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Context: The persistence and the recurrence of posterior medial knee pain (PKP) after anterior cruciate ligament reconstruction (ACLR) using hamstring tendon graft are often overlooked during rehabilitation. Design: Cross-sectional observational study. Methods: The study aimed (1) to evaluate the prevalence of these types of PKP before 4 months post-ACLR, (2) to measure their consequences on the knee flexors strength, and (3) to evaluate the role of the type of ACLR. From a cohort of patients operated on with hamstring tendon procedures, the persistent and the recurrent PKP were sought at 4 months post-ACLR. The evolution of isokinetic muscle strength recovery in PKP subjects was compared with those of nonpainful subjects. The functional deficit was measured at 6/7 months post-ACLR by a hop test. Results: Three hundred seventeen subjects (25.8 [6.0] y) were included. At 4 months post-ACLR, 2 populations were identified based on the recurrent onset of PKP (PKP+, n = 40) or the absence of knee pain (PKP−, n = 277). The prevalence of PKP was 8.3%. At the fourth month post-ACLR, the PKP+ group had a higher flexor strength deficit compared with the PKP− group (limb symmetry index at 60°/s: 67.2% [12.4%] vs 84.3% [12.6%]; P <.05). At 6/7 months, the loss of strength persisted (limb symmetry index at 60°/s: 82.3% [13.4%] vs 87.7% [12.8%]; P <.05). The hop test deficit was comparable, and no difference was shown according to the type of graft. Conclusions: Persistent and recurrent PKP during the rehabilitation period were not uncommon and were associated with a worsening of flexors strength loss on the ACLR side. [ABSTRACT FROM AUTHOR]

Acute sleep restriction (SR) reduces strength through an unknown mechanism. Purpose: To determine how SR affects quadriceps contractile function and recruitment. Methods: Eighteen healthy subjects (9 M, 9F, age 23.8 ± 2.8y) underwent isometric (maximal and submaximal), isokinetic (300–60°·s−1), and interpolated twitch (ITT) assessment of knee extensors following 3d of adequate sleep (SA; 7–9 h·night−1), 3d of SR (5 h·night−1), and 7d of washout (WO; 7-9 h·night−1). Results: Compared to SA (227.9 ± 76.6Nm) and WO (228.19 ± 62.9Nm), MVIC was lesser following SR (209.9 ± 73.9Nm; p = 0.006) and this effect was greater for males (− 9.8 v. − 4.8%). There was no significant effect of sleep or sleep x speed interaction on peak isokinetic torque. Peak twitch torque was greater in the potentiated state, but no significant effect of sleep was noted. Males displayed greater potentiation of peak twitch torque (12 v. 7.5%) and rate of torque development (16.7 v. 8.2%) than females but this was not affected by sleep condition. ITT-assessed voluntary activation did not vary among sleep conditions (SA: 81.8 ± 13.1% v. SR: 84.4 ± 12.6% v. WO 84.9 ± 12.6%; p = 0.093). SR induced a leftward shift in Torque-EMG relationship at high torque output in both sexes. Compared to SA, females displayed greater y-intercept and lesser slope with SR and WO and males displayed lesser y-intercept and greater slope with SR and WO. Conclusions: Three nights of SR decreases voluntary isometric knee extensor strength, but not twitch contractile properties. Sex-specific differences in neuromuscular efficiency may explain the greater MVIC reduction in males following SR. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this pilot study was to analyze the potential financial loss and a range of potential risk factors for hamstring muscle injuries in elite Brazilian soccer. Methods: Thirty-four male players (age: 25 ± 6 years; stature: 180 ± 8 cm; body mass: 78 ± 9 kg; minutes played in matches: 2243 ± 1423 min) from an elite professional soccer club were monitored during a 12-month season. Muscle injury was identified by magnetic resonance imaging and the severity was defined according to the number of days away: minimal (1-3 days), mild (4-7 days), moderate (8-28 days), severe (>28 days). Potential financial loss due to the team's under achievements was determined. Dorsiflexion range of motion, eccentric knee flexor strength and isokinetic tests were performed during the pre-season. Association between dependent variables and the occurrence of injury was evaluated. Results: Nine hamstring muscle injuries with moderate severity were found in 8 athletes. Recovery time was 22 days off the field on average. Potential financial loss was $-43.2 million USD and earnings on merit money was 21%. Previous injury, increased flexor deficit 60°/sec and increased flexor fatigue index 300°/sec were all associated with a greater chance of hamstring muscle injury. Ankle dorsiflexion range of motion was significantly lower in the injured group (35.6 ± 3° vs. 39.1 ± 4.9°; p = 0.017, effect size = -0.74). Conclusion: High financial burden was found in elite Brazilian soccer during one full season. Injured athletes had high hamstring fatigue index, knee flexor strength deficit, ankle range of motion restriction and previous hamstring muscle injury when compared to non-injured athletes. Therefore, preventive approaches in professional soccer players with previous hamstring injuries should be a priority. [ABSTRACT FROM AUTHOR]

Background: Isokinetic normative data in females' soccer players is scarce in comparison to males. Furthermore, evaluation protocols employed to obtain those data in female's studies, strongly differ from each other, using different ranges of speeds and movement patterns, thus producing different output data. Thus, it is difficult for the researcher and the clinician to choose a correct protocol for knee isokinetic test in female soccer players. Aim of this paper is to review the literature to provide updated information on how to interpret a knee isokinetic testing in healthy females. Methods: Google Scholar, PubMed, Sport Discus, and Psych info databases were queried, and 17 papers were selected. Following PRISMA methodology and PEDro scale, we classified the retrieved papers and assessed the quality. Results: In this review some common features of isokinetic testing in female soccer players of various levels of qualification are highlighted. The isokinetic performance indexes widely accepted are the hamstring/quadriceps (H/Q) ratio and dominant/non-dominant (D/ND) ratio. It also emerges that, 3 reps at the speed of 60°/sec in knee flexion/extension are preferable due to the higher reliability and that the optimal H/Q ratio in healthy female soccer players of different level of qualification and age is 50%, while the interlimb differences (D/ND) should be below 10%. Conclusions: Normative data and methodologies reviewed can be useful for the isokinetic test of female soccer players. It emerges that simplifying test procedures limiting at few testing speed and considering selected H/Q and D/ND gives all the necessary relevant informations. [ABSTRACT FROM AUTHOR]

We systematically reviewed and synthesized the evidence for the relationship between hip strength and hip and knee biomechanics during single-leg tasks in uninjured and injured populations. We searched CINAHL, EMBASE, PubMed, SportDiscus, and Web of Science from inception to July 2024. We included cross-sectional studies with uninjured and/or injured participants that reported correlations between hip strength and hip or knee kinematics during a single-leg task. We identified 41 articles that reported the correlations between hip strength and hip or knee kinematics during a single–leg task for uninjured (n = 33) and/or injured (n = 12) populations. We identified moderate–to-strong evidence for no-to-poor relationships between most hip strength and hip and knee kinematics during a single-leg task for uninjured (r = –0.33–0.45) and injured populations (r = –0.24–0.24). We observed limited-to-moderate evidence for fair-to-moderate negative relationships between concentric and eccentric hip abduction strength and hip adduction (r = –0.52) and knee abduction kinematics (r = –0.45–0.59) for uninjured populations. Isometric hip strength may not play as important of a role in controlling lower extremity motion during single-leg tasks as previously perceived, but isokinetic strength may be a better indicator of lower extremity motion during single-leg tasks. Trial Registration:PROSPERO#CRD42020153166. [ABSTRACT FROM AUTHOR]

Background: Patellar dislocation is a knee injury affecting generally young, active individuals, damaging joint ligaments and structures, and impacting sports activity and quality of life. Objective: This review aimed to evaluate the role of the quadriceps femoris muscle in knee extension and to consider whether extensor strength deficits are present in patients who have suffered from a primary or recurrent patellar dislocation and have been treated surgically or conservatively. Methods: This systematic literature review with meta-analysis was performed following the PRISMA Statement criteria. The search engines consulted to select studies were MEDLINE/PubMed, Scopus, and Web of Science/ISI. The JBI Critical Appraisal Checklist tools were applied for the quality assessment based on the specific study design. The outcomes were measurements of the knee extension force of the quadriceps femoris muscle, which were objectively quantifiable with an isokinetic or mobile dynamometer. Results: Of the 891 articles initially identified through the databases, 10 studies with a total of 370 patients were included in the analysis. The results indicated a strength deficit of the quadriceps in patients who had undergone a patellar dislocation, in comparison with the control group, when examining the uninvolved limb or in comparison with the pre-operative values. The overall effect size was large, with a value of −0.99. Conclusions: Our review concluded that after a primary or recurrent patellar dislocation, strength deficits of the quadriceps femoris muscle in the knee extension of the affected limb are frequently observed in surgically or conservatively treated patients. This deficit may persist even after a protracted follow-up of up to three years after injury. [ABSTRACT FROM AUTHOR]

Background: Systematizing reliable protocols and procedures for strength assessment in handball has allowed for a more thorough kinetic analysis and increased precision in detecting training-induced changes in muscular strength. The evaluation of upper limb strength with a bilateral standing press (BSP) exercise in handball players approximates blocking actions in the defensive phase, pushing and fixation. Aim: The aim of this study was to analyze the relative and absolute reliability of intra-session comparisons in an isometric peak muscle strength protocol in a bilateral standing press (BSP) exercise among female handball players. Methods: Sixteen young female handball players at an international level, aged between 22 ± 4 years, with no prior experience in using functional electromechanical dynamometers (FEMD) participated in this study. The participants initiated the assessment of maximum isometric force in a bipedal stance with a forward projection of the dominant foot between 20 and 30 cm. The knees were kept semi-flexed, and the hip extension of the non-dominant limb ranged from 15 to 20°. Bilateral anterior push of the upper limb was performed with shoulder abduction and elbow flexion at 90°, maintaining a pronated hand position. Participants were instructed to exert three sets of maximal force for 5 s in BSP exercise. Relative reliability was assessed using the model intraclass correlation (ICC) and absolute reliability was assessed using the coefficient of variation (CV) and standard error of measurement (SEM). For this study, the parameters of maximum and mean muscle strength were considered. Results: The results demonstrated high relative reliability (ICC 0.93–0.97) and absolute reliability (SEM 0.19–2.79) y (CV 4.78–9.03) for both mean force and peak force, with no significant differences between the sets (p > 0.05), indicating a negligible effect size (0.01−0.12). Conclusion: The mean and peak isometric muscle strength for the BSP exercise controlled with FEMD in female handball players exhibits high relative and absolute reliability between series. [ABSTRACT FROM AUTHOR]

There are a considerable number of patients who, after anterior cruciate ligament reconstruction (ACL), suffer from relapses or reduced performance. Data collected from isokinetic dynamometry can provide useful information on the condition of the knee during rehabilitation. Seventy-one young sports patients with ACL reconstruction performed concentric (CON) isokinetic dynamometry (CON/CON 90°/s and CON/CON 240°/s) to assess the muscle strength of the quadriceps (Q) and hamstrings (H) in both knees at 6 months after ACL reconstruction. Limb symmetry index (LSI) and the H/Q ratio were calculated. Comparative statistical tests and multivariate regression were performed. At 90°/s, 57 patients (80.3%) had an LSI below 90% for quadriceps and 28 (60.6%) for hamstring. The number of imbalanced patients according to H/Q ratio was higher in the non-operated knee (n = 56, 78.9%) (p < 0.001). At 240°/s, 49 cases (69.1%) had LSI values above 90% for quadriceps and 37 (52.1%) for hamstrings. Regarding H/Q, imbalanced cases were higher in the non-operated limb (n = 60, 84.5%) (p < 0.001). Strength data at 6 months after ACL reconstruction and post-operative rehabilitation indicated greater unilateral (H/Q) muscle imbalance in the non-operated knee than in the operated knee. Most patients did not achieve the adequate LSI values. [ABSTRACT FROM AUTHOR]

Abstract Background Isokinetic normative data in females’ soccer players is scarce in comparison to males. Furthermore, evaluation protocols employed to obtain those data in female’s studies, strongly differ from each other, using different ranges of speeds and movement patterns, thus producing different output data. Thus, it is difficult for the researcher and the clinician to choose a correct protocol for knee isokinetic test in female soccer players. Aim of this paper is to review the literature to provide updated information on how to interpret a knee isokinetic testing in healthy females. Methods Google Scholar, PubMed, Sport Discus, and Psych info databases were queried, and 17 papers were selected. Following PRISMA methodology and PEDro scale, we classified the retrieved papers and assessed the quality. Results In this review some common features of isokinetic testing in female soccer players of various levels of qualification are highlighted. The isokinetic performance indexes widely accepted are the hamstring/quadriceps (H/Q) ratio and dominant/non-dominant (D/ND) ratio. It also emerges that, 3 reps at the speed of 60°/sec in knee flexion/extension are preferable due to the higher reliability and that the optimal H/Q ratio in healthy female soccer players of different level of qualification and age is 50%, while the interlimb differences (D/ND) should be below 10%. Conclusions Normative data and methodologies reviewed can be useful for the isokinetic test of female soccer players. It emerges that simplifying test procedures limiting at few testing speed and considering selected H/Q and D/ND gives all the necessary relevant informations.

Context: Hip muscle strength and hop performance limb symmetries after anterior cruciate ligament reconstruction (ACLR) are not well studied. This study aimed to determine the differences in hip abductors' (ABD) and external rotators' (ER) muscle strength measures between limbs, and the relationship between hip ABD and ER muscle strengths and hop performance limb symmetry indices (LSIs) 2 years after ACLR. Design: Cross-sectional study. Methods: Forty (level I/II) men athletes 2 years after unilateral ACLR completed 4 single-legged hop tests and involved hip ABD and ER strength testing (maximum voluntary isometric contraction [MVIC]; isokinetic peak torque [PKTQ] at 60°, 180°, and 300°/s; and isotonic peak velocity at 75% of their MVICs). Muscle strength measures were normalized to body mass, and hop performances were reported as LSIs. Paired t test was used to determine strength differences between limbs, and the Pearson correlation coefficient was used to assess the relationship between involved hip muscle strength measures and hop performance LSIs. Results: Hip ER-MVIC (involved: 60.26 [12.01], uninvolved: 63.68 [13.17] N·m/kg) and ER eccentric PKTQ at 60°/s (involved: 32.59 [9.28]; uninvolved: 35.73 [10.50] N·m/kg) were significantly different between limbs (P ≤.018). Single-hop LSI correlated with hip ER-PKTQ at 180°/s (r =.354) and 300°/s (r =.324, P ≤.041), while triple-hop LSI correlated with hip ER-MVIC (r =.320), concentric ER-PKTQ at 180°/s (r =.355), eccentric ER-PKTQ at 60°/s (r =.314), and hip ABD-PKTQ at 60°/s (r =.364) and 300°/s (r =.336, P ≤.049). Conclusions: Men athletes demonstrated symmetrical hop performance and hip muscle strengths, except for ER hip's MVIC and isokinetic eccentric peak torque at 60°/s 2 years after ACLR. Hop performance LSIs had a few, yet positive moderate relationships with involved hip ABDs and ER strength measures. This may indicate that hip ABD and ER muscle strength measures contribute to athletes' hop performances 2 years after ACLR. Post-ACLR rehabilitation programs might incorporate hip muscle strengthening training to improve athletes' functional performances. [ABSTRACT FROM AUTHOR]

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aimed to examine the effects of black maca supplementation on isokinetic muscle function and inflammatory markers in athletes and to extend these findings to non-athletes. The study involved 24 male participants, including 16 elite athletes (soft tennis and table tennis players) and 8 non-athletes (university students). Participants consumed capsules containing 2.5 g of 100% concentrated black maca extract over a 12-week period. Isokinetic muscle performance and physical fitness (strength, muscular endurance, flexibility, power, agility, cardiovascular endurance) assessments were conducted at baseline and after 12 weeks of supplementation. Two-way within-factor ANOVA showed a significant group × time interaction for 120°/s flexor movements (p < 0.05). Paired t-tests demonstrated significant improvements in 30°/s and 120°/s extensor and flexor movements in both athlete groups (p < 0.05, p < 0.01). Similarly, significant enhancements were observed in the non-athletes for the 30°/s flexor and 120°/s extensor and flexor movements (p < 0.01). Furthermore, reductions in interleukin-6 (from 137.9 ± 8.8 to 132.7 ± 4.6, p < 0.05) and tumor necrosis factor-alpha (from 274.1 ± 13.4 to 264.2 ± 3.2, p < 0.05) were noted in the soft tennis group. The table tennis group also showed significant decreases in interleukin-6 (from 135.9 ± 4.7 to 131.3 ± 2.5, p < 0.01) and tumor necrosis factor-alpha (from 282.1 ± 19.2 to 267.0 ± 6.4, p < 0.05). No significant changes were observed in the non-athlete group. Black maca supplementation may enhance isokinetic muscle function in elite athletes by reducing muscle contraction fatigue and improving anti-inflammatory responses. [ABSTRACT FROM AUTHOR]

Photobiomodulation therapy (PBMT) applied as a preconditioning treatment before exercise has been shown to attenuate fatigue and improve skeletal muscle contractile function during high-intensity resistance exercise. Practical implications for preconditioning muscles with PBMT before fatiguing exercise include a safe and noninvasive means to enhance performance and reduce the risk of musculoskeletal injury. To examine the muscle fatigue–attenuating effects of PBMT on performance of the shoulder external-rotator muscle group when applied as a preconditioning treatment before high-intensity, high-volume resistance exercise. Sham-controlled, crossover design. Laboratory. Twenty healthy men (n = 8) and women (n = 12) between the ages of 18 and 30 years. Photobiomodulation therapy was administered using a near-infrared laser (λ = 810/980 N·m, 1.8 W/cm2, treatment area = 80–120 cm2) to the shoulder external-rotator muscles at a radiant exposure of 10 J/cm2. Participants performed 12 sets of isokinetic shoulder exercise. Each set consisted of 21 concentric contractions of internal and external rotation at 60°/s. The sets were subdivided into 3 blocks of exercise (block 1: sets 1–4; block 2: sets 5–8; block 3: sets 9–12). Normalized peak torque (N·m/kg), average peak torque (N·m), total work (N·m), and average power (W). During the last block of exercise (sets 9–12), all performance measures for the active PBMT condition were 6.2% to 10% greater than the sham PBMT values (P <.02 to P <.001). Photobiomodulation therapy attenuated fatigue and improved muscular performance of the shoulder external rotators in the latter stages of strenuous resistance exercise. [ABSTRACT FROM AUTHOR]

Lower limb injury rates have increased dramatically in line with increased female sport participation levels. Muscle strength is a modifiable lower limb injury risk factor, guiding performance monitoring and rehabilitation. The aim of this study was to investigate the test-retest reliability of isokinetic and isometric lower limb peak torque to body mass of muscles acting on the hip, knee, and ankle in female team sport athletes. It was hypothesised the test-retest reliability would be good (intraclass correlation coefficients (ICC) ≥ 0.75). Thirty-eight female athletes (Australian Rules Football = 18, netball = 12, soccer = 8) aged 16–35 years participated in this study. Participants performed isokinetic (60°/s and 120°/s) and isometric testing on a Biodex Isokinetic Dynamometer on three separate days. Poor to good reliability was demonstrated for all joint movements (ICC = 0.38–0.88) with small to moderate effect sizes (0.00–0.43) and typical errors (5.65–24.49). Differences in peak torque to body mass were observed between sessions one and two and/or one and three, demonstrating a learning effect. Therefore, three testing sessions, and/or the inclusion of a familiarisation session, is recommended for future assessments in populations unfamiliar with dynamometry. • Lower limb strength does not comprise of just a single joint (hip, knee and ankle). • Differences in peak torque between sessions demonstrate potential learning effects. • In future, a familiarisation session or three testing sessions are recommended. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

It has been demonstrated that maximum isometric muscle moment can surpass maximum eccentric muscle moment at individually adjusted joint angles in men. However, no information about these muscle mechanics is available for women. To examine the maximum muscle moment hierarchy with equal conditions in women. Maximum voluntary concentric, eccentric, and isometric muscle moments of ankle, knee, and hip flexors and extensors as well as hip adductors and abductors were tested in eighteen young women. The sequence of muscle group testing was the same for all subjects, and the sequence of contraction types was randomized. All dynamic contractions were performed at 60∘/s. Peak moment angle of concentric contractions was applied for isometric moment testing. A repeated measures ANOVA with posthoc Bonferroni correction was used to compare means between contraction types. Differences in maximum moment mean values between the three contraction types were apparent for all muscle groups (p< 0.001). Concentric muscle moment was significantly the weakest contraction type. Eccentric contractions generated significantly higher moments than isometric contractions in dorsiflexion, plantarflexion, knee flexion, and hip adduction. Significant differences in maximum lower body muscle moments exist between concentric, eccentric, and isometric contractions in women. Compared to previous research for men there appears to be a sex-specific contraction type hierarchy with women exhibiting superior ability to generate higher eccentric muscle moment relative to other contraction types. These results should be considered when designing contractiontype specific intervention programs. [ABSTRACT FROM AUTHOR]

Purpose: The relationship between functional shoulder deficits in children with neonatal brachial plexus palsy (NBPP) and magnetic resonance imaging (MRI) shoulder abnormalities was evaluated. Methods: Shoulder function was assessed in 16 children (mean age: 5.8 years; range: 3–12 years) with NBPP based on shoulder rotator muscle strength, as measured using an isokinetic dynamometer and the modified Mallet score. The thickness and fatty infiltration of the subscapularis and infraspinatus muscles, and the morphology of the glenoid on MRI, were also determined. Results: The highest subscapularis fatty infiltration subgroup of NBPP patients promoted the highest alteration muscle thickness and modified Mallet score. Conclusions: In NBPP children, subscapularis impairments play a major role in the functional limitations. This study of pediatric NBPP patients highlighted the value of adding an examination of the muscles to routine MRI assessment of bone parameters in the shoulders of NBPP children. Trial registration: NCT03440658. [ABSTRACT FROM AUTHOR]

This study aimed to determine the absolute and relative reliability of concentric and eccentric flexion, extension, horizontal abduction, and adduction movements of the shoulder using a functional electromechanical dynamometer (FEMD). Forty-three active male university students (23.51 ± 4.72 years) were examined for concentric and eccentric strength of shoulder flexion, extension, horizontal abduction, and horizontal adduction with an isokinetic test at 0.80 m·s−1. Relative reliability was determined by intraclass correlation coefficients (ICCs) with 95% confidence intervals. Absolute reliability was quantified by the standard error of measurement (SEM) and coefficient of variation (CV). Reliability was very high to extremely high for all movements on concentric and eccentric strength measurements (ICC: 0.76–0.94, SEM: 0.63–6.57%, CV: 9.40–19.63%). The results of this study provide compelling evidence for the absolute and relative reliability of concentric and eccentric flexion, extension, horizontal abduction, and horizontal adduction shoulder isokinetic strength tests in asymptomatic adults. The mean concentric force was the most reliable strength value for all tests. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Isokinetic testing is a maximal muscle strength test which requires adequate patient's preparation and observer's care. While the available data suggests that isokinetic devices are safe, their use may rarely cause severe injuries. The screening of predisposing anatomical factors could help preventing injuries before testing. A 29‐year‐old athletic man presented an acute patellar dislocation on a healthy right knee during isokinetic muscle strength testing, which was conducted in the setting of an intensive physical rehabilitation program, for persistent left knee pain after arthroscopic surgery for meniscal tear. This is the first case to occur in an adult male without clear risk factors such as patellar dysplasia. Predisposing factors may include slightly elevated patellar tilt and lateral shift compared to the contralateral knee (researched from subsequent review of pre‐injury X‐rays), and an elevated quadricipital strength in the context of recreational bodybuilding. The dislocation occurred during eccentric extension phase of testing. Medial patellofemoral ligament reconstruction was conducted 6 months later. Isokinetic muscle strength testing is generally considered as a safe method, despite limited data on the devices' safety. Since severe injuries might rarely occur, adequate patient preparation is needed, as well as the screening of predisposing factors. [ABSTRACT FROM AUTHOR]

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. 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. 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. The presence of HFrEF in patients with COPD worsens muscular weakness when compared to isolated COPD. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the relationship between rectus femoris muscle architecture and isokinetic concentric peak knee extension torque at various velocities. Twenty physically active men (age =21.1±1.41 years, weight =69.9±5.7 kg, height =176.4±7.07 cm) had their isokinetic concentric knee extensor (Biodex 4 Pro, Biodex Medical Inc, Shirley, USA) strength assessed at 60°/sec, 180°/sec and 300°/sec. Pennation angle, muscle thickness, and fascicle length of the rectus femoris was measured using real-time B-mode ultrasound (Logiq P5, GE Healthcare, UK). Pennation angle had a significant positive correlation to peak torque at 60°/sec (r=0.731, p=0.001), 180°/sec (r=0.802, p=0.001) and 300°/sec (r=0.685, p=0.001). There was a significant positive correlation between muscle thickness and peak torque at 60°/sec (r=0.718, p=0.001), 180°/sec (r=0.749, p=0.001) and 300°/sec (r=0.722, p=0.001). However, there was no significant correlation between fascicle length and the isokinetic peak torque values (p>0.05). In addition, pennation angle and muscle thickness were found to be significant contributors for predicting isokinetic knee extension torque (R2=0.47-0.64; p<0.01). Pennation angle and muscle thickness best predicted peak knee extension torque at 180°/sec (explained variance =64% and 56%, respectively). This study suggests that pennation angle and muscle thickness can be used to predict isokinetic knee extension torque in physically active men. [ABSTRACT FROM AUTHOR]

Background Systematizing reliable protocols and procedures for strength assessment in handball has allowed for a more thorough kinetic analysis and increased precision in detecting training-induced changes in muscular strength. The evaluation of upper limb strength with a bilateral standing press (BSP) exercise in handball players approximates blocking actions in the defensive phase, pushing and fixation. Aim The aim of this study was to analyze the relative and absolute reliability of intra-session comparisons in an isometric peak muscle strength protocol in a bilateral standing press (BSP) exercise among female handball players. Methods Sixteen young female handball players at an international level, aged between 22 ± 4 years, with no prior experience in using functional electromechanical dynamometers (FEMD) participated in this study. The participants initiated the assessment of maximum isometric force in a bipedal stance with a forward projection of the dominant foot between 20 and 30 cm. The knees were kept semi-flexed, and the hip extension of the non-dominant limb ranged from 15 to 20°. Bilateral anterior push of the upper limb was performed with shoulder abduction and elbow flexion at 90°, maintaining a pronated hand position. Participants were instructed to exert three sets of maximal force for 5 s in BSP exercise. Relative reliability was assessed using the model intraclass correlation (ICC) and absolute reliability was assessed using the coefficient of variation (CV) and standard error of measurement (SEM). For this study, the parameters of maximum and mean muscle strength were considered. Results The results demonstrated high relative reliability (ICC 0.93–0.97) and absolute reliability (SEM 0.19–2.79) y (CV 4.78–9.03) for both mean force and peak force, with no significant differences between the sets (p > 0.05), indicating a negligible effect size (0.01−0.12). Conclusion The mean and peak isometric muscle strength for the BSP exercise controlled with FEMD in female handball players exhibits high relative and absolute reliability between series.

PurposeThe aim of this pilot study was to analyze the potential financial loss and a range of potential risk factors for hamstring muscle injuries in elite Brazilian soccer.MethodsThirty-four male players (age: 25 ± 6 years; stature: 180 ± 8 cm; body mass: 78 ± 9 kg; minutes played in matches: 2243 ± 1423 min) from an elite professional soccer club were monitored during a 12-month season. Muscle injury was identified by magnetic resonance imaging and the severity was defined according to the number of days away: minimal (1–3 days), mild (4–7 days), moderate (8–28 days), severe (>28 days). Potential financial loss due to the team's under achievements was determined. Dorsiflexion range of motion, eccentric knee flexor strength and isokinetic tests were performed during the pre-season. Association between dependent variables and the occurrence of injury was evaluated.ResultsNine hamstring muscle injuries with moderate severity were found in 8 athletes. Recovery time was 22 days off the field on average. Potential financial loss was $-43.2 million USD and earnings on merit money was 21%. Previous injury, increased flexor deficit 60° /sec and increased flexor fatigue index 300°/sec were all associated with a greater chance of hamstring muscle injury. Ankle dorsiflexion range of motion was significantly lower in the injured group (35.6 ± 3° vs. 39.1 ± 4.9°; p = 0.017, effect size = −0.74).ConclusionHigh financial burden was found in elite Brazilian soccer during one full season. Injured athletes had high hamstring fatigue index, knee flexor strength deficit, ankle range of motion restriction and previous hamstring muscle injury when compared to non-injured athletes. Therefore, preventive approaches in professional soccer players with previous hamstring injuries should be a priority.

IntroductionIsokinetic exercise can improve joint muscle strength and stability, making it suitable for early rehabilitation of stroke patients. However, traditional isokinetic equipment is bulky and costly, and cannot effectively avoid external environmental interference.MethodsThis paper designed a lightweight upper limb joint isokinetic rehabilitation training equipment, with a control system that includes a speed planning strategy and speed control with disturbance rejection. Based on the established human-machine kinematic closed-loop model between the equipment and the user, a dynamic evaluation method of torque at the joint level was proposed.ResultsTo validate the effectiveness of the equipment, experiments were conducted by manually applying random disturbances to the equipment operated at an isokinetic speed. The results showed that the root mean square error between the observed torque curve of the second-order linear extended state observer used in this paper and the actual disturbance curve was 0.52, and the maximum speed tracking error of the speed control algorithm was 1.27%. In fast and slow sinusoidal speed curve tracking experiments, the root mean square errors of the speed tracking results for this algorithm were 9.65 and 5.27, respectively, while the tracking errors for the PID speed control algorithm under the same environment were 19.94 and 12.11.DiscussionThe research results indicate that compared with traditional PID control method, the proposed control strategy demonstrates superior performance in achieving isokinetic control and suppressing external disturbances, thereby exhibiting significant potential in promoting upper limb rehabilitation among patients.

Introduction: Quadriceps weakness after knee surgery is the most common consequence that can have different consequences not only for the knee itself but also for the locomotor system in general. This study aimed to compare the results of isokinetic and isotonic exercise on torque restoration quadriceps on knee surgery. Methods: A sample of 180 subjects was analyzed and divided into two subsamples according to the type of rehabilitation protocol that was implemented. The examined group A-isokinetic consisted of 90 male subjects aged 28.54 ± 4.44 years, with a rehabilitation protocol based on the isokinetic exercise of the quadriceps. The examined group B-isotonic also consisted of 90 male subjects aged 27.93 ± 4.27 years, with a rehabilitation protocol for strengthening the quadriceps that applied an exercise program with additional resistance, i.e., isotonic exercise in the gym. Before the start of the rehabilitation treatment, an initial isokinetic test was performed at an angular speed of 60 °/s in all subjects. After 3 and 6 weeks of rehabilitation treatment, the control tests were performed in the same way as in the initial test. Results: Based on the values of MANOVA analysis and discriminative analysis, significantly better results of isokinetic tests were found in the examined group A-isokinetic compared with those in the examined group B-isotonic. At the final measurement of group A, 83 respondents (92.2%) were placed in the "biggest" class out of the 90 respondents. Conclusion: Based on the obtained research results, we conclude that isokinetic exercise is more effective in terms of physiotherapy of quadriceps hypotrophy after knee surgery. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the effect of step load in hypoxia on the effectiveness of preoperative rehabilitation (PR) and hormone levels based on a case study. Introduction: We assessed the impact of variables such as rate of movement and time under tension (TUT) in normobaric hypoxia on the levels of growth hormone (GH), insulin-like growth factor 1 (IGF-1), and erythropoietin (EPO). Additionally, the impact of step load on the hypertrophy and strength of knee extensors and flexors was assessed. Methods: The work uses a case study, the research subject of which was a 23-year-old female professional handball player. The tests included an isokinetic assessment of the peak torque of knee extensors and flexors as well as body composition analysis. Results: The results showed a more than (10.81-fold) increase in GH after the microcycle with time under tension (TUT). The deficit between the lower limbs was also reduced. Conclusions: Using a hypoxic environment based on an appropriate altitude, combined with changes such as a short rest break between sets and a controlled tempo of movement with an eccentric phase, TUT may offer an alternative to the PR process, especially among athletes who care about fast RTS. [ABSTRACT FROM AUTHOR]

Background: Low muscle mass quantity/quality is needed to confirm sarcopenia diagnosis; however, no validated cut-off points exist. This study aimed to determine the diagnostic accuracy of sarcopenia through muscle mass quantity/quality parameters, using the bioimpedance analysis (BIA), isokinetic, and ultrasound tools in probable sarcopenic community-dwelling older adults (≥60 years). Also, it aimed to suggest possible new cut-off points to confirm sarcopenia diagnosis. Methods: A cross-sectional exploratory analysis study was performed with probable sarcopenic and non-sarcopenic older adults. BIA, isokinetic, and ultrasound parameters were evaluated. The protocol was registered on ClinicalTrials.gov (NCT05485402). Results: A total of 50 individuals were included, 38 with probable sarcopenia (69.63 ± 4.14 years; 7 men and 31 women) and 12 non-sarcopenic (67.58 ± 4.54 years; 7 men and 5 women). The phase angle (cut-off: 5.10° men, p = 0.003; 4.95° women, p < 0.001), peak torque (cut-off: 66.75 Newtons-meters (N-m) men, p < 0.001; 48.35 N-m women, p < 0.001), total work (cut-off: 64.00 Joules (J) men, p = 0.007; 54.70 J women, p = 0.001), and mean power (cut-off: 87.8 Watts (W) men, p = 0.003; 48.95 W women, p = 0.008) in leg extension, as well as the the forearm muscle thickness (cut-off: 1.41 cm (cm) men, p = 0.017; 0.94 cm women, p = 0.041), had great diagnostic accuracy in both sexes. Conclusions: The phase angle, peak torque, total work, and mean power in leg extension, as well as forearm muscle thickness, had great diagnostic accuracy in regard to sarcopenia, and the suggested cut-off points could lead to the confirmation of sarcopenia diagnosis, but more studies are needed to confirm this. [ABSTRACT FROM AUTHOR]

There are no reports in the literature of powerlifting success after amputation. We had the unique opportunity to characterize functional outcomes, strength, muscle contractility and size, and corticospinal excitability in an accomplished, competitive powerlifter (best competition squat = 205.0 kg, deadlift = 262.7 kg) with a unilateral, transtibial amputation relative to amputee controls. Four men (age range = 23-49 years) with unilateral, lower-limb amputation (3 transtibial, 1 transfemoral) participated in 1 laboratory visit. We assessed 10-m gait speed, the timed up and go (TUG) test, 5-time sit-to-stand performance (5TSTS), contractile properties of the vastus lateralis (VL) and medial gastrocnemius by tensiomyography, and VL cross-sectional area (CSA) by ultrasonography. Unilateral assessments for the intact limb included isokinetic knee extension and flexion torque and power and transcranial magnetic stimulation derived corticospinal excitability. An interview with the powerlifter provided contextual perspective. Compared with the control subjects, the powerlifter performed the 5TSTS faster (6.8%), exhibited faster VL contraction times (intact limb = 12.2%; residual limb = 23.9%), and showed larger VL CSA for the intact limb (46.7%). The powerlifter exhibited greater knee extension and flexion peak torque and mean power, particularly at 180°·s -1, as well as greater corticospinal excitability for the intact VL (65.6%) and tibialis anterior (79.6%). By contrast, the control subjects were faster in the TUG (18.3%) and comfortable (13.0%) and fast (21.4%) in the 10-m walk test. The major themes of our interview included needing to modify lifting mechanics, persistence, and remarkable pain tolerance. Our findings highlight the impressive neuromuscular adaptations that are attainable after lower-limb amputation. [ABSTRACT FROM AUTHOR]

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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. [ABSTRACT FROM AUTHOR]

The phenomenon of post-activation performance enhancement plays an unidentified role in movement eccentric speed and individual muscle group responses. Therefore, this study aimed to determine whether the loaded front squat (FSq) speed of the eccentric phase would influence the post-activation performance enhancement effect and whether the FSq would elicit similar performance enhancement of knee flexion, knee extension, hip flexion, and hip extension muscles. Twenty resistance-trained handball players performed the FSq under maximum eccentric-concentric speed and 2-s eccentric speed (only the eccentric phase performed), while pre- and post-front squat countermovement jump, knee, and hip isokinetic flexion/extension performance were tested. The FSq conditioning activity was performed in a single set of three repetitions with either 90% (maximum eccentric-concentric speed) or 120% (2-s eccentric speed) of one repetition maximum, and post-performance was measured 4--12 min after the FSq. Athletes randomly changed the FSq eccentric speed and tested the hip or knee isokinetic flexion/extension strength at 180°/s. ANOVA showed that the rate of force development during the jump increased (Cohen d = 0.59--0.77) with no differences between 2-s eccentric and maximum speed eccentric protocols. Isokinetic strength increased after the 2-s eccentric FSq in hip extension (d = 0.76--0.86), knee flexion (d = 0.74--0.88), and hip flexion (d = 0.82), with no differences in knee extension strength. After maximum eccentric-concentric speed, isokinetic strength increased in hip extension (d = 1.25). In conclusion, the FSq conditioning activity enhances hip extensors' performance more than knee extensors' performance. Different eccentric types of muscle action during a conditioning activity alter the level of local muscle enhancement. [ABSTRACT FROM AUTHOR]

Background: Understanding differential strength capability between sexes is critical in ergonomics and task design. Variations in study designs and outcome measures generates challenges in establishing workplace guidelines for strength requirements to minimize upper extremity risk for workers. The purpose of this systematic review was to collate and summarize sex differences in strength at the shoulder across movement directions and contraction types. Methods: A total of 3,294 articles were screened from four databases (Embase, Medline, SCOPUS, and Web of Science). Eligibility criteria included observational studies, direct measurement of muscular joint, and healthy adult participants (18-65 years old). Strength outcome measures were normalized to percentages of male outputs to allow comparisons across articles. Results: A total of 63 studies were included within the final review. Majority of articles observed increased strength in males; the gap between male-female strength was greater in flexion and internal/external rotation, with females generating ~30% of male strength; scaption strength ratios were most consistent of the movement groups, with females generating 55-62% of male strength. Conclusion: Sex strength differences should be considered as an important factor for workplace task design as women are more at risk for occupational-related injuries than men in equivalent strength requirements. Differences in strength were not synonymous across motions; females demonstrated increased disparity relative to male strength in horizontal flexion/extension, forward flexion and internal/external rotation. Some movements had an extremely limited pool of available studies for examination which identified critical research gaps within the literature. Collating and quantifying strength differences is critical for effective workstation design with a range of users to mitigate potential overexertion risk and musculoskeletal injury. [ABSTRACT FROM AUTHOR]

BackgroundAbnormal brain activation patterns in patients with knee osteoarthritis (KOA) at rest have been revealed, but it is unclear how brain activation patterns change during movement. This study aimed to investigate the alterations in brain activation patterns in KOA patients during knee isokinetic movement, and the correlation between cortical activity changes and pain severity and dysfunction.MethodsEighteen patients with KOA and 18 healthy controls (HC) were recruited, and to performed the knee isokinetic test with three speeds. Functional near-infrared spectroscopy (fNIRS) was used to detect the cerebral cortex hemodynamics changes of primary somatosensory (S1), primary motor (M1) and somatosensory association cortex (SAC) in the region of interest (ROI) during movement. Then, we evaluated potential correlations between M1, S1 and SAC values and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and visual analog scale (VAS) scores.ResultsThe results showed that peak torque of knee extension in KOA patients was significantly smaller than that in HC. For HC, unilateral knee movement activated bilateral ROIs. The contralateral activation was dominant, showing the phenomenon of high contralateral activation. For KOA patients, there were no statistical difference in the activation level between the left and right of the cerebral cortex, with both sides showing lower activation levels compared to HC. Further analysis found that the contralateral M1, S1, and SAC of the affected knee in KOA patients were significantly lower than those in HC, while no difference was found on the ipsilateral side. Moreover, during isokinetic movement at 180°/s, VAS score in KOA patients was negatively correlated with the activation level of the contralateral S1 and M1 values, and WOMAC was negatively correlated with the activation level of the contralateral M1 value.ConclusionContralateral activation of the sensorimotor cortex exists during unilateral knee movement, but in KOA patients, this contralateral cortical activation is suppressed. Furthermore, the clinical pain and dysfunction in KOA patients are associated with activation levels of specific brain regions. These findings can provide a better understanding of KOA brain science and are expected to contribute to the development of central intervention for the disease.

Background: Multidisciplinary functional restoration programs (FRPs) aim to improve pain and function in people with chronic low back pain (CLBP). The intensity and content of FRPs varies; the benefits of one program over another are unclear. Objective: To assess changes in trunk muscle strength and endurance after an intensive (IFRP) (for people on sick leave for >6 months with high levels of fear-avoidance beliefs about physical activity and work) or semi-intensive (SIFRP) (for people working) FRP in people with CLBP. Methods: Longitudinal retrospective study from March 2016 to December 2019. Setting: rehabilitation department of a tertiary care center. Trunk flexor and extensor muscle strength (60°.s−1) and endurance (120°.s−1) were measured with the Humac NORM isokinetic dynamometer at pre and post FRP. Change in isokinetic variables (peak torque, total work and flexor/extensor ratio) after each program was assessed with a paired t-test (p

Key Clinical Message Isokinetic testing is a maximal muscle strength test which requires adequate patient's preparation and observer's care. While the available data suggests that isokinetic devices are safe, their use may rarely cause severe injuries. The screening of predisposing anatomical factors could help preventing injuries before testing. Abstract A 29‐year‐old athletic man presented an acute patellar dislocation on a healthy right knee during isokinetic muscle strength testing, which was conducted in the setting of an intensive physical rehabilitation program, for persistent left knee pain after arthroscopic surgery for meniscal tear. This is the first case to occur in an adult male without clear risk factors such as patellar dysplasia. Predisposing factors may include slightly elevated patellar tilt and lateral shift compared to the contralateral knee (researched from subsequent review of pre‐injury X‐rays), and an elevated quadricipital strength in the context of recreational bodybuilding. The dislocation occurred during eccentric extension phase of testing. Medial patellofemoral ligament reconstruction was conducted 6 months later. Isokinetic muscle strength testing is generally considered as a safe method, despite limited data on the devices' safety. Since severe injuries might rarely occur, adequate patient preparation is needed, as well as the screening of predisposing factors.

Abstract Background Transient progressive weakness and disability of lower limb during the early stage after TKR will increase the risk of fall, but the superior postoperative strength training mode have not been elucidated for functional restoration. This study aimed to compare whether the isokinetic lower limb training is superior to either isotonic or home isometric exercise during early stage after TKR in older people. Methods A total of 43 recruited old participants (mean age, 68.40 years old) receiving TKR were divided randomly based on the different four-week training modes into three groups including isokinetic, isotonic, and home isometric exercise (control group). The primary outcome was set as functional performance in terms of Timed Up and Go (TUG) test and the secondary outcomes include the peak torque of knee at 60 and 120 degree/ second, Short-Form 36 Health Survey (SF-36), and Western Ontario and McMaster Universities Arthritis index (WOMAC). Results All of the peak torque measurements of the knee improved significantly in both the isokinetic and the isotonic group, but not in the control group. Although isotonic training resulted in more strength gains, a significant enhancement in TUG test was observed in the isokinetic group only (p = 0.003). However, there were no significantly improvement of TUG test after training in other two groups. SF-36 and WOMAC improved after training in all three groups, with no significant difference in the degree of improvement between groups. Conclusion Isokinetic training for 4 weeks following TKR effectively improved all the outcome parameters in this study, including the TUG test, lower limb strength, and functional scores. However, both isokinetic and isotonic training modes could be recommended after TKR because of no significant difference in the degree of improvement between these two groups. Trial registration Clinical trial registration number: NCT02938416. Level of evidence I

Study aim: This study aimed to investigate the effect of the FIFA 11+ injury prevention programme on strength and on muscle strength and landing biomechanical markers of anterior cruciate ligament (ACL) injury during fatigue among youth recreational soccer players.

Abstract Background This study aimed to develop alternative prediction equations to predict isokinetic muscle strength at 60°/s based on anthropometric characteristics, including body mass, height, age, and sex for young and middle-aged non-athlete populations. Methods Three hundred and thirty-two healthy non-athletic participants (174 females, 158 males) between 20 and 59 years underwent a 60°/s isokinetic knee joint concentric contraction test. Forty people were randomly selected for retesting to assess the reliability of the isokinetic instrument. Multivariate linear regression was used to establish extension peak torque (EPT) and flexion peak torque (FPT) prediction equations. Sixty extra participants were used individually to validate the prediction equations, and Bland Altman plots were constructed to assess the agreement of predicted values with actual measurements. Results The result demonstrated that the instrument we used has excellent reliability. The multivariable linear regression model showed that body mass, age, and sex were significant predictors of PT (EPT: Adjusted R2 = 0.804, p

OBJECTIVE: To compare the quadriceps isokinetic strength parameters of athletes and non-athletes. METHODOLOGY: The cross-sectional study was conducted from July to December 2019 at the Pakistan Sports Board, Islamabad. The sample size was 81, selected through a non-probability convenience sampling technique and calculated by the Rao Soft tool. The 41 participants were in the athletes' group, and 40 were in the non-athletes' group. Individuals with a history of sprain, strain, or fracture in the lower limbs within the last six months were excluded. The self-structured questionnaire includes demographic data, waist-to-hip ratio, thigh circumference, peak torque values and agility t-test score. The isokinetic strength of the right lower limb (RLL) was measured via Biodex system Pro 3. Data was analyzed through SPSS 22, and an independent t-test was applied for analysis between groups. Pearson test was used for the correlation coefficient. RESULTS: Athletes had significantly higher quadriceps muscle strength than non-athletes (p

Abstract Background Accurate measurements of muscular performance are important for diagnostics, for example during rehabilitation after traumatic injuries but also in competitive sports. For these purposes, dynamometric devices are widely used and considered the gold standard for muscle strength testing. However, few previous studies have tested the reproducibility of peak moment (PM) at velocities close to the maximum device capability, and in general, reproducibility results cannot be transferred to other devices or test protocols. The purpose of this study was to evaluate the reproducibility of PM for different isometric and isokinetic knee extension exercises using the IsoMed 2000. Methods Thirty subjects volunteered in three repeated test sessions, including isometric knee extension (100° and 140° knee angle) and isokinetic knee extension (30°/s and 400°/s). Statistical analysis for comparison of sessions two and three included paired sample t-test, calculation of intraclass correlation coefficient (ICC) and standard error of measurement (SEM). Additionally, Bland Altman statistics and corresponding plots were created. Results A significant difference between sessions in PM was found for isometric knee extension in one leg (140° left). Reproducibility was high for all conditions with ICC ranging from 0.964 to 0.988 and SEM in the range of 7.6 to 10.5 Nm. Bland Altman statistics revealed a bias between − 7.3 and 0.7 Nm. Conclusions Reproducibility of PM using the IsoMed 2000 was good after an initial familiarization trial with high values of relative reproducibility. Absolute reproducibility can be interpreted as appropriate for most common practical applications.

Background/Objectives: Sarcopenia is a muscular disease characterized by loss of muscular strength and function, affecting mainly women, and associated with increased mortality risk. The aim of this study was to compare active women with inactive women of different age groups regarding muscle mass, strength, and muscle quality. Methods: This study included 147 women (85 runners and 62 inactive), divided into p < 0.001) on absolute PT (Nm); an age group effect (F(2.146) = 44.1; p < 0.001) and a physical activity group effect (F(2.146) = 113.0; p < 0.001) on PT adjusted by body mass (Nm/kg); and an age group effect (F(2.146) = 36.9; p < 0.001) and a physical activity group effect (F(2.146) = 6.1; p = 0.014) on PT adjusted by lean mass (Nm/kgLM). There was no interaction effect. Conclusion: In both age groups, active women had greater strength and higher muscle quality than inactive women, but the difference in strength, muscle mass, and muscle quality between younger and older women were the same among runners and inactive women.

There are a considerable number of patients who, after anterior cruciate ligament reconstruction (ACL), suffer from relapses or reduced performance. Data collected from isokinetic dynamometry can provide useful information on the condition of the knee during rehabilitation. Seventy-one young sports patients with ACL reconstruction performed concentric (CON) isokinetic dynamometry (CON/CON 90°/s and CON/CON 240°/s) to assess the muscle strength of the quadriceps (Q) and hamstrings (H) in both knees at 6 months after ACL reconstruction. Limb symmetry index (LSI) and the H/Q ratio were calculated. Comparative statistical tests and multivariate regression were performed. At 90°/s, 57 patients (80.3%) had an LSI below 90% for quadriceps and 28 (60.6%) for hamstring. The number of imbalanced patients according to H/Q ratio was higher in the non-operated knee (n = 56, 78.9%) (p < 0.001). At 240°/s, 49 cases (69.1%) had LSI values above 90% for quadriceps and 37 (52.1%) for hamstrings. Regarding H/Q, imbalanced cases were higher in the non-operated limb (n = 60, 84.5%) (p < 0.001). Strength data at 6 months after ACL reconstruction and post-operative rehabilitation indicated greater unilateral (H/Q) muscle imbalance in the non-operated knee than in the operated knee. Most patients did not achieve the adequate LSI values.

Background: Transient progressive weakness and disability of lower limb during the early stage after TKR will increase the risk of fall, but the superior postoperative strength training mode have not been elucidated for functional restoration. This study aimed to compare whether the isokinetic lower limb training is superior to either isotonic or home isometric exercise during early stage after TKR in older people. Methods: A total of 43 recruited old participants (mean age, 68.40 years old) receiving TKR were divided randomly based on the different four-week training modes into three groups including isokinetic, isotonic, and home isometric exercise (control group). The primary outcome was set as functional performance in terms of Timed Up and Go (TUG) test and the secondary outcomes include the peak torque of knee at 60 and 120 degree/ second, Short-Form 36 Health Survey (SF-36), and Western Ontario and McMaster Universities Arthritis index (WOMAC). Results: All of the peak torque measurements of the knee improved significantly in both the isokinetic and the isotonic group, but not in the control group. Although isotonic training resulted in more strength gains, a significant enhancement in TUG test was observed in the isokinetic group only (p = 0.003). However, there were no significantly improvement of TUG test after training in other two groups. SF-36 and WOMAC improved after training in all three groups, with no significant difference in the degree of improvement between groups. Conclusion: Isokinetic training for 4 weeks following TKR effectively improved all the outcome parameters in this study, including the TUG test, lower limb strength, and functional scores. However, both isokinetic and isotonic training modes could be recommended after TKR because of no significant difference in the degree of improvement between these two groups. Trial registration: Clinical trial registration number: NCT02938416. Level of evidence: I [ABSTRACT FROM AUTHOR]

In light of previous research highlighting the prevalence of asymmetries in soccer players and possible links to injury risks, there is a crucial gap in the biomechanical understanding of complex relationships between lower extremity and trunk asymmetries in elite soccer players. The purpose of this study was to investigate the level, relationships, and differences among twelve different parameters of strength, morphological, and neuromuscular asymmetries in elite soccer players. Methods: Elite male soccer players (n = 25, age 21.7 ± 3.9 years) were tested in the following tests: bilateral fluid distribution, hip flexor range of motion, postural stability, isokinetic strength of knee extensors and flexors, isometric lateral trunk rotation strength, eccentric strength of knee flexors, isometric bilateral strength of hip adductors, and vertical ground reaction force in counter-movement jumpfree arms, counter-movement jump, squat jump, and drop jump tests. One-way ANOVA, Pearson’s coefficient (r), and partial eta squared (ηp²) were used for data analysis. Results: Significant differences in asymmetries were found in elite soccer players (F11,299 = 11.01, p < .01). The magnitude of asymmetry over 10% was in postural stability and drop jump parameters. The lowest magnitudes of asymmetries were in the fluid distribution of the lower limbs and the vertical ground reaction force during the take-off phase in squat jumps. The highest asymmetries between the dominant and non-dominant sides were found in postural stability and drop jump. A total of eleven significant correlations (p < 0.05, r = 0.41–0.63, R² = 0.17–0.40) were detected between the analyzed asymmetries in elite soccer players. The lateral trunk rotation asymmetries were significantly correlated to vertical ground reaction force asymmetries and knee extensors. Conclusion: Long-term exposure in elite soccer leads to unilateral biomechanical loading that induces abnormal strength and morphological adaptations in favor of the dominant side while linking lower limb and trunk strength asymmetries. By unraveling these complex relationships, we strive to contribute novel methods that could inform targeted training regimens and injury prevention strategies in the elite soccer community. The data should encourage future researchers and coaches to monitor and develop trunk strength linked to lower body kinematics. [ABSTRACT FROM AUTHOR]

Monitoring the muscle mechanical properties and functions of female athletes throughout their training season is relevant to understand the relationships between these factors and to predict noncontact injuries, which are prevalent among female athletes. The first aim of this study was to determine whether female handball players' passive stiffness of the hamstring muscles is associated with hamstring extensibility, strength of knee flexors and extensors, and lower limb stiffness. Additionally, the study monitored fluctuations in these factors over 25 weeks. The study utilized an isokinetic dynamometer to record hamstring passive stiffness, extensibility, and hamstring and quadriceps strength of 18 young handball players. Lower limb stiffness was determined from a countermovement vertical jump conducted on a force plate. The countermovement jump involved the calculation of the peak force during the eccentric phase and the mean force during the concentric phase. The results showed a positive correlation between hamstring passive stiffness and lower limb stiffness (r = 0.660, p < 0.01), knee flexion and extension strength (r = 0.592, p < 0.01 and r = 0.497, p < 0.05, respectively), and eccentric peak force (r = 0.587, p < 0.01) during jumping. The strength of knee extensors increased significantly after 6 weeks, and hamstring stiffness after 12 weeks of training. In conclusion, the increased hamstring stiffness following training did not match other factors associated with injury risk. Therefore, preventing multifactorial injury risk requires a comprehensive approach, and monitoring one factor alone is insufficient to predict noncontact injuries in female handball players. [ABSTRACT FROM AUTHOR]

Background: The Latarjet procedure is an effective shoulder stabilizing surgery, however, the procedure results in an alteration of anatomy that may result in shoulder and elbow weakness. Thus, the purpose of this study was to assess post-operative shoulder and elbow strength after the Latarjet procedure. We hypothesized that shoulder and elbow strength are not affected after the procedure. Methods: The study group consisted of patients that had undergone the arthroscopic Latarjet procedure. An isokinetic dynamometer was used to evaluate the strength of bilateral shoulder internal rotation, elbow flexion, forearm supination using peak torque (N/m), as well as grip strength (kilograms). Shoulder range of motion and the potential effects of hand dominance were further analysed. Results: Nineteen patients with a mean age of 29 years and an average follow up of 47 months were included. Shoulder internal rotation strength, elbow flexion and forearm supination strength and grip strength were not significantly different when compared to the non-operative side (p > 0.13). The range of shoulder external rotation was significantly reduced (p < 0.001) on the Latarjet side. Conclusion: The results from this study demonstrate no statistically significant differences in the strength of shoulder internal rotation, elbow flexion, forearm supination or grip strength despite the surgical alterations to the subscapularis and conjoint tendon. [ABSTRACT FROM AUTHOR]