Knee Extension Strength Research Articles

Comparison Between Total Hip and Knee Arthroplasty on Short-Term Performance-Based Outcomes and Factors Associated with the Improvement of Gait Function During Post-Acute Inpatient Rehabilitation

Background: Data on the differences in functional recovery between inpatient rehabilitation for total hip arthroplasty (THA) and total knee arthroplasty (TKA) are lacking, and the factors influencing the improvement of short-term functional mobility remain unknown. In this study, we compared the short-term functional outcomes of both procedures and identified early postoperative predictors of physical function gain during post-acute rehabilitation. Methods: A total of 435 patients who underwent THA and TKA were included. The main outcomes were knee extension strength, the motor component of the Functional Independence Measure, Numerical Rating Scale, 10 Meter Walk Test, Timed Up and Go (TUG) test, and the Berg Balance Scale. The recovery process and rehabilitation outcomes were compared between patients with THA and TKA. Additionally, predictors related to physical performance improvement were examined for each procedure. Results: Patients with THA and TKA achieved significant short-term functional recovery after multidisciplinary rehabilitation (time; p < 0.001). However, the pain score was higher at discharge in patients with TKA (p < 0.001). Age (β: −0.264, p = 0.009) and TUG test (β: −0.884, p < 0.001) in THA, and non-operated knee extension strength (β: 0.234, p = 0.016) and TUG test (β: −0.783, p < 0.001) in TKA were significant early postoperative predictors of functional mobility. Conclusions: Multidisciplinary rehabilitation was beneficial for functional improvement in patients with THA and TKA despite persistent pain at discharge after TKA. Baseline functional levels in both groups and non-operated knee extension strength in TKA can be useful performance-based predictors of short-term gait function improvement.

Predicting cognitive function changes from oral health status: a longitudinal cohort study

Recent studies indicate a potential link between oral health and cognitive function; however, long-term associations remain unclear. This study aimed to identify oral health factors that predict changes in cognitive function among older adults over time. The study included 583 independent older adults (201 male, 382 female) with a mean age of 72.7 years. Cognitive function was assessed using Mini-Mental State Examination (MMSE) at baseline and follow-up over two years, with relative change in MMSE (rMMSE) calculated. Baseline oral health variables included number of remaining teeth, masticatory performance, occlusal force, oral diadochokinesis and tongue pressure. Physical performance and confounding factors were also considered. The relationship between rMMSE and the variables was analyzed using Pearson’s correlation, Mann-Whitney U test, and multiple linear regression analysis. Cognitive function declined in 196 subjects, with rMMSE significantly correlated with oral diadochokinesis. Regression analysis revealed significant associations between cognitive changes and oral diadochokinesis (p = 0.020) and knee extension strength as a physical performance (p = 0.047). Our findings suggest that cognitive decline may be indicated by declines in both physical and oral motor performance. Incorporating oral diadochokinesis testing into health screenings could aid early detection of cognitive decline, improving outcomes and reducing healthcare burdens.

Effectiveness of community-based Baduanjin exercise intervention for older adults with varying frailty status: a randomized controlled trial

BackgroundDue to poorer exercise tolerance, it may be challenging for frail older adults to engage in moderate- or vigorous-intensity exercise. While low-intensity exercise interventions may be more feasible, its effectiveness for such population group remains unclear. We examined the effectiveness and implementation of community-based Baduanjin Qigong, a low-intensity exercise program in older adults with varying frailty status.MethodsA two-arm, multicenter assessor-blind parallel group randomized controlled trial was conducted at three local senior activity centers. Fifty-six community-dwelling older adults with low handgrip strength were randomly allocated to either the intervention (IG) or wait-list control (CG) group. The IG underwent a supervised 16-week Baduanjin exercise program at a frequency of 2–3 × 60 min sessions/week. The CG was instructed to maintain their usual activity and received a monthly health education talk. The primary outcome measures were knee extension strength, vital exhaustion, and fear of falling. Secondary outcome measures include physiological falls risk, handgrip strength, gait speed, timed up and go test, 30-second sit-to-stand, quality of life, depression, and frailty. All outcome measures were assessed at baseline and 4-month follow-up.ResultsOverall, there were no statistically significant differences in all outcome measures between CG and IG at 4-month follow-up. However, in exploratory compliance analysis, a statistically significant group x time interaction was found for vital exhaustion (B = -3.65, 95% CI [-7.13, -0.16], p = .047) among participants with at least 75% attendance. In post-hoc within-group comparisons, IG showed improved vital exhaustion by 4.31 points (95% CI [1.41, 7.20], d = 0.60). The average participant attendance rate was 81.3%. No major adverse events occurred, and all participants reported positive experiences with the exercise intervention.ConclusionsOur study demonstrated that Baduanjin is a safe, feasible, and acceptable exercise program that can be successfully implemented in community settings for older adults with varying frailty status. With good adherence, Baduanjin exercise could potentially be effective in alleviating vital exhaustion. However, the effectiveness of Baduanjin on physical performance, psychological measures and frailty in community-dwelling older adults remains equivocal.Trial registrationClinicalTrials.gov NCT04549103. Registered September 16, 2020.

Quadriceps Muscle Geometry and Strength Throughout Maturation in National-Level Male Soccer Players: A Cross-Sectional Study.

Adolescent soccer players experience distinct physiological changes due to chronological and biological maturation, impacting their soccer performance. Here, we explored age-related variations and associations between quadriceps geometry and strength in male national-level adolescent soccer players. We used ultrasonography to examine the regional architecture and morphology of the rectus femoris (RF) and vastus lateralis (VL) muscles, and we assessed knee extension strength by isometric and isokinetic dynamometry. Players were categorized into four age groups: under (U) 15 (n=18, age=13.7±0.5 years), U16 (n=15, age=14.7±0.5), U17 (n=19, age=15.7±0.5), U18 (n=18, age=16.7±0.5) and U21 (n=25, age=18.5±0.5). The absolute and relative strengths were higher in the U16 compared to U15 by 12-15% and 6-8%, 11-12% and 6-7% in the U17 compared to U16, 5-7% and -1-2% in the U18 compared to U17 and 0-15% and -1-11% in the U21 compared to U18 age groups, respectively. VL architecture did not change relevantly between the age groups. The muscle anatomical cross-sectional area (ACSA) of the VL and RF differed non-uniformly and muscle region-specific by 10-36%, with highest values in the U21 age group. Moderate correlations between the VL architecture and knee extension strength in both legs were observed only in the U16 age group. The quadriceps ACSA showed age-specific correlations with knee extension strength. Our findings highlight non-uniform differences in quadriceps muscle morphology and absolute and relative strength among male national-level adolescent soccer players in different age groups. The correlations observed between muscle morphology or architecture and strength were muscle, muscle region, leg and age dependent.

Fitness, Gray Matter Volume, and Executive Function in Cognitively Normal Older Adults: Cross-Sectional Findings From the AGUEDA Trial.

The aim of the study is to investigate the association of cardiorespiratory fitness (CRF) and muscular strength indicators with gray matter volume (GMV) and to study whether fitness-related regions of GMV are associated to executive function (EF) in cognitively normal older adults. Ninety-one cognitively normal older adults (71.69 ± 3.91 years; 57.14% females) participated in this study from the AGUEDA trial. CRF was measured by a 2-km walking test and a 6-min walking test. Muscular strength was measured by handgrip, biceps curl, squats, and isokinetic strength tests. T1-weigthed images were obtained through a magnetic resonance scan. GMV was determined by voxel-based morphometric analysis. Standardized EF tests were performed. CRF did not show any positive association with GMV. Handgrip strength was positively associated with GMV (p < 0.001) in nine regions (β from 0.6 to 0.8 and k from 106 to 1927) and knee extension strength in three regions (β from 0.4 to 0.5 and k from 76 to 2776). Squats strength was negatively associated with GMV (p < 0.001) in two regions (β = -0.3, k = 1102 and k = 152) and the 2-km walking test in one region (β = -0.4, k = 99). Only handgrip strength-related GMV was associated with cognitive flexibility (p = 0.039, β = 0.215) and spatial working memory (p < 0.03, β 0.247-0.317), but not with EF score (p > 0.05). Muscular strength, but no CRF, may be positively related to GMV in cortical and subcortical regions, with implications for specific cognitive domains rather than the overall EF score. Specifically, handgrip strength was the indicator most associated with higher GMV, while squats strength and CRF were negatively related to GMV. ClinicalTrials.gov identifier: NCT05186090.

Test–Retest Reliability of Concentric and Eccentric Muscle Strength in Knee Flexion–Extension Controlled by Functional Electromechanical Dynamometry in Female Soccer

In the field of sports performance, sports medicine, and physical rehabilitation, there is a great interest in the development of protocols and reliable techniques and instruments for the evaluation of strength produced by athletes. In the last ten years, women’s football has increased its popularity and participation in numerous countries, which has contributed to players developing more professionally and requiring more specific muscle strength training to improve their performance. The aim of this study was to analyze the absolute and relative test–retest reliabilities of peak muscle strength in knee flexion (FLE) and extension (EXT) controlled using a functional electromechanical dynamometer (FEMD) in a group of seventeen professional female soccer players (age = 18.64 ± 0.62 years; weight = 54.72 ± 7.03 kg; height = 1.58 ± 0.04 m; BMI = 21.62 ± 2.70 kg/m2). Peak muscle strength was measured with knee flexion (FLE) and extension (EXT) movements at a speed of 0.4 m·s−1 unilaterally in a concentric phase (CON) and an eccentric phase (ECC). No significant mean differences were found in the test–retest analysis (p &gt; 0.05; effect size &lt; 0.14), and high reliability was reported for peak muscle strength assessments in both the CON (ICC) = 0.90–0.95) and the ECC (ICC = 0.85–0.97). Furthermore, stable repeatability was presented for extension in the CON (CV = 7.39–9.91%) and ECC (CV = 8.65–13.64). The main findings of this study show that peak muscle strength in knee flexion and extension in CON and ECC is a measure with acceptable absolute reliability and extremely high relative reliability using the FEMD in professional female soccer players.

Volumetric muscle composition analysis in sporadic inclusion body myositis using fat-referenced magnetic resonance imaging: Disease pattern, repeatability, and natural progression.

Fat-referenced magnetic resonance imaging (MRI) has emerged as a promising volumetric technique for measuring muscular volume and fat in neuromuscular disorders, but the experience in inflammatory myopathies remains limited. Therefore, this work aimed at describing how sporadic inclusion body myositis (sIBM) manifests on standardized volumetric fat-referenced MRI muscle measurements, including within-scanner repeatability, natural progression rate, and relationship to clinical parameters. Ten sIBM patients underwent whole-leg Dixon MRI at baseline (test-retest) and after 12 months. The lean muscle volume (LMV), muscle fat fraction (MFF), and muscle fat infiltration (MFI) of the quadriceps, hamstrings, adductors, medial gastrocnemius, and tibialis anterior were computed. Clinical assessments of IBM Functional Rating Scale (IBMFRS) and knee extension strength were also performed. The baseline test-retest MRI measurements were used to estimate the within-subject standard deviation (sw). 12-month changes were derived for all parameters. The MRI measurements showed high repeatability in all muscles; sw ranged from 2.7 to 18.0 mL for LMV, 0.7-1.3 percentage points (pp) for MFF, and 0.2-0.7 pp for MFI. Over 12 months, average LMV decreased by 7.4% while MFF and MFI increased by 3.8 pp and 1.8 pp, respectively. Mean IBMFRS decreased by 2.4 and mean knee extension strength decreased by 32.8 N. The MRI measurements showed high repeatability and 12-month changes consistent with muscle atrophy and fat replacement as well as a decrease in both muscle strength and IBMFRS. Our findings suggest that fat-referenced MRI measurements are suitable for assessing disease progression and treatment response in inflammatory myopathies.

Comparing the Acute Effects of Diagonal Mobilization and Nordic Hamstring Curls on Knee Flexion and Extension Strength: A Randomized, Double-Blinded Parallel Study in Young Soccer Players

Background: Understanding the diverse acute effects elicited by physiotherapists in soccer players may be pertinent for enhancing performance and aiding in the mitigation of injury risk. Methods: Fifty regional-level soccer players aged 13 to 15 took part in a randomized double-blind trial. They were allocated randomly to either receive diagonal manual mobilization (DM) treatment or undergo a Nordic hamstring curl (NHC) intervention, designated as the control group. Evaluations were carried out before and after the interventions to gauge standing knee extensors (KE) and knee flexors (KF) strength using the ForceFrame Strength Testing System. The recorded variables encompassed average, maximal force, and maximal impulse for both KE and KF. Results: Following the intervention, evaluations showed no significant differences between groups in KF maximal force (F1,48 = 1.238; p = 0.271; ηp2 = 0.025), KF average force (F1,48 = 0.957; p = 0.333; ηp2 = 0.020), KF maximal impulse (F1,48 = 0.246; p = 0.622; ηp2 = 0.005), KE maximal force (F1,48 = 1.514; p = 0.225; ηp2 = 0.031), KE average force (F1,48 = 0.118; p = 0.733; ηp2 = 0.002), and KE maximal impulse (F1,48 = 2.540; p = 0.118; ηp2 = 0.050). Analysis within the DM group showed significant differences in KF maximal force (24.2 N; p = 0.004), KF average force (23.4 N; p = 0.001), KE maximal force (25.8 N; p = 0.005), KE average force (20.0 N; p = 0.044), and KE maximal impulse (265.9 Ns; p = 0.027), although no significant differences were found in KF maximal impulse (150.1 Ns; p = 0.058). Conclusions: This study indicates that both DM and NHC elicit similar effects on acute responses in KE and KF strength following intervention, although DM shows more favorable adaptations within the group. Perhaps DM could serve as a suitable warm-up strategy in specific circumstances, immediately influencing readiness for strength activities.

Associations of Usual and Fast Gait Speed With Physical Performance and Balance Confidence in Community-Dwelling Older Adults: Implications for Assessment.

Gait speed is a robust measure that offers many advantages clinically. However, decisions concerning its utilization exist, including whether to assess usual or fast gait speed. The current study aimed to identify whether usual or fast gait speed was more strongly associated with physical performance measures and balance confidence. A secondary aim was to explore these relationships within subgroups based on fall risk status. This was an observational study with a cross-sectional design involving 57 community-dwelling older adults (77.2% female; mean age = 68.8, SD = 6.5 years, range = 60-87 years) who were assessed on the following variables: usual and fast gait speed, knee extension strength, step execution time, 6-minute walk test (6MWT), and Activities-specific Balance Confidence Scale (ABC-6). Spearman ρ correlations were computed to determine bivariate associations of usual and fast gait speed with physical performance measures and balance confidence for the whole sample and within subgroups based on fall risk [lower fall risk (n = 28) vs higher fall risk (n = 29)]. Multiple linear regression models were estimated with either usual or fast gait speed as key predictors of knee extension strength, step execution time, 6MWT, and ABC-6. Stronger correlations were observed for fast gait speed compared with usual gait speed with all physical performance measures and balance confidence for the entire sample and within the higher fall risk group. Multiple regression results indicated that models with fast rather than usual gait speed as the key predictor explained more of the variance in 6MWT ( R2 = 64.5% vs 45.6%), ABC-6 ( R2 = 28.5% vs 25.4%), step execution time ( R2 = 24.9% vs 19.0%), and knee extension strength ( R2 = 15.7% vs 7.2%). Fast gait speed showed stronger associations and better predictive capabilities compared with usual gait speed with physical performance measures and balance confidence in older adults. Despite being measured less often than usual gait speed, fast gait speed assessment warrants additional consideration.

Increased knee-extension strength and steps per day after a novel post-hospitalization rehabilitative program in older adults (65+): Secondary analyses of a randomized controlled single-blinded trial using an expanded sample size

IntroductionOlder adults are at risk of developing new or worsened disability when hospitalized for acute medical illness. This study is a secondary analysis of the STAND-Cph trial on the effect of a simple strength training intervention initiated during hospitalization and continued after discharge. We investigated the between-group difference in change in functional performance outcomes, the characteristics of patients who experienced a relevant effect of the intervention, and the characteristics of those who were compliant with the intervention, using an expanded sample size as protocolized. MethodsThe STAND-Cph was a randomized controlled trial conducted at a major Danish university hospital. Acutely admitted older adult patients (65+) from the Emergency Department were randomized to the intervention group receiving progressive strength training and a protein supplement during and after hospitalization (12 sessions over 4 weeks) or control group receiving usual care. The primary outcome was the de Morton Mobility Index assessed at baseline and 4 weeks after discharge. The secondary outcomes were 24-h mobility (assessed by ActivPAL accelerometers), isometric knee-extension strength, 30 s. sit-to-stand performance, and habitual gait speed. ResultsBetween September 2013 and September 2018, a total of 158 patients were included and randomized to either the intervention group (N = 80; mean age 79.9 ± 7.6 years) or the control group (N = 78; mean age 80.8 ± 7.4 years). We found no significant between-group difference in change in our primary outcome (p > 0.05). Both the intention-to-treat (difference in change 0.14 Nm/kg (95 % CI 0.03;0.24), p = 0.01) and the per protocol (difference in change 0.16 Nm/kg (95 % CI 0.04;0.29), p = 0.008) analyses showed that between baseline and 4 weeks, knee-extension strength increased significantly more in the intervention group than in the control group. Also, the per protocol analysis showed that the intervention group increased their daily number of steps significantly more than the control group (difference in change 1088 steps (95 % CI 44; 2132); p = 0.04). When examining subgroups of patients, we found no significant differences neither between those who experienced a clinically relevant improvement in the de Morton Mobility Index and those who did not, nor between those who were compliant and those who were not. ConclusionThis exploratory analysis indicates that while simple progressive strength training and protein supplementation does not improve functional performance assessed by the de Morton Mobility Index, it can benefit specific facets of physical activity and muscle strength among geriatric patients.

Effect of Combined Exercise and Nutrition Interventions During Inpatient Chemotherapy in Acute Leukemia and Malignant Lymphoma Patients: A Randomized Controlled Trial

The aim of the present study was to determine the effectiveness of combined exercise and nutrition interventions on physical function and quality of life (QOL) in patients with acute leukemia or malignant lymphoma (ML) during inpatient chemotherapy. The study was a randomized controlled trial where patients with acute leukemia or ML who were receiving inpatient chemotherapy and exercise therapy were divided into an intervention group (IG) and a control group (CG). Both groups underwent resistance training and aerobic exercise. The patients in the IG were instructed to take nutritional supplements twice a day. Assessment items were muscle strength (handgrip strength and knee extension strength), 6-min walking test, skeletal muscle mass, QOL, nutritional status, and fatigue. Two-way analysis of variance showed a significant interaction for bilateral handgrip strength and knee extension strength. No significant interactions were found for the other items. The results of the present study showed improved muscle strength in the IG compared to the CG, indicating the effectiveness of combined exercise and nutrition interventions during inpatient chemotherapy in patients with acute leukemia or ML.

Comparative analysis of body composition using torso CT from PET/CT with bioelectrical impedance and muscle strength in healthy adults

The role of torso computed tomography (CT) in evaluating body composition has been unexplored. This study assessed the potential of low-dose torso CT from positron emission tomography (PET)/CT for analyzing body composition and its relation to muscle strength. We retrospectively recruited 384 healthy Korean adults (231 men, 153 women) who underwent torso 18F-FDG PET/CT, bioelectrical impedance analysis (BIA), and muscle strength tests (handgrip strength [HGS] and knee extension strength [KES]). CT images were segmented into three compartments: torso volumetric, abdominal volumetric, and abdominal areal. Muscle amounts from each compartment were indexed to height (m2). BIA and HGS served as reference standards, with correlation coefficients (r) calculated. Torso muscle volumetric index (TorsoMVI) had the strongest correlations with BIA-derived values (r = 0.80 for men; r = 0.73 for women), surpassing those from the abdominal compartments. TorsoMVI was also correlated significantly with HGS (r = 0.39, p < 0.01) and differentiated between normal and possible sarcopenia in men (n = 225, 5960 ± 785 cm3/m2 vs. n = 6, 5210 ± 487 cm3/m2, p = 0.02). In women, KES correlated more strongly with muscle parameters than HGS. Despite gender-specific variations, torso CT-derived parameters show promise for evaluating body composition and sarcopenia.

The Effects of Imeglimin on Muscle Strength in Patients with Type 2 Diabetes: A Prospective Cohort Study.

A bidirectional relationship has been observed between type 2 diabetes mellitus and sarcopenia, especially among older adults. While previous studies have reported that imeglimin improves mitochondrial function, they have not assessed its effects on muscle strength in patients with type 2 diabetes. Therefore, we aimed to investigate the effects of imeglimin on muscle strength in patients with type 2 diabetes. In this prospective cohort study, we recruited consenting patients with type 2 diabetes (20-75years). Changes in lean body mass (LBM), fat mass, quadriceps muscle strength, and grip strength from baseline (week 0) to week 24 were evaluated and compared between patients treated with imeglimin therapy (group I) and those who did not take imeglimin (controls, group C). We recruited 27 patients treated with imeglimin (group I) and 29 controls (group C), and 50 of them completed the study (group I: n = 23; group C: n = 27). The change in LBM, total body fat mass, or skeletal muscle index from baseline to week 24 did not differ significantly between the two groups. However, group I exhibited a significantly higher percent change in quadriceps knee extension strength from baseline to week 24 than group C (13 ± 19% and 2.1 ± 14%, p = 0.022). Conversely, the difference in percent change in grip strength was not significant. Multivariable analysis showed that imeglimin use was significantly associated with a percent change in quadriceps knee extension strength, independent of age, sex, body mass index, and skeletal mass index (β = 0.325, p = 0.0014). Imeglimin positively affected muscle strength in patients with type 2 diabetes without altering LBM. Therefore, imeglimin exerts a unique effect on skeletal muscles in humans. Further randomized controlled trials are needed to validate these findings. This research was registered in the University Hospital Medical Information Network (UMIN, UMIN000054715).

Effects of muscle quantity, muscle quality, and phase angle on whole-body reaction time in 5164 adults aged 20-91years.

Muscle quantity, defined as appendicular lean mass (ALM); muscle quality, defined as the ratio of muscle strength to ALM; and bioelectrical impedance analysis (BIA)-derived phase angle (PhA) are determinants of physical performance. We examined whether muscle quality indices were significant predictors of the whole-body reaction time (WBRT) in healthy female and male adults aged 20-91years. Data from 5164 adults (2869 women and 2295 men; mean age ± standard deviation, 60.9 ± 15.6years) were analyzed. Height and weight were measured, and body mass index was calculated. ALM was estimated using a previously validated 8-electrode multi-frequency BIA. PhA was measured at 50kHz using a BIA device. Knee extension strength (KES), leg extension power (LEP), and flexibility were examined. The ALM to weight (ALM/weight), KES to ALM (KES/ALM), and LEP to KES (LEP/KES) ratios were calculated. In the WBRT test, participants were asked to stand on a force plate and jump upright as quickly as possible in response to a light stimulus. The WBRT was divided into the response initiation and motion execution phases. ALM/weight, KES/ALM, LEP/KES, PhA, and flexibility were significant independent predictors of WBRT and the time of the motion execution phase (p < 0.001). However, PhA was not a significant predictor of the time of response initiation phase. Muscle quantity (ALM/weight), muscle quality (KES/ALM and LEP/KES), PhA, and flexibility are determinants of WBRT test performance, particularly in the motion execution phase.

Predicting the Recovery of Isokinetic Knee Strength 6 Months After Anterior Cruciate Ligament Reconstruction.

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

Systematic Evaluation of Isometric Maximal Muscle Strength in an Orthopaedic Cohort.

Although the lower extremities are essential for movement function and human gait, no normalized isometric maximum strength values, which include the factors gender, age, weight, height, and body mass index (BMI), have been defined to date for orthopaedic patients. To systematically analyze the isometric maximal muscle strength of a cohort in an orthopaedic outpatient clinic and to evaluate its relation to gender, age, weight, height, BMI, and the differences between diseases. Cross-sectional study. Level 4. Isometric maximal muscle strength of knee extension, knee flexion, hip abduction, and hip adduction was measured in orthopaedic patients of an outpatient clinic using a specific muscle strength measurement device. Correlation analysis was performed for age, gender, height, weight, and BMI. Patients were grouped by disease characteristics. The cohort consisted of 311 subjects (sex: 164 male, 147 female; age: 48.63 years, SD = 16.595; BMI: 26.56 kg/m², SD = 4.9). Age correlated significantly with maximal isometric muscle strength. At the age of 54 years onward, based on 133 patients, a decline in maximum isometric muscle strength was detected. Gender showed a strong influence on maximal isometric muscle strength, with significantly higher values for male patients. Furthermore, weight and height, but not BMI, correlated significantly with muscle strength. For clinical studies comparing different evidence-based training interventions for rehabilitation, it is important to consider determinants such as gender, age, weight, and height for isometric maximum strength measurement. For further validation, follow-up examinations taking into account the performance level, other target groups, and other muscle groups are required to avoid the wide dispersion of isometric maximum strength values. These results and associated determinants are highly clinically relevant and can be used as a reference for further studies in the field of musculoskeletal regeneration.

The isometric and isokinetic knee extension and flexion muscle strength profile of elite soccer players

BackgroundThis study aimed to further complete normative data sets for the strength profile of the thigh in soccer players by performing isometric and isokinetic measurements in a large sample per player position.MethodsIn total, 364 soccer players were divided into subgroups according to their pitch position. All players performed isometric and isokinetic strength measurements during active competition period using an isokinetic dynamometer (System 3, Biodex®, ENRAF-NONIUS, New York, USA).ResultsIsokinetic strength of m. Quadriceps was significantly (p = 0.023) higher in strikers compared to central midfielders in both the dominant (+ 9%) and the non-dominant (+ 4%) leg. No further differences were found in isometric or isokinetic strength per playing positions.ConclusionsWe have shown that strength profiles do not differ between playing positions on the field. This is valuable information for elite soccer high performance coaches and medical staffs aiming to improve daily training efficiency and rehabilitation of their players.

Clinical application research of intelligent monitoring system for knee rehabilitation: a randomized controlled trial

BackgroundThis study investigates the effectiveness of a self-developed intelligent monitoring system for home-based knee rehabilitation following total knee arthroplasty (TKA).MethodsIn this randomized controlled trial, 120 patients undergoing TKA were divided using random digit allocation. Preoperative and one-month postoperative assessments of knee function, quality of life, and isometric knee extension strength were conducted with the Intelligent Monitoring System. Patients received group-specific rehabilitation instructions pre-discharge and performed exercises for one month.ResultsChanges in isometric knee extensor strength on the affected side within one month post-surgery for the brace-monitored rehabilitation group showed a significant decrease three days after surgery compared to one day before surgery. Subsequent measurements taken at postoperative days 5, 7, 14, and 21 indicated a gradual increase in strength, although these increases did not reach statistical significance when compared with previous measurements. One month post-surgery, all groups demonstrated significant improvements in knee joint function and mobility compared to pre-surgery levels. Notably, the brace-monitored group showed statistically significant improvements in 36-Item Short-Form Health Survey (SF-36) scores over the conventional rehabilitation group.ConclusionsThe Intelligent Monitoring System provides effective real-time monitoring and guidance for home-based knee rehabilitation post-TKA. It significantly enhances knee joint function, isometric knee extension strength, and quality of life shortly after surgery compared to traditional rehabilitation methods. This system offers a promising approach for improving postoperative recovery in TKA patients.Trial registrationThis study was approved by the Medical Ethics Committee of Xiangya Hospital, Central South University (Ethics Approval Number 202209008-2). It was registered with the China Clinical Trial Registry, a primary registry of the World Health Organization’s International Clinical Trials Registry Platform (Registration Number ChiCTR2300068852).

Association of muscle quantity and quality with knee extension strength in knee osteoarthritis: the Nagahama study.

We aimed to examine whether lower-limb muscle quantity and quality assessed by bioelectrical impedance analysis (BIA) were associated with knee extension strength and if the association differed with knee osteoarthritis (OA) severity. We included 1,525 participants (63.6% women; mean age, 68.0±5.3 years) from the Nagahama Prospective Cohort. Knee extension strength was measured during maximum voluntary isometric contraction. Lower limb muscle mass and extracellular-to-intracellular water (ECW/ICW) ratio were used as indicators of muscle quantity and quality, respectively, and assessed via a BIA device. We executed multiple linear regression analyses to investigate the association of muscle quantity and quality with knee extension strength. Additionally, participants were classified into three groups with respect to OA severity and symptoms: control, early, and advanced OA groups; subgroup analyses were also executed. The muscle mass (p<0.001) and ECW/ICW ratio (p=0.009) were significantly associated with knee extension strength. In the subgroup analysis, the muscle mass was significantly associated with knee extension strength (p<0.001), but there was no association between ECW/ICW ratio and knee extension strength (p=0.731) in the control group. In the early and advanced OA groups, the muscle mass (both p<0.001) and ECW/ICW ratio (early OA: p=0.034, advanced OA: p=0.015) were significantly associated with knee extension strength. Lower limb muscle quality was associated with knee extension strength, and the association was stronger in patients with knee OA. These findings suggest that both muscle quantity as well as quality should be assessed to better understand muscle function in patients with knee OA.

Angle-Specific Analysis of Isokinetic Quadriceps and Hamstring Strength at 6 and 12 Months After Unilateral ACL Reconstruction.

Quadriceps and hamstring strength deficits are related to the increased risk of reinjury after anterior cruciate ligament reconstruction (ACLR). Knee angle-specific quadriceps and hamstring strength differences would be observed in patients with ACLR 6 and 12 months after surgery. Case-series. Level 4. A total of 23 postprimary unilateral ACLR patients followed-up at 6 and 12 months postoperatively and 25 controls were included. Isokinetic knee extension and flexion strength were evaluated at 60 deg/s from 20° to 90°. Statistical parametric mapping were performed to explore the angle-specific strength and the limb symmetry index (LSI). At 6 months postoperatively, the reconstructed leg demonstrated lower knee extension and flexion strength than the contralateral (20°-77°, 24°-90°) (P < 0.01) and control legs (22°-90°, 40°-82°) (P < 0.01). From 6 months to 12 months, knee extension (60°-90°) and flexion (20°-79°) strength improved in the reconstructed leg (P < 0.05), while LSI remained unchanged (P > 0.02). At 12 months, knee extension strength differences persisted in the reconstructed leg compared with the contralateral (20°-81°) and controls (25°-63°) (P < 0.01). ACLR patients had lower LSI of knee extension strength at 6 (20°-59°) and 12 (24°-57°) months postoperatively than the controls (P < 0.02). The reconstructed leg exhibited differences in knee extension strength compared with the contralateral and control legs. Although bilateral knee extension strength increased from 6 to 12 months postoperatively, LSI did not show improvement during this period. Quadriceps restoration was observed only in knee flexion angles greater than 60° compared with controls. Future studies should investigate whether knee extension strength, especially in lower flexion angles, can be enhanced through rehabilitation programs. Furthermore, assessing the impact of this improvement on long-term outcomes and reinjury risk in ACLR patients is warranted.