Knee Extension Research Articles

The influence of knee position during static calibration trials on evaluation of knee loading during gait in individual with medial knee osteoarthritis

Quantitative three-dimensional gait analysis has been used to evaluate the loading at the knee (i.e. external knee adduction moment, EKAM) during level ground walking in individuals with knee osteoarthritis (OA). The magnitude of EKAM can be influenced by some factors, such as knee marker position and foot placement angles in static calibration trials, which may lead to inaccurate functional assessments and intervention planning. This study aimed to clarify the effects of knee position during static calibration trials on the evaluation of knee loading during gait in individuals with medial knee OA. Seventeen individuals with medial knee OA completed three different static standing trials; (1) knee flexed at 0 degrees, (2) knee flexed at 15 degrees, and (3) knee flexed at 30 degrees before walking at their self-selected speed. A sixteen-camera three-dimensional VICON gait analysis system with four AMTI force platforms was used to collect the EKAM, knee adduction angular impulse (KAAI), knee joint center (KJC), and other knee kinematic and kinetic variables during gait. A repeated measures ANOVA was used to investigate the differences between conditions. The 1st peak of EKAM, the 1st peak EKAM arm, KAAI, and knee extension moment were significantly increased at the 15-degree and 30-degree conditions in comparison with the 0-degree condition (P < 0.05). Additionally, the knee flexion moment and knee external rotation moment were significantly reduced at the 15-degree and 30-degree conditions in comparison with the 0-degree condition (P < 0.05). All biomechanical variables were influenced by the localization of the KJC during static calibration trials. The changes in knee position during static trials significantly affected the 1st peak EKAM, KAAI, and other knee kinematics and kinetics variables during gait. Therefore, future studies should consider keeping the participants’ knees in a consistent position during static trials between visits, as the variations in knee position could mask or exaggerate the differences between groups and interventions.

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.

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.

Effects of applying sports liniment with massage on muscular relative strength of hip flexion and knee extension among male Muay Thai athletes: a randomised control trial

Background: Muay Thai, Thailand’s national sport, widely practiced globally, is known for using sports liniment before training and fights. A popular product is ‘Namman Muay’, an iconic symbol of Thailand, though its direct impact on performance lacks research. Objectives: Investigate the impact of Namman Muay on the rectus femoris of the dominant leg. Focus on muscular strength exercises – seated hip flexion and supine knee extension – with relative strength as the primary outcome. Material and Methods: A randomised control trial with 24 male Muay Thai fighters, divided into 12 in the Baby Oil (BO) and 12 in the Namman Muay (NM) group. Both groups received effleurage massage on the dominant kicking legs, followed by a RAMP warm-up. Performance measurements using Lafayette Handheld Dynamometer evaluated two isometric strength tests. Results: NM intervention showed significant increases in hip flexion and knee extension strength. Within groups, a 3% decrease was seen in the BO and an 11.6% increase in NM for hip flexion strength, and 1% decrease in BO and 6.9% increase in NM for knee extension strength. Conclusion: This study provides valuable insight to Muay Thai fighters and trainers, showing that 5 ml NM boosts relative muscular strength of hip flexion and knee extension. This could improve male Muay Thai fighters’ performance particularly when using kicking techniques.

Effects of gait retraining in knee joint position sense

BackgroundJoint position sense (JPS) is crucial for maintaining posture, protecting joints, and carrying out daily activities such as walking. Studies show that exercises to strengthen muscles and improve proprioception can positively impact JPS during passive and less complex activities. Evidence suggests that motor training can effectively enhance sensory function, including JPS, due to the extensive connections between the motor cortex and somatosensory areas. Gait retraining using real-time feedback has improved outcomes among patients with musculoskeletal disorders. The effect of gait retraining on JPS has not been investigated. This study assessed the effects of gait retraining to reduce knee extension in joint position sense in individuals with knee hyperextension walking patterns. MethodsTen women with asymptomatic knee hyperextension (KH) >5° during overground walking participated in this study. Sagittal-plane kinematics were assessed using a three-dimensional (3D) motion analysis system. The JPS was assessed using the Knee Position Active Reproduction Test. The knee with the highest hyperextension was the focus of the gait retraining intervention, which consisted of six 1-h sessions using verbal instructions and visual kinematic feedback. Comparisons of peak knee extension during walking and knee JPS overall error (RMSE) were made using a paired t-test. ResultsGait retraining intervention significantly reduced knee extension angle during walking (83.8 % change; p < 0.001; Cohen's d = −1.6) and improved knee JPS (62 % change; p = 0.023; Cohen's d = 0.8) post-training. In addition, the improvements in joint kinematics (36.7 % change; p = 0.005; Cohen's d = −1.2) and JPS (52.6 % change; p = 0.015; Cohen's d = 0.9) were observed in the untrained knee. SignificanceGait retraining can improve joint position sense. This study addresses a gap in our understanding of how gait retraining can influence JPS. Our results corroborate that gait retraining is an evolving and promising strategy for improving gait outcomes, particularly in individuals with KH walking patterns.

The efficacy of the Novel Hybrid Passive Spring Damper Ankle Foot Orthosis regard to kinetic and kinematic parameters of patients with Multiple Sclerosis: An intervention study

ABSTRACT Drop foot is a common consequence of Multiple Sclerosis (MS), which may be improved somewhat by an ankle-foot orthosis (AFO). This study aimed to examine the immediate effect of using the recently developed Novel Hybrid Passive Spring Damper AFO (the novel HPSDAFO) on the kinetic and kinematic parameters of patients with MS (PwMS) in the sagittal plane. Twelve PwMS who suffered a unilateral drop foot participated in this study and fitted with the novel HPSDAFO. They walked with the novel HPSDAFO on the affected side and shoe on the affected side at a self-selected speed. Walking by the novel HPSDAFO, the symmetry of all of the evaluated sagittal kinetic and kinematic parameters improved noticeably. The range of ankle plantarflexion and knee flexion increased significantly at the stance phase. Power generation increased at all three joints. The peak of ankle dorsiflexion at early stances and the first peak of knee extension moments increased significantly but decreased at the hip joint. Changes in sagittal ROM, moment, and power generation in the plane and the improved symmetry revealed a more normal walking by using the novel HPSDAFO on the affected limb of PwMS.

Effects of lower-limb active resistance exercise on mobility, physical function, knee strength and pain intensity in patients with total knee arthroplasty: a systematic review and meta-analysis

BackgroundTotal knee arthroplasty (TKA) successfully alleviates pain from knee osteoarthritis, but muscle strength and function are reduced for a long period postoperatively. Postoperative active resistance exercise may play a relevant role.PurposeTo systematically evaluate effects of lower-limb active resistance exercise (ARE) on mobility, physical function, muscle strength and pain intensity in patients with TKA.MethodsA search was conducted in PubMed, EMBASE, and Cochrane Library databases from inception to September 2023. Only randomized controlled trials (RCTs) that compared the effects of ARE and no intervention or other rehabilitation program without PRE were included. The outcome variables were mobility (Maximal walking speed [MWS]/6-Minute Walk Test[6MWT]), physical function (Stair Climb Test [SCT]/Timed Up and Go [TUG]), knee extension/ flexion power(KEP/KFP), joint range of motion (ROM) and pain. Standardized Mean Differences (SMD) or Mean Differences (MD) and 95% confidence intervals (CI) were calculated and combined in meta-analyses. The Cochrane Collaboration’s Handbook were used for the methodological quality assessments. GRADE was used to assess the quality of evidence. The meta-analysis was performed using the RevMan 5.4 software.ResultsA total of 14 randomized controlled trials, involving 880 patients, were finally included. The lower-limb ARE exhibited significantly greater improvement in MWS (MD 0.13, 95%CI 0.08–0.18, P < 0.00001), TUG(MD -0.92, 95%CI -1.55– -0.28, P = 0.005), KEP (SMD 0.58, 95%CI 0.20–0.96, P = 0.003), KFP (SMD 0.38, 95%CI 0.13–0.63, P = 0.003), ROM-flexion (MD 2.74, 95%CI 1.82–3.67, P < 0.00001) and VAS (MD − 4.65, 95% CI − 7.86– -1.44, p = 0.005) compared to conventional exercise(CE) immediately post-intervention. However, there were no statistically significant differences between both groups in regard to 6MWT (MD 7.98, 95%CI -4.60–20.56, P = 0.21), SCT (MD -0.79, 95%CI -1.69–0.10, P = 0.08) and ROM-extension (MD -0.60, 95%CI -1.23–0.03, P = 0.06).ConclusionsAccording to the results of meta-analysis, patients undergoing TKA who receive the lower extremity ARE show better clinical effects in terms of pain relief, strength recovery and knee ROM. Simultaneously, it may be beneficial to improve mobility and physical function of patients after TKA.

Biomechanical Gait Analysis Using a Smartphone-Based Motion Capture System (OpenCap) in Patients with Neurological Disorders.

This study evaluates the utility of OpenCap (v0.3), a smartphone-based motion capture system, for performing gait analysis in patients with neurological disorders. We compared kinematic and kinetic gait parameters between 10 healthy controls and 10 patients with neurological conditions, including stroke, Parkinson's disease, and cerebral palsy. OpenCap captured 3D movement dynamics using two smartphones, with data processed through musculoskeletal modeling. The key findings indicate that the patient group exhibited significantly slower gait speeds (0.67 m/s vs. 1.10 m/s, p = 0.002), shorter stride lengths (0.81 m vs. 1.29 m, p = 0.001), and greater step length asymmetry (107.43% vs. 91.23%, p = 0.023) compared to the controls. Joint kinematic analysis revealed increased variability in pelvic tilt, hip flexion, knee extension, and ankle dorsiflexion throughout the gait cycle in patients, indicating impaired motor control and compensatory strategies. These results indicate that OpenCap can effectively identify significant gait differences, which may serve as valuable biomarkers for neurological disorders, thereby enhancing its utility in clinical settings where traditional motion capture systems are impractical. OpenCap has the potential to improve access to biomechanical assessments, thereby enabling better monitoring of gait abnormalities and informing therapeutic interventions for individuals with neurological disorders.

The relationship between executed cut angle and speed with lower extremity joint angles during unanticipated side-step cutting in soccer players

BackgroundCertain movements patterns have been indicated in knee injuries during cutting while running tasks. Differences in the executed cut angle (ECA) could partially account for group differences in joint kinematics previously observed, including sex differences. Research QuestionAre there relationships between joint angles with entry speed and ECA during side-step cutting in soccer players? MethodsThis cross-sectional study recruited 21 (10 females) soccer players. Participants completed 45o unanticipated side-step cuts in both directions. Kinematic data were captured with a 12 camera motion capture system with 46 reflective markers placed on the participants. Peak joint angles were determined during the stance phase of the cutting task. Entry speed and ECA were determined from pelvis markers. Hierarchical linear models examined relationships between angles, entry speed, and ECA, after accounting for age, sex, and leg preference. Regression coefficients with 95% confidence intervals were reported and statistical significance (p<0.05) were examined using the Wald statistic. ResultsThe mean ECA (24.6o) was lower than the intended 45o angle. Peak joint angles were significantly related to both ECA and entry speed. Specifically, an increase in ECA by 10o (i.e., sharper cuts) would increase hip internal rotation and ankle plantarflexion by 1.8 to 2.1o, and decrease hip adduction, knee abduction and ankle eversion by 1.3 to 2.4o. Faster entry speeds by 0.5m/s would increase hip flexion, hip internal rotation and knee extension angles by 1.8 to 3.8o, and decrease knee abduction by 2.6o. SignificanceStudies evaluating cutting while running should consider ECA and entry speed in their design. Potential differences could confound between-group comparisons of joint angles, including when comparing sexes, and impact interpretations of injury risk.

Does the timing of anterior cruciate ligament reconstruction surgery affect flexion contracture formation in rats?

BackgroundAnterior cruciate ligament injuries are commonly treated with ligament reconstruction surgery, but post-operative joint contracture is a major complication. The optimal timing for anterior cruciate ligament reconstruction remains controversial, with some clinical studies suggesting that early surgery may increase the risk of joint contractures, while others have found no such association. To clarify this, we investigated the effects of the timing of reconstruction surgery on contracture formation using a rat model. MethodsAnterior cruciate ligament-transected rats were divided into groups based on the timing of reconstruction: immediate, early, and delayed (1, 14, and 28 days after transection, respectively). Some anterior cruciate ligament-transected rats did not receive reconstruction surgery. Untreated rats served as controls. At 56 days after ligament transection, we assessed knee extension range of motion before (including both myogenic and arthrogenic factors) and after myotomy (arthrogenic factor only), as well as fibrotic changes in the joint capsule. FindingAnterior cruciate ligament transection alone significantly decreased range of motion before myotomy, but not after myotomy. In all reconstructed groups, both range of motions before and after myotomy were significantly reduced compared to the control, indicating the induction of arthrogenic contracture by reconstruction surgery. Fibrotic changes in the joint capsule were observed in all reconstructed groups, contributing to arthrogenic contracture formation. However, the timing of reconstruction had no effect on range of motions and fibrotic changes in the joint capsule. InterpretationOur findings may help guide clinical decision-making regarding the timing of anterior cruciate ligament reconstruction surgery.

Unveiling human biomechanics: insights into lower limb responses to disturbances that can trigger a fall.

Slip-related falls are a significant concern, particularly for vulnerable populations such as the elderly and individuals with gait disorders, necessitating effective preventive measures. This manuscript presents a biomechanical study of how the lower limbs react to perturbations that can trigger a slip-like fall, with the ultimate goal of identifying target specifications for developing a wearable robotic system for slip-like fall prevention. Our analysis provides a comprehensive understanding of the natural human biomechanical response to slip perturbations in both slipping and trailing legs, by innovatively collecting parameters from both the sagittal and frontal plane since both play pivotal roles in maintaining stability and preventing falls and thus provide new insights to fall prevention. We investigated various external factors, including gait speed, surface inclination, slipping foot, and perturbation intensity, while collecting diverse data sets encompassing kinematic, spatiotemporal parameters, electromyographic data, as well as torque, range of motion, rotations per minute, detection, and actuation times. The biomechanical response to slip-like perturbations by the hips, knees, and ankles of the slipping leg was characterized by extension, flexion, and plantarflexion moments, respectively. In the trailing leg, responses included hip flexion, knee extension, and ankle plantarflexion. Additionally, these responses were influenced by gait speed, surface inclination, and perturbation intensity. Our study identified target range of motion parameters of 85.19°, 106.34°, and 95.23° for the hips, knees, and ankles, respectively. Furthermore, rotations per minute values ranged from 17.85 to 51.10 for the hip, 21.73 to 63.80 for the knee, and 17.52 to 57.14 for the ankle joints. Finally, flexion/extension torque values were estimated as -3.05 to 3.22 Nm/kg for the hip, -1.70 to 2.34 Nm/kg for the knee, and -2.21 to 0.90 Nm/kg for the ankle joints. This study contributes valuable insights into the biomechanical aspects of slip-like fall prevention and informs the development of wearable robotic systems to enhance safety in vulnerable populations.

Postoperative Supine Sleeping Position Following Total Knee Arthroplasty Decreases Knee Flexion Contractures

Background Total knee arthroplasty (TKA) is an orthopaedic operation that improves quality of life and reduces pain in patients with disabling arthritis of the knee. One commonly recognized postoperative complication is flexion contracture of the knee. While early physical therapy and range of motion (ROM) exercises have helped improve ROM postoperatively, flexion contractures still remain a significant postoperative complication of TKA. This study evaluated postoperative sleeping position and its effect on terminal knee extension and ROM following primary TKA. We hypothesized that patients who slept in the supine position would achieve earlier knee extension and ROM when compared to those in the lateral recumbent position. Methods A total of 150 consecutive primary total knee arthroplasties (TKAs) were conducted by a single surgeon (JMC). Prospective data collection included assessments of preoperative range of motion (ROM), postoperative ROM, patient-reported outcome measures, and sleeping positions. Functional outcomes and patient-reported measures were compared between pre- and postoperative phases, as well as across different sleeping position groups. Results Postoperative follow up was a mean of 29.6 days. Mean postoperative terminal extension ROM at one month was 2.98 degrees in the supine group versus 6.03 degrees in the lateral group (P &lt; 0.001). Overall, there was significant improvement in patient reported outcome measures (WOMAC, Oxford, and pain) after surgery, but no difference existed between sleeping groups. For knee extension, a two-way ANOVA revealed that there was a statistically significant interaction between the effects of surgery and sleep position (p = 0.0053). Conclusions Our results demonstrate that sleeping position does affect initial postoperative knee terminal extension; however, there is no effect on patient reported outcomes. We found a statistically significant difference in extension when comparing patients in the supine versus lateral group. Patients who slept in the lateral position lacked 6.03 degrees of extension which is greater than the 5 degrees threshold needed for normal gait mechanics. Conversely, those in the supine group only lacked 2.98 degrees of extension, allowing for normal gait mechanics. This study identifies an easy, effective means of increasing patient knee range of motion following TKA.

The influence of different intensity of Tan Tui exercises on the posture control of students in the Tai Chi Elective Course: protocol for a randomized controlled trial

BackgroundTai Chi (TC) holds a unique and valued place in promoting the physical and mental health of college students. Its significance is underscored by its incorporation as a compulsory physical education course in every university in China. TC, with its rich tradition, places a strong emphasis on posture control as a core sports ability. However, the students in Tai Chi Elective Course (TCEC) have very poor posture control ability. This study protocol investigates the potential of Tan Tui (TT) to address these issues, as TT is a fundamental skill for beginners of traditional Chinese martial arts and has a track record of enhancing lower limb strength and balance, making it a promising choice for improving posture control in TCEC.Methods/designTo investigate the impact of different intensities of TT exercises on posture control in TCEC students, we have designed a randomized, double-blind, parallel-controlled trial. Seventy-six students in the TCEC will be randomly divided into low-intensity Tan Tui (LTT), medium-intensity Tan Tui (MTT), and high-intensity Tan Tui exercises group (HTT) and control group (CON), each with 19 people. The LTT group, MTT group, and HTT group will be given different intensity of TT exercises, and the CON group will be given regular TCEC. The intervention period will be 6 weeks (2 times a week, 20 min each time). At baseline (before), 4 weeks of intervention (middle), and 6 weeks of intervention (after), the Unipedal Stance Test (UST), the Star Excursion Balance Test (SEBT), 60°/s angular velocity knee joint flexion and extension relative peak torque (RPT), and knee joint position perception (KJPP) will be evaluated.DiscussionThis is the first randomized controlled trial protocol from the perspective of training intensity to evaluate the effect of different intensity of TT exercises on posture control of students in TCEC. Should our research reveal a significant intervention effect, the results will offer preliminary, higher-quality evidence supporting the positive impact of varying intensities of Tan Tui exercises on posture control in TCEC students.Trial registrationChinese Clinical Trial Registry ChiCTR2000039109. Registered on October 17, 2020.

Comparative efficacy of muscle energy technique and Bowen technique on hamstrings muscle tightness in chronic low back pain patients.

To compare the effects of the Muscle Energy Technique (MET) and the Bowen Technique on hamstring muscle tightness in chronic low back pain (CLBP) patients. A randomized clinical trial (RCT) designed study in which 62 participants were recruited through the purposive sampling technique were divided into two groups by the lottery method. Subjects who had pain for more than six months in the back and hamstring tightness were included. The duration of the study was four months from February to May 2023 conducted at Madinah Teaching Hospital Faisalabad. Subjects in Group-A were given the Bowen technique, whereas subjects in Group-B were given the MET. Numeric pain rating scale (NPRS), Oswestry disability index (ODI), and active knee extension (AKE) tests were used for measurements of outcomes. Intra-group comparison by using Friedman test revealed that both Group-A & B subject's pain were reduced (P<0.000), their tightness in back thigh muscles were significantly reduced (P<0.000) and functional activities of subjects were also improved (P<0.000). Mann Whitney test was used to determine the between group comparison. P-value ≤ 0.05 was considered as significant. Inter Group-Analysis revealed that there was no statistically significant difference between effects of Bowen technique & MET on pain, hamstring tightness and disability as both techniques improved pain, flexibility & disability. This study revealed that both groups treated by MET and Bowen Technique had significantly reduced pain, improved flexibility of back thigh muscle and reduced functional disability.

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.

Caffeine, but not paracetamol (acetaminophen), enhances muscular endurance, strength, and power.

Caffeine is one of the most popular ergogenic aids consumed by athletes. Caffeine's ergogenic effect has been generally explained by its ability to bind to adenosine receptors, thus modulating pain and reducing perceived exertion. Another pharmacological agent that may improve performance due to its analgesic proprieties is paracetamol. This study aimed to explore the effects of caffeine, paracetamol, and caffeine + paracetamol consumption on muscular endurance, strength, power, anaerobic endurance, and jumping performance. In this randomized, crossover, double-blind study, 29 resistance-trained participants (11 men and 18 women) ingested either a placebo, caffeine (3 mg/kg), paracetamol (1500 mg) or caffeine + paracetamol 45 min before the testing sessions. The testing sessions included performing the bench press exercise with 75% of one-repetition maximum to momentary muscular failure, isokinetic knee extension and flexion at angular velocities of 60°/sec and 180°/sec, Wingate, and countermovement jump (CMJ) tests. Compared to placebo, isolated caffeine ingestion increased the number of repetitions performed in the bench press (p = 0.005; d = 0.42). Compared to placebo, isolated caffeine ingestion and/or caffeine + paracetamol consumption was ergogenic for strength (torque), muscular endurance (total work), or power in the isokinetic assessment, particularly at slower angular velocities (p = 0.027 to 0.002; d = 0.16 to 0.26). No significant differences between the conditions were observed for outcomes related to the Wingate and CMJ tests. This study provided novel evidence into the effectiveness of caffeine, paracetamol, and their combination on exercise performance. We found improvements in muscular endurance, strength, or power only when caffeine was consumed in isolation, or in combination with paracetamol. Isolated paracetamol consumption did not improve performance for any of the analyzed outcomes, thus calling into question its ergogenic potential.

Is There a Strength Deficit of the Quadriceps Femoris Muscle in Patients Treated Conservatively or Surgically after Primary or Recurrent Patellar Dislocations? A Systematic Review and Meta-Analysis.

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.

Feasibility and Reproducibility of Isokinetic Dynamometry in Children with Neuromuscular Diseases.

Background/Objectives: High-precision measurement tools are needed to measure relevant changes in strength and power in children with neuromuscular diseases. The aim of this study was to determine the feasibility (i), reproducibility (ii), and validity (iii) of isokinetic dynamometry in this population. Methods: Isometric and isokinetic knee and elbow flexion and extension were measured twice on the same day. Feasibility was based on completion rate and acceptability. Acceptability was measured with a 100 mm visual analog scale. We measured reproducibility as the intraclass correlation coefficient (ICC-agreement), standard error of measurement (SEM), and smallest detectable change (SDC). We investigated relationships between isometric strength and isokinetic power with Pearson's correlation coefficient. ROC curves were used to determine the cutoff of isometric strength to conduct isokinetic measurements. Results: Fifty children with NMDs participated with completion rates of 78-90% for isometric and 39-75% for isokinetic measurements. Acceptability was high (mean (SD) = 73 (19) mm). The ICCs for all measurements were over 0.9 (95% confidence interval (CI) = 0.932-0.998). The SEM% ranged from 5 to 14% and the SDC% from 14 to 28%. The correlations of strength and power were high (Pearson's correlation coefficient >0.9 (95% CI: 0.89-0.98)). The isometric strength needed to conduct isokinetic measurements ranged from 11.1 N in elbow flexors to 24.9 N in knee extensors. Conclusions: Isokinetic dynamometry is a feasible and reproducible method for measuring isometric strength in children with neuromuscular diseases with moderate weakness to normal strength, and isokinetic measurements are only feasible in knee extension for children with moderate weakness to normal strength. The convergent validity between isometric strength and power at low velocities is high.

Acute Effects of Soft Tissue Modalities on Muscular Ultrasound Characteristics and Isometric Performance

Prior to training, many athletes perform different soft-tissue preparation protocols. Many of these protocols involve stretching, foam rolling, and/or percussion massage. Many of these modalities have been studied, but not as a group to observe muscle alterations and differences in males and females. In total, 40 (20 males, 20 females) participants performed five minutes of static stretching, foam rolling, and percussion massage. Pre- and post-isometric leg strength, muscle activation and ultrasound assessments (cross-sectional area, echo intensity, pennation angle, fascicle length, and muscle thickness) were taken. The results indicate that there is no significant difference among modalities, and that they do not significantly alter any muscle characteristic or improve performance. There is a significant difference in size between males and female, with males having larger muscle and greater pennation angles than females. This allows males to generate significantly more muscle force. However, they both respond similarly to each modality. In conclusion, the muscle response to static stretching, foam rolling, and percussion massage do not differ among modalities and do not contribute to an increase or decrease in maximal isometric knee extension with similar effects between males and females.