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The purpose of the study was to analyze the test-retest reliability of an isometric and isometric/vibratory muscular strength protocol in the bilateral seated bench press (BSBP), bilateral seated rowing (BSR), unilateral seated right knee extension (USKER), and left knee extension (USKEL) tests controlled using functional electromechanical dynamometry (FEMD) in healthy young adults. A repeated measures design was used to determine the reliability of a muscular strength protocol in isometric and isometric vibration modes with FEMD. No significant differences were found in test-retest analysis (p > 0.05; ES < 0.20); and high reliability (CV = 4.65-5.02%; ICC = 0.99-0.98) was found for BSBP measures, and acceptable reliability (CV = 3.71-9.61%; ICC = 0.98-0.95) was found for BSR, USKER, and USKEL. Furthermore, the coefficients between the two measures were strong (r = 0.963-0.839) and highly significant (p = 0.001) for maximal strength in the isometric and maximal isometric/vibratory assessment of muscle strength in all muscle strength tests. This study demonstrates that isometric and maximal isometric/vibratory strength in the BSBP, BSR, USKER, and USKEL tests can be measured with high reliability and reproducibility using the FEMD.

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INTRODUCTION: The self-paced adopted by wheelchair users in their postural transfers and locomotion may require sufficient levels of speed-strength in the upper limbs. In clinical practice, we observed limited functional independence and social participation. OBJECTIVES: This study aimed to investigate and compare the speed-strength relationship between wheelchair users with spina bifida (SB) and typically developing youth. In particular, to analyze if SB wheelchair users reached the preset velocities in the isokinetic evaluation of shoulder and elbow. DESIGN: Cross-sectional observational study. SETTING: Ribeirão Preto Medical School of the University of São Paulo. PARTICIPANTS AND PROCEDURES: SB (SB; n = 11) and controls (CT; n = 22) performed the isokinetic assessment of shoulder abductors (SAB), adductors (SAD), flexors (SFL), extensors (SEX), and elbow flexors (EFL) and extensors (EEX) at velocities of 60 and 120degree.s-1. The analysis of covariance was used to identify the intergroup differences in muscle performance. OUTCOME MEASURES: The values of peak torque (PT), power (Pow), time to peak torque (tPT) and the percentage to reach the isokinetic velocity. RESULTS: The percentage to reach 120degree.s-1 was moderate-to-low for both groups (26-75.9%). CT presented a significantly greater relative risk of reaching the preset velocities than SB. SB presented higher PT and Pow for SAB and SFL at 60degree.s-1, higher PT for SFL and EEX at 120degree.s-1, and lower tPT for SFL at 120degree.s-1 compared to CT. CONCLUSION: SB had difficulty reaching 120degree.s-1, probably related to neuromuscular differences. However, arm movements in their daily tasks seem to maintain the ability to produce PT and Pow.

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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.

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BACKGROUND: To identify inter-limb asymmetries through the knee's muscular and lower limb functional performance in young male soccer athletes. METHODS: Twenty male soccer athletes aged 17 to 19 from an under-20 team performed isokinetic tests at 60°/s., 120°/s., 180°/s., and 240°/s. To assess the knee extensors and flexors muscles and functional tests (hop tests and Y-balance test). RESULTS: There were no significant differences between the dominant limb (DL) and non-dominant limb (NDL) in the knee extensors and flexors peak torque and hamstrings (H)/quadriceps(Q) conventional ratio. Moreover, no angular velocities observed inter-limb asymmetries seen by values higher than 10% in the isokinetic parameters. However, the H/Q conventional ratio shows borderline values in low angular velocities (60°/s. and 120°/s.). No significant changes were observed in the functional test performance between the DL and NDL. Furthermore, we did not see inter-limb asymmetries in both hop and Y-balance tests. On the contrary, the anterior distance reached was lower than found in the literature, and the composite score of the Y-balance test demonstrated values below the normative (>94%). CONCLUSION: The data demonstrated that soccer athletes have muscular and functional inter-limb symmetry. However, they tend to have knee muscle imbalance in low velocities and dynamic balance deficits that might increase the risk of musculoskeletal injury.

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The objective of the study was to investigate the impact of photobiomodulation (PBM) on the paretic upper limb in post-stroke patients with spastic hemiparesis and to understand the potential of PBM as a long-term non-invasive therapy for reducing the side effects caused by spasticity in the hemiparetic upper limb after a stroke. This is a double-blind randomized clinical trial constituted of 27 participants, being Control group (CG = 12 healthy individuals) and PBM group (PBMG = 15 post-stroke individuals). In the CG, the baseline blood lactate (BL) was evaluated, followed by the evaluation of the IC torque of the biceps and triceps muscles, with the isokinetic dynamometer associated with surface electromyography (EMG) and, subsequently, a new measurement of BL. The PBMG received 10 sessions of treatment with PBM (780 nm, Power: 100 mV, Power Density: 3.18 W/cm2, Energy: 4 J, Fluency: 127.4 J/cm2, Time: 40 s per point and 1.280 s total, Spot: 0.0314 cm2, 32 Points: 16 points (brachial biceps) and 16 points (brachial triceps) applied with contact at 90°, Total Energy: 64 J), which in the pre-treatment evaluation measured BL, the visual analogue scale (VAS) of pain; torque and EMG of the same muscles in the IC, subsequently, a new measurement of VAS and BL, and measurement of range of motion (ROM) during the reaching movement. At the conclusion of the ten sessions, all participants underwent a reassessment, wherein all tests originally administered during the initial evaluation were repeated. Subsequently, the data were analyzed using the Shapiro-Wilk normality test. For related data, the paired t-test was used for normal distributions and the Wilcoxon test for non-normal data. For unrelated data, the t test was used for normal distributions and the Mann-Whitney test for non-normal data. Muscle torque was higher for the CG, with a significant difference (CGxPBMG = p < 0.0001). There was no significant difference between the EMG values of the CG in relation to the Pre-PBM phase and with the Post-PBM phase of the PBMG (p > 0.05). On the other hand, there was a 38% reduction in pain reported by hemiparetic patients (p = 0.0127) and a decrease in BL in the PBMG. Post-PBM ROM increased by 46.1% in the elbow extension of the paretic limb. In conclusion, Photobiomodulation (PBM) demonstrated significant improvements in muscle performance, reducing fatigue and pain levels, and enhancing range of motion in post-stroke patients with spastic hemiparesis. These findings support the potential integration of PBM into rehabilitation protocols, but further research and clinical trials are needed to validate and expand upon these promising outcomes.

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PURPOSE: Exercise intolerance and dyspnoea are clinical symptoms in both heart failure (HF) reduced ejection fraction (HFrEF) and chronic obstructive pulmonary disease (COPD), which are suggested to be associated with musculoskeletal dysfunction. We tested the hypothesis that HFrEF + COPD patients would present lower muscle strength and greater fatigue compared to compared to the COPD group. METHODS: We included 25 patients with HFrEF + COPD (100% male, age 67.8 ± 6.9) and 25 patients with COPD alone (100% male, age 66.1 ± 9.1). In both groups, COPD severity was determined as moderate-to-severe according to the GOLD classification (FEV1/FVC < 0.7 and predicted post-bronchodilator FEV1 between 30%-80%). Knee flexor-extensor muscle performance (torque, work, power and fatigue) were measured by isokinetic dynamometry in age and sex-matched patients with HFrEF + COPD and COPD alone; Functional capacity was assessed by the cardiopulmonary exercise test, the 6-min walk test (6MWT) and the four-minute step test. RESULTS: The COPD group exhibited reduced lung function compared to the HFrEF + COPD group, as evidenced by lower FEV1/FVC (58.0 ± 4.0 vs. 65.5 ± 13.9; p < 0.0001, respectively) and FEV1 (51.3 ± 17.0 vs. 62.5 ± 17.4; p = 0.026, respectively) values. Regarding musculoskeletal function, the HFrEF + COPD group showed a knee flexor muscles impairment, however this fact was not observed in the knee extensors muscles. Power peak of the knee flexor corrected by muscle mass was significantly correlated with the 6MWT (r = 0.40; p < 0.05), number of steps (r = 0.30; p < 0.05) and work ratepeak (r = 0.40; p < 0.05) in the HFrEF + COPD and COPD groups. CONCLUSION: The presence of HFrEF in patients with COPD worsens muscular weakness when compared to isolated COPD.

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The aim of the present study was to summarize the effectiveness of amino acid supplementation on muscle strength, muscle volume, and functional capacity in patients undergoing total knee arthroplasty. For this, in November 2022, a search was carried out in the PubMed, Cochrane Library, and EMBASE databases, identifying a total of 2182 documents, of which only 4 were included in the present review. The included studies had 148 participants (47 men and 101 women), with a minimum age of 53 and a maximum of 92 years, and supplementation times of 13 to 30 days (1 to 3 times a day). For the results, in relation to muscle performance, when comparing the control and experimental groups, greater muscle atrophy was observed in the pre- and post-moments of the control group, in relation to the experimental group. In addition, studies suggest a good tendency for muscle mass gain, and improvement in the functional capacities of patients who used supplementation. Therefore, the use of amino acids after TKA surgery reduces muscle atrophy, which preserves muscle mass and leads to better performance in tests of strength and functional capacity, when compared to the use of a placebo.

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The aims of the present study are to investigate the magnitude and direction of the elbow torque asymmetries in manual wheelchair users and to verify the agreement levels of the asymmetry's direction between different velocities and contraction modes in the isokinetic test. The sample was composed of 14 manual wheelchair users (four women, 10 men). The peak torque of the elbow flexors and extensors were measured on the dominant and non-dominant limbs, using a set of concentric/eccentric contractions at speeds of 60°â€…s-1 and 180°â€…s-1. Asymmetries were calculated by a specific equation, and the levels of agreement of the asymmetry's direction were calculated using Kappa coefficient. The main results showed a large variability in the magnitude of the asymmetries, ranging from -73.1% (ND) to 59.9% (D) between participants. The agreement levels of the elbow flexors and extensors between the different contraction modes were great (k = 0.71-0.85) for most of the velocities [except for flexors of 60°â€…s-1 (k = 0.29)], but the agreement levels were only slight to fair (k = 0.16-0.31) for most of the contraction modes when comparing between velocities [except for flexors eccentric (k = 0.71)]. In conclusion, the elbow torque asymmetries are highly variable between subjects in terms of magnitude. In addition, in general, the limb favored by the asymmetry is the same when comparing between velocities, but not when comparing between contraction modes.

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Robotic-assisted rehabilitation is currently being applied to improve the effectiveness of human gait rehabilitation and recover the mobility and strength after a stroke or spinal cord injury; a robotic assistant can allow the active participation of the patient and the supervision of the collected data and decrease the labor required from therapists during the patient's training exercises. The goal of gait rehabilitation with robotic-based assistance is to restore motor function by using diverse control strategies, taking account of the physical interaction with the lower limbs of the patient. Over the last few years, researchers have extracted useful information from the patient's biological signals that can effectively reflect movement intention and muscle activation. One way to evaluate progress in rehabilitation is through isokinetic prototype tests that describe the dynamic characteristics of an isokinetic leg extension device for rehabilitation and control action. These tests use an isokinetic system to assess muscle strength and performance in a patient during isometric or isokinetic contraction. An experimental prototype shown in the following work allows the device's performance to be evaluated in a controlled environment before the patient's use. New features provide a control system that can be teleoperated for distributed structures, enabling the remote operation and management of the device. In order to achieve physical recovery from musculoskeletal injuries in the lower limbs and the reintegration of the affected subject into society as an independent and autonomous individual in their daily activities, a control model that introduces a medical isokinetic rehabilitation protocol is presented, in which the element that carries out such protocol consists of a magnetic particle brake whose control action is strongly influenced by the dynamics of the system when in contact with the end user-specifically, the patient's legs in the stretch from the knee to the ankle. The results of these tests are valuable for health professionals seeking to measure their patient's progress during the rehabilitation process and determine when it is safe and appropriate to advance in their treatment.

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A common pre-season injury prevention assessment conducted by professional football clubs is the hamstring-to-quadriceps (H:Q) strength ratio calculated by peak torque (PT). However, it is debatable whether players that present low pre-season H:Q ratios are more susceptible to further sustaining in-season hamstring strain injuries (HSI). Based upon retrospective data from a Brazilian Serie A football squad, a particular season came to our attention as ten out of seventeen (~59%) professional male football players sustained HSI. Therefore, we examined the pre-season H:Q ratios of these players. H:Q conventional (CR) and functional (FR) ratios, and the respective knee extensor/flexor PT from the limbs of players further sustaining in-season HSI (injured players, IP) were compared to the proportional number of dominant/non-dominant limbs from uninjured players (UP) in the squad. FR and CR were ~18-22% lower (p < 0.01), whereas quadriceps concentric PT was ~25% greater for IP than UP (p = 0.002). Low scores of FR and CR were correlated (p < 0.01) with high levels of quadriceps concentric PT (r = -0.66 to -0.77). In conclusion, players who sustained in-season HSI had lower pre-season FR and CR compared to UP, which appears to be associated with higher levels of quadriceps concentric torque than hamstring concentric or eccentric torque.

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Muscular weakness and strength imbalance between the thigh muscles are considered risk factors for knee injuries. Hormonal changes, characteristic of puberty, strongly affect muscle strength; however, it is unknown whether they affect muscular strength balance. The present study aimed to compare knee flexor strength, knee extensor strength, and strength balance ratio, called the conventional ratio (CR), between prepubertal and postpubertal swimmers of both sexes. A total of 56 boys and 22 girls aged between 10 and 20 years participated in the study. Peak torque, CR, and body composition were measured using an isokinetic dynamometer and dual-energy X-ray absorptiometry, respectively. The postpubertal boys group presented significantly higher fat-free mass (p < 0.001) and lower fat mass (p = 0.001) than the prepubertal group. There were no significant differences among the female swimmers. Peak torque for both flexor and extensor muscles was significantly greater in postpubertal male (p < 0.001, both) and female swimmers (p < 0.001 and p = 0.001, respectively) than in prepubertal swimmers. The CR did not differ between the pre- and postpubertal groups. However, the mean CR values were lower than the literature recommendations, which brings attention to a higher risk of knee injuries.

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CONTEXT: Despite increasing use of reference values in isokinetic measurements and increasing importance, there is no systematic review of the reference values for lower and upper limb isokinetic muscle strength. OBJECTIVE: A systematic review to analyze studies on the reference values and protocols for the measurement for upper and lower limb isokinetic muscle strength in an untrained and noninjured healthy population. DATA SOURCES: MEDLINE, Scopus, Scielo, and CINAHL (from the earliest date available to June 2020). STUDY SELECTION: Studies that measured a set of reference values for isokinetic muscle strength. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: Two reviewers selected studies independently. Data related to participants characteristics, outcomes of interest, isokinetic parameters, reference values for isokinetic muscle strength, and quality of evidence assessment were systematically reviewed independently by 2 authors. RESULTS: A total of 31 studies met the study criteria. The included studies were used to synthesize the isokinetic muscle strength data according to age-group and sex. We extracted 1845 normative data related to isokinetic strength. Of these, 1181 items referred to lower limbs and 664 items to upper limbs. CONCLUSION: In general, agonist muscle groups are stronger than antagonist muscles, and the men tend to obtain higher strength values than women. The angular velocity varied from 10 to 300 deg/s. The reference values identified can be useful for professionals to obtain during the isokinetic evaluation of the diagnostic parameters of muscle deficiency.

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Durante a prática de taekwondo com movimentos repetitivos, sistematizados e com certa sobrecarga de treino, o indivíduo pode gerar possíveis adaptações orgânicas que resultam em problemas posturais com grandes chances de desencadear desequilíbrio muscular. Objetivo: Verificar a presença de desequilíbrio entre os grupos musculares agonistas e antagonistas da articulação do joelho e entre membros dominantes e não dominantes de praticantes de taekwondo por meio da dinamometria isocinética. Método: Estudo transversal, observacional e descritivo realizado com nove praticantes de taekwondo do sexo masculino. Utilizou-se um dinamômetro isocinético para investigar o pico de torque, pico de torque por peso corporal, trabalho total, potência média, relação agonista/antagonista e índice de fadiga. Os dados dos membros dominante e não dominante foram comparados por meio do teste t-student para amostras pareadas. Foram calculados o intervalo de confiança de 95% da diferença média, o tamanho de efeito e o poder das análises. Resultados: Os músculos extensores dos membros dominante e não dominante apresentaram diferença média significante de 15,49 Nm (IC95% 7,27; 23,70; p=0,002) para pico de torque e de 22,64% (IC95% 11,83; 33,46; p=0,001) para pico de torque por peso corporal a 60°/s, representando tamanho de efeito médio. Conclusão: Os atletas de taekwondo apresentaram maior pico de torque e maior pico de torque por peso corporal dos músculos extensores do joelho a 60º/s no lado dominante. A relação agonista/ antagonista foi inferior a 60% e mais da metade dos atletas apresentaram uma diferença maior que 10% no pico de torque flexor no lado não dominante.

During taekwondo practice with the repetitive motions, systematized and with certain training overload, the person can generate possible organic adaptations that result in postural problems with a great chances of triggering muscle imbalance. Objective: To verify the presence of imbalance between agonist and antagonist muscle groups of knee joint and between dominant and non-dominant limbs through isokinetic dynamometry. Methods: Cross-sectional, observational and descriptive study realized with nine male taekwondo practitioners. An isokinetic dynamometer was used to investigate the peak torque, peak torque by body weight, total work, average power, agonist/antagonist ratio and fatigue index. Data from the dominant and non-dominant limbs were compared by t-student test for pared samples. The 95% confidence interval of the mean difference, the effect size and the power of analyses power were calculated. Results: The extensor muscles of the dominant and non-dominant limbs showed mean difference of 15,49 Nm (IC95% 7,27; 23,70; p=0,002) for peak torque and of 22,64% (IC95% 11,83; 33,46; p=0,001) for peak torque by body weight at 60°/s, representing average effect size. Conclusion: The taekwondo athletes had higher peak torque and higher peak torque by body weight of the knee extensors muscles in the dominant side. The agonist/ antagonist ratio was less than 60% and more than half of the athletes showed a difference greater than 10% in the peak flexor torque on the non-dominant side.

Durante la práctica de taekwondo con los movimientos repetitivos, sistematizados y con cierta sobrecarga de entrenamiento, la persona puede generar posibles adaptaciones orgánicas que deriven en problemas posturales con grandes posibilidades de desencadenar desequilibrios musculares. Objetivo: Verificar la presencia de desequilibrio entre grupos musculares agonistas y antagonistas de la articulación de la rodilla y entre miembros dominantes y no dominantes mediante dinamometría isocinética. Métodos: Estudio transversal, observacional y descriptivo realizado con nueve practicantes masculinos de taekwondo. Se utilizó un dinamómetro isocinético para investigar el par máximo, el par máximo por peso corporal, el trabajo total, la potencia media, la relación agonista/antagonista y el índice de fatiga. Los datos de las extremidades dominantes y no dominantes se compararon mediante la prueba t- student para muestras de pared. Se calcularon el intervalo de confianza del 95% de la diferencia media, el tamaño del efecto y la potencia de los análisis. Resultados: Los músculos extensores de los miembros dominantes y no dominantes mostraron una diferencia media de 15,49 Nm (IC95% 7,27; 23,70; p=0,002) para el par máximo y de 22,64% (IC95% 11,83; 33,46; p=0,001) para el par máximo por peso corporal a 60°/s, lo que representa el tamaño medio del efecto. Conclusiones: Los atletas de taekwondo presentaron un mayor par máximo y un mayor par máximo por peso corporal de los músculos extensores de la rodilla en el lado dominante. La relación agonista/antagonista fue inferior al 60% y más de la mitad de los atletas mostraron una diferencia superior al 10% en el pico de par flexor en el lado no dominante.

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The main aims of this study were to compare the magnitude of inter-limb asymmetry (ILA) and the relation with self-reported knee function between maximal and explosive knee extensor strength outcomes in professional soccer players. Forty-six male soccer players completed different maximal isokinetic and isometric contractions of the knee extensors for the assessment of maximal strength (peak torque and maximal voluntary contraction (MVC) torque) and explosive strength (early, intermediate, late, and peak rate of torque development (RTD)). Self-reported knee function was assessed with the International Knee Documentation Committee (IKDC) and Lysholm knee scoring scales. Peak torque and MVC torque showed comparable ILAs (8-9%), both being significantly lower than all RTD ILAs (16% on average; p < 0.001). ILAs for early RTD (21%) and peak RTD (19%) were significantly higher than all the other variables (p < 0.05). Only early and intermediate RTD were significantly correlated - though weakly - with both IKDC (rho = 0.32 for both) and Lysholm (rho = 0.36 and 0.30, respectively) scores. We conclude that explosive knee extensor strength - early RTD in particular - exhibited larger ILAs and better relations with self-reported knee function than peak torque and MVC torque in professional soccer players. These results confirm the validity and functional relevance of early RTD and the need for its inclusion in routine performance testing for soccer players.Highlights Professional soccer players exhibited larger inter-limb deficits in knee extension strength for explosive actions than for the widely-used isokinetic test.Self-reported knee function was significantly correlated with explosive strength of the knee extensor muscles but not with maximal strength.The first 50 ms of an explosive knee extension seem to be crucial for self-perceived sport performance and possibly for injury prevention.

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The present study aimed to examine the changes that occurred in vertical jump and isokinetic dynamometer (ISK) performances at the beginning of a preparatory period (PRE) and at the start of the competitive period (POST). Sixteen U-17 elite female volleyball players, from a national level (15.34 ± 1.19 years; 66.35 ± 7.95 kg; 169.22 ± 24.79 cm), performed bilateral squat jump (SJ), bilateral and unilateral countermovement jump (CMJ) and unilateral ISK tests for knee flexors (Fl) and extensors (Ex) both at 60°/s and at 300°/s. Peak torque (PT) and the hamstring-to-quadriceps (H:Q) ratio were assessed by concentric actions. Asymmetries were calculated by the percentage differences between dominant (DOM) and nondominant legs (NDOM). The paired Student's t-test was used for comparisons at a level of significance of 5%. The effect size was also calculated. A significant increase was found for both SJ (15%; p = 0.004; ES = 0.82) and CMJ (12%; p = 0.017; ES = 0.62). The PT of NDOM flexors at 60°/s was significantly lower than DOM both at PRE (4.6%; p = 0.048; ES = -0.22) and POST (6.3%; p = 0.037; ES = -0.33). The NDOM extensors at 60°/s had a significantly lower PT than DOM at POST (7.0%; p = 0.048; ES = -0.23). Both DOM and NDOM flexors at 60°/s had a PT enhancement at POST related to PRE (6.7%; p = 0.031; ES = 0.51 and 5.6%; p = 0.037; ES = 0.48, respectively). The PT of NDOM extensors at 300°/s increased at POST in comparison to PRE (7.9%; p = 0.038; ES = 0.27). The NDOM at 300°/s had a H:Q ratio higher than DOM both in PRE and POST (8.6%; p = 0.041; ES = 0.37 and 11.6%; p = 0.013; ES = 0.71, respectively), and the highest H:Q ratios were lower than the reference values (<80%). The asymmetry of the unilateral CMJ was higher at POST than at PRE (102%; p = 0.03; ES = 0.81). The PT for the flexors at 300°/s and the H:Q ratio at POST exceeded 10%. In conclusion, a training program of 15 weeks increased the neuromuscular performance of young volleyball athletes, but many H:Q ratios and asymmetries remained out of the normal recommendation. Volleyball professionals should carefully apply an adequate training program to enhance physical fitness performance without increasing the risk of lower limb injuries concurrently.

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BACKGROUND: Hip torque ratios are considered a useful measure for patients with hip pain. However, evidence regarding this measure for patients with femoroacetabular impingement syndrome is scarce. The primary aim of this study was to compare hip external-internal rotation and abduction-adduction torque ratios between patients with femoroacetabular impingement syndrome and asymptomatic individuals. The secondary aim was to compare hip torque ratios between the asymptomatic group and femoroacetabular impingement syndrome patients grouped according to the severity of symptoms and functional limitations. METHODS: Hip abduction-adduction and external-internal rotation torque ratios of 134 individuals with femoroacetabular impingement syndrome and 134 asymptomatic matched controls was assessed through isokinetic testing. Severity of symptoms and functional limitations was assessed through the iHOT-33. Mann Whitney U and Kruskall-Wallis tests were used to compare hip torque ratios between asymptomatic individuals and patients with femoroacetabular impingement syndrome and to patients with femoroacetabular impingement syndrome with different severities of symptoms and functional limitations. FINDINGS: No differences were identified in hip abduction-adduction (U = 7659.5, p = 0.192) and external-internal rotation (U = 8787.5, p = 0.764) torque ratios between patients with femoroacetabular impingement syndrome and asymptomatic individuals. Hip abduction-adduction torque ratio was higher (p = 0.0127) in patients with a severe state (median = 1.80, IQR = 0.61) when compared to asymptomatic individuals (median = 1.52, IQR = 0.45) (moderate effect size, r = 0.45). INTERPRETATION: Patients with severe symptoms and functional limitations related to FAI syndrome presented greater hip abduction-adduction torque ratio than asymptomatic individuals, suggesting a decreased adduction torque capacity relative to abduction torque in this subgroup of femoroacetabular impingement.

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We aimed to analyse the relationship of peak torque (PT) of the knee extensors (Ext) and flexors (Fle) with age, and the relationship between conventional ratio and age progression in volleyball players. A total of 41 elite male volleyball players (age: 25.0 ± 6.1 years, body mass: 93.0 ± 9.8 kg, height: 198.0 ± 6.8 cm) were evaluated in a isokinetic dynamometer at speeds of 60, 180 and 300 deg/s, and at dominant (D) and non-dominant (ND) legs. In general, the knee flexor and extensor muscles varied greatly among the athletes (from 81 to 156 N.m for flexors; from 116 to 250 N.m for extensors at 300 deg/s and at dominant side). The mass-specific PT of knee extensors showed strong and negative correlation with ageing at 60 and 180 deg/s (r = -0.52-0.62, p < 0.01). The conventional ratio showed regular and positive relationship at all evaluated velocities (60°.s-1, r = 0.453, p < 0.01; 180°.s-1, r = 0.498, p < 0.01; 300°.s-1, r = 0.316, p = 0.04). The results demonstrated that volleyball players are susceptible to age-related effects on muscular performance during their career; this finding illustrates the importance of adopting training strategies to improve the production of strength in the lower limbs, which is essential for vertical jumps.

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CONTEXT: In the elderly, weak lower limb muscles impair functional tasks' performance. OBJECTIVE: To evaluate the healthy elderly's ankle dorsiflexion and plantarflexion maximum torque and its variability in two sets of 5 RM isokinetics evaluation. METHOD: 50 women (68.0 ± 4.6 years old) and 50 men (72.7 ± 8.5 years old) did two sets of ankle plantar flexor and dorsiflexor isokinetic tests at 30°/s. Peak torque, total work, and coefficient of variation were analyzed. RESULTS: Men did the strongest plantarflexion torque (p < 0.05) and dorsiflexion torque (p < 0.05); their highest peak torque occurred at set 2 (p < 0.05), while the largest plantarflexion torque variability (p < 0.05), dorsiflexion torque variability (p < 0.05), and the largest plantarflexion torque variability occurred at set 1 (p < 0.05). Men did the highest plantarflexion and dorsiflexion total work (p < 0.05) at set 2 (p < 0.05). CONCLUSION: Older men are stronger than older women. The torque variability, in men, was higher during the first set, suggesting an adaptation to the isokinetics evaluation. Clinicians and researchers should consider that different muscles might need different numbers of sets and trials to measure their maximal muscle strength.

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CONTEXT: Anterior Cruciate Ligament (ACL) injury is disabling in several sports because it causes knee instability and functional deficit. Usually, surgical treatments produce the best functional outcomes, however, sometimes they are not always able to fully restore stability and function. OBJECTIVE: The objective of this study was to evaluate postural balance, muscle strength, and functional performance of young athletes with an ACL injury before and after ACL reconstruction. DESIGN: This was a longitudinal observational prospective study. METHOD: 74 athletes, 60 men, and 14 women, aged between 16 and 45, divided into two groups: the Group-Lesion of ACL with 34 athletes (24.1 years) and the Group-Control with 40 athletes without ACL lesion (27.7 years old). All volunteers performed posturography, isokinetic dynamometry, and the Hop-Test. The ACL-Group was evaluated before and 12 months after the reconstruction and the control group was evaluated once. RESULTS: The Postoperative ACL Group presented greater limb symmetry, 0.96 (± 0.12), than the preoperative ACL Group, 0.87 (± 0.17), p < 0.01 in the Hop-Test. In the posturography, the displacement area was smaller in the postoperative ACL Group, 19.85 (± 5.74), compared to the preoperative ACL Group, 24.20 (± 8.97), p < 0.01. In isokinetic dynamometry the torque peak was greater in the postoperative ACL Group, 0.91 (± 0.14), than in the preoperative ACL Group, 0.74 (± 0.15), p < 0.01. CONCLUSION: The functional outcomes increased in ACL reconstruction athletes after 12 months, but not at the same level as in the Control Group. The result indicates an incomplete functional recovery, adaptive changes in postural control after injury, reconstruction, and return to sport.

Assuntos

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BACKGROUND: Imbalance between flexor and extensor muscles of the trunk could negatively influence spinal stability. OBJECTIVES: Investigate the strength balance between flexor and extensor muscles of the trunk in military firefighters with non-specific chronic low back pain (NSCLBP). METHODS: One hundred and two male firefighters were assessed in an isokinetic dynamometer at 120°/s and 60°/s to investigate the balance ratio between flexor and extensor (F/E) muscles. RESULTS: An F/E ratio of 0.72 (SD: 0.22; 95% CI: 0.67-0.76; SEM: 0.02) was observed at 60°/s and 0.94 (SD: 0.41; 95% CI: 0.85-1.03; SEM: 0.04) at 120°/s. The mean peak torque of the extensor muscles was 343.1 N.m/Kg (SD: 94.87; 95% CI: 322.8-363.5; SEM: 10.23) at 60°/s and 270.5 N.m/Kg (SD: 113; 95% CI 246.3-294.8; SEM: 12.18) at 120°/s. The mean peak torque of the flexor muscles was 232.4 N.m/Kg (SD: 53.86; 95% CI 220.8-243.9; SEM: 5.81) at 60°/s and 223.8 N.m/Kg (SD: 66.34; 95% CI 209.6-238.1; SEM: 7.15) at 120°/s. All torques generated by the extensor muscles were higher than the flexor muscles (p < 0.05). CONCLUSIONS: Firefighters with NSCLBP presented a normal F/E balance ratio and higher strength of extensor muscles of the trunk.

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