scholarly journals Comparação de dois critérios de classificação de jogadores de futebol profissional da assimetria lateral de força dos membros inferiores

2017 ◽  
Vol 19 (6) ◽  
pp. 644-651 ◽  
Author(s):  
Sílvia Ribeiro Santos Araujo ◽  
Fabiola Bertu Medeiros ◽  
Alvaro Dressler Zaidan ◽  
Eduardo Mendonça Pimenta ◽  
Edgardo Alvares de Campos Abreu ◽  
...  
Keyword(s):  
General Population ◽  
Confidence Interval ◽  
Peak Torque ◽  
Cutoff Point ◽  
Soccer Players ◽  
Knee Extensors ◽  
Lateral Asymmetry ◽  
Professional Soccer ◽  
Isokinetic Test ◽  
Cutoff Points

Prospective studies have indicated that assessing muscle function by the isokinetic test in the preseason is able to identify muscle strength variables that can be associated with injuries in the hamstring muscles of professional soccer players. However, the results are conflicting and could be related to the different cutoff points for the categorization of athletes in asymmetric or symmetric. Based on these conflicting results, the present study aims to: i) Identify the cutoff points of lateral asymmetry (LA) of the 95% confidence interval for the peak torque in soccer players, evaluated by the isokinetic test, taking into consideration the mean population value; ii) Compare LA between 15% cutoff point proposed in literature and the upper limit of 95% confidence interval (UP) of the study population. Sixty-four professional soccer players performed five knee flexion and extension repetitions at rate of 60°/s, with a one-minute interval. To determine the cutoff point for strength asymmetries, the UP was used, and for the purpose of diagnostic concordance of information among the different values, the McNemar’s χ² test was applied. The proportion between symmetric and asymmetric athletes was not different from the 15% cutoff point and the general population, both for knee flexors (χ² = 0.5, p = 0.250) and the knee extensors (χ² = 2.0, p = 0.125). It was concluded that the cutoff point of 15% referenced in literature for the general population provides similar diagnostic information for the classification of professional soccer players. 

Peak torque angle, acceleration time and time to peak torque as additional parameters extracted from isokinetic test in professional soccer players: a cross-sectional study

2020 ◽  
pp. 1-12
Author(s):  
Daniel Germano Maciel ◽  
Glauko André Figueiredo Dantas ◽  
Mikhail Santos Cerqueira ◽  
Jean Artur Mendonça Barboza ◽  
Vinícius Vieira De Alencar Caldas ◽  
...  
Keyword(s):  
Peak Torque ◽  
Cross Sectional Study ◽  
Soccer Players ◽  
Sectional Study ◽  
Cross Sectional ◽  
Acceleration Time ◽  
Time To Peak ◽  
Professional Soccer ◽  
Isokinetic Test ◽  
Torque Angle

scholarly journals Influence of Fatigue on the Rapid Hamstring/Quadriceps Force Capacity in Soccer Players

2021 ◽  
Vol 12 ◽  
Author(s):  
Qingshan Zhang ◽  
Baptiste Morel ◽  
Robin Trama ◽  
Christophe A. Hautier
Keyword(s):  
Injury Risk ◽  
Muscle Activation ◽  
Statistical Parametric Mapping ◽  
Peak Torque ◽  
Frequency Component ◽  
Surface Emg ◽  
Knee Extension ◽  
Soccer Players ◽  
Knee Extensors ◽  
Professional Soccer

The objective of this study was to examine the effect of fatigue on maximal and rapid force capacities and muscular activation of the knee extensors and flexors. Seventeen professional soccer players volunteered to participate in this study. Peak torque (Tpeak) and rate of torque development (RTD) of knee flexor (90°. s–1, −30°. s–1) and extensor (90°. s–1) muscles were measured before and after fatigue (i.e., 30 maximal knee extension and flexion repetitions at 180°s–1) performed on an isokinetic dynamometer. Hamstring to quadriceps peak strength and RTD ratios were calculated. Besides, using surface EMG, the mean level of activation (RMSmean), Rate of EMG Rise (RER), and EMG Frequency-Time maps were measured on quadriceps and hamstring muscles. Following fatigue, Tpeak, RTD, RER declined significantly in the two muscle groups (all p < 0.05) without modification of RMSmean. No decrease in conventional and functional H/Q ratios was observed after fatigue except for a significant increase in the Hecc30/Qcon180 ratios (1.03 ± 0.19 vs. 1.36 ± 0.33, p < 0.001). Besides, the RTD H/Q ratios decreased significantly after fatigue, and the statistical parametric mapping analysis (SPM) performed on the EMG/angle curves, and EMG Frequency-Time maps showed that fatigue strongly influenced the muscle activation during the first 100 ms of the movement, following the higher EMG frequency component shift toward the lower frequency component. Our results show that the reduction of RTD and RER during the first 100 ms of the contraction after fatigue exercise makes more sense than any H/Q ratio modification in understanding injury risk in soccer players.

scholarly journals 25(OH)D3 Levels Relative to Muscle Strength and Maximum Oxygen Uptake in Athletes

2016 ◽  
Vol 50 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Anna Książek ◽  
Aleksandra Zagrodna ◽  
Wioletta Dziubek ◽  
Bogdan Pietraszewski ◽  
Bartosz Ochmann ◽  
...  
Keyword(s):  
Vitamin D ◽  
Muscle Strength ◽  
Oxygen Uptake ◽  
Lower Limb ◽  
Peak Torque ◽  
Maximum Oxygen Uptake ◽  
Soccer Players ◽  
Knee Extensors ◽  
Vitamin D Receptors ◽  
Professional Soccer

AbstractVitamin D is mainly known for its effects on the bone and calcium metabolism. The discovery of Vitamin D receptors in many extraskeletal cells suggests that it may also play a significant role in other organs and systems. The aim of our study was to assess the relationship between 25(OH)D3 levels, lower limb isokinetic strength and maximum oxygen uptake in well-trained professional football players. We enrolled 43 Polish premier league soccer players. The mean age was 22.7±5.3 years. Our study showed decreased serum 25(OH)D3 levels in 74.4% of the professional players. The results also demonstrated a lack of statistically significant correlation between 25(OH)D3 levels and lower limb muscle strength with the exception of peak torque of the left knee extensors at an angular velocity of 150°/s (r=0.41). No significant correlations were found between hand grip strength and maximum oxygen uptake. Based on our study we concluded that in well-trained professional soccer players, there was no correlation between serum levels of 25(OH)D3 and muscle strength or maximum oxygen uptake.

scholarly journals Concentric and eccentric isokinetic hamstring injury risk among 582 professional elite soccer players: a 10-years retrospective cohort study

2020 ◽  
Vol 6 (1) ◽  
pp. e000868
Author(s):  
Ricardo Lima Burigo ◽  
Robson Dias Scoz ◽  
Bruno Mazziotti de Oliveira Alves ◽  
Rubens Alexandre da Silva ◽  
Cesar Augusto Melo-Silva ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Cohort Study ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Injury Risk ◽  
Peak Torque ◽  
Soccer Players ◽  
Complex Data ◽  
Isokinetic Test ◽  
Clinical Records

Background/AimDifferent authors have tried to correlate the peak isokinetic torque values with the incidence of soccer match injuries. However, due to the wide variety of assessment testing protocols, such an inference becomes difficult. This study aimed to verify the capacity of an isokinetic test to establish injury risk reference values for hamstring strain injuries.MethodsA retrospective cohort study based on isokinetic data and clinical records from the last 10 years was conducted in 582 Brazilian elite-professional soccer players, who were subjected to the same isokinetic test protocol, machine, and tester. A Multivariate Logistic Regression Analysis for Complex Data Sampling was used to generate injury risk statistical indexes.ResultsMultivariate regression analysis of both legs provided important data to identify the cut-off values of Concentric Peak Torque (181.82 Newton/*metres), Concentric Work (236.23 watts) and Concentric Power (130.11 joules).ConclusionsThe injury risk indexes indicate that an increase of just one Newton unit in CPT (Concentric Peak Torque) and CJ (Concentric Power) above those cut-off values, can reduce the risk of future injuries by 2% and 2.7%, respectively.

scholarly journals ISOKINETIC PROFILES AND REFERENCE VALUES OF PROFESSIONAL SOCCER PLAYERS

2021 ◽  
Vol 27 (6) ◽  
pp. 610-615
Author(s):  
Guillermo Charneco Salguero ◽  
Francisco García-Muro San José ◽  
Arturo Pérez Gosalvez ◽  
Jose Miguel Cárdenas Rebollo ◽  
Isabel Brígido Fernández ◽  
...  
Keyword(s):  
Reference Values ◽  
Health Professionals ◽  
High Speed ◽  
Peak Torque ◽  
Soccer Players ◽  
Level Of Evidence ◽  
Warm Up ◽  
Professional Soccer ◽  
Average Work ◽  
Torque Values

ABSTRACT Introduction: Isokinetics is a tool commonly used in professional soccer. There is ongoing debate among researchers as to the isokinetic reference values a player should have. Objectives: To determine the absolute peak torque (PT) and average work of professional soccer players in relation to their positions on the field, and to establish the reference values for these variables. Methods: Purposeful sampling was used to select 289 professional soccer players. The sample included 32 goalkeepers, 100 defenders, 98 midfielders, and 59 strikers. The participants were measured preseason. The players were asked to perform a 10-minute warm-up on an exercise bike, and then to perform 5 repetitions at low speed, 10 at medium speed, and 25 at high speed, with 30 to 40-s of rest between each set of repetitions. The contraction method was concentric-concentric in a dynamometer Isomed 2000. Results: The average age, weight, and height of the players was 21.9 years, 74.3 kilograms, and 1.8 meters, respectively. The goalkeepers presented higher PT at the 3 measured speeds, and the higher average work at 180°/s and 240°/s in relation to defenders and midfielders. The strikers presented higher average work at 240°/s in relation to midfielders, and higher PT in relation to the defenders and midfielders. Absolute values were shown and reference values were established. Conclusions: The goalkeepers and strikers were the players that showed the greatest differences in their favor in relation to the other positions. The peak torque values and average work were described in relation to the player's position on the field. This study resulted in the creation of a tool for health professionals working with professional soccer players, providing reference values for these players in relation to their position on the field that can be used as benchmarks, by health professionals, to optimize soccer players’ performance. Level of evidence II, Prospective comparative study.

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

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12461
Author(s):  
Robert Śliwowski ◽  
Jakub Marynowicz ◽  
Łukasz Jadczak ◽  
Monika Grygorowicz ◽  
Paweł Kalinowski ◽  
...  
Keyword(s):  
Angular Velocity ◽  
Balance Control ◽  
Peak Torque ◽  
Soccer Players ◽  
Knee Extensors ◽  
Measurement Tool ◽  
Strength Performance ◽  
Angular Velocities ◽  
Postural System ◽  
The Relationship

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.

scholarly journals Evaluating injury risk in first and second league professional Portuguese soccer: muscular strength and asymmetry

2016 ◽  
Vol 51 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Alberto Carvalho ◽  
Scott Brown ◽  
Eduardo Abade
Keyword(s):  
Muscle Strength ◽  
Injury Risk ◽  
Dynamic Control ◽  
Peak Torque ◽  
Soccer Players ◽  
Bilateral Asymmetry ◽  
Hamstring Strain ◽  
Professional Soccer ◽  
Maximal Peak ◽  
The Right

AbstractStrength imbalances between the hamstrings and quadriceps are an essential predictor for hamstring strain in soccer. The study aimed to investigate and compare the muscle strength imbalances of professional soccer players of different performance levels. One hundred and fifty nine senior male professional soccer players from first (n = 75) and second league (n = 84) Portuguese clubs participated in this study. Muscle strength was evaluated with a REV9000 isokinetic dynamometer. Maximal peak torque data were used to calculate quadriceps and hamstrings strength during concentric and eccentric actions, bilateral asymmetry, conventional strength ratios and dynamic control ratios. Second league athletes produced slightly lower conventional strength ratios in the right and left legs (ES = 0.22, p = 0.17 and ES = 0.36, p = 0.023, respectively) compared to the first league athletes. No significant differences were found in dynamic control ratios or in bilateral asymmetry among first and second league athletes. These findings do not show a clear link between the competitive level and injury risk in soccer players. However, some of the differences found, particularly in conventional strength ratios, highlight the importance of performing off-season and pre-season strength assessments to prescribe and adjust individual strength training programs among professional soccer players.

scholarly journals Isokinetic Strength Responses to Season-long Training and Competition in Turkish Elite Soccer Players

2012 ◽  
Vol 31 (1) ◽  
pp. 159-168 ◽  
Author(s):  
Niyazi Eniseler ◽  
Çağatay Şahan ◽  
Hikmet Vurgun ◽  
Hasan Mavi
Keyword(s):  
Knee Extensor ◽  
Peak Torque ◽  
Soccer Players ◽  
Isokinetic Strength ◽  
Professional Soccer ◽  
Knee Strength ◽  
Flexor Muscles ◽  
Angular Velocities ◽  
Soccer Training ◽  
Knee Flexors

Isokinetic Strength Responses to Season-long Training and Competition in Turkish Elite Soccer PlayersThere are not enough studies that describe the isokinetic strength of professional soccer players at high angular velocities. The purpose of this study was to evaluate the seasonal changes in isokinetic strength of Turkish professional soccer players (n=14) over the course of a 24-week soccer season. The isokinetic strength of players who underwent usual soccer training and weekly competition throughout the soccer season was assessed by means of the Biodex System 3 dynamometer with the knee attachment. The peak torque of knee extensor and flexor muscles were measured at angular velocities of 60°/s, 300°/s and 500°/s. Players were tested at the beginning and end of the competitive season. While the first- and second-test measurements did not show significant changes at 60°/s and 300°/s angular velocities, at the end of the training period, players' knee strength changed significantly at 500°/s angular velocities. In addition, the H/Q ratio improved significantly for the dominant as well as non-dominant leg at 500°/s. Significant bilateral strength improvements for knee flexors were also observed at 500°/s. The findings of this study suggest that usual daily soccer training (technical, tactical, power, strength, endurance, flexibility, etc.) and weekly competition might produce changes in knee strength at high angular velocities.

scholarly journals Lower-Extremity Force Decrements Identify Early Mobility Decline Among Community-Dwelling Older Adults

2012 ◽  
Vol 92 (9) ◽  
pp. 1148-1159 ◽  
Author(s):  
Moshe Marko ◽  
Christopher G. Neville ◽  
Mark A. Prince ◽  
Lori L. Ploutz-Snyder
Keyword(s):  
Older Adults ◽  
Confidence Interval ◽  
Lower Extremity ◽  
Likelihood Ratio ◽  
Community Dwelling ◽  
Knee Extensors ◽  
Cross Sectional ◽  
Lower Extremity Muscle ◽  
Cutoff Points ◽  
Community Dwelling Older Adults

BackgroundMany apparently independent older adults modify daily tasks. Task modifications strongly predict future mobility disability. Clinically intuitive, easily measured “biomarkers” associated with task modifications would offer quantifiable treatment targets for prevention of age-related functional limitations.ObjectiveThe objective of the study was to examine lower-extremity muscle strength deficits and functionally relevant cutoff points associated with daily task modifications in community dwelling older adults living independently.DesignThis was a cross-sectional observational study.MethodsFifty-three participants (mean age=76.4 years, SD=5.2) were tested for task modifications and leg strength. Task modifications were assessed using a previously described tool (summary task modification score). Twenty-six of the participants were classified as task modifiers (TM group), and 27 participants were classified as non–task modifiers (NTM group). A net antigravity leg force in the sagittal plane (NETforce) was calculated by summing the normalized isometric and isokinetic torques from the hip extensors, knee extensors, and ankle plantar flexors.ResultsCompared with the NTM group, the TM group exhibited 30.0% and 33.5% reduction in lower-extremity isometric and isokinetic NETforces, respectively. Isometric and isokinetic NETforce cutoff points for task modifications were ≤4.24 and 2.77 N·m/kg body weight, respectively. The isometric and isokinetic models both yielded sensitivity and specificity values of 74.1% and 80.8%, respectively (positive likelihood ratio=3.852, 95% confidence interval=1.699–8.735; negative likelihood ratio=0.321, 95% confidence interval=0.167–0.618). Isometric and isokinetic NETforces were significantly associated with task modifications (odds ratio=2.50 and 2.42, respectively).LimitationsThe cross-sectional design of this study does not allow for a test of causal relationships. This study used a modest yet adequate sample size that may limit generalization of the results.ConclusionsIsometric and isokinetic NETforce cutoff points provide quantifiable biomarkers that discriminate community-dwelling older adults who modify daily tasks from those who do not.

scholarly journals Intra- and Inter-Limb Strength Asymmetry in Soccer: A Comparison of Professional and Under-18 Players

Sports ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 129
Author(s):  
Chris Bishop ◽  
Giuseppe Coratella ◽  
Marco Beato
Keyword(s):  
Knee Extensor ◽  
Peak Torque ◽  
Soccer Players ◽  
Knee Extensors ◽  
Isokinetic Dynamometer ◽  
Percentage Difference ◽  
Strength Asymmetry ◽  
Limb Asymmetry ◽  
Limb Dominance ◽  
Anterior Posterior

(1) Background: the present study examined the isokinetic peak torque exerted by both knee extensors and flexors, anterior–posterior imbalance and the magnitude and direction of inter-limb asymmetry in professional and academy soccer players. (2) Methods: one hundred soccer players (professional = 50, elite academy = 50) volunteered to take part in this investigation. An isokinetic dynamometer was used to measure the knee extensor (quadriceps) and flexors muscle (hamstrings) torques of the limbs as well as inter-limb asymmetries—using a standard percentage difference equation. (3) Results: professional players exhibited significantly greater (effect size [ES] = large) strength levels in the quadriceps and hamstrings under both testing conditions, significantly higher (small to moderate) intra-limb ratio values for 60°·s−1 but not for the 300°·s−1 test condition, significantly (small to moderate) lower inter-limb asymmetry values for all test conditions, with the exception of the hamstrings at 60°·s−1 and the direction of asymmetry was poor to slight, indicating that limb dominance was rarely the same between groups. (4) Conclusions: this study shows that isokinetic assessments, i.e., peak torque exerted by both knee extensors and flexors and intra-limb ratio, and the subsequent inter-limb asymmetry, i.e., magnitude and direction, can differentiate between professional and academy soccer players.

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