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This study investigated the effect of plyometric training with and without additional load on young male soccer players' jumping ability and isokinetic strength. Methods: In this randomized controlled trial, 39 U-17 male trained soccer players were randomly divided into plyometric training with additional load (PT+AL), plyometric training with just bodyweight (PTBW) and control (CON) groups. PT+AL and PTBW were performed for six weeks (2 days/week). Absolute peak torque (APT), relative peak torque (RPT), average peak torque (AvPT), time-to-peak torque (TPT), average rate of force development (AvRFD), vertical jump height (VJH), standing long jump (SLJ) and 15-second repeated jump tests (RJ15s) were assessed before and after the interventions. The findings showed that the performance of knee extensors in TPT-60°/s and AvRFD-60°/s, and knee flexors in APT-60°/s, RPT-60°/s, AvPT-60°/s, AvPT-120°/s, AvRFD-60°/s and AvRFD-120°/s significantly increased after PT+AL, compared to the CON (p < 0.05). Also, a significant improvement in jumping ability was observed in PT+AL compared to CON (p < 0.05). Additionally, PTBW also improved the performance of knee flexors in TPT-120°/s and AvRFD-120°/s, as well as RJ15s performance compared to the CON (p < 0.05). Furthermore, knee flexors AvRFD-60°/s increased significantly after PT+AL, compared to PTBW (p < 0.05). SO, plyometric training, with or without additional load, improved young male soccer players' strength and jumping ability. However, strength parameters – especially the rate of force development – showed a greater increase following PT + AL compared to PTBW. [ABSTRACT FROM AUTHOR]

In soccer, knee and hip muscle strength assessments have been recommended for injury prevention. The aims of this study were threefold: (1) to compare knee and hip muscle strength between professional players competing at different levels; (2) to compare strength performance according to the preferred leg (PL) and the non-preferred leg (NPL); and (3) to compare knee and hip muscle strength performance at two moments of the season. This study included 33 professional soccer players: 13 were in the elite group (EG), and 20 were in the sub-elite group (SEG). Body composition, isokinetic knee strength at 60°/s, and hip adduction strength were assessed at two different moments (M1 and M2). Values of peak torque (PT), peak torque/bodyweight (PT/BW), and the hamstring-to-quadriceps strength ratio (H:Q) for knee extensors (KEs) and knee flexors (KFs) for both legs were used for analysis. The statistical analysis included the Mann-Whitney U and the Wilcoxon Signed Rank tests. At M1, the EG presented a significantly better performance in KF PT/BW and in the squeeze strength test for the PL and the NPL (p ≤ 0.01). At M2, the EG performed substantially better in KE PT/BW and KF PT/BW (p ≤ 0.01). No substantial strength differences were observed in knee and hip muscle performance between the PL and the NPL. From M1 to M2, significant increases were found in knee strength in both groups (p ≤ 0.01). Overall, the EG players outperformed significantly their lower-division peers in strength assessments. The results indicate significant knee and hip muscle strength increases during the season, probably as a response to the exposure to training and competition. [ABSTRACT FROM AUTHOR]

Background: The limb symmetry index (LSI) is a metric of strength restoration. It is key to successfully return to sports after anterior cruciate ligament (ACL) reconstruction. The threshold for return to sports is generally considered an LSI of ≥85%. Purpose: To develop a statistical model for predicting the recovery of knee extension and flexion strength (with LSI ≥85%) at 6 months after ACL reconstruction. Study Design: Case-control study; Level of evidence: 3. Methods: Patients who underwent arthroscopic ACL reconstruction between November 2015 and December 2020 were included. The patients were classified into 2 groups: "pass" if the LSI at 6 months postoperatively was ≥85% and "fail" if the LSI was <85%. Factors in 25 categories with 74 levels, including patient characteristics, periarticular procedures, intra-articular lesions and treatment, and perioperative management, were collected. A multivariable logistic regression combined with backward variable elimination was used to determine the predictive parameters for recovery of knee extension and flexion strength. Results: A total of 948 patients were included. Graft site, preoperative isokinetic strength, treatment of meniscal injury, and injured side (left vs right) were identified as general predictors for both knee extension and flexion strength. For knee extension strength, age at injury and partial weightbearing duration were identified as additional predictors. For knee flexion strength, type of meniscal injury, surgeon volume, cartilage procedures, and periarticular procedures were identified as additional predictors. The Nagelkerke R 2 of the final model was 0.178, and the c -statistic was 0.716 (95% CI, 0.676-0.754). The Hosmer-Lemeshow test indicated good calibration (P =.879). Conclusion: Several factors including preoperative isokinetic strength, treatment of meniscal injuries, left vs. right side and graft site were found to predict recovery of ≥85% LSI in knee extension and flexion strength. Despite the numerous factors that were analyzed, the predictive power was moderate (c-statistic = 0.716), indicating there were other nonincluded factors that significantly influence strength performance at 6 months postoperatively. [ABSTRACT FROM AUTHOR]

Recovery of the isokinetic knee extensor strength on the operated side following anterior cruciate ligament (ACL) reconstruction is commonly calculated as a ratio with the value from the non-operated side serving as the denominator. However, the validity of the values of the non-operated side remains unclear. This study aimed to determine the relationship between whole-body muscle mass and non-operated knee extensor strength after ACL reconstruction. In 27 patients who underwent ACL reconstruction, muscle mass was measured using bioelectrical impedance analysis, and bilateral concentric knee extensor strength was measured using an isokinetic dynamometer at angular velocities of 60∘/s and 180∘/s. Correlation and single regression analyses were performed to examine the relationship between whole-body muscle mass and knee extensor strength. There was a strong to very strong positive association between whole-body muscle mass and non-operated knee extensor strength (60∘/s: r= 0.85, 180∘/s: r= 0.90, P< 0.01). Univariate regression analysis showed that whole-body muscle mass was a strong predictor of non-operated knee extensor strength (R2= 0.71–0.81). Assessing both whole-body muscle mass and knee extensor strength may be used to determine whether muscle strength on the non-operated side is appropriate for the individual’s body composition. [ABSTRACT FROM AUTHOR]

This study develops a comprehensive genotype-phenotype model for predicting the effects of resistance training on leg press performance. A cohort of physically inactive adults (N=193) underwent 12 weeks of resistance training, and measurements of maximum isokinetic leg press peak force, muscle mass, and thickness were taken before and after the intervention. Whole-genome genotyping was performed, and genome-wide association analysis identified 85 novel SNPs significantly associated with changes in leg press strength after training. A prediction model was constructed using stepwise linear regression, incorporating seven lead SNPs that explained 40.4% of the training effect variance. The polygenic score showed a significant positive correlation with changes in leg press strength. By integrating genomic markers and phenotypic indicators, the comprehensive prediction model explained 75.4% of the variance in the training effect. Additionally, five SNPs were found to potentially impact muscle contraction, metabolism, growth, and development through their association with REACTOME pathways. Individual responses to resistance training varied, with changes in leg press strength ranging from −55.83% to 151.20%. The study highlights the importance of genetic factors in predicting training outcomes and provides insights into the potential biological functions underlying resistance training effects. The comprehensive model offers valuable guidance for personalized fitness programs based on individual genetic profiles and phenotypic characteristics. [ABSTRACT FROM AUTHOR]

The association of pre-participation knee muscle strength status with lower limb injury occurrence was investigated. Knee extensors and flexors muscle strength status including the traditional hamstrings/quadriceps (H/Q), Q/Q, H/H, and the non-dominant H/Q: dominant H/Q, HQ:HQ, ratios were recorded before the 10 month judo activity. Fifteen lower limb sport injuries were recorded for 53 judokas during the follow-up questionnaires. Significant accuracy of dominant H/Q ratio 60º/s (AUC 0.702, 95% CI 0.520 to.883, p = 0.023), as well as HQ:HQ ratios 300º/s (AUC.318, 95% CI 0.138 to 0.497, p = 0.040), and 60 º/s (AUC 0.311, 95% CI 0.130 to 0.491, p =.033) were revealed discriminating between injured and uninjured judokas. The optimum cut-off of dominant H/Q ratio associated with belonging to uninjured judokas group was 43.2% (sensitivity, 0.974; specificity, 0.533). Isokinetic knee muscle dynamometry is useful for predicting the likelihood of lower limb injuries in professional judokas during competitive activity. Pre-participation testing of ipsilateral and bilateral knee extensors and flexors strength ratios can contribute to an injury prevention program for judokas. Ipsilateral and bilateral strength ratios should be monitored at lower and higher angular isokinetic velocities. [ABSTRACT FROM AUTHOR]

Study aim: This study aimed to analyze the relationships between weekly training frequency, changes in training duration, and Maximal Aerobic Speed (MAS), Maximum Oxygen Uptake (VO2max), and Isokinetic Strength over an 8-week period (preseason 8 weeks). Material and methods: Eighteen hearing-impaired handball players (age: 26.78±2.26 years; height: 177.76±4.40 cm; body weight: 64.94±2.73 kg, training experience 13.1±2.6 years) were positioned in defense and offense based on their playing positions and were monitored for 8 weeks. Repeated Measures ANOVA test was performed for the pretest and post-test comparisons of defense and offense players, frequency and distribution is observed, average standard deviation, maximum, and minimum values were taken. Results: The analysis results revealed a significant large positive difference in the agonist/antagonist ratio in the right extremity (p < 0.01). Conclusion: Throughout the study, fluctuating changes in the numbers and durations of training sessions were observed to significantly increase and correlate with changes in the players' fitness status. There is a statistically significant difference between pre-test and post-test values for maximal oxygen consumption (VO2max), maximal aerobic speed (MAS), and maximal heart rate (HRmax) (p< 0.01). However, the variability in the large positive difference in the agonist/antagonist ratio in the right extremity suggests that it cannot be solely explained by the number and duration of training sessions in terms of fitness level. [ABSTRACT FROM AUTHOR]

To investigate whether lower limb strength is reduced in people with patellar tendinopathy (PT) compared with asymptomatic control individuals or the asymptomatic contralateral limb. MEDLINE, PubMed, Scopus, and Web of Science. To be included in the systematic review and meta-analysis, studies were required to be peer reviewed, published in the English language, and case control investigations; include participants with a clinical diagnosis of PT and an asymptomatic control or contralateral limb group; and include an objective measure of lower limb maximal strength. We extracted descriptive statistics for maximal strength for the symptomatic and asymptomatic limbs of individuals with PT and the limb(s) of the asymptomatic control group, inferential statistics for between-groups differences, participant characteristics, and details of the strength-testing protocol. The risk of bias was assessed using the Joanna Briggs Institute critical appraisal tool for analytical cross-sectional studies. Of the 23 included studies, 21 reported knee strength, 3 reported hip strength, and 1 reported ankle strength. Random-effects models (Hedges g) were used to calculate the pooled effect sizes (ESs) of muscle strength according to the direction of joint movement and type of contraction. The pooled ESs (95% CI) for maximal voluntary isometric contraction knee-extension strength, concentric knee-extension strength, and concentric knee-flexion strength were 0.54 (0.27, 0.80), 0.78 (0.30, 1.33), and 0.41 (0.04, 0.78), respectively, with all favoring greater strength in the asymptomatic control group. Researchers of 2 studies described maximal eccentric knee-extensor strength with no differences between the PT and asymptomatic control groups. In 3 studies, researchers measured maximal hip strength (abduction, extension, and external rotation), and all within-study ESs favored greater strength in the asymptomatic control group. Isometric and concentric knee-extensor strength are reduced in people with PT compared with asymptomatic control individuals. In contrast, evidence for reduced eccentric knee-extension strength in people with PT compared with asymptomatic control individuals is limited and inconsistent. Although evidence is emerging that both knee-flexion and hip strength may be reduced in people with PT, more examination is needed to confirm this observation. [ABSTRACT FROM AUTHOR]

Upper Limb Strength and Performance Deficits after Glenohumeral Joint Stabilization Surgery in Contact and Collision Athletes. Med. Sci. Sports Exerc., Vol. 56, No. 1, pp. 13-21, 2024. Purpose: The primary aim was to identify and quantify differences in interlimb asymmetry magnitudes across a battery of upper extremity strength and performance tests at 4 and 6 months after glenohumeral joint stabilization surgery shoulder stabilization in contact and collision athletes compared with an un-injured group. A secondary aim was to investigate if identified asymmetry magnitudes changed from 4 to 6 months after glenohumeral joint stabilization surgery. The third aim was to explore associations within the different performance and strength variables. Methods: Fifty-six male contact and collision sport athletes who had had undergone unilateral glenohumeral joint stabilization were tested at 4 and 6 months after surgery. An un-injured control group (n = 39 for upper extremity performance tests, n = 47 for isokinetic dynamometry) were tested on a single occasion. Three upper extremity force platform-based performance tests and angle-specific concentric internal and external isokinetic shoulder rotational strength were assessed, and interlimb asymmetries were compared between the two groups. Results: At 4 months after surgery, the glenohumeral joint stabilization group demonstrated significantly higher absolute interlimb asymmetry values than the un-injured group for almost all the performance test variables. In the ballistic upper-body performance tests, the glenohumeral joint stabilization group achieved only half the body elevation reached by the un-injured (counter-movement push-up jump height (η² = 0.50) and press-jump jump height (η² = 0.39)). At 6 months after surgery, absolute interlimb asymmetries reduced for the performance test variables, but some asymmetry persisted. The glenohumeral joint stabilization group had significantly greater absolute interlimb asymmetries for five out the eight isokinetic variables. Conclusions: Contact and collision athletes who may be cleared to return to sport at 4 to 6 months after glenohumeral joint stabilization surgery shoulder stabilization continue to demonstrate upper limb strength and performance deficits when compared with their un-injured limb and their un-injured counterparts. [ABSTRACT FROM AUTHOR]

Background: Impaired quadriceps muscle strength after anterior cruciate ligament reconstruction (ACLR) is associated with worse clinical outcomes and a risk of reinjuries. Yet, we know little about quadriceps muscle strength in patients reconstructed with a quadriceps tendon (QT) graft, which is increasing in popularity worldwide. Purpose: To describe and compare isokinetic quadriceps strength in patients undergoing ACLR with a QT, hamstring tendon (HT), or bone–patellar tendon–bone (BPTB) autograft. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We included patients with QT grafts (n = 104) and matched them to patients with HT (n = 104) and BPTB (n = 104) grafts based on age, sex, and associated meniscal surgery. Data were collected through clinical strength testing at a mean of 7 ± 1 months postoperatively. Isokinetic strength was measured at 90 deg/s, and quadriceps strength was expressed as the limb symmetry index (LSI) for peak torque, total work, torque at 30° of knee flexion, and time to peak torque. Results: Patients with QT grafts had the most impaired isokinetic quadriceps strength, with the LSI ranging between 67.5% and 75.1%, followed by those with BPTB grafts (74.4%-81.5%) and HT grafts (84.0%-89.0%). Patients with QT grafts had a significantly lower LSI for all variables compared with patients with HT grafts (mean difference: peak torque: −17.4% [95% CI, −21.7 to −13.2], P <.001; total work: −15.9% [95% CI, −20.6 to −11.1], P <.001; torque at 30° of knee flexion: −8.8% [95% CI, −14.7 to −2.9], P =.001; time to peak torque: −17.7% [95% CI, −25.8 to −9.6], P <.001). Compared with patients with BPTB grafts, patients with QT grafts had a significantly lower LSI for all variables (mean difference: peak torque: −6.9% [95% CI, −11.2 to −2.7], P <.001; total work: −7.7% [95% CI, −12.4 to −2.9], P <.001; torque at 30° of knee flexion: −6.3% [95% CI, −12.2 to −0.5], P =.03; time to peak torque: −8.8% [95% CI, −16.9 to −0.7], P =.03). None of the graft groups reached a mean LSI of >90% for peak torque (QT: 67.5% [95% CI, 64.8-70.1]; HT: 84.9% [95% CI, 82.4-87.4]; BPTB: 74.4% [95% CI, 72.0-76.9]). Conclusion: At 7 months after ACLR, patients with QT grafts had significantly worse isokinetic quadriceps strength than patients with HT and BPTB grafts. None of the 3 graft groups reached a mean LSI of >90% in quadriceps strength. [ABSTRACT FROM AUTHOR]

Background and aim: Cricket is the most commonly played and followed sport in India and demands a high level of performance from the fast bowler. Large ground reaction forces generated at front foot contact put fast bowlers at high risk of lower limb and lumbar spine injury. Precise dynamic coordination of lower body segments is needed to absorb these forces and transfer the energy via the core to the upper limb to propel the ball at faster speeds. Thus, knowledge of lower quadrant strength, especially dynamic knee strength, can be useful for injury prevention and better performance in fast bowlers. There is a lack of literature on this subject in Indian fast bowlers despite the popularity of the sport. This study aims to evaluate isokinetic knee strength and determine the relevant asymmetries and strength imbalances in relation to injury risk in cricket fast bowlers. Methods: A total of 42 male Indian state-level fast bowlers underwent isokinetic knee strength testing. Peak torques (PT) normalized to body weight (BW) were obtained for quadriceps concentric (Qconc), quadriceps eccentric (Qecc), hamstring concentric (Hconc), and hamstring eccentric (Hecc). Bilateral strength asymmetries (BSA) and dynamic control ratio (DCR) (hamstring DCR (H-DCR) = Hecc/Qconc and quadriceps DCR (Q-DCR) = Qecc/Hconc) were evaluated. Descriptive statistical analysis of data was done. Results: Around 67% of bowlers had significant Qecc strength asymmetry. In addition, 40% had poor hamstrings DCR and 19% had poor Q-DCR on the front limb. Conclusion: A significant proportion of fast bowlers have unfavorable strength asymmetry and DCR and could be at risk of injury. Improving dynamic knee strength through plyometric training could help optimize performance and reduce injury risk. Clinical significance: This study highlights key areas of possible injury risk that can be targeted with strength and conditioning to prevent lower limb and lumbar spine injuries in fast bowlers. [ABSTRACT FROM AUTHOR]

In football, knee and hip muscle strength assessment have been recommended for injury prevention (Mosler et al., 2017; Namazi et al., 2019). Additionally, bilateral strength differences in the knee and hip joints have been related to an increased risk of injury. The aims of this study were threefold: (1) to compare knee and hip muscle strength performance between professional players competing at different levels; (2) to assess bilateral strength differences according to the preferred leg (PL) and the non-preferred leg (NPL); and (3) to compare knee and hip muscle strength performance in two-time moments of the season. This study considered 33 professional football players: 13 were in the elite group (EG) competing in the First Portuguese Football League, and 20 were in the sub-elite group (SEG) competing in the Fourth Portuguese Football League. Participants were assessed for body composition, isokinetic knee strength at 60º/s, and hip adduction strength at two-time moments (TM) separated by five months. Peak torque normalised by bodyweight (PT/BW) of knee extensors (KE) and knee flexors (KF) were used for analysis. The differences between groups in strength were analysed using the Mann-Whitney U test. The Wilcoxon Signed Rank Test was conducted to verify differences between the performance of the PL and NPL in each group and to compare the performance between TM1 and TM2. At TM1, the EG presented a significantly better performance in KF PT/BW and hip adduction strength for the PL and NPL (p £ 0.01). In TM2, the EG performed substantially better in KE PT/BW and KF PT/BW (p £ 0.01). In both groups, no substantial bilateral strength differences were observed in knee and hip adduction performance. From TM1 to TM2, significant increases were found in knee strength in both groups (p £ 0.01). Overall, the EG players outperformed their lower-division peers in strength assessments significantly. The results also indicate significant knee and hip muscle strength increases during the season (except for the EG in hip adduction strength), probably as a response to the exposure to training and competition.

The shot performance of female soccer players is one of the most critical factors in winning a soccer match. It is essential to thoroughly clarify the kinetic factors that can improve shot performance. This study explores the connections between ball velocity post-shooting and isokinetic knee extension (EXT) and flexion (FLX) strength performances among female soccer players. Thirteen voluntary players from professional leagues took part in the research study. The study analyzed the average and peak concentric (Con) and eccentric (Ecc) torques, isometric (Iso) strength performances at angular velocities of 60°/s, 180°/s and 300°/s, the time required to reach peak torque, and ball velocities during shooting. The relationships among these variables were investigated separately for the dominant (D) and non-dominant (ND) legs. The analysis unveiled significant correlations between ball velocities and D-EXT (Absolute) peak torque at an angular velocity of 60°/s (r = 0.597; p < 0.05), D-%IPS (r = −0.580; p < 0.05), and ND-FLX (Absolute) average torque (r = 0.559; p < 0.05). Moreover, notable associations were observed between ball velocities and ND-EXT (Absolute) (r = 0.581; p < 0.05), as well as ND-FLX (Absolute) (r = 0.602; p < 0.05) average torques at an angular velocity of 180°/s. Additionally, significant relationships were found between ball velocities and peak (r = 0.664; p = 0.013) and average (r = 0.660; p = 0.014) torques generated during ND-EXT (Absolute) at an angular velocity of 300°/s. However, the connections between the time to reach peak torque, eccentric and isometric forces, and ball velocities were not statistically significant (p > 0.05). The results of the study indicate that enhancing concentric isokinetic strength development at 60°/s, 180°/s, and 300°/s angular velocities, along with balanced strengthening of the ND extremity, holds paramount importance in elevating shot performance among female soccer players, particularly in the context of rapid shot strategies. [ABSTRACT FROM AUTHOR]

The aim was to analyse the relationship between isokinetic strength, dynamic stability, muscular extensibility and impacts transmission during fatigued running. Low- and high-frequency impacts—related to body movements and the severity of impacts, respectively—were assessed in 17 male recreational runners, before and after a treadmill running fatigue protocol, using a triaxial accelerometry system. High-frequency impacts in the tibia were negatively correlated to the knee angle at which the quadriceps peak torque was reached (p = 0.014), and also to the extensibility of the hamstrings and soleus (p = 0.001 and p = 0.023, respectively). The increases of high-frequency impacts in tibia caused by fatigue were positively related to the knee angle at which the hamstrings peak torque was reached (p = 0.001) and to stability after landing (p = 0.007). The attenuation of high-frequency impacts was positively related to hamstrings/quadriceps ratio of strength (p = 0.010) and to stability (p = 0.006). Limiting possible deficits in hamstring and soleus range of motion, improving stability after landing, developing hamstring and quadriceps strength in elongated muscle range, and maintaining a balanced ratio of hamstring/quadriceps strength could help to reduce the injury risk in running. [ABSTRACT FROM AUTHOR]

Abstract Background Both Kinesio Tape (KT) and Compression Sleeves (CS) can relieve Delayed Onset Muscle Soreness (DOMS) to a certain extent, but there is no study report on the difference in the effectiveness of the KT and CS whether the effect is better when used at the same time. The purpose of this study was to compare the effects of KT and CS on the recovery of muscle soreness, isokinetic strength, and body fatigue after DOMS. Methods In this single-blinded randomized controlled trial, 32 participants aged 18 to 24 years were randomly divided into Control group (CG), Compression Sleeves group (CSG), Kinesio Tape group (KTG), Compression Sleeves and Kinesio Tape group (CSKTG), between October 2021 and January 2022. KTG uses Kinesio Tape, CSG wears Compression Sleeves, and CSKTG uses both Compression Sleeves and Kinesio Tape. Outcomes were performed at five-time points (baseline, 0 h, 24 h, 48 h, 72 h), Primary outcome was pain level Visual Analogue Scale (VAS), and Secondary outcomes were Interleukin 6, Peak Torque/Body Weight, Work Fatigue. Statistical analyses were performed using the repeated measures analysis of variance method. Setting: Laboratory. Results After the intervention, VAS reached the highest at 24 h after exercise-induced muscle soreness, while the KTG and CSG at each time point were less than CG, and the scores of CSKTG at 24 h and 48 h were less than those of KTG and CSG in the same period (P

Introduction: Continuous evaluations of athletes, including strength testing, can help control performance improvement or facilitate the restoration of normality after an injury. The aim of the present study was to prospectively determine the peak torque (PT), angle at which PT is achieved, and functional ratios of flexors and extensors thigh muscles during one season. Material and methods: Thirty semi-professional male athletes competing in long jumping (n = 10), javelin throwing (n = 10), and sprinting (n = 10) participated. PT was evaluated in relation to limb length; the angle at which PT was achieved was obtained from the force-curve displayed in the isokinetic dynamometer; functional ratios were calculated by dividing concentric hamstring strength by eccentric quadriceps strength (flexor ratio) or vice-versa for the extensor ratio. Assessment was performed at 60º/s and 300º/s. Results: Significant variations were seen for both extensor and flexor PTs at different stages of the season, with moderate to large effect sizes observed (effect size (d) = 0.49–0.93). Functional ratios and the angle at which peak torque was achieved remained stable throughout the season. Conclusions: Thigh muscle strength is unstable throughout a track and field season, coaches or medical staff should consider these findings when programming training sessions or rehabilitating an athlete.

Introduction: The recovery of periarticular strength is a major criterion in return-to-play testing. The rationale of the study was to assess the impact of the delay of surgery (∆ between injury and surgery) on knee extensor and knee flexor strength of anterior cruciate ligament (ACL)-deficient patients six months after reconstruction. Materials and methods: In a retrospective cohort study, all patients with ACL ruptures between 03/2015 and 12/2019 were analyzed. Inclusion criteria were isolated ACL rupture without any associated lesions undergoing a reconstruction using ipsilateral hamstring tendon autograft and adherence to isokinetic strength testing before and at 5–7 months postoperatively. These patients were then clustered into three groups: EARLY reconstruction (∆ < 42 days), DELAYED reconstruction (∆42-180d), and CHRONIC (∆ > 180d). Knee extensor and flexor strength of the ipsi- and contralateral leg were analyzed by concentric isokinetic measurement (60°/s). Primary outcomes were the maximal knee extension and flexion torque, hamstrings-to-quadriceps ratio (H/Q) ratio), and the corresponding limb symmetry indices. Results: n = 444 patients met the inclusion criteria. From EARLY to DELAYED to CHRONIC, a progressive reduction in postoperative strength performance was observed in knee extension (1.65 ± 0.45 to 1.62 ± 0.52 to 1.51 ± 0.5 Nm/kg resp.) and flexion (1.22 ± 0.29 to 1.18 ± 0.3 to 1.13 ± 0.31 Nm/kg resp.) strength on the ACL reconstructed leg. This general loss in periarticular strength was already apparent in the preoperative performance even on the healthy side. When controlling for the preoperative performance using ANCOVA analysis, EARLY performed significantly better than DELAYED (extension p = 0.001, flexion p =.02) and CHRONIC (extension p = 0.005, flexion p < 0.001). Also, there were significantly higher values for H/Q ratio in the injured leg across all groups where the H/Q ratio increased from EARLY to CHRONIC and from pre- to postoperative values. Conclusions: With respect to the force generating capacity when returning-to-play, it is advantageous to seek for an early ACL reconstruction within the first 12 weeks after the injury. The increasing loss of thigh muscle strength observed in delayed or chronic cases affects the injured and also the non-injured leg. Level of Evidence: III, retrospective cohort study. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this study was to demonstrate that patients undergoing ACL reconstruction with quadrupled semitendinosus suspensory femoral and tibial fixation have comparable results in muscle strength and knee function to those undergoing ACL reconstruction with four-strand semitendinosus-gracilis suspensory femoral fixation and a bioabsorbable tibial interference screw fixation. Materials and Methods: Between 2017 and 2019, 64 patients who were operated on by the same surgeon were included. Patients underwent ACL reconstruction technique with quadrupled semitendinosus suspensory femoral and tibial button fixation in Group 1, and patients underwent ACL reconstruction with coupled four-strand semitendinosus-gracilis suspensory femoral fixation and a bioabsorbable tibial interference screw in Group 2. Evaluation of patients was performed with the Lysholm and Tegner activity scale preoperatively and at the 1st and 6th months postoperatively. At the 6-month visit, isokinetic testing of the operated and non-operated limbs was performed in both groups. Results: There was no significant difference in the age, weight, and BMI values of the patients in Groups 1 and 2 (p < 0.05). According to the strength values of the operated sides of the patients in Group 1 and Group 2, there was no significant difference in the angular velocities of 60° s−1, 180° s−1, and 240° s−1 in both extension and flexion phases between the operated sides of Groups 1 and 2 (p < 0.05). Conclusions: Patients who have ACL reconstruction with quadrupled semitendinosus suspensory femoral and tibial fixation have comparable muscle strength and knee function to those who undergo ACL reconstruction with four-strand semitendinosus-gracilis suspensory femoral fixation and a bioabsorbable tibial interference screw. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

BACKGROUND: Muscle strength in the upper and lower limbs is a major contributing factor to punch force and is one of the keys to success in boxing. OBJECTIVE: This study aimed to investigate the relationship between knee and shoulder strength and punching force in boxers. METHODS: Twenty-one boxers completed knee flexion, knee extension, shoulder external rotation and internal rotation isokinetic concentric contractions at slow (60 ∘ /s) and fast (180 ∘ /s) angular velocities. Maximal punch force tests included lead and rear straight arm punching were assessed using a force platform. RESULTS: Pearson's correlation coefficients revealed that knee extension (r = 0.646–0.848) and knee flexion (r = 0.470–0.646) peak torques were moderately to very strongly correlated with maximal punching force in lead and rear arms. The shoulder internal rotation (r = 0.492–0.634) and shoulder external rotation (r = 0.441–0.588) peak torques were moderate to strongly correlated with maximal punching force. Moreover, knee extension peak torques at 60 ∘ /s had higher correlation with maximal punching force. In contrast, shoulder internal rotation peak torques at 180 ∘ /s had a larger correlation with maximal punching force. CONCLUSIONS: The main findings indicated the importance of the capacity to generate maximum knee extension and rapid shoulder internal rotation strength, contributing to punch force production. [ABSTRACT FROM AUTHOR]

Background: Both Kinesio Tape (KT) and Compression Sleeves (CS) can relieve Delayed Onset Muscle Soreness (DOMS) to a certain extent, but there is no study report on the difference in the effectiveness of the KT and CS whether the effect is better when used at the same time. The purpose of this study was to compare the effects of KT and CS on the recovery of muscle soreness, isokinetic strength, and body fatigue after DOMS. Methods: In this single-blinded randomized controlled trial, 32 participants aged 18 to 24 years were randomly divided into Control group (CG), Compression Sleeves group (CSG), Kinesio Tape group (KTG), Compression Sleeves and Kinesio Tape group (CSKTG), between October 2021 and January 2022. KTG uses Kinesio Tape, CSG wears Compression Sleeves, and CSKTG uses both Compression Sleeves and Kinesio Tape. Outcomes were performed at five-time points (baseline, 0 h, 24 h, 48 h, 72 h), Primary outcome was pain level Visual Analogue Scale (VAS), and Secondary outcomes were Interleukin 6, Peak Torque/Body Weight, Work Fatigue. Statistical analyses were performed using the repeated measures analysis of variance method. Setting: Laboratory. Results: After the intervention, VAS reached the highest at 24 h after exercise-induced muscle soreness, while the KTG and CSG at each time point were less than CG, and the scores of CSKTG at 24 h and 48 h were less than those of KTG and CSG in the same period (P < 0.05). Interleukin 6, at 24 h, CSKTG is lower than KTG 0.71(95%CI: 0.43 to 1.86) and CG 1.68(95%CI: 0.06 to 3.29). Peak Torque/Body Weight, at 24 h, CG was lower than CSKTG 0.99(95%CI: 0.42 to 1.56), KTG 0.94(95%CI: 0.37 to 1.52), and CSG 0.72(95%CI: 0.14 to 1.29); at 72 h, CG was lower than CSKTG 0.65(95%CI: 0.13 to 1.17) and KTG 0.58(95%CI: 0.06 to 1.10). Work Fatigue, at 24 h, CG was lower than KTG 0.10(95%CI: 0.02 to 1.78) and CSKTG 0.01(95%CI: -0.07 to 0.09). At 48 h, CG was lower than KTG 0.10(95%CI: 0.13 to 1.17) and CSKTG 0.11(95%CI: 0.03 to 0.18). Conclusions: Kinesio Tape can significantly reduce DOMS pain, and Kinesio Tape has a better recovery effect on Delayed Onset Muscle Soreness than Compression Sleeves. Kinesio Tape combined with Compression Sleeves is helpful to alleviate the Delayed Onset Muscle Soreness pain, speeding up the recovery of muscle strength, and shortening the recovery time after Delayed Onset Muscle Soreness. Trial registration: Registration number: This study was also registered on 11/10/2021, at the Chinese Clinical Trial Registry (ChiCTR2100051973). [ABSTRACT FROM AUTHOR]

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PURPOSE This study investigated the effect of non-linear periodization strength training on basic and professional fitness of national cross-country skiers. METHODS The body composition (height, weight, BMI, body fat %), basic physical strength (grip strength, lung capacity), anaerobic power (peak power, average power), graded exercise test (maximum heart rate, running time, VO2max, lactic acid), isokinetic strength (trunk strength), and 1RM (bench press, dead-lift, squat, shoulder press, leg curl, bicep curl, cable triceps extension) of nine national cross-country skiers (male: 5, female: 4) were measured. All analyses were performed using SPSS 25.0, Kruskal-Wallis H tests were applied to observe the changes by training methods. Mann-Whitney U tests were used as Post Hoc. RESULTS The results indicated that running time and VO2max post-test improved compared to that for the pre-test for graded exercise test. The lumbar extension strength of the post-test was higher than that for pre-test. There was no significant difference in other variables. CONCLUSIONS It is suggested that nonlinear periodization strength training can be expected to improve running time, VO2max, and trunk strength for cross-country athletes; however, it does not affect the overall changes.

This study aims to compare the physical and physiological profiles between elite men and women wrestlers of free style category. The research group consist of twenty-nine men and twenty-one women freestyle wrestlers who camped for performance tests at the Turkish Olympic Preparation Center in Ankara 2 months before the European Wrestling Championship in Budapest on March 28-April 3, 2022. Subjects performed the leg and arm Wingate anaerobic test (anaerobic power and capacity), VO2max (aerobic endurance), Reactive agility, isokinetic and isometric strength test. The results showed that Lower Extremity anaerobic power obtained from men, knee flexor at VO2max, 60°/s and 180°/s peak torque, isometric force values of arm and trunk extensor muscles, are higher than in women (p0.05). As a result, it can be said that the endurance capacity, isometric, and isokinetic strength parameters are more effective than the force parameter in gender. These results can be used by coaches, strength and conditioning specialists, and sport scientists to create a comprehensive physical and physiological profile of wrestlers that will help them adapt their training programs.

The aim of this review was to perform a meta-analysis examining the effects of cold-water immersion (CWI) coupled with resistance training on gains in muscular strength. Four databases were searched to find relevant studies. Their methodological quality and risk of bias were evaluated using the PEDro checklist. The effects of CWI vs. control on muscular strength were examined in a random-effects meta-analysis. Ten studies (n = 170; 92% males), with 11 comparisons across 22 groups, were included in the analysis. Studies were classified as of good or fair methodological quality. The main meta-analysis found that CWI attenuated muscular strength gains (effect size [ES]: –0.23; 95% confidence interval [CI]: –0.45, –0.01; p = 0.041). In the analysis of data from studies applying CWI only to the trained limbs, CWI attenuated muscular strength gains (ES: –0.31; 95% CI: –0.61, –0.01; p = 0.041). In the analysis of data from studies using whole-body CWI, there was no significant difference in muscular strength gains between CWI and control (ES: –0.08; 95% CI: –0.53, 0.38; p = 0.743). In summary, this meta-analysis found that the use of CWI following resistance exercise sessions attenuates muscular strength gains in males. However, when CWI was applied to the whole body, there was no significant difference between CWI and control for muscular strength. Due to the attenuated gains in muscular strength found with single limb CWI, the use and/or timing of CWI in resistance training should be carefully considered and individualized. [ABSTRACT FROM AUTHOR]

Shoulder pain is common among elite swimmers due to the tremendous stress over shoulders during swimming. Supraspinatus muscle is one of the major prime movers and stabilizers of shoulder and is highly susceptible to overloading and tendinopathy. An understanding of the relationship between supraspinatus tendon and pain; and between supraspinatus tendon and strength would assist health care practitioners for developing training regime. The objectives of this study are to evaluate 1) the association between structural abnormality of supraspinatus tendon and shoulder pain and 2) the association between structural abnormality of supraspinatus tendon and shoulder strength. We hypothesized that structural abnormality of supraspinatus tendons positively associated with shoulder pain and negatively associated with shoulder muscle strength among elite swimmers. 44 elite swimmers were recruited from the Hong Kong China Swimming Association. Supraspinatus tendon condition was evaluated using diagnostic ultrasound imaging and shoulder internal and external rotation strength was evaluated by the isokinetic dynamometer. Pearson's R was used to study the correlation between shoulder pain and supraspinatus tendon condition and to evaluate the association between isokinetic strength of shoulders and supraspinatus tendon condition. 82 shoulders had supraspinatus tendinopathy or tendon tear (93.18%). However, there was no statistically significant association between structural abnormality of supraspinatus tendon and shoulder pain. The results showed that there was no association between supraspinatus tendon abnormality and shoulder pain and there was a significant correlation between left maximal supraspinatus tendon thickness (LMSTT) and left external rotation/ concentric (LER/Con) and left external rotation/ eccentric (LER/Ecc) shoulder strength (p < 0.05) while internal rotation/ external rotation (IR/ER) ratio can also be a significant predicator on LMSTT >6mm (R² = 0.462, F = 7.016, df = 1, p = 0.038). Structural change of supraspinatus tendon was not associated with shoulder pain, but could be a predictor on MSTT >6mm in elite swimmers. [ABSTRACT FROM AUTHOR]

Purpose: The recovery of strength is a key element in successfully returning to sports after ACL reconstruction. The type of anaesthesia has been suspected an influential factor in the post-operative recovery of muscle function. Methods: In this retrospective analysis, n = 442 consecutive patients undergoing primary isolated ACL reconstruction using a hamstring autograft were analysed by pre- and post-operative isokinetic tests in a single orthopaedic centre. These were subdivided into four cohorts: (1) general anaesthesia (n = 47), (2) general anaesthesia with prolonged (48 h) on-demand femoral nerve block (n = 37), (3) spinal anaesthesia (n = 169) and (4) spinal anaesthesia with prolonged (48 h) on-demand femoral nerve block (n = 185). Primary outcome was the change from pre- to post-operative isokinetic strength during knee extension and flexion. Results: Using one-way ANOVA, there was no significant influence of the type of anaesthesia. The main effect of anaesthesia on change in extension forces was not significant, and effect sizes were very small (n.s.). Similarly, the main effect of anaesthesia on change in flexion forces was statistically not significant (n.s.). Conclusions: The findings of this study support the interpretation that the type of anaesthesia has no significant effect on the ability to recover thigh muscle strength 6 months after isolated hamstring ACL reconstruction. With regard to the recovery of athletic performance and return-to-sports testing criteria, there is no reason to avoid regional anaesthesia. Level of evidence: III. [ABSTRACT FROM AUTHOR]

Later-stage rehabilitation following anterior cruciate ligament (ACL) reconstruction (ACLR) provides a valuable opportunity to target performance deficits before return to sport. This study aimed to: (1) evaluate bilateral counter-movement jump (CMJ) phase-specific impulse and isokinetic strength inter-limb asymmetry progression from 6 to 9 months post-ACLR; and (2) examine the extent to which individual changes in strength asymmetry could explain changes in impulse asymmetry. Male athletes (n = 44) with a hamstring tendon or bone-patellar tendon-bone autograft were tested 6 and 9 months post-ACLR. Two-way mixed-model ANOVAs were used to identify inter-session and inter-graft differences in CMJ phase-specific impulse asymmetries and knee isokinetic flexor and extensor strength asymmetries, as well as in absolute impulse and strength values of independent (ACLR/uninvolved) limbs. Linear regression models were used to assess the relationship between changes in impulse asymmetry and strength asymmetry. Reductions in strength asymmetry arose from improved ACLR-limb performance, whereas concentric impulse asymmetry reduced consequent to decreased uninvolved-limb performance and eccentric deceleration impulses decreased bilaterally. Graft type did not modulate findings. Changes in strength asymmetry had little or no ability to explain changes in impulse asymmetry. Consideration of approaches that may influence persisting deficits observed bi-laterally throughout vertical jumping performance post-ACLR may enhance rehabilitation practice. [ABSTRACT FROM AUTHOR]

BACKGROUND: Dynamic stretching (DS) and ballistic stretching (BS) are similar stretching methods, but the differences between them are unclear. OBJECTIVE: To examine the immediate effects of unilateral hamstring DS and BS on straight leg raise (SLR), knee flexion range of motion (KF-ROM), and KF and knee extension maximal isokinetic peak torque (KF-MIPT and KE-MIPT) of the bilateral limbs. METHODS: Twelve healthy adult men performed four sets of 2 min each of non-stretching, DS, or BS of the right lower extremity. Bilateral SLR, KF-ROM, KF-MIPT, and KE-MIPT were measured pre- and post-intervention; a three-way (intervention ) limb ) time) repeated-measures analysis of variance (ANOVA) was used. RESULTS: The SLR of the stretched limb (p < 0.01) was higher with DS than that pre-intervention. SLR (p < 0.01) and KF-ROM (p < 0.05) of the stretched limb and SLR (p < 0.05) and KF-ROM (p < 0.05) of the contralateral limb were higher with BS than those pre-intervention. There was no significant main effect or interaction between KF-MIPT and KE-MIPT. CONCLUSION: DS and BS had slightly different effects on ROM, and neither affected muscle strength; thus, combining the techniques during warm-up might be helpful. [ABSTRACT FROM AUTHOR]

Background: Objective criteria to accurately evaluate the ability of a patient to make a risk-free return to their previous level of activity after anterior cruciate ligament reconstruction (ACLR) and to progress through stages of the rehabilitation process are still widely discussed. Objective: The goal of the study was to investigate the functional status of non-elite football players 6 months after ACLR based on the Functional Movement Screen test (FMS) and side-to-side differences of isokinetic quadriceps and hamstring peak torque between the operated (OP) and non-operated (NOP) extremities. Methods: A total of 35 football players (male:female ratio 31:4, mean age 24.7 ± 2.8 years) who had undergone primary and isolated ACLR were assessed 6 months (mean 6.1 ± 2.6) after surgery. Functional performance evaluation included the FMS test and isokinetic quadriceps/hamstring peak torque values examined using the Biodex Testing System at angular velocities of 60 deg/s and 180 deg/s. In addition, side-to-side differences for flexion and extension at both angular velocities were calculated by the limb symmetry index. Results: In the functional assessment, the overall score of the FMS test was 15.34 ± 2.60. Moreover, inter-extremity differences in all isokinetic strength tests were statistically significant. Isokinetic strength peak torques of quadriceps and hamstring of NOP were significantly higher than those of OP at both angular velocities (p < .001). The limb symmetry index results for recorded peak torques at 60 deg/s were 75% in extension and 88% in flexion and at 180 deg/s were 79% in extension and 86% in flexion. Conclusion: The presented data indicate explicit inter-extremity muscles strength differences and disturbances in global movement patterns after ACLR. Delayed recovery of muscle strength and disparities between the OP and NOP limbs 6 months after ACLR may undermine the patient's readiness to return to preoperative activity. [ABSTRACT FROM AUTHOR]

This study aims to compare the physical and physiological profiles between elite men and women wrestlers of free style category. The research group consist of twenty-nine men and twenty-one women freestyle wrestlers who camped for performance tests at the Turkish Olympic Preparation Center in Ankara 2 months before the European Wrestling Championship in Budapest on March 28-April 3, 2022. Subjects performed the leg and arm Wingate anaerobic test (anaerobic power and capacity), VO2max (aerobic endurance), Reactive agility, isokinetic and isometric strength test. The results showed that Lower Extremity anaerobic power obtained from men, knee flexor at VO2max, 60°/s and 180°/s peak torque, isometric force values of arm and trunk extensor muscles, are higher than in women (p<0.05). In contrast, upper extremity anaerobic power values seem to be similar (p>0.05). As a result, it can be said that the endurance capacity, isometric, and isokinetic strength parameters are more effective than the force parameter in gender. These results can be used by coaches, strength and conditioning specialists, and sport scientists to create a comprehensive physical and physiological profile of wrestlers that will help them adapt their training programs. [ABSTRACT FROM AUTHOR]

The shot performance of female soccer players is one of the most critical factors in winning a soccer match. It is essential to thoroughly clarify the kinetic factors that can improve shot performance. This study explores the connections between ball velocity post-shooting and isokinetic knee extension (EXT) and flexion (FLX) strength performances among female soccer players. Thirteen voluntary players from professional leagues took part in the research study. The study analyzed the average and peak concentric (Con) and eccentric (Ecc) torques, isometric (Iso) strength performances at angular velocities of 60°/s, 180°/s and 300°/s, the time required to reach peak torque, and ball velocities during shooting. The relationships among these variables were investigated separately for the dominant (D) and non-dominant (ND) legs. The analysis unveiled significant correlations between ball velocities and D-EXT (Absolute) peak torque at an angular velocity of 60°/s (r = 0.597; p < 0.05), D-%IPS (r = −0.580; p < 0.05), and ND-FLX (Absolute) average torque (r = 0.559; p < 0.05). Moreover, notable associations were observed between ball velocities and ND-EXT (Absolute) (r = 0.581; p < 0.05), as well as ND-FLX (Absolute) (r = 0.602; p < 0.05) average torques at an angular velocity of 180°/s. Additionally, significant relationships were found between ball velocities and peak (r = 0.664; p = 0.013) and average (r = 0.660; p = 0.014) torques generated during ND-EXT (Absolute) at an angular velocity of 300°/s. However, the connections between the time to reach peak torque, eccentric and isometric forces, and ball velocities were not statistically significant (p > 0.05). The results of the study indicate that enhancing concentric isokinetic strength development at 60°/s, 180°/s, and 300°/s angular velocities, along with balanced strengthening of the ND extremity, holds paramount importance in elevating shot performance among female soccer players, particularly in the context of rapid shot strategies.

Abstract Background Wrestling is considered one of the oldest sports in the world. There is a high rate of injuries in Wrestling. To prevent injuries, it is necessary to identify the risk factors. Despite the functional importance of strength in wrestling, few studies have investigated the relationship between isokinetic strength and the rate of injuries in the sport. Objectives The objective of the present study was to investigate the relationship between the isokinetic strength of elite wrestlers and the rate of injuries prospectively. Method A total of 72 young wrestlers with at least 2 years of experience in the Tehran Wrestling Premier League participated in this study. Before the start of the competition season, the isokinetic strength of flexor and extensor muscles of the knee and shoulder were measured at different velocities by an isokinetic dynamometer. The injuries and training hours of these wrestlers were then recorded for nine months. Results The study results showed no significant relationship between isokinetic strength of flexor and extensor muscles of the knee or shoulder at different angular speeds of 60, 180, and 300°/s. There was neither significant between the ratio of the strength flexor/extensor for knee and/or shoulder in young elite wrestlers with injuries. Conclusion Isokinetic strength of lower and upper limb muscles alone cannot predict wrestlers' injuries. Therefore, the use of these tests is not recommended to evaluate the risk of injury in this population.

Kicking is a fundamental skill and a primary noncontact mechanism of injury in soccer, with injury incidence increasing during the latter stages of match-play. Ten male professional soccer players completed a 90-minute treadmill protocol based on the velocity profile of soccer match-play. Preexercise, and at 15-minute intervals, players completed a maximal velocity kick subjected to kinematic analysis at 200 Hz. Preexercise, and at the end of each half, players also completed isokinetic concentric knee extensor repetitions at 180°·s−1, 300°·s−1, and 60°·s−1. Kicking foot speed was maintained at ∼19 m·s−1, with no main effect for exercise duration. In relation to proximal–distal sequencing during the kicking action, there was a significant increase in the duration (but not magnitude) of thigh rotation, with a compensatory decrease in the duration (but not magnitude) of shank rotation during the latter stages of the exercise protocol. In relation to long-axis rotation, pelvic orientation at ball contact was maintained at ∼6°, representing a total pelvic rotation in the order of ∼15° during the kicking action. Peak knee extensor torque at all speeds was also maintained throughout the protocol, such that kinematic modifications are not attributable to a decline in knee extensor strength. [ABSTRACT FROM AUTHOR]

Physical capacities, health and quality of life (QOL) are improved through physical exercise in individuals with Intellectual Disability (ID). The aim of the present study was to verify the association of physical fitness with the perception of physical well-being and QOL in individuals with ID. Sixteen individuals with ID were evaluated by bioimpedance, functional tests ("6-minute walk test" (6MIN), "Timed Up and Go" (TUG), "30-s Chair Stand" (L/S), and "medicine ball throw") and isokinetic dynamometer (lower limbs [LL]). The Personal Outcomes Scale (POS) was used to measure "Physical Well-Being" and "Total QoL". Pearson and Spearman correlations were applied (p< 0.05). Correlations were found only in the female gender between the muscular strength in the extension/flexion of the LL (60°/s) and the responses of the reference technicians in the domains of "Physical Well-Being" (respectively, r= 0.729, p= 0.026; r= 0.802, p= 0.009) and "Total QOL" (respectively, r= 0.706, p= 0.033; r= 0.767, p= 0.016). It was found that strength, endurance and aerobic capacity do not seem to be associated with the physical well-being and QOL of the sample. [ABSTRACT FROM AUTHOR]

Background and objective: Peak torque, as measured by the gold standard method of isokinetic dynamometry, is affected by consumed of dietary nitrate (NO3-) in the form of beetroot juice (BRJ). The increasing strength performance effect of BRJ has also started to arouse interest in combat sports. This study aims to investigate the effects of acute dietary nitrate supplementation on lower and upper body isokinetic strength of trained Greco-Roman wrestlers. Materials and methods: The study is a double-blind, randomized, crossover design in which eight trained male Greco-Roman wrestlers (21.87 ± 2.3 years; height 176.87 cm ± 4.1 cm; body weight 76.75 kg ± 5.4 kg) consumed beetroot juice (140 mL) or placebo (140 mL, cherry juice with lemon juice) 150 min before performing isokinetic strength. Participants performed knee extensors and flexors and shoulder internal and external rotator isokinetic strength test (in the dominant limbs) concentrically at 60∘ with by Cybex device (Cybex NORM®, Humac, CA, USA). The same trial procedure was repeated with the other supplement (BRJ or Placebo) in a second testing session five days later. BRJ and Placebo trials’ isokinetic strength values were compared with parametric testing (paired sample T-test). Results: Although there was a significant difference in peak torque of shoulder internal and external rotator values in favor of BRJ (P < 0.05), there was no significant difference in the knee strength test. Additionally, all average isokinetic strength values were significantly increased in the BRJ trial (P < 0.05). Conclusions: These results suggest that BRJ can be used as an ergogenic effect for improving strength values in Greco-Roman wrestling.

IntroductionBrachial plexus birth injury (BPBI) and cerebral palsy (CP) both cause disabling contractures for which no curative treatments exist, largely because contracture pathophysiology is incompletely understood. The distinct neurologic nature of BPBI and CP suggest different potential contracture etiologies, although imbalanced muscle strength and insufficient muscle length have been variably implicated. The current study directly compares the muscle phenotype of elbow flexion contractures in human subjects with BPBI and CP to test the hypothesis that both conditions cause contractures characterized by a deficit in muscle length rather than an excess in muscle strength.MethodsSubjects over 6 years of age with unilateral BPBI or hemiplegic CP, and with elbow flexion contractures greater than 10 degrees on the affected side, underwent bilateral elbow flexion isokinetic strength testing to identify peak torque and impulse, or area under the torque-angle curve. Subjects then underwent needle microendoscopic sarcomere length measurement of bilateral biceps brachii muscles at symmetric joint angles.ResultsIn five subjects with unilateral BPBI and five with hemiplegic CP, peak torque and impulse were significantly lower on the affected versus unaffected sides, with no differences between BPBI and CP subjects in the percent reduction of either strength measurement. In both BPBI and CP, the percent reduction of impulse was significantly greater than that of peak torque, consistent with functionally shorter muscles. Similarly, in both conditions, affected muscles had significantly longer sarcomeres than unaffected muscles at symmetric joint angles, indicating fewer sarcomeres in series, with no differences between BPBI and CP subjects in relative sarcomere overstretch.DiscussionThe current study reveals a common phenotype of muscle contracture in BPBI and CP, with contractures in both conditions characterized by a similar deficit in muscle length rather than an excess in muscle strength. These findings support contracture treatments that lengthen rather than weaken affected muscles. Moreover, the discovery of a common contracture phenotype between CP and BPBI challenges the presumed dichotomy between upper and lower motor neuron lesions in contracture pathogenesis, instead revealing the broader concept of “myobrevopathy”, or disorder of short muscle, warranting increased investigation into the poorly understood mechanisms regulating muscle length.

Abstract Background When planning rehabilitation and conditioning for performance enhancement and a return to sports after anterior cruciate ligament reconstruction, identifying the elements of physical function associated with single-leg hop is important. The purpose of this study was to clarify the relationship between single-leg hop distances in three directions and knee extensor and flexor strengths at 6 months after reconstruction. Methods Participants were 47 patients taking part in training sessions for sports involving cutting, pivoting, and jump-landing 6 months after reconstruction using a hamstring tendon. Single-leg hop distances in 3 directions (anterior, lateral, and medial) and isokinetic concentric strengths of knee extension and flexion were assessed at an angular velocity of 60°/s and 180°/s. Simple regression analyses using Spearman’s rank correlation coefficient were performed to assess relationships between single-leg hop distances and knee strengths. Results In the involved limb, correlations between single-leg hop distances in 3 directions and knee strengths were significant (P < 0.01) and correlation coefficients ranged from 0.48 to 0.65. Correlation coefficients between all single-leg hop parameters and knee extension/flexion strengths at an angular velocity of 180°/s were greater than those of 60°/s. Conclusions In this cross-sectional study of patients who participated in sports training sessions that required jump-landings and cutting approximately 6 months after reconstruction using hamstring grafts, isokinetic knee flexor, and extensor torques were moderately to strongly associated with single-leg hop distances in lateral, medial, and anterior directions. Given these relationships, assessments and exercises for knee strength and single-leg hop distances should be planned.

Abstract To study the correlation between lower limb joint muscle strength at different angular velocities and dynamic balance among college students in soccer. Methods: 30 college students from Zunyi Medical University had a regular football training more than 16 weeks. The ISO-MED2000 was used to test the peak flexion and extension torque of the hip, knee and ankle at different angular velocities, and the Y-Balance Test was used to test the dynamic balance of lower extremities. Results: The relative peak of hip flexion and extension was associated well with balance ability at an angular velocity of 180°/ s; the relative peak torque of flexion and extension of the knee was well correlated with the balance ability at 30°/ s and 180°/ s (P>0.01); the ankle flexion was well correlated with balance ability at 30°/ s and 90°/ s(P>0.01). Conclusions: Muscular strength of lower extremities play different effects on dynamic balance ability at different velocity. [ABSTRACT FROM AUTHOR]

BACKGROUND: Knee strength weakness is a major problem frequently observed in patients during postoperative rehabilitation following anterior cruciate ligament reconstruction (ACLR). OBJECTIVE: To investigate whether knee strength normalized to muscle volume could better detect side-to-side differences than that normalized to body weight following ACLR. METHOD: This study included 17 patients who had undergone primary ACLR (11.6 ± 2.3 months). Body weight and total muscle volume were measured using a bioelectrical impedance analysis composition scale. Isokinetic knee extension and flexion moment were measured at 60 ∘ /s and 180 ∘ /s, respectively. Bivariate correlation analysis was used to examine correlations between body composition and knee strength. Differences in knee strength between the operated and unoperated legs were analyzed using a paired t -test, which calculated the effect size. RESULTS: There was a significant correlation between knee strength and body weight (r = 0.53–0.67); however, a stronger correlation was observed between knee strength and total muscle volume (ρ = 0.80–0.87). The effect size was larger for knee strength expressed as % total muscle volume than for knee strength expressed as % body weight. CONCLUSION: Strength expressed as % total muscle volume may be more accurate than that expressed as % body weight for detecting side-to-side differences in knee strength following ACLR. [ABSTRACT FROM AUTHOR]

We compared the acute effects of parallel back squat performed from different resistance training configurations on neuromuscular performance. Twenty-eight young adults underwent 4 experimental conditions: inter-repetition rest, traditional, traditional to failure, and rest-pause in the parallel back squat in a randomized, counterbalanced, and cross-over design. The neuromuscular performance was assessed through peak torque of knee extensors and flexors at two angular velocities (90 and 120 º/s) in three moments (before, post, and post-30 min). The peak torque of the knee extensors and flexors at 90 and 120 º/s decreased immediately after training for traditional, traditional to failure, and rest-pause (–8.1% to –17.7%, P <0.001). A greater reduction in the extensor peak torque was found at 120 º/s (P <0.05) in the rest-pause (–17.7%) when compared to traditional (–10.8%). The peak torque returned to baseline values only at post-30 min for the traditional configuration for the knee flexion action at 120 º/s. The peak torque remained similar for the muscular actions and angular velocities for the inter-repetition rest (P >0.05). Our results suggest the inter-repetition rest configuration seems to be a more appropriate strategy for maintaining the lower limb neuromuscular performance after a resistance training session. [ABSTRACT FROM AUTHOR]

Background: Wrestling is considered one of the oldest sports in the world. There is a high rate of injuries in Wrestling. To prevent injuries, it is necessary to identify the risk factors. Despite the functional importance of strength in wrestling, few studies have investigated the relationship between isokinetic strength and the rate of injuries in the sport. Objectives: The objective of the present study was to investigate the relationship between the isokinetic strength of elite wrestlers and the rate of injuries prospectively. Method: A total of 72 young wrestlers with at least 2 years of experience in the Tehran Wrestling Premier League participated in this study. Before the start of the competition season, the isokinetic strength of flexor and extensor muscles of the knee and shoulder were measured at different velocities by an isokinetic dynamometer. The injuries and training hours of these wrestlers were then recorded for nine months. Results: The study results showed no significant relationship between isokinetic strength of flexor and extensor muscles of the knee or shoulder at different angular speeds of 60, 180, and 300°/s. There was neither significant between the ratio of the strength flexor/extensor for knee and/or shoulder in young elite wrestlers with injuries. Conclusion: Isokinetic strength of lower and upper limb muscles alone cannot predict wrestlers' injuries. Therefore, the use of these tests is not recommended to evaluate the risk of injury in this population. [ABSTRACT FROM AUTHOR]

Background: Pilates-based core stability training (PBCST) is a controlled form of exercise that may improve the transmission of torque from the upper extremities and trunk to the lower extremities by enabling the core muscles to activate effectively. Objectives: The aim of this study was to investigate the effects of PBCST given as supervised or home-based on lower extremity strength and postural control in multiple sclerosis. Methods: Fifty individuals were enrolled and randomly allocated into two groups. Primary outcome measures were knee muscle strength and postural sway in different conditions. The supervised group received PBCST 2 days per week for 8 weeks at the clinic, and the other group performed PBCST at home. Exercises were progressed every 2 weeks in both groups. Results: Between groups, the supervised group was mostly superior to the home group (p < 0.05). A significant improvement was noted in all parameters in both groups, except some sub-parameters of postural sway in home PBCST (p < 0.05). Conclusions: Supervised PBCST was determined to be more effective than home PBCST in improving strength, postural control, core stability, physical capacity, and fatigue. Although supervised training is the primary choice, home training can be recommended to patients who have limitations attending supervised sessions. [ABSTRACT FROM AUTHOR]

Abstract Background A considerable portion of the elderly population are increasingly afflicted by degenerative spinal deformity (DSD), which seriously affects patient health-related quality of life (HRQoL). HRQoL index is used across many studies to show correlations between radio-graphical alignment, disability, and pain in patients with DSD. However, imaged structural deformity represents only one aspect for consideration, namely, the disability effect of DSD. We assessed the isokinetic strength of trunk muscle in patients with degenerative spinal deformity (DSD), and investigated its relationship with HRQoL. Methods In total, 38 patients with DSD (DSD group) and 32 healthy individuals (control group) were recruited. Both groups were homogeneous for age, weight, height and body mass index (BMI). Assessments were performed using the isokinetic dynamometer IsoMed-2000; trunk extensor, flexor strength and flexion/extension (F/E) ratios were explored concentrically at speeds of 30°, 60° and 120° per second. The grip strength of both hands was measured using a hand-held dynamometer. Visual analogue scale (VAS) scores, the Oswestry Disability Index (ODI), a Roland-Morris disability questionnaire (RDQ), and a 36-item Short Form Health Survey (SF-36) evaluated patient HRQoL. Correlations between trunk strength and HRQoL were analyzed. Results When compared with the control group, the DSD group showed lower trunk extensor strength at three velocity movements, and higher F/E ratios at 60° and 120°/s (p 0.05). In DSD group, trunk extensor strength at 60°/s was negatively associated with ODI and RDQ (p

Background and Study Aim. The aim of this study was to investigate the effect of 6 weeks theraband training on respiratory parameters, upper extremity muscle strength and 50-100m swimming performance in swimming athletes. Material and Methods. Totally 12 male swimmers participated voluntarily and were divided into two groups as control group (n=6) and experimental group (n=6). Control group did only swimming training, experimental group did theraband exercises in addition to swimming exercises. Respiratory parameters, upper extremity anaerobic performance, shoulder extension/flexion strength and swimming performance were measured. Mann Whitney-U Test was used to determine the differences between two groups. Wilcoxon Test was used to determine intra-group differences. Results. There was no statistically significant difference between the pre and post-test values of respiratory parameters, anaerobic performance values and swimming measurements of the experimental groups (p>0.05). There was a statistically significant difference between shoulder extension and flexion values (p0.05). There was a statistically significant difference between the post-test values ​​of the experimental and control groups shoulder extension and flexion values (p0.05). Conclusions. As a result of the findings, it can be said that theraband training which is done as a land work with swimming training leads to positive effects in the upper extremity muscle strength and swimming performance development of youth swimmers.

Purpose: Muscle strength is needed to perform many movements and skills in football such as speed decreasing, shooting, dribbling, rotating, and jumping. Several studies shown that lower limb muscle strength can increase the quality of exercise skills. But, few studies have compared the strength of players at different levels. Therefore, the present study intends to investigate the strength of the isokinetic and isometric knee muscles of the elite, sub-elite and amateur football players of Iran. Methods: The isokinetic strength of the knee muscles in 102 soccer players including 29 players of the national under-23 football team of Iran (elite), 29 players of 1st division of under-23 football team of Iran (sub-elite) and 44 players of 2nd division of under-23 football team of Tehran province (amateur) was measured for angular momentum of 60 and 180 degrees per second by the isokinetic Biodex. The isometric strength of flexor and extensor muscles of knee were measured at an angle of 60 degree. Results: The results of the ANOVA test showed that elite player had superior strength of flexor and extensor knee muscles in both momentum angles of 60 and 180 degrees per second and flexor/ extensor isokinetic strength ratio at 180 degrees per second speed than sub-elite and amateur players significantly. However, there was no significant difference in the ratio of flexor/ extensor isokinetic strength ratio at 60 degrees per second. Conclusions: Considering the results of the present study, it can be concluded that competition level affect the isokinetic and isometric strength of the knee muscles of young football players of Iran.

Purpose The purpose of this study was to find out the physical characteristics of Wushu athletes by comparing the differences on the results of physical fitness between the male athletes of the Wushu national team Taolu and the Sanda group. Methods Measurement of basic and professional fitness based on muscle function, targeting 37 men Wushu national team players (24 taolu, 13 Sanda) in the selection and evaluation contests twice in 2018 and 2019. Body composition, isometric muscle strength, flexibility and equilibrium, anaerobic power, and isokinetic muscle strength. The fitness factors were divided into two groups, Taolu and Sanda. Results First, body fat rate of the Sanda athlete group was significantly lower than that of the taolu athlete group (p

Abstract Background Strength deficits, muscle imbalances, and quadriceps inhibition are common after the total knee arthroplasty (TKA). It was suggested that theoretically single radius (SR) femoral protheses could provide longer extensor moment arm compared to the multiple radius (MR) design. However, quantitative evidence has not yet been reported. Thus, the aim of the study was to investigate the differences in isokinetic data and to compare the patient-reported outcome scores between TKA SR and MR design. Method The present retrospective study included 36 TKA involving 16 knees (9 patients) using SR design implant and 20 knees (11 patients) using MR design implant. The mean follow-up time was longer than 1 year. Isokinetic knee flexion and extension torques of the operated leg were evaluated at 60°/s and 180°/s. Quadriceps and hamstring torques and ratios, work and power were recorded. Angle-specific torques were also collected at different extension or flexion angles. Results Both groups showed improvement in knee society scores (KSS) and knee injury, and osteoarthritis outcome score (KOOS) after operation. Patients in SR group had significantly higher scores in KSS-knee, symptoms and activities of daily living KOOS sub-score than those in the MR group at the end of the follow-up. The peak knee flexion torque, peak knee extension torque and maximum knee flexion work were greater in SR group at 180°/s and 60°/s. At 60°/s, and SR group had higher average knee flexion power and average knee extension power than MR group. In the isometric contraction test, the knee extension torque was higher in SR group than in MR group. At 180°/s, SR group showed higher flexion torques at 30°, 40°, 50°, 60° compared with MR group. At 60°/s, SR group showed higher flexion torques at 30°, 40°, 50°, 60°, 80° when compared with MR group. Additionally, SR group also provided higher extension torques at 40°, 50°, 60° than the MR group. There were no differences in other isokinetic and isometric parameters between the two groups. Conclusion Femoral design exerted an influence on quadriceps and hamstring strength after TKA, and SR design shows advantages, in terms of higher extension and flexion strength, over MR design.