for that sports discipline. A comprehensive training approach including speed, agility, and resistance training based on specific movement patterns should be applied by strength and conditioning practitioners in soccer teams to achieve peak physical performance and reduce injury risk due to the partial elimination of muscular asymmetries.