Knee Extensor Strength Research Articles

Sit-to-stand power predicts functional performance and patient-reported outcomes in patients with advanced knee osteoarthritis. A cross-sectional study

BackgroundLower limb muscle power is positively associated with functional performance and patient-reported outcomes (PROMs) and suggested as an important variable to evaluate in patients with advanced knee osteoarthritis (OA). ObjectivesTo explore the association between muscle power derived from the 30-sec sit-to-stand test (STS power) with functional performance and PROMs compared to maximal isometric knee extensor strength (KE MVC) in male- and female patients with advanced OA. Study designCross-sectional design. MethodsEighty-six patients (66.6 [64.9–67.7]years) with advanced knee OA were included. Dependent variables were STS power and KE MVC. Independent variables were Timed Up&Go (TUG), 40-m fast-paced walk test (40mFWT), Knee injury and Osteoarthritis Outcome Score (KOOS) subscales. CovariateAge. AnalysesSimple linear- and multiple regression analyses with and without adjusting for age. Pitman's test was used to evaluate differences in correlation strength among dependent variables. ResultsSTS power demonstrated a statistical relationship with TUG and 40mFWT for both sexes (β coefficients −1.11 to −4.36 (p < 0.05), r2 = 0.47–0.55 (p < 0.05)), and with KOOS Pain, ADL, and Sport for male patients (β coefficients 6.53 to 7.17 (p < 0.05), r2 = 0.29–0.33 (p < 0.05)). Knee extensor MVC demonstrated no relationship with any outcomes for male patients or female patients. STS power displayed statistically stronger correlation to functional performance. ConclusionSTS power was associated with functional performance in both male patients and female patients suffering from advanced knee OA. Moreover, STS power was associated with KOOS Pain, Sport, and ADLin male patients. The assessment of STS power should be considered in the evaluation of patients with advanced knee OA. Trial registration numberNCT04081493.

Association of Lower Extremity Muscle Strength and Function with Renal Resistive Index in Individuals with and without Chronic Kidney Disease.

Age-related loss of lower extremity muscle strength is pronounced in individuals with chronic kidney disease (CKD). In contrast, an increase in intrarenal flow pulsatility results in initial age-related changes in renal hemodynamics, leading to the development of CKD. To date, it remains unclear whether lower extremity muscle strength determines elevated renal flow pulsatility. This study aimed to determine the association of lower extremity muscle strength and function with intrarenal hemodynamics in individuals with and without CKD. One hundred seventy-six individuals without CKD (aged 63 ± 9 years) and 101 individuals with CKD (aged 66 ± 8 years) were included in this study. Using Doppler ultrasound, the renal resistive index (RI) was measured as a parameter of renal hemodynamics. Knee extensor muscle strength (KES), gait speed (GS), and the 30 s chair stand test (30s-CST) were used to measure lower extremity muscle strength and function. Multivariate analyses showed that GS and 30s-CST scores were independent determinants of renal RI, whereas the KES score was not associated with renal RI in individuals with and without CKD. In the two-way analysis of covariance, renal RI was the highest in individuals with CKD who had lower KES, GS, and 30s-CST scores. Reduced lower extremity muscle strength and function are independent determinants of elevated renal flow pulsatility in individuals with and without CKD.

Age-Related Differences in Muscle Size and Strength between Individuals with Cerebral Palsy and Individuals with Typical Development

Aim Examine age-related differences in muscle size and strength of the knee extensors in individuals with cerebral palsy (CP) and individuals with typical development (TD). Methods 54 individuals with CP (14.5 ± 4.5 years, GMFCS I–V) and 33 individuals with TD (16.2 ± 5.5 years) were included. Relationships between rectus femoris (RF) and vastus lateralis (VL) muscle volume and isokinetic knee extensor strength with age were examined with linear regression and ANCOVA to test age-related differences between groups. Results Linear regression for muscle volume with age was statistically significant in TD (VL: r 2 = 0.48, RF: r 2 = 0.56, p < .05) and those with CP (VL: r = 0.36, RF: r 2 = 0.27, p < .05) with no differences in regression slopes between groups (p > .05). Age-related strength differences were observed in TD (r 2 = 0.66, p < .001) and those with CP (r 2 = 0.096, p = .024), but the slopes were significantly different between CP and TD (p < .001). Conclusion Age-related linear differences in muscle volume and strength were observed in both groups. The linear slope of the age-related differences in knee extensor muscle strength and strength-to-body mass ratio were significantly lower in individuals with CP compared to individuals with TD, suggesting that strength is insufficient to keep up with gains in body mass during growth.

Effectiveness of an online management platform (Joint Cloud) versus standard process for patients undergoing total knee arthroplasty: study protocol for a prospective randomised controlled trial

IntroductionOsteoarthritis (OA) is one of the main causes of mobility impairment in the elderly worldwide. Therefore, total knee arthroplasty (TKA) is often performed and is one of the most successful...

Comparison of Single and Combined Treatment with Exercise Therapy and Collagen Supplementation on Early Knee Arthritis among Athletes—A Quasi-Randomized Trial

Athletic injuries are commonly implicated in the development of early osteoarthritic (EOA) changes in the knee. These changes have a significant impact on athletic performance, and therefore the early detection of EOA is paramount. The objective of the study is to assess the impact of different interventions on individuals with EOA, particularly focusing on recreational athletes. The study aims to evaluate the effectiveness of three treatment groups in improving various aspects related to knee EOA, including pain, range of motion, strength, and function. A study was undertaken with 48 recreational athletes with EOA who were assigned to one of three groups by the referring orthopedic surgeon: collagen (Col), exercise (Ex), or collagen and exercise (ColEx) groups. All the participants received their respective group-based intervention for 12 weeks. Visual analog scale (VAS), knee flexion range of motion (ROM) knee flexors and extensors strength, and KOOS were assessed at baseline, and after 4 weeks, 8 weeks, and 12 weeks of intervention. VAS for activity improved in all treatment groups, with no difference between groups. The between-group analysis for knee ROM revealed a significant difference (p = 0.022) in the Col vs. Ex group at 12 weeks. The knee flexor and extensor strength and the KOOS scores improved considerably in the Ex and the ColEx group (p &lt; 0.05) at 12 weeks. Exercise therapy improved pain, strength and function in subjects with EOA, whereas the association of collagen seems to have accentuated the effects of exercise in bringing about clinical improvements.

Home-based exercise program and Health education in patients with patellofemoral pain: a randomized controlled trial

BackgroundPatellofemoral pain (PFP) is one of the most common disorders of the knee joint. Home-based exercise is an effective intervention to achieve self-management for chronic diseases. This study evaluated the effects of home-based exercise and health education in patients with PFP.MethodsPatients who had PFP were randomly allocated to an intervention group (IG) or control group (CG). Patients in the IG received a 6-week tailored home-based exercise program with health education via remote support, while patients in the CG group only received health education. Clinical outcomes were compared using the Anterior Knee Pain Scale (AKPS) to measure function and the Visual Analog Scale (VAS) to measure “worst pain” and “pain with daily activity”. Muscle strength was measured according to the peak torque of the knee muscles using an isokinetic system.ResultsAmong a total of 112 participants screened for eligibility, 38 were randomized and analyzed, including 19 participants in the intervention group and 19 participants in the control group. There were no significant differences in baseline characteristics between the groups. At 6-week follow-up, the intervention group showed a greater worst pain reduction (between-group difference, -19.3 [95%CI, -23.2 to -15.5]; P < 0.01) and pain with daily activity (between-group difference, -22.9 [95%CI, -28.3 to -17.4]; P < 0.01) than the control group. Similarly, the intervention group had better improvements in AKPS (between-group difference, 9.0 [95%CI, 4.1 to 13.9]; P < 0.01) and knee extensor strength (between-group difference, 20.1 [95%CI, 14.5 to 25.8]; P < 0.01), compared to the control group. No adverse events were reported.ConclusionHome-based exercise and health education resulted in less pain, better function, and higher knee muscle strength compared with no exercise in patients with PFP. A large randomized controlled trial with long-term follow-up is required to confirm these findings.Trial registrationChinese Clinical Trial Registry, ChiCTR2200056224 (https://www.chictr.org.cn/showproj.aspx?proj=135506). Registered on February 1, 2022.

Sex Differences in Knee Extensor Neuromuscular Function in Individuals With and Without Patellofemoral Pain.

Impaired knee extensor neuromuscular function has been frequently observed in individuals with patellofemoral pain (PFP); however, few researchers have aimed to understand the influence of sex on knee extensor neuromuscular function in this pathological population. The authors aimed to determine whether there are differences in knee extensor neuromuscular function between sexes in individuals with and without PFP. Women with PFP would exhibit greater deficits in knee extensor neuromuscular function than men with PFP, compared with sex-matched individuals without PFP. Cross-sectional, case-control study. Level 4. A total of 110 individuals were classified into 4 groups: women with PFP (n = 25); men with PFP (n = 30); women without PFP (n = 25); and men without PFP (n = 30). Knee extensor strength (isometric peak torque [PT]), activation (central activation ratio), early, late, and total phase rate of torque development (RTD0-100, RTD100-200, and RTD20-80%), and endurance (isokinetic average PT) were assessed using an isokinetic dynamometer. Group differences were assessed using a 2-way multivariate analysis of variance (sex by PFP). Both women and men with PFP exhibited lower knee extensor strength, activation, early, late, and total phase RTD, and endurance versus sex-matched individuals without PFP (P < 0.05 for all comparisons). Women with PFP exhibited lower early phase (7.91 ± 2.02 versus 9.78 ± 2.43 N·m/s/kg; P < 0.01; Cohen d = 0.83), late phase (5.34 ± 1.02 versus 7.28±2.28 N·m/s/kg; P < 0.01; Cohen d = 1.37), and total phase (7.40 ± 2.57 versus 8.72 ± 2.57 N·m/s/kg; P = 0.03; Cohen d = 0.51) RTD than men with PFP. Compared with sex-matched pain-free individuals, women with PFP displayed lower RTD than men with PFP. Clinicians should note that among individuals with PFP, women are more likely to experience a greater impairment in their knee extensor torque-generating capacity than men. Additional treatment strategies that effectively improve the ability to rapidly generate torque should be developed and implemented, especially when treating women with PFP.

Exploring the Relationship between Muscular Strength, Flexibility, and mSEBT Test Performance in Saudi Arabian Women

Saudi females exhibit a higher susceptibility to musculoskeletal disorders (MSD), particularly impacting balance, in comparison to their male counterparts. The current study was aimed at determining the association between the modified Star Excursion Balancing Test (mSEBT) score and the muscular strength and flexibility of the lower-extremity muscles among a group of young healthy Saudi females. The mSEBT assessed balance, complemented by measurements of lower-extremity muscle strength and flexibility. Statistical analysis, utilizing SPSS software (version 26.0), with a significance level of p &lt; 0.05, unveiled valuable insights. Results indicate a moderate positive correlation between hip flexor strength and reach distance, notably in the anterior and posteromedial directions. Conversely, no statistically significant associations emerged between hip extensor, hip abductor, or knee extensor strength and reach distances across all directions. Furthermore, there were weak negative correlations between hip flexion angle (assessed via the Thomas test) and reach distances, primarily within the anterior direction. Interestingly, the sit-and-reach flexibility test demonstrated no significant correlations with reach distances. These findings underscore the role of hip flexor strength and flexibility in influencing mSEBT performance in young, healthy Saudi females. This study advocates for the incorporation of the mSEBT as a diagnostic and therapeutic tool for identifying individuals with deficits in lower extremity muscle strength and flexibility.

Asociación de fuerza prensil y extensores de rodilla con estado nutricional de adultos mayores pertenecientes a la comunidad

AimTo determine the association of hand grip strength and knee extensor strength with the nutritional status of community-dwelling older adults. Material and methodsObservational cross-sectional study. Weight and height of 847 older adults were analyzed according to body mass index and classified into four nutritional categories according to the Chilean Ministry of Health. Hand grip and knee extensors strength for both extremities were evaluated. Strength was normalized by body mass. Spearman's correlation between body mass index and muscle strength was used. ResultsThe sample was 582 women, 265 men and an average age of 71.72±7.09. The women had a BMI of 30.03±5.48 and the men of 27.64 ± 4.05, the most numerous category was normal weight (n = 288) and the lowest low weight (n = 74). Hand grip strength presented a higher correlation than knee extensors, specifically, right hand grip strength (r: −0.40). The highest correlation and significance were presented by the obese category for all strength measurements, with right hand grip strength being the highest (r: −0.29). ConclusionsThe increase in the nutritional status of older adults has a negative influence on muscle strength. The best association between body mass index and muscle strength was the right hand grip. The finding of the increase in life expectancy as the nutritional status of the sample decreases stands out. Future studies are needed to generate percentiles and normalized values in the Chilean population.

Abnormal gait pattern in downhill hiking is related to muscular deficits of the knee flexors and extensors in active patients with total knee arthroplasty

BackgroundTo assess the in-field walking mechanics during downhill hiking of patients with total knee arthroplasty five to 14 months after surgery and an age-matched healthy control group and relate them to the knee flexor and extensor muscle strength. MethodsParticipants walked on a predetermined hiking trail at a self-selected, comfortable pace wearing an inertial sensor system for recording the whole-body 3D kinematics. Sagittal plane hip, knee, and ankle joint angles were evaluated over the gait cycle at level walking and two different negative slopes. The concentric and eccentric lower extremity muscle strength of the knee flexors and extensors isokinetically at 50 and 120°/s were measured. FindingsLess knee flexion angles during stance have been measured in patients in the operated limb compared to healthy controls in all conditions (level walking, moderate downhill, steep downhill). The differences increased with steepness. Muscle strength was lower in patients for both muscle groups and all measured conditions. The functional hamstrings to quadriceps ratio at 120°/sec correlated with knee angle during level and downhill walking at the moderate slope in patients, showing higher ratios with lower peak knee flexion angles. InterpretationThe study shows that even if rehabilitation has been completed successfully and complication-free, five to 14 months after surgery, the muscular condition was still insufficient to display a normal gait pattern during downhill hiking. The muscle balance between quadriceps and hamstring muscles seems related to the persistence of a stiff knee gait pattern after knee arthroplasty. LoE: III.

The association between knee muscle performance and clinical outcomes of knee function 1–4 years after a sport-related knee joint injury

ObjectiveEstimate the association between index leg knee muscle strength and rate of torque development (RTD), and self-reported and performance-based (i.e., hop) knee function in persons 1–4 years after a sport-related knee joint injury. MethodsData were collected at baseline of a clinical trial. Assessments included the Knee injury and Osteoarthritis Outcome Score Sport & Recreation subscale (KOOSsport), 6-m timed hop (TH), and peak concentric isokinetic knee extensor and flexor torque and isometric RTD. Associations between peak torque and RTD with KOOSsport and TH were assessed using multivariable regression with nonlinear transformations. Results53 participants (64.2% female) were included. Knee extensor peak torque was nonlinearly related to TH time, with a strong inverse relationship at lower torque values that changed as torque increased. Results were inconsistent for flexor peak torque, extensor RTD and flexor RTD, with inconsistencies in relationship shape and estimates of association between primary and sensitivity analyses. There was no association between strength/RTD and KOOSsport. ConclusionThere was a nonlinear relationship between knee extensor strength and hop function, with lower strength being associated with a stronger relationship. As strength values increased, the relationship attenuated. Knee extensor and flexor strength, or RTD, were not associated with self-reported function.

Effects of blood-flow restricted exercise versus conventional resistance training in musculoskeletal disorders—a systematic review and meta-analysis

ObjectiveTo compare the effect of low-load blood flow restricted resistance training (BFR-RT) versus high-load resistance training (HL-RT) on muscle strength, muscle mass, physical function, patient-reported outcomes, and adherence to training in clinical musculoskeletal populations.Data sourcesWeb of Science, Cochrane Central, Medline, Embase, SportDiscus was searched on the 30th May 2022.Review methodsThis study was conducted as a systematic review and meta-analysis. Randomized Controlled Trials (RCTs) were included if they (i) included patients, (ii) comprised of a BFR-RT intervention protocol and a group who performed HL-RT (≥ 70%1RM) for at least eight exercise sessions, and (iii) involved at least 1 exercise that targeted the lower limbs. The Cochrane Risk of Bias tool was used to evaluate the risk of bias. The meta-analyses were performed using a random effects model with an adjustment to the confidence interval.ResultsSeven RCTs comprising 303 participants (BFR-RT: n = 151; HL-RT: n = 152) were identified. HL-RT and BFR-RT showed similar gains in dynamic (1-10RM) knee extensor strength and leg press strength, quadriceps cross sectional area, sit-to-stand performance, and patient reported pain and function. There was a moderate effect favoring BFR-RT for increasing maximal isometric knee extensor strength. The grading of certainty in evidence was low-to-very low for all outcome variables.ConclusionThis systematic review and meta-analysis extends our current knowledge about BFR-RT and HL-RT as equally effective exercise methods for inducing gains in maximal muscle strength in healthy populations, by now also comprising patients suffering from various clinical musculoskeletal conditions. The certainty in the estimates was low-to-very low, prompting the inclusion of future higher-quality trials.Trial registrationPROSPERO ID (CRD42022337173). Registered June 18th 2022.

Limited preoperative knee extension in anterior cruciate ligament reconstruction using a hamstring tendon affects improvement of postoperative knee extensor strength.

This study aimed to determine the factors affecting knee extensor strength 6months after anterior cruciate ligament (ACL) reconstruction using autograft hamstring tendon. 144 patients who could undergo regular follow-up after ACL reconstruction were divided into 2 groups: those with greater than 90% (Group A: n = 95) and less than 85% (Group B: n = 49) isokinetic knee contraction at 60°/s 6months post-ACL reconstruction. Basic information, injury status, limited preoperative knee extension, and knee extensor strength at 3 and 6months postoperatively were compared between the groups. Multivariate logistic analysis was performed and included variables that showed statistically significant differences between the groups in the univariate analysis. In addition, the cut-off value for the limb symmetry index (LSI) at 3months postoperatively needed to exceed an LSI of 90% at 6months postoperatively was calculated using the receiver operating characteristics curve. Age, preoperative waiting period, limited preoperative knee extension, and knee extensor strength at 3months postoperatively were significantly different between the two groups. The multivariate logistic analysis showed that all the variables affected the improvement in knee extensor strength at 6months postoperatively. Limited preoperative knee extension was the most significant factor (odds ratio: 15.1, 95% confidence interval: 2.57-118.56, p < 0.01). The LSI cut-off value at 3months postoperatively was 72.0%. Key factors in achieving the necessary knee extensor strength criteria for return to sports at 6months post-ACL reconstruction include addressing limited preoperative knee extension and achieving an LSI ≥ 72% in knee extensor strength at 3months postoperatively. Level III.

Hamstring stiffness and injury risk factors during the handball season in female players.

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.

Comparison of time courses in postoperative functional outcomes between simultaneous bilateral and unilateral total knee arthroplasty with propensity score matching.

No consensus has been reached on which is better in terms of functional outcomes between simultaneous bilateral and unilateral total knee arthroplasty (TKA). As patient characteristics, such as age, sex, and body mass index, have significant effects on functional outcomes after TKA, these factors should be matched before comparisons are made. This study aimed to compare time courses in functional outcomes between simultaneous bilateral TKA and unilateral TKA after matching the patient characteristics. In this retrospective study, the clinical records of patients admitted to a hospital were reviewed. Of 425 patients, 43 underwent simultaneous bilateral TKA, whereas 382 underwent unilateral TKA. Propensity score matching was performed for age, sex, and body mass index between simultaneous bilateral and unilateral TKA patients. Therapists measured pain intensity, knee extensor strength, and knee-specific functional outcomes by using the new knee society score, including total score, symptoms, patient satisfaction, patient expectations, and functional activities preoperatively and 3 and 12months postoperatively. Two-way repeated analysis of variance was performed to compare the time courses in functional outcomes between simultaneous bilateral and unilateral TKA. After propensity score matching, 40 patients each for underwent bilateral TKA and unilateral TKA were selected. Knee extensor strength in simultaneous bilateral TKA patients was significantly lower than that in unilateral TKA patients at 3months postoperatively (p = 0.04). A significant interaction was observed between the effects of time and group on knee extensor strength (F [1, 78] = 3.338; interaction: p = 0.042; η2 = 0.052). No significant interactions were found among the other variables measured. Patients who underwent simultaneous bilateral TKA should undergo postoperative rehabilitation focused on alleviating delayed recovery in knee extensor strength during the acute phase.

Cut-off values of preoperative knee extensor strength and hip abductor strength for predicting good walking ability after total knee arthroplasty.

Total knee arthroplasty (TKA) reduces pain and improves physical function; however, not all patients have successful outcomes after surgery. To identify these patients would be critical information for improving rehabilitation programs. The purpose of this study was to clarify the cut-off values of lower extremity muscle strength for predicting postoperative good walking ability. Timed Up and Go test of 105 patients was measured at 6months postoperatively, and participants were divided into good (< 9.1s) and poor (≥ 9.1s) walking ability. Both sides of knee extensor strength (KES) and hip abductor strength (HAS) were measured using hand-held dynamometer preoperatively. Receiver operating characteristic (ROC) curve analysis was used to identify cut-off values for classifying the participants into the two groups. Of the 105 patients, 54 were allocated in the poor walking ability group, whereas 51 were allocated in the good walking ability group. KES and HAS were significantly greater in the good walking ability group than in the poor walking ability group. ROC curve analysis revealed that the cut-off value for KES was 0.79 Nm/kg (area under the curve (AUC) 0.68; sensitivity 64.7%; specificity 68.5%) on the involved side and 0.86 Nm/kg (AUC 0.73; sensitivity 84.6%; specificity 55.6%) on the uninvolved side, and for HAS was 0.57 Nm/kg (AUC 0.71; sensitivity 60.8%; specificity 71.7%) on the involved side and 0.61 Nm/kg (AUC 0.76; sensitivity 66.7%; specificity 77.4%) on the uninvolved side. The cut-off values of preoperative KES and HAS for predicting good walking ability after TKA are 0.79 Nm/kg on the involved side and 0.86 Nm/kg on the uninvolved side, and 0.57 Nm/kg on the involved side and 0.61 Nm/kg on the uninvolved side, respectively. We should provide enhanced pre- and post-operative rehabilitation programs for patients with muscle strength lower than these values.

Effect of isokinetic muscle strength training on knee muscle strength, proprioception, and balance ability in athletes with anterior cruciate ligament reconstruction: a randomised control trial.

Objective: This study aimed to investigate the effects of regular isokinetic muscle strength training on knee muscle strength, proprioception, and balance ability in athletes after anterior cruciate ligament (ACL) reconstruction. Methods: Forty-one athletes who underwent ACL reconstruction were randomly divided into the experimental (n = 21) and control (n = 20) groups. The experimental group used an isokinetic muscle strength tester for 4weeks (five times/ week) of knee flexion and extension isokinetic muscle strength training. The control group used the knee joint trainer (pneumatic resistance) for the same exercise regimen as the experimental group. Results: 1) Four weeks when compared with the baseline. Experimental group: the knee flexion and extension PT (60°/s and 240°/s) increased by 31.7%, 40.3%, 23.4%, and 42.9% (p < 0.01), and the flexion muscular endurance increased by 21.4% and 19.7% (p < 0.01). The flexion and extension kinaesthesia and the 30° and 60° position sense decreased by 36.2%, 32.3%, 40.0%, and 18.9% (p < 0.05). The anterior-posterior and medial-lateral displacement and speed decreased by 30.2%, 44.2%, 38.4%, and 24.0% (p < 0.05). Control group: the knee peak torque (60°/s) increased by 18.8% (p < 0.01). The anterior-posterior and medial-lateral displacement and speed decreased by 14.9%, 40.0%, 26.8%, and 19.5% (p < 0.01). 2) After 4weeks, compared with the control group, the knee flexion and extension peak torque (60°/s), extension, peak torque (240°/s), and extension muscular endurance of the treatment group increased to varying degrees (p < 0.05). However, the kinaesthesia, 30° position sense, and anterior-posterior displacement decreased to varying degrees (p < 0.05). Conclusion: Adding regular isokinetic muscle strength training to rehabilitation training further improved the knee flexion and extensor strength and extensor endurance of athletes with ACL reconstruction, as well as enhanced the kinaesthesia and 30° position sense and the balance between the anterior and posterior directions. However, the treatment had limited effects on knee flexion kinaesthesia and muscle endurance.

Adolescent and young adult hip and knee strength profiles relate to running gait biomechanics

ObjectivesCompare and assess relationships between strength and running biomechanics among healthy adolescents and young adult males and females. DesignRetrospective cohort. SettingClinic. Participants802 healthy participants (570 F, 232 M; 16.6 ± 2.3 years). Main outcome measuresMass-normalized knee flexor and extensor strength, hip adductor and abductor strength, hamstrings-to-quadriceps (H:Q), and abductor-to-adductor (Abd:Add) ratios were obtained using hand-held dynamometry. Mass-normalized peak vertical ground reaction force (vGRF), %stance, cadence, and stride length were obtained using an instrumented treadmill. Multivariate analyses of variance were used to compare strength and biomechanics across ages and sexes. Linear regressions were used to assess the relationships between strength and biomechanics, accounting for speed, age, and sex. Independent t-tests were used to compare strength between strength ratio profiles. ResultsStrength and running biomechanics significantly differed between sexes (p-range: <0.001–0.05) and age groups (p-range: <0.001–0.02). Strength and strength ratios were significantly associated with increased cadence (p-range:0.001–0.04) and stride lengths (p-range:0.004–0.03), and decreased vGRF (p < 0.001). Lower H:Q ratios had significantly lower strength measures (p < 0.001). Higher Abd:Add ratios had significantly increased abductor strength (p < 0.001). ConclusionsStrength and running biomechanics differed by sexes and ages. Hip and knee strength and strength ratios were related to select spatiotemporal and kinetic biomechanical features.

Association between frailty and physical performance in older patients with heart failure.

Frailty is an issue in patients with heart failure (HF). A Korean version of the frailty scale (K-FRAIL) has been developed. We aimed to analyze the relationship between the K-FRAIL scale and physical performance in patients with HF. This study included 142 patients with HF aged ≥65 years from a single center. Muscular fitness was assessed using the handgrip test and knee extensor strength measurement. Aerobic capacity was assessed using the cardiopulmonary exercise test and 6-min walk test (6MWT). Frailty was assessed using the K-FRAIL questionnaire. Peak VO2 and 6MWT scores significantly decreased as frailty worsened, but handgrip and knee extensor strength did not. In the multivariate analysis, peak VO2 (β = -.31; p = .002) and 6MWT score (β = -.38; p < .001) showed significant inverse associations with the K-FRAIL score. Based on the receiver operating characteristic curve analysis, the cut-off values of peak VO2 (hazard ratio, 5.08; p = .023) and 6MWT (hazard ratio, 3.99; p = .020) were independent predictors of frailty. In older patients with HF, physical performance correlates with the degree of frailty. The K-FRAIL scale is correlated with the peak VO2 and 6MWT.

The relationship of knee flexor and extensor muscle strength and tightness with squat performance in children with cerebral palsy

The relationship of knee flexor and extensor muscle strength and tightness with squat performance in children with cerebral palsy