Different neuromuscular parameters influence dynamic balance in male and female football players

Assessment of Strength and Power Capacities in Elite Male Soccer: A Systematic Review of Test Protocols Used in Practice and Research

BACKGROUND

Strength and power represent two crucial physical qualities for the attainment of a high level of performance considering the frequency and the importance of explosive actions occurring during elite soccer match-play. Evaluation of strength and power is a multifaceted concept involving a vast array of tests and outcome variables. Nevertheless, a comprehensive and systematic search of strength and power assessment procedures in elite soccer has yet to be undertaken.

OBJECTIVES

The aims of this systematic review were to: (1) identify the tests and outcome variables used to assess strength and power of elite male soccer players; (2) provide normative values for the most common tests of strength and power across different playing levels; and (3) report the reliability values of these strength and power tests.

METHODS

A systematic review of the academic databases MEDLINE, CINAHL, SPORTDiscus, Web of Science and OVID for studies published until August 2023 was conducted, following the Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were eligible for inclusion if they: (1) were original research studies, published in a peer-reviewed journal, and written in English language; (2) had the primary aim to assess strength and/or power; (3) players were male and older than 17 years of age (i.e., mean age of the group); and (4) their playing level was defined as "professional", "international" or "elite".

RESULTS

Regarding strength testing, 115 studies and 29 different tests were identified. The three most frequent strength tests were the knee extensor isokinetic strength test (58 studies), the knee flexor isokinetic strength test (55 studies) and the Nordic hamstring strength test (13 studies). In terms of power testing, 127 studies with 31 different tests were included. The three most frequent power tests were the countermovement jump with hands fixed on hips (99 studies), the squat jump (48 studies) and the vertical jump with arm swing (29 studies).

CONCLUSIONS

The wide range of different tests and outcome variables identified in this systematic review highlights the large diversity in the employed testing procedures. The establishment of a hybrid testing approach, combining standardised and widely accepted tests for establishing normative standards and enabling comparisons across different contexts, with flexible context-specific testing batteries, has the potential to maximise the impact of testing information for practitioners. In addition, the limited reporting of reliability data across studies highlights the need for practitioners to establish their own reliability measure within their specific contexts, informing the selection of certain tests and outcome variables.

Lower extremity movement quality in professional team sport athletes: Inter-rater agreement and relationships with quantitative results from the corresponding pattern

BACKGROUND

Adequate movement control and quality can be prerequisite functions for performance of the lower extremity. The purposes of our work were 1) to explore the agreement of an efficient test battery assessing qualitative movement execution and 2) to determine its consistency with quantitative performance tests from the corresponding movement pattern.

METHODS

The participants were professional male association football players competing in the first German Bundesliga. They performed four movement quality tests (Single-limb balance squat, Balance forward hop, Balance side hop, Balance 90° rotation hop) and the corresponding performance tests (Y-balance test, Forward hop for distance, Side hop test, Square hop test). Qualitative tests were judged by two experienced raters; the ratings were compared to determine inter-rater agreement using Kappa statistics. The relationship with the quantitative tests was determined using Spearman's rank correlations.

RESULTS

Thirty participants (19 to 33 years old) were included in this study. We found an at least substantial level of agreement (Cohen's Kappa, 0.64-0.84) with an excellent percentage of exact (83-93%) agreement between the two raters for the movement quality tests. Our findings revealed that the quantitative test results are only slightly related to the movement quality outcomes (ρ(27) <|0.3| and P > 0.2).

CONCLUSIONS

Consequently, the qualitative test results provide unique information and complement corresponding quantitative performance tests in professional football athletes. Their observational judgement of foot position, lower limb alignment and upper body control in sagittal, frontal, and transverse planes is agreeable.

What is the influence of biomechanical variables on the Y balance test performance in recreational runners?

BACKGROUND

Asymmetries and poor Y balance test (YBT) performance are associated with an increased risk of injuries in athletes. The aim of this study was to investigate the association between YBT performance with biomechanical variables in runners.

METHODS

The runners underwent the YBT, followed by the assessment of center of pressure, plank position, muscle strength (MS) of hip flexors, extensors, abductors, and external rotators, knee extensors, ankle dorsiflexion range of motion (ROM), Q angle, forefoot alignment, and passive hip internal rotation. Associations between variables were examined using multiple linear regression models with the Bayesian Information Criterion.

RESULTS

122 cases were analyzed. The R2 values were 0.38; 0.05; 0.06; and 0.15 for the anterior, posteromedial, posterolateral and composite directions models, respectively. The anterior reach in the YBT was associated with ankle dorsiflexion ROM [Sβ 95%IC: 0.43 (0.32-0.55)], passive hip internal rotation [Sβ 95%IC: 0.35 (0.24-0.47)], MS of the hip extensors [Sβ 95%IC: 0.19 (0.07-0.31)] and forefoot alignment [Sβ 95%IC: 0.14 (-0.25-0.02)]. The posteromedial and posterolateral reach were associated with MS of the hip flexors [Sβ 95%IC: 0.23 (0.09-0.37) and 0.24 (0.11-0.38)], respectively. The composite score was associated with MS of the hip flexors [Sβ 95%IC: 0.31 (0.18-0.45)], ankle dorsiflexion ROM [Sβ 95%IC: 0.24 (0.10-0.37)] and Q angle [Sβ 95%IC: 0.18 (0.04-0.31)].

CONCLUSION

YBT performance in different directions demonstrated specific associations with key biomechanical factors.

Are trunk stability and endurance determinant factors for whole-body dynamic balance in physically active young males? A multidimensional analysis

OBJECTIVES

Determine if (a) a better trunk stability and endurance are associated with an improved whole-body dynamic balance, and if (b) the assessment tests can be interchanged within each capability.

METHODS

Sixty-three physically active young males performed three trunk stability (i.e., the lumbopelvic stability, the unstable sitting and the sudden loading sitting tests), three trunk muscle endurance (i.e., the Biering-Sørensen, the side bridge and the front bridge tests) and four whole-body dynamic balance (i.e., the tandem and the single-leg stance, the Y-Balance, and the single-leg triple hop tests) tests two times. After assessing the reliability of the variables, a Pearson correlation analysis was performed.

RESULTS

The correlations between trunk stability and endurance tests with dynamic balance tests were non-significant except for the unstable sitting test with both the tandem (r = 0.502) and the single-leg stance (r = 0.522) tests. Moreover, no relationships were observed between the trunk stability and the trunk muscle endurance tests. Interestingly, no relationships were found between most tests within each capability (i.e., trunk stability, trunk endurance, and dynamic balance) except: (i) the front bridge stability test and the back (r = 0.461) and the side (r = 0.499) bridge stability tests; (ii) the two side bridge endurance tests (r = 0.786); (iii) the tandem and the single-leg stance tests (0.439 ≤ r ≤ 0.463); (iv) the Y-Balance and the single-leg triple hop tests (0.446 ≤ r ≤ 0.477).

CONCLUSION

Better trunk function does not seem to be a relevant factor for dynamic balance in young active males. In this population, specific measures are needed as the test interchangeability is questioned.

Scalable musculoskeletal model for dynamic simulations of lower body movement

A musculoskeletal (MSK) model is an important tool for analysing human motions, calculating joint torques during movement, enhancing sports activity, and developing exoskeletons and prostheses. To enable biomechanical investigation of human motion, this work presents an open-source lower body MSK model. The MSK model of the lower body consists of 7 body segments (pelvis, left/right thigh, left/right leg, and left/right foot). The model has 20 degrees of freedom (DoFs) and 28 muscle torque generators (MTGs), which are developed from experimental data. The model can be modified for different anthropometric measurements and subject body characteristics, including sex, age, body mass, height, physical activity, and skin temperature. The model is validated by simulating the torque within the range of motion (ROM) of isolated movements; all simulation findings exhibit a good level of agreement with the literature.

Anterior component of Y-Balance test is correlated to ankle dorsiflexion range of motion in futsal players: A cross-sectional study

BACKGROUND AND PURPOSE

Restricted dorsiflexion range of motion (DFROM) could impact dynamic balance in sports. This study aimed to investigate the relationship between dorsiflexion range of motion and the Y-Balance Test (YBT) in elite futsal players.

METHODS

Sixty-one asymptomatic male futsal players (mean age 26.57 (5.64) years, a mean body mass index of 25.40 (2.69) kg/m2 ) were included. DFROM was measured by the weight-bearing lunge test (WBLT). DFROM data were obtained using smartphone-based motion capture. The Pearson correlation coefficient verified the correlation between the variables.

RESULTS

Dominant and nondominant leg ankle DFROM was significantly correlated with the anterior component of YBT (r = 0.27 and 0.51, respectively). The posteromedial component and the composite score of the YBT were also significantly correlated with nondominant leg ankle DFROM (r = 0.31 and 0.34, respectively)]. The other measures were not statistically significant. DFROM explained between 7% and 24% of the variation of the distances reached in the YBT.

CONCLUSION

Dorsiflexion range of motion measured by weight bearing lunge test is positively correlated with dynamic balance in futsal players.

Comparison of ACL and Anterolateral Ligament Reconstruction With Isolated ACL Reconstruction Using Hamstring Autograft: Outcomes in Young Female Patients With High-Grade Pivot Shift

Background

Inferior return to sports (RTS) and functional outcomes have been reported in women after anterior cruciate ligament reconstruction (ACLR).

Purpose/Hypothesis

The purpose was to evaluate the results of combined ACLR and anterolateral ligament reconstruction (ALLR) in young women with a high-grade pivot shift (grade ≥2). It was hypothesized that combined ACLR and ALLR would result in better RTS and rotational stability than isolated ACLR.

Study Design

Cohort study; Level of evidence, 3.

Methods

Two groups were retrospectively evaluated and compared. Group I (n = 39; mean age, 31.1 ± 5.7 years) underwent isolated ACLR using hamstring autografts; group C (n = 39; mean age, 30.4 ± 6.1 years) underwent combined ACLR and ALLR. Subjective outcome measures included the International Knee Documentation Committee subjective form, Lysholm, Tegner, and ACL-Return to Sport after Injury (ACL-RSI). Objective tests included a KT-2000 arthrometer stress test, a pivot-shift test, an isokinetic strength test, a Y-balance test, and a single-leg hop test. A postoperative questionnaire was administered to determine the rates and types of RTS, quality of sports performance, and reinjury and satisfaction rates. Subjective scores and clinical tests were performed at 2 years. Magnetic resonance imaging and second-look arthroscopy were conducted during the 1- and 2-year follow-ups, respectively.

Results

The mean follow-up for groups I and C were 30.4 ± 3.9 and 29.3 ± 3.5 months, respectively (P = .194). Patients in group C had better anteroposterior (P = .001) and rotational (P = .005) stability and higher ACL-RSI scores (P = .025) than those in group I. Group C had higher composite and posteromedial reach scores on the Y-balance test than group I (P = .014 and P = .010, respectively). A total of 26 (66.7%) patients in group C and 17 (43.6%) in group I returned to their prior level of sports (P = .040). Rerupture of the ACL graft and contralateral ACL rupture occurred in 2 (5.1%) and 2 (5.1%) patients in group I, respectively, compared with no rerupture or contralateral ACL rupture in group C.

Conclusion

Combined ACLR and ALLR in young women with a high-grade pivot shift was associated with better knee stability parameters, dynamic postural stability, and psychological readiness to RTS than isolated ACLR.

Short-Term Effects of Specific Sensorimotor Training on Postural Assessment in Healthy Individuals: A Pilot Study with a Randomized Placebo-Controlled Trial

It is well-known that sensorimotor training aims to increase the performance of the sensorimotor system to maintain an upright position. Through the use of a randomized placebo-controlled trial, the specific aim of this study was to investigate the short-term effects of a specific session of sensorimotor training on postural balance, stability and coordination in healthy, recreationally active participants. Ninety subjects were randomly allocated into three groups: experimental (n = 30), placebo (n = 32) and control (n = 28). The experimental group performed a 5 min warm-up, with the sensorimotor training consisting of 60-min specific sensorimotor exercises; the control group was not allowed to perform any sensorimotor training; the placebo group observed a video clip of an individual belonging to the experimental group performing the sensorimotor training accurately. All participants were seen three times per week for 4 weeks. Before and after the entire training, all groups of participants undertook stabilometric parameter assessment. The intervention-mediated sensorimotor training confirmed significant enhancement in the proprioceptive system. Significant improvement in the motor and/or sensory function was observed in the experimental and placebo groups. In conclusion, our findings suggest that specific sensorimotor training performed 3 days per week for 4 weeks could improve postural balance, stability and coordination in healthy individuals.

Outcomes of a novel all-inside arthroscopic anterior talofibular ligament repair for chronic ankle instability

PURPOSE

This study aimed to introduce a novel all-inside arthroscopic anterior talofibular ligament (ATFL) repair for chronic ankle instability (CAI) with a knotless suture anchor technique-Hugging Repair, evaluate clinical outcomes, and analyze the associated risk factors.

METHODS

A total of 84 patients (42 males and 42 females, mean age: 36.1 ± 11.2 years, range: 19-68 years) who underwent Hugging Repair from January 1, 2016 to December 31, 2018, were enrolled in this retrospective study. The American Orthopedic Foot and Ankle Society (AOFAS) score, Karlsson Ankle Functional Score (KAFS), Foot and Ankle Outcome Score (FAOS), Tegner score, and Numerical Rating Scale (NRS) were evaluated pre-operatively and at final follow-up. The potential risk factors such as age, body mass index (BMI), sex, post-injury duration (time from injury to surgery), follow-up time, number of anchors, concomitant injuries [e.g., osteochondral defects (OCD), sinus tarsi syndrome (STS), anterior ankle impingement (AAI)], first-time treatment, and number of ankle sprains were also analyzed through multiple regression analysis.

RESULTS

There were 68 (81%) patients followed up for a mean time of 42 (range: 35-50) months. The median AOFAS score increased from 65 (35-72) to 90 (77-100), KAFS increased from 64 (38-71) to 90 (62-100), FAOS increased from 68 (50-70) to 97 (68-100), Tegner score increased from 1 (1-3) to 4 (2-7), and NRS increased from 3.5 (2-5) to 1 (0-3). No correlation was found between the functional scores and risk factors mentioned above. In the multivariate model, age was significantly negatively associated with KAFS, FAOS, and Tegner activity scale (P = 0.013; P = 0.002; P = 0.000); female was significantly associated with poorer Tegner activity scale (P = 0.004); and the presence of concomitant injuries was significantly negatively associated with AOFAS score (P = 0.033).

CONCLUSION

The novel all-inside arthroscopic ATFL repair for CAI with a knotless suture anchor technique-Hugging Repair is a safe and suitable technique that achieves satisfactory clinical outcomes and provides an effective option for the treatment of CAI. Risk factors for patients who underwent all-inside ATFL repair were older age, female sex, and concomitant injuries.

Isokinetic leg muscle strength relationship to dynamic balance reflects gymnast-specific differences in adolescent females

Balance, together with other motor qualities, plays an important role in the successful execution of specific gymnastic skills. However, it is also not clear whether different demands on dynamic balance and power produced by lower limb can be observed in sport-specific differences among gymnasts of various modalities. The question also is as to what extent isokinetic leg muscle strength contributes to anterior and posterior postural stability in gymnasts. Therefore, the aim of the study was i) to compare variables of dynamic balance and isokinetic leg muscle strength in rhythmic, artistic, and aerobic gymnasts, and ii) to investigate the relationship of reach distances in anterior, posteromedial, and posterolateral directions, as well as the composite score in the Y-balance test with an isokinetic muscle strength during knee extension and flexion at different velocities in female gymnasts of various disciplines. Altogether seven aerobic, five artistic, and six rhythmic gymnasts performed the Y-balance test and isokinetic leg muscle strength test at 60°/s, 180°/s, and 300°/s. Results showed significant between-group differences in the composite score in the Y-balance test of the dominant (F = 3.536, p = .041) and non-dominant symmetry (F = 4.804, p = .015). Similarly, average power produced during knee extension and knee flexion at 60°/s, 180°/s and 300°/s differed significantly among these groups (all at p˂0.05). In addition, there was a significant relationship between the composite score of the dominant limb symmetry and isokinetic dominant limb extension strength at 60°/s (r = .54), 180°/s (r = .87), and 300°/s (r = .84) in aerobic gymnasts. The composite score of the dominant limb symmetry was also associated with isokinetic dominant limb extension strength, albeit only at 60°/s in both artistic (r = .60) and rhythmic gymnasts (r = .55). Such between-group differences may be ascribed to their different demands on maintenance of balance under dynamic conditions and leg muscle power within their sport specializations. Taking into account significant association between the dominant limb symmetry and isokinetic dominant limb extension strength, it may be concluded that both muscle strength and fast speeds contribute to dynamic balance in adolescent gymnasts.

DEDICATED TRAINING OF EXPLOSIVE STRENGTH IN THE ABDOMINAL CORE OF SOCCER PLAYERS

ABSTRACT Introduction: Physical confrontation in soccer games presents greater demands on athletes’ physical fitness. A soccer player’s speed, strength, flexibility, coordination, endurance, and explosiveness can affect the body’s fighting capacity. Objective: This study analyzes the relationship between strength training in soccer players’ abdominal core and physical fitness. Methods: The effect of abdominal core stability strength training on performance improvement in volunteer soccer players selected as research subjects was verified by random division into two groups (experimental and control groups). Both groups performed daily training. The experimental group added special abdominal core training. Mathematical-statistical algorithms were used to statistically analyze the physical indicators of the two groups of volunteers. Results: The indices of physical fitness and body explosiveness of the two groups of athletes were significantly improved (P<0.05). After systematic training, the competition performance of the experimental group and the physiological and biochemical indicators were better than the control group (P<0.05). Conclusion: After abdominal core training, soccer players’ physical fitness and explosive power indexes were improved. Research shows that strength training can help improve abdominal core performance in soccer players. It is recommended that coaches implement abdominal core strength training in the daily training of athletes. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

REPERCUSSIONS OF BALANCE TRAINING ON SOCCER PLAYERS’ LOWER LIMB INJURIES

ABSTRACT Introduction Soccer is a combative event that requires particular skills and physical fitness. The unique soccer characteristics determine the high incidence of joint injuries in the lower limbs. In this regard, balance training has proven to be particularly important, as research indicates a reduction in lower limb injuries justified by the gain in the athletes’ muscle control capacity. Objective This paper analyzes the repercussions of balance training on lower limb injuries in soccer players. Methods 16 soccer players were randomly divided into experimental and control groups, without statistical difference. Both performed routine training first, with subsequent adherence to balance training by the experimental group. The experiment lasted eight weeks, and the balance training was based on an exercise protocol of approximately 30 minutes, three times a week, for eight weeks. Indexers on recovery from lower limb injury were statistically analyzed and compared. Results After balance training, soccer players in the experimental group improved faster. At the same time, the lower limb injury was effectively improved. Conclusion The balance training method can reduce the probability of lower limb injuries in soccer players. Evidence Level II; Therapeutic Studies - Investigating the result.

Effects of different intermittent pneumatic compression stimuli on ankle dorsiflexion range of motion

Despite substantial evidence of the effectiveness of intermittent pneumatic compression (IPC) treatments for range of motion (ROM) improvement, little evidence is available regarding how different IPC stimuli affect ankle dorsiflexion (DF) ROM. This study aimed to investigate the effects of different IPC stimuli on the ankle DF ROM. Fourteen, university intermittent team sport male athletes (age: 21 ± 1 year, height: 1.74 ± 0.05 m, body mass: 70.9 ± 7.7 kg, body fat percentage: 14.2 ± 3.6%, body mass index: 23.5 ± 2.5 kg/m²; mean ± standard deviation) completed four experimental trials in a random order: 1) no compression with wearing IPC devices (SHAM), 2) the sequential compression at approximately 80 mmHg (SQUEE80), 3) the uniform compression at approximately 80 mmHg (BOOST80), and 4) the uniform compression at approximately 135 mmHg (BOOST135). For the experimental trials, the participants were initially at rest for 10 min and then assigned to either a 30-min SHAM, SQUEE80, BOOST80, or BOOST135. Participants rested for 20 min after IPC treatment. The Weight-Bearing Lunge Test (WBLT), popliteal artery blood flow, pressure-to-pain threshold (PPT), muscle hardness, heart rate variability, and perceived relaxation were measured before (Pre) and immediately after IPC treatment (Post-0) and 20 min after IPC treatment (Post-20), and the changes in all variables from Pre (Δ) were calculated. ΔWBLT performance, ΔPPT, and Δperceived relaxation in all IPC treatments were significantly higher than those in SHAM at Post-0 and Post-20 (p < 0.05). ΔPopliteal artery blood flow in BOOST80 and BOOST135 was significantly higher than that in SHAM and SQUEE80 at Post-0 (p < 0.05). ΔMuscle hardness and Δheart rate variability did not differ significantly between trials. In conclusion, IPC treatments, irrespective of applied pressure and mode of compression, increased ankle DF ROM. This resulted from decreased pain sensitivity (i.e., increased PPT). In addition, high inflation pressure and frequency did not provide additional benefits in increasing ankle DF ROM.

CORE STRENGTH TRAINING ON PHYSICAL CONDITIONING OF COLLEGE MALE SOCCER PLAYERS

ABSTRACT Introduction: The concept of CORE emerged in mechanical-neurological studies of rehabilitation in the 80s, referring to the central muscles of the human trunk, including the lumbar-pelvis-abdominal-perineal-hip complex responsible for the body orthostatic stability and support. Strengthening the CORE has received increasing attention from sports medicine specialists after the 2000s, and strength training is the subject of recent research in competitive sports. However, there is still a lack of conceptual studies of protocols for training focused on soccer athletes. Objective: Verify a CORE strength training protocol based on the analysis of the CORE training concept, its main functions, and introductory practical examples. Methods: Literature data collection, experimental and statistical-mathematical methods, and theoretical analysis about CORE training focused on explosive strength performance in soccer players are used. The developed protocol experiments with 44 athletes, divided into experimental and control groups, by sex. Information is collected on goal shooting, 30-meter pass, balance, stability, and symmetry. Results: The group experienced better results in both sexes(P<0.05). Conclusion: The explosion strength indicators of the players were significantly improved. Whether male or female athletes, the higher the skill level, the stronger the CORE stability in players. Therefore, the CORE stability and strengthening in athletes promote a benefit in the technical level of soccer players. Evidence Level II; Therapeutic Studies - Investigating the result.

Postural balance asymmetry and subsequent noncontact lower extremity musculoskeletal injuries among Tunisian soccer players with groin pain: A prospective case control study

BACKGROUND

Recent studies reported postural balance disorders in patients and soccer players with groin pain (GP) compared to controls. Since postural balance asymmetry identified after an initial injury contributes for subsequent injuries, identification of this asymmetry in soccer players with GP may highlight the risk of sustaining subsequent noncontact lower extremity musculoskeletal injuries in these players. Therefore, the aims of this study were to (i) examine static and dynamic unipedal postural balance asymmetry in soccer players with GP compared to healthy ones, and (ii) quantify the risk of subsequent noncontact lower extremity injuries in these players.

RESEARCH QUESTION

Do soccer players with GP exhibit higher static and dynamic unipedal postural balance asymmetry, and higher risk of sustaining subsequent injuries compared to controls?

METHODS

In this prospective case control study, 27 soccer players with non-time loss GP (GP group: GPG), and 27 healthy ones (control group: CG) were enrolled. Static and dynamic unipedal postural balance asymmetry were evaluated with a force platform using symmetry index (SI), and Y-balance test (Y-BT), respectively. Additionally, subsequent noncontact lower extremity musculoskeletal injuries were tracked for 10 months.

RESULTS

The GPG revealed higher (p < 0.01) SI in eyes closed condition, higher (p < 0.001) side-to-side asymmetry in anterior, posteromedial and posterolateral reach distances and in composite Y-BT score compared to CG. They showed lower (p < 0.001) composite score for injured limb and higher (p < 0.001) side-to-side asymmetry in posteromedial reach distance compared to the cut-off values of 89.6 % and 4 cm, respectively. Moreover, GPG exhibited higher odds (OR= 7.48; 95 % CI = 2.15, 26.00; p < 0.01) of sustaining subsequent injuries compared to CG.

SIGNIFICANCE

The Y-BT should be instituted into existing pre-participation physical examinations to screen for soccer players with non-time loss GP at an elevated risk of sustaining subsequent injuries. This could help coaches and clinicians make valid return to play decisions.

Impact of Flexibility on Vertical Jump, Balance and Speed in Amateur Football Players

Muscle strength, power, balance and speed assume decisive roles in football performance. This study aims to investigate whether lower limb flexibility, particularly the hip flexors and knee extensor and flexor muscles, are correlated with vertical jump performance, balance and speed in adult football players. A sample of 22 male amateur football players (age: 22.3 ± 3 years; height: 175.4 ± 7.4 cm; weight: 74.9 ± 11.6 kg; BMI: 24.2 ± 2.6 kg/m2) were assessed for lower limb flexibility, vertical jump, balance and speed. Results indicated that vertical jump ability is moderately correlated with left knee extensors flexibility (ρ = −0.426; p = 0.048), which did not occur on the right side. There were no statistically significant correlations between vertical jump and knee flexors flexibility (ρ = 0.330; p = 0.133). In balance, the reaching distance on the right side presented a moderate and statistically significant correlation with the knee flexors flexibility (ρ = 0.411; p = 0.040), which was not observed on the left side. Velocity was not correlated with the knee extensors flexibility (right: ρ = 0.360; p = 0.100; left: ρ = 0.386; p = 0.076), or with the knee flexors flexibility (ρ = −0.173; p = 0.440). In conclusion, the influence of flexibility on vertical jump ability, balance and speed appears to exist. Further research should seek to clarify the associations between these abilities.

Measuring Recovery and Understanding Long-Term Deficits in Balance, Ankle Mobility and Hip Strength in People after an Open Reduction and Internal Fixation of Bimalleolar Fracture and Their Impact on Functionality: A 12-Month Longitudinal Study

To analyze how balance and other physical capacities evolved after surgery in patients with a bimalleolar fracture and how these capacities and clinical variables (immobilization or unloading time) contribute to restoring patients’ functionality, 22 patients and 10 healthy people (HC) were assessed for static and dynamic balance (Y-Balance test, YBT), dorsiflexion ankle mobility (ADFROM) and hip strength at 6 and 12 months after surgery. Patients’ functional status was assessed through the Olerud Molander Ankle Score (OMAS) and the American Orthopaedic Foot and Ankle Society (AOFAS) score. Twenty-one patients with ankle fractures who completed the study showed a worse static and dynamic balance at 6 months. The YBT in the anterior direction (YBTA) revealed balance deficits in the operated limb at 12 months compared to the non-operated limb (−5.6%) and the HC (−6.7%). They also showed a decreased ADFROM compared to the non-operated limb (−7.4°) and the HC (−11°). In addition, medium-term (6 months) deficits in abductor strength hip but no hip strength deficits were found at 12 months after surgery. Relative weight analyses showed that ADFROM and hip strength explained 35–63% of the YBTA variance and AOFAS/OMAS scores. Balance, hip strength and ADFROM seem to be reliable indexes for assessing the functional status of these patients. These results could help to understand the relationship between these physical capacities and the patients’ perceived functional status.

Predicting Hamstring Strains in Soccer Players Based on ROM: An Analysis From a Gender Perspective

Purpose: The aim of this study was to explore if specific hip and knee range-of-movement (ROM) tests can predict a risk factor for hamstring strain (HS) injury in male and female soccer players. Methods: One hundred amateur soccer players (56 men and 44 women) performed six tests to determine hip and knee ROM: straight leg raise test (SLR), modified Thomas test (TT), hip internal and external rotation (ER), hip abduction and adduction, Nachlas test and Ridge test. A logistic regression analysis was carried out to create a predictive model for HS injuries. Results: The percentage of HS injury was 20.45% and 30.35%, for female and male players. The logistic regression showed a significant model for both genders on the logit of suffering an HS injury with active-SLR and TT variables for females (R²_CS = 0.491; R²_N = 0.771) and active SLR and ER variables for males (R²_CS = 0.623; R²_N = 0.882). The predictive models correctly classify 95.5% and 94.6% of cases presenting good sensitivity (77.8% and 88.2%) and full (100%) and high (97.4%) specificity respectively. Furthermore, female players showed a greater ROM than males (p ≤ 0.01). Conclusion: Both female and male soccer players that suffered a HS injury had lower ROM in SLR, NT and RT and higher ROM in the TT that non-injured players. The tests that most likely predict HS injury are SLR and TT in females and SLR and ER in males. Thus, it is suggested to including specific exercises in amateur soccer players training programs to improve hip and knee ROM for injury prevention.

Throwing Injury Prevention Strategies with a Whole Kinetic Chain-Focused Approach

Purpose of Review

This review examines the relationship between the baseball pitching motion and the kinetic chain. The goal was to determine the underlying causes of a deficiency in throwing mechanics throughout a throwing motion, and to provide an evidence-based approach on how to prevent injuries caused by a lack of proper mechanics. In doing so, we sought to provide a warm-up strategy that can be added to every baseball player’s daily on-field routine that is tailored to each phase of the throwing motion.

Recent Findings

To help minimize the risk of injury to overhead throwing athletes, a thorough understanding of the throwing motion is critical. Throwing a ball places extreme stress on the body, notably the shoulder and elbow joints. With a clear understanding of the biomechanics of throwing, we can develop an injury prevention routine to minimize unnecessary stresses throughout the kinetic chain.

Summary

The throwing cycle is a complex motion that places various stresses throughout the thrower’s body, from the ankle to the core, and from the back to the shoulder and elbow. A thorough understanding of the mechanics of this motion, along with specific exercises to target the specific actions of each phase, may allow for throwers, regardless of their age and experience, to minimize injury risk.

Impact of hip abductor and adductor strength on dynamic balance and ankle biomechanics in young elite female basketball players

This study aimed to evaluate, in an isolated and relative manner, hip abductor (ABD) and adductor (AD) strength and to study the extent to which these factors are related to balance and ankle dorsiflexion mobility in young elite female basketball players. Sixty trainee-level elite female basketball players (13–18 years old), who voluntarily agreed to participate in the study, were divided into three subgroups based on competition age divisions (U14, U16, U18). Isometric hip ABD and AD strength in each leg was evaluated using the ForceFrame Strength Testing System, also calculating the strength ratio and imbalance between legs. Y Balance Test (YBT) and ankle dorsiflexion mobility were also assessed. ANOVA was used for between-group differences analysis. Likewise, the impact of hip strength on balance and ankle mobility was analyzed using Pearson's correlation coefficient. A linear regression model for dependent variables was created with all variables that exhibited significant correlations. A between-group comparison analysis for the three competition age subgroups (U14, U16, U18) revealed non-significant differences (p > 0.005) for the hip strength variables except for hip ABD strength. The correlation study showed low-moderate effect sizes for hip ABD (in both the contralateral and homolateral limb) and AD strength (only the homolateral limb) with YBT and ankle dorsiflexion. However, when performing a regression model, only right hip ABD significantly predicted right limb YBT scores (β = 0.592, p = 0.048). The present study indicated that, although both hip ABD and AD strength correlate with balance and ankle mobility with low-moderate effect sizes, only hip ABD strength was found to significantly predict YBT scores. Therefore, the potential role of hip ABD strength in particular, but also hip AD strength, for monitoring and enhancing balance and ankle mobility outcomes, should be taken into consideration when designing and implementing preventive strategies for lower-limb injuries.

Does induced fatigue alter dynamic balance in athletes? A systematic review

OBJECTIVES

To determine the influence of induced fatigue on dynamic balance in healthy athletes.

DESIGN

Systematic review.

DATA SOURCES

PUBMED, MEDLINE, CINAHL, Sports Discus, and the Cochrane library from onset to May 28, 2019.

ELIGIBILITY CRITERIA

Eligible studies included any study examining the effects of induced-fatigue on dynamic balance, as measured by the SEBT/YBT, in healthy athletic populations. Studies with a low risk of bias were considered scientifically admissible for a best evidence synthesis.

RESULTS

Fifteen studies with low risk of bias were included - seven investigated recreational athletes while eight focused on competitive athletes. In the recreational population, five of the studies found significant decrease in dynamic balance following the fatiguing intervention. However, the remaining two concluded with insignificant changes. As for the competitive population, three studies showed significant effects of induced fatigue on dynamic balance, while five showed no effects.

CONCLUSION

There are conflicting results regarding the effects of induced fatigue on dynamic balance. The majority of studies focused on competitive athletes found that fatigue did not alter their dynamic balance. Per contra, the majority of studies focused on recreational athletes concluded the opposite - fatigue did indeed affect dynamic balance.

The relationships between knee extensors/ flexors strength and balance control in elite male soccer players

Background

Strength and balance are important factors for soccer players to be successful. This study’s aim was to determine the relationship between lower-limb muscle strength and balance control in elite male soccer players (n = 77).

Methods

Concentric isokinetic strength (peak torque of quadriceps (PT-Q) and hamstrings (PT-H), hamstrings/quadriceps (H/Q) ratio) was measured for the dominant and non-dominant leg at angular velocities of 60°s⁻¹and 240°s⁻¹, as well as the total work for extensors (TW-Q) and flexors (TW-H) for both legs (at an angular velocity of 240°s⁻¹only). Balance score (BAL score) was used for unilateral assessment of balance control using a Delos Postural System Test measurement tool. Hierarchical multiple regression analyses were performed to predict balance control using isokinetic knee strength performance for dominant and non-dominant legs.

Results

Final modelling included peak torque of hamstrings at 240°s⁻¹ and peak torque of the quadriceps at 240°s⁻¹ for the non-dominant leg (R² = 19.6%; p ≤ 0.001) and only peak hamstring torque at 240°s⁻¹ for the dominant leg (R² = 11.3%; p = 0.003) as significant predictors of balance score.

Conclusion

Findings indicate that balance control is widely influenced by peak hamstring torque and peak quadriceps torque at high angular velocity particularly in the non-dominant leg i.e., the supporting leg in soccer players.

Functional and Anthropometrical Screening Test among High Performance Female Football Players: A Descriptive Study with Injury Incidence Analysis, the Basque Female Football Cohort (BFFC) Study

The main objectives of the present study were to describe the injury incidence and to analyze the anthropometric and physical characteristics of players from three high-level women's football teams. The present study involved 54 female football players (21.9 ± 4.9 years old) from three different teams competing in the Spanish Reto Iberdrola-Segunda División PRO league. A battery of tests was carried out to determine the anthropometric and physical performance characteristics of the players along with an injury incidence record during a full competitive season. The obtained results showed that there was a high incidence of injury, as 38% of the players suffered some type of injury during the season (range 1-5; 1.75 ± 1.02 injuries per player). Injuries occurred in both matches and during training at a similar percentage (48.6 vs. 51.4%), and the majority of the registered episodes were graded as moderate or severe injury types (60%). Players suffering from an injury accumulated a total of 1587 chronological days off work due to injury during the season, with a recurrence rate of 55%. Considering the high incidence of injury, and the injury burden and the reinjure rate observed in this research, it seems necessary to apply the most efficient prevention and recovery measures possible in these female football teams. These descriptive data could serve athletic trainers and medical staff of female football teams to better understand their own screening procedure-derived data.

Systematic Review and Meta-Analysis of the Y-Balance Test Lower Quarter: Reliability, Discriminant Validity, and Predictive Validity

BACKGROUND

Deficits in dynamic neuromuscular control have been associated with post-injury sequelae and increased injury risk. The Y-Balance Test Lower Quarter (YBT-LQ) has emerged as a tool to identify these deficits.

PURPOSE

To review the reliability of the YBT-LQ, determine if performance on the YBT-LQ varies among populations (i.e., sex, sport/activity, and competition level), and to determine the injury risk identification validity of the YBT-LQ based on asymmetry, individual reach direction performance, or composite score.

STUDY DESIGN

Systematic Review.

METHODS

A comprehensive search was performed of 10 online databases from inception to October 30, 2019. Only studies that tested dynamic single leg balance using the YBT-LQ were included. Studies were excluded if the Y-Balance Test kit was not utilized during testing or if there was a major deviation from the Y-Balance test procedure. For methodological quality assessment, the modified Downs and Black scale and the Newcastle-Ottawa Scale were used.

RESULTS

Fifty-seven studies (four in multiple categories) were included with nine studies assessing reliability, 36 assessing population differences, and 16 assessing injury prediction were included. Intra-rater reliability ranged from 0.85-0.91. Sex differences were observed in the posteromedial direction (males: 109.6 [95%CI 107.4-111.8]; females: 102.3 [95%CI 97.2-107.4; p = 0.01]) and posterolateral direction (males: 107.0 [95%CI 105.0-109.1]; females: 102.0 [95%CI 97.8-106.2]). However, no difference was observed between sexes in the anterior reach direction (males: 71.9 [95%CI 69.5-74.5]; females: 70.8 [95%CI 65.7-75.9]; p=0.708). Differences in composite score were noted between soccer (97.6; 95%CI 95.9-99.3) and basketball (92.8; 95%CI 90.4-95.3; p <0.01), and baseball (97.4; 95%CI 94.6-100.2) and basketball (92.8; 95%CI 90.4-95.3; p=0.02). Given the heterogeneity of injury prediction studies, a meta-analysis of these data was not possible. Three of the 13 studies reported a relationship between anterior reach asymmetry reach and injury risk, three of 10 studies for posteromedial and posterolateral reach asymmetry, and one of 13 studies reported relationship with composite reach asymmetry.

CONCLUSIONS

There was moderate to high quality evidence demonstrating that the YBT-LQ is a reliable dynamic neuromuscular control test. Significant differences in sex and sport were observed. If general cut points (i.e., not population specific) are used, the YBT-LQ may not be predictive of injury. Clinical population specific requirements (e.g., age, sex, sport/activity) should be considered when interpreting YBT-LQ performance, particularly when used to identify risk factors for injury.

LEVEL OF EVIDENCE

1b.

Effects of a 6-week core stabilization training program on dynamic balance and trunk stabilization endurance of horse riders

The purpose of this study was to examine the effectiveness of a 6-week core stabilization training program (CSTP) in improving dynamic balance and back-extensor endurance of horse riders; and develop a measurement tool in assessing the dynamic postural stabilization endurance for horse riders. Twelve male horse riders (age: 23.58 ± 1.93 years; height: 165.09 ± 4.60 cm; weight: 56.53 ± 4.75 kg; experience in horse racing: 1.75 ± 0.34 years) completed 12 training sessions in 6 weeks. Subjects performed the CSTP with two progressions. CSTP started with the basic consciousness activation exercises, and then eliminated visual feedback in dynamic balance task on unstable surfaces and finished with switching the center of gravity. Moderate-to-large difference was demonstrated in the Y-Balance test scores for right leg (102.81 ± 8.32 vs 106.471 ± 4.35 cm, d = 0.55, 95% CL 0.00 to 1.08) and left leg (102.04 ± 3.20 vs 106.29 ± 3.62 cm, d = 1.25, 95% CL 0.41 to 2.05) following 6 weeks CSTP. However, trivial to small differences was reported between left and right leg in pre (d = 0.12, 95% CL − 0.49 to 0.73) and post 6-week CSTP (d = 0.04, 95% CL − 0.69 to 0.78). Biering–Sørensen test (BST) shows largely greater performance after 6-week CSTP (98.3 ± 30.1 vs 131.8 ± 19.0 s, d = 1.33, 95% CL 0.54–2.09). A novel measurement, Swiss ball four-point kneeling test was shown to be correlated with the change in BST (r = 0.633).

Postural balance impairment in Tunisian second division soccer players with groin pain: A case-control study

OBJECTIVE

To compare postural balance outcomes between soccer players with and without groin pain (GP).

DESIGN

Case-control study.

SETTING

Laboratory.

PARTICIPANTS

Fifty-four soccer players, 27 with GP (GP group: GPG) and 27 healthy ones (control group: CG).

MAIN OUTCOME MEASURES

Static and dynamic postural balance were assessed with a force platform and Y-balance test (Y-BT), respectively. Hip abduction, internal rotation (IR), external rotation (ER) and total rotation (TR) of both limbs were evaluated.

RESULTS

The GPG exhibited significant higher centre of pressure values in the bipedal posture only on the foam surface in eyes opened and closed compared to controls. Besides, they had lower anterior, posteromedial and posterolateral reach distances and composite Y-BT score on the injured limb (IL) compared to non-injured limb (NIL) and dominant-limb (DL) of the CG. Moreover, they showed lower abduction, IR, ER, and TR on the IL compared to NIL and DL.

CONCLUSIONS

Dynamic unipedal postural balance disorder could be one of the limiting factors of performance in soccer players with non-time loss GP. Hence, postural balance data in these players could enable sport coaches and physical therapists to better understand the mechanisms contributing for performance decrease.

The role of the dominant leg while assessing balance performance. A systematic review and meta-analysis

BACKGROUND

Good balance is a pre-requisite for various activities of daily life and sports. Physiotherapists thus regularly assess and train patient's balance capacities. In order to interpret the test results of unilateral balance tests, a comparison with normative data is common. In patients who had an injury or a surgery, the performance of the injured leg is often compared with performance of the non-injured leg. Nevertheless, it remains unclear if unilateral balance performance differs between the dominant and non- dominant legs. If so, this should take into consideration when interpreting test results.

RESEARCH QUESTION

This meta-analysis summarized the current evidence to determine if the balance performance of healthy adults was influenced by the leg's dominance.

METHODS

Articles were searched in PubMed, CINAHL, Cochrane and Embase. Data from studies meeting the pre-defined inclusion criteria were extracted in a standardized form. A meta-analysis was conducted using a random effect model.

RESULTS

Forty-six studies were included. Their data were allocated in 7 categories of balance tests. Significant differences between the dominant and the non-dominant legs were not found in any of the categories (surface stable, eyes open: -0.04, 95 % CI -0.12 to 0.05, surface stable eyes closed: -0.06, 95 % CI -0.22 to 0.11, surface unstable, eyes open: -0.15, 95 % CI -0.38 to 0.07, surface unstable, eyes closed: -0.06, 95 % CI -0.27 to 0.15, BESS (Balance Error Scoring System): 0.03, 95 % CI -1.09 to 1.14, SEBT (Star Excursion Balance Test)/YBT (Y Balance Test): 0.06, 95 % CI -0.04 to 0.16, jump: 0.04, 95 % CI -0.28 to 0.36).

SIGNIFICANCE

Results indicate that balance performance is not influenced by the leg's dominance. This means that performances of both legs can be used as reference. Evidence is strong for the one leg stance. However, future studies are needed to confirm our results for stabilization tasks after a jump landing.

The Relationship between Dynamic Balance and Jumping Tests among Adolescent Amateur Rugby Players. A Preliminary Study

Rugby is a demanding contact sport. In light of research, poor balance, reduced jumping ability, muscle strength, and incorrect landing patterns might contribute to the increased risk of injury in athletes. Investigating the relationship between tests assessing these abilities might not only allow for the skillful programming of preventive training but also helps in assessing the risk of injury to athletes. Thus, the main purpose of this study was to investigate the relationship between dynamic balance, vertical and horizontal jumps, and jump-landings movement patterns. Thirty-one healthy amateur adolescent rugby players (age: 14.3 ± 1.6 years, height 171.4 ± 9.7 cm, body mass 80 ± 26 kg) participated in the study. Data were collected by the Y-balance Test (YBT), Counter Movement Jump (CMJ), Single Leg Hop for Distance (SLHD), and Landing Error Score System (LESS). Significant positive correlations were found between SLHD both legs (SLHDb) and YBT Composite both legs (COMb) (r = 0.51, p = 0.0037) and between SLHDb and CMJ (r = 0.72, p < 0.0001). A relationship was also observed between the CMJ and YBT COMb test (r = 0.51, p = 0.006). Moderate positive correlations were found between the dominant legs in SLHD and the posterolateral (r = 0.40, p = 0.027), posteromedial (r = 0.43, p = 0.014), and composite (r = 0.48, p = 0.006) directions of the YBT. These results indicate that variables that are dependent on each other can support in the assessment of injury-risk and in enhancing sports performance of young athletes.

Neuromuscular training for the prevention of ankle sprains in female athletes: a systematic review

Ankle sprains are a common sports-related injury, and female athletes are more likely to sustain this injury than their male counterparts. Previous reviews have evaluated the efficacy of prevention programs in reducing ankle sprains in athletes, but no reviews have specifically focused on female athletes. The objective of this systematic review was to examine the sex-specific effectiveness of neuromuscular training (NMT) programs in reducing the risk of ankle sprains in female athletes. A search of PubMed, Ovid Medline, Embase, and Web of Science databases was performed using the terms: (proprioception OR proprioceptive OR balance OR neuromuscular OR stability OR sensorimotor) AND training AND (ankle sprain OR ankle injury OR inversion injury OR ankle instability) AND (sport* OR athlet* or basketball OR volleyball OR soccer OR handball OR tennis OR netball OR hockey OR softball OR gymnastics OR danc* OR ballet OR cheerlead*) AND (female OR women OR girl). Studies selected for inclusion were written in English, evaluated female athletes in organized athletics or reported female-specific data for mixed-sex cohorts, included a non-NMT comparison, and used ankle injury rate outcome measures. Seven articles were selected for inclusion, which evaluated a combined 5,187 female basketball, handball, volleyball, soccer, and floorball players. Two studies reported significant differences between NMT participants and controls, concluding the greatest effects were observed in preventing non-contact ankle sprains. The remaining 5 studies, although not statistically significant, revealed an evident trend toward the efficacy of ankle injury prevention with NMT programs. Current available evidence supports the efficacy of NMT in preventing ankle sprains in female athletes. When designing NMT programs, investigators should consider utilizing comprehensive approaches that incorporate strength, balance, plyometric, and agility training as the studies with significant findings created comprehensive NMT programs. Further investigations into sport- and female-specific programs are warranted.

The Effect of Proprioceptive Training on Directional Dynamic Stabilization

OBJECTIVES

Significant loss of playing time and the impact of treatment costs due to lower limb injury in football demonstrates a need for improved protocols for injury risk reduction. The aim of the present study is to assess the effect of a proprioceptive training program on the lower limb dynamic stability of elite footballers.

METHODS

A total of 16 elite premier league footballers were randomly allocated by matched pair design to a 8-week proprioception training group (group A, n = 8) or nontraining group (group B, n = 8), to determine the effect of this training over a 16-week period. Group A completed 8 weeks of bilateral proprioceptive training, 5 times per week for 10 minutes. The Biodex Stability System measures of overall stability index, anterior-posterior (A-P), and medial-lateral stability (M-L) at levels 8-6-4-1 were taken for both groups at baseline, 4, 8, and 16 weeks. Main effects of time, level of stability, and direction of stability were determined, with comparisons of effect made between the 2 groups.

RESULTS

The training group displayed significant differences for multidirectional stability at week 8 (P ≤ .05). The A-P stability within the training group displayed significant differences between baseline measures and 16 weeks (P > .05), with significant increases in scores displayed for M-L and A-P stability between weeks 8 and 16 (P ≤ .05), representing a detraining effect. No significant differences were detected at any time point for the nontraining group (P > .05).

CONCLUSIONS

Proprioceptive training over 8 weeks has a positive effect on all directions of stability. Greater declines in A-P stability were evident at 16 weeks when compared with M-L and overall stability index. Consideration must be given to the increased stability scores presented pretesting for A-P when compared with M-L. Findings of this work present implications for training design.

A Bayesian Network approach to study the relationships between several neuromuscular performance measures and dynamic postural control in futsal players

Purpose

The purpose of this study was to analyse the relationship between several parameters of neuromuscular performance with dynamic postural control using a Bayesian Network Classifiers (BN) based analysis.

Methods

The y-balance test (measure of dynamic postural control), isokinetic (concentric and eccentric) knee flexion and extension strength, isometric hip abduction and adduction strength, lower extremity joint range of motion (ROM) and core stability were assessed in 44 elite male futsal players. A feature selection process was carried out before building a BN (using the Tabu search algorithm) for each leg. The BN models built were used to make belief updating processes to study the individual and concurrent contributions of the selected parameters of neuromuscular performance on dynamic postural control.

Results

The BNs generated using the selected features by the algorithms correlation attribute evaluator and chi squared reported the highest evaluation criteria (area under the receiver operating characteristic curve [AUC]) for the dominant (AUC = 0.899) and non-dominant (AUC = 0.879) legs, respectively.

Conclusions

The BNs demonstrated that performance achieved in the y-balance test appears to be widely influenced by hip and knee flexion and ankle dorsiflexion ROM measures in the sagittal plane, as well as by measures of static but mainly dynamic core stability in the frontal plane. Therefore, training interventions aimed at improving or maintaining dynamic postural control in elite male futsal players should include, among other things, exercises that produce ROM scores equal or higher than 127° of hip flexion, 132.5° of knee flexion as well as 34° and 30.5° of ankle dorsiflexion with the knee flexed and extended, respectively. Likewise, these training interventions should also include exercises to maintain or improve both the static and dynamic (medial-lateral plane) core stability so that futsal players can achieve medial radial error values lower than 6.69 and 8.79 mm, respectively.