Isometric Knee Flexor Strength Research Articles

Intersession reliability of lower limb muscle strength assessments in adults with obesity eligible for bariatric surgery.

The aim of this study was to examine the test-retest reliability in lower limb muscle strength and rate of torque development (RTD) using isokinetic dynamometry in adults with obesity, with a body mass index (BMI) ≥ 35 kg/m2. Thirty-two adults with a BMI of 43.8 ± 6.6 kg/m2 eligible for bariatric surgery were enroled in the study. Isokinetic and isometric knee extensor (KE) and flexor (KF) strength were assessed in an isokinetic dynamometer (Biodex 4) during three test sessions separated by 3-7 days. There were no statistical differences in peak KE and KF torque for any test modalities between sessions. Intraclass correlation (ICC) was 0.91-0.94 between sessions 1 and 2 and 0.94-0.97 between sessions 2 and 3. Standard error of measurement (SEM%) and coefficient of variation (CV) ranged across test sessions from 4.3% to 7.3%. KE RTD showed high test-retest reliability following familiarization, with ICC, CVand SEM% values ranging from 0.84 to 0.90, 13.3%-20.3%and 14.6%-24.9%, respectively. Maximal lower limb muscle strength measured by isokinetic dynamometry showed excellent test-retest reliability manifested by small measurement errors and low CV. Reliability was slightly improved by including a familiarization session. KE RTD but not KF RTD demonstrated high test-retest reliability following familiarization. The present data indicate that isokinetic dynamometry can be used to detect even small changes in lower limb muscle strength in adults with obesity.

Six Weeks of Unilateral Flywheel Hip-Extension and Leg-Curl Training Improves Flywheel Eccentric Peak Power but Does Not Enhance Hamstring Isokinetic or Isometric Strength.

This preregistered trial investigated how 6 weeks of unilateral flywheel leg-curl and hip-extension training impact isokinetic, isometric, and flywheel strength and power outcomes. The study involved 11 male university athletes (age 22 [2]y; body mass 77.2 [11.3]kg; height 1.74 [0.09]m) with one leg randomly allocated to flywheel training and one leg to control. Unilateral eccentric and isometric knee-flexion torque and flywheel unilateral leg-curl and hip-extension peak power were tested. Training intensity and volume (3-4 sets of 6 + 2 repetitions) were progressively increased. The intervention enhanced hip-extension concentric (P < .01, d = 1.76, large) and eccentric (P < .01, d = 1.33, large) peak power more than the control (significant interaction effect). Similarly, eccentric (P = .023, d = 1.05, moderate) peak power was enhanced for the leg curl. No statistically significant differences between conditions were found for isokinetic eccentric (P = .086, d = 0.77, moderate) and isometric (P = .431, d = 0.36, small) knee-flexor strength or leg-curl concentric peak power (P = .339, d = 0.52, small). Statistical parametric mapping analysis of torque-angle curves also revealed no significant (P > .05) time-limb interaction effect at any joint angle. Unilateral flywheel hamstring training improved knee-flexor eccentric peak power during unilateral flywheel exercise but not flywheel concentric, isokinetic eccentric, or isometric (long-lever) knee-flexor strength.

Low-load blood flow restriction strength training in patients with COPD: a randomised single-blind pilot study

ObjectiveThe objective of this study is to compare the effectiveness of lower limb low-load blood flow restriction training (LL-BFRT) with high-load strength training (HL-ST) as part of an outpatient pulmonary...

The Effect of Eccentric or Isometric Training on Strength, Architecture, and Sprinting across an Australian Football Season.

This study aimed to investigate the effect of an isometric (ISO) or Nordic hamstring exercise (NHE) intervention, alongside a sprint training program on hamstring strength, architecture, and sprinting performance in Australian footballers. Twenty-five male athletes undertook NHE ( n = 13) or ISO ( n = 12) training across a 38-wk period (including preseason and in season). Biceps femoris long head (BFlh) architecture, ISO, and eccentric knee flexor strength were assessed at baseline, at the end of preseason (14 wk), and at the conclusion of the intervention. Sprint times and force-velocity profiles were determined at baseline and at the end of preseason. After the intervention, both groups had significant improvements in BFlh fascicle length (NHE: 1.16 cm, 95% CI = 0.68 to 1.63 cm, d = 1.88, P < 0.001; ISO: 0.82 cm, 95% CI = 0.57 to 1.06 cm, d = 1.70, P < 0.001), muscle thickness (NHE: 0.11 cm, 95% CI = 0.01 to 0.21 cm, d = 0.51, P = 0.032; ISO: 0.21 cm, 95% CI = 0.10 to 0.32 cm, d = 0.86, P = 0.002), and eccentric strength (NHE: 83 N, 95% CI = 53 to 114 N, d = 1.79, P < 0.001; ISO: 83 N, 95% CI = 17 to 151 N, d = 1.17, P = 0.018). Both groups also finished the intervention weaker isometrically than they started (NHE: -45 N, 95% CI = -81 to -8 N, d = -1.03, P = 0.022; ISO: -80 N, 95% CI = -104 to -56 N, d = -3.35, P < 0.001). At the end of preseason, the NHE group had improved their 5-m sprint time by 3.3% ± 2.0%), and their maximum horizontal velocity was 3% ± 2.1% greater than the ISO group who saw no changes. Both ISO and NHE training with a periodized sprinting program can increase BFlh fascicle length, thickness, and eccentric strength in Australian footballers. NHE training also improves 5-m sprint time and maximum velocity. However, both interventions reduced ISO strength. These findings provide unique, contextually relevant insights into the adaptations possible in semiprofessional athletes.

Moderate-to-high Intensity Group Exercise Improves Function of Stroke Survivors (P12-8.009)

<h3>Objective:</h3> The aim of this study is to investigate the effect and feasibility of moderate-to-high intensity exercise in stroke survivors. <h3>Background:</h3> Post-stroke exercise need to be encouraged to facilitate optimal recovery and to improve both physical and mental health. However, stroke survivors are easily predisposed to sedentary lifestyle due to physical impairment and functional compromise. Moreover, many clinicians as well as patients tend to be discouraged by exercise-related risk of injury of falls or comorbidities. <h3>Design/Methods:</h3> This study is a randomized controlled trial. Subjects were randomly assigned to either intervention or control group. Subjects in intervention group completed 16 sessions of 90-minute moderate-to-high intensity group-based exercise for 8 weeks. Isometric muscle strength and grip strength of the affected and unaffected side, 10 repetition sit-to-stand test (STS10), 60 second sit-to-stand test (STS60), Short Physical Performance Battery (SPPB), multidirectional reach test, Berg’s Balance scale (BBS), 10-meter walk test, 6 minute walk test, Timed-up-and-go test, physiological cost index, Korean version of modified Barthel index, and Korean version of Montreal Cognitive Assessment (MoCA-K) were measured at baseline and postintervention. <h3>Results:</h3> Total 30 stroke survivors were enrolled in the study and 22 were randomized to group-based moderate-to-high exercise and 8 were randomzied to home-based low intensity exercise. Intervention group showed high compliance as well as high attendance rate. Adverse event was only 2 uneventful falls in 1 subject. After 8 weeks of moderate-to-high intensity group exercise, subjects showed significant improvement in isometric muscle strength of hip extensors and knee flexors and grip strength both in affected and unaffected limbs, and isometric muscle strength of affected shoulder abductor. Also, STS60, SPPB, BBS, and MoCA-K were significantly improved in the intervention group after 8-week of moderate-to-high intensity exercise. <h3>Conclusions:</h3> Moderate-to-high intensity group-based exercise is feasible and safe and improves physical and cognitive function of chronic stroke survivors. <b>Disclosure:</b> The institution of Prof. Jung has received research support from National Rehabilitation Center, Ministry of Health and Welfare, South Korea. Miss Cho has nothing to disclose. Mr. Yoon has nothing to disclose.

Reliability of a Custom Device Used to Measure Isometric Knee Flexor and Extensor Strength in Standing Position

Background: Assessing lower limb strength in the field is problematic, as the "gold standard assessment" with isokinetic strength is cumbersome, and the device is costly and not transportable and keeps the angle of the hip at around 90°. Methods: We evaluated isometric muscle strength in a standing position with the help of an exoskeleton that holds the subject and makes the test easily repeatable. Results: The optimal device angles for hip and knee were, respectively, 20° and 80° for flexor tests and 30° and 40° for extensor tests. Test-retest reliability was very high for the right knee extensor (ICC 0.96-0.98), left knee extensor (ICC 0.96-0.97), right knee flexor (ICC 0.91-0.96), and left knee flexor (ICC 0.96-0.97). Furthermore, the typical error in percent (T.E.%) ranged from 2.50 to 5.50%, and the change in the mean in percent ranged from 0.84 to 7.72%, making it possible to determine even a slight variation in force. Conclusions: this new method could represent a valid alternative for assessing strength, due to the high reliability and the favorable joint position, particularly in football.

Functional outcomes and length of stay with early and high-intensity rehabilitation after simultaneous bilateral total knee arthroplasty.

Length of stay and functional outcomes after total knee arthroplasty (TKA) are related to the timing and intensity of post-operative rehabilitation. To determine the effectiveness of early and high-intensity rehabilitation after simultaneous bilateral TKA. Prospective cohort data of 156 patients (11 men and 145 women; average age 72.0 ± 5.6 years) who underwent simultaneous bilateral primary TKA were analyzed. The intervention group (n= 82) underwent a high-intensity rehabilitation (phase II) after early postoperative standard rehabilitation (phase I) between June 2019 and May 2021. The control group (n= 74) underwent a lower-intensity rehabilitation (phase II) after phase I rehabilitation between July 2017 and May 2019. The timed up-and-go (TUG) test, timed stair climbing test (SCT), 6-minute walk test, isometric knee extensor and flexor strength of both knees, knee flexion and extension range of motion, Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) for pain, stiffness, and functional levels, and the EuroQol five-dimension questionnaire were assessed preoperatively and 6 weeks after TKA. The average length of hospital stay was shortened by 5.7 days (p< 0.001). Phase II rehabilitation started earlier in the intervention group than in the control group (7.7 ± 1.3 vs 13.5 ± 2.0, p< 0.001). Compared with the control group, the intervention group showed significant improvements in the measures of mobility (WOMAC-function and SCT) and strength (isometric strength of both knee extensors and flexors) 6 weeks after TKA by statistically controlling for age and preoperative functional status. This study demonstrated that early and high-intensity rehabilitation could achieve functional improvement and shorten the length of hospital stay.

Effect of intramuscular fat in the thigh muscles on muscle architecture and physical performance in the middle-aged women with knee osteoarthritis

BackgroundWe investigated intramuscular fat (IMF) in quadriceps femoris (QF) and hamstring muscles in the middle-aged women with knee osteoarthritis (KOA). We also examined the relationship between muscular infiltration of QF and hamstring muscles and muscle architecture and physical performance of the women with KOA. MethodsIn this cross-sectional study, 72 women were included. Body muscle and fat mass were measured by BIA, isometric muscle strength was evaluated by hand-held dynamometer. IMF and muscle architecture were calculated from rectus femoris (RF), vastus intermedius (VIM), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), semitendinosus (ST) and semimembranosus (SM) using B-mode ultrasonography. KOA-related symptoms and functions were assessed with KOOS. The functional performance assessments were evaluated with Stair Climbing Test, 20-Meter Walking Test. ResultsWomen with KOA had more IMF in RF, VIM, VL, VM and BF, ST, SM muscles compared to the healthy women. Pennation angles decreased as the IMF in the RF, VM, BF and ST decreased. As the IMF of the RF and VM increased isometric knee extensor strength decreased and KOOS symptom score, pain score and ADL score increased in women with KOA. Walking and stair climbing speed deteriorated as the IMF in RF, VIM, VM, BF increased in the middle-aged women. As the IMF in BF increased isometric knee flexor strength decreased and KOOS scores increased. Physical performance scores deteriorated as the IMF in BF increased in middle-aged women with KOA. ConclusionIMF in QF and hamstring muscles were higher in the middle-aged women with KOA group compared with that in the healthy group. Weakness of the QF and hamstring muscles may due to the changes in architectural properties of muscle depending on muscular infiltration. IMF in knee muscles is an important determining factor in performance and physical function of middle-aged women with KOA.

Study protocol for double-blind, randomised placebo-controlled trial evaluating semitendinosus function and morbidity following tendon harvesting for anterior cruciate ligament reconstruction augmented by platelet-rich plasma

IntroductionAnterior cruciate ligament (ACL) rupture is debilitating, often requiring surgical reconstruction. An ACL reconstruction (ACLR) using a tendon autograft harvested from the semitendinosus results in substantial injury to the donor...

Comparison of bilateral isokinetic and isometric strength differences in elite young male and female taekwondo athletes.

Definition of strength imbalance between legs and muscles does not only play a decisive role for higher performance but also prevents sport injury. The purpose of this study was to determine bilateral differences on isokinetic and isometric strength of knee extensor and flexor muscles in male and female elite young taekwondo athletes. Ten male (age: 19.40±0.84 years) and female (age: 18.24±1.42 years) taekwondo athletes of the Turkish national team between 17–20-year of age participated in the study. Concentric peak torque of hamstring (H) and quadriceps (Q) of the dominant (D) and nondominant leg (ND) was evaluated using isokinetic machine (Cybex Humac Norm) at 60° and 180°/sec. Isometric peak torque of both legs was determined at 60°. Significant differences were found between genders (P<0.05). Concentric and isometric knee strength was significantly greater in male than that of female (P< 0.05). Although no significant bilateral strength difference was found in both sexes in concentric and isometric strength (P>0.05), and isometric H strength was in favor of the dominant leg 15% for men athletes and 11% for women. H/Q ratio was similar between gender and legs. The study revealed no bilateral knee strength asymmetry in both male and female taekwondo athletes. However, male had 20%–30% higher isometric and concentric knee extensor and flexor strength than female in both legs.

The deficits of isometric knee flexor strength in lengthened hamstring position after hamstring strain injury

ObjectiveTo investigate the effects of knee flexion angle on peak torque, rate of torque development (RTD) during isometric contraction and hamstring flexibility after hamstring strain injury (HSI). DesignCross-sectional. SettingControlled laboratory research. ParticipantsFourteen male athletes with a history of HSI and 14 athletes without HSI (controls). Main outcome measuresHamstring flexibility was evaluated using active knee extension test. Isometric knee flexion peak torque and RTD were determined at 30°, 60°, and 90° of knee flexion measured by an isokinetic dynamometer. ResultsIndividuals with a history of HSI had statistically significant, moderate deficits in isometric peak torque at 30° of knee flexion (P = 0.037; effect size = 0.55) in the HSI limb than in the uninjured limb, but not at 60° and 90° of knee flexion. In the control group, no significant differences in isometric peak torque at any angle were found between limbs. No differences in peak RTD and flexibility were found between limbs in both groups. ConclusionsIsometric peak torque at 30° of knee flexion was lower in the injured limb than in the uninjured limb. Isometric strength deficits after HSI tended to be affected by lengthened hamstring angles.

Increased short interval intracortical inhibition in participants with previous hamstring strain injury.

Cortical mechanisms may contribute to weakness in participants with previous hamstring strain injury. This study aims to examine intra-cortical inhibition (SICI) and corticospinal excitability in previously injured participants. In this cross-sectional study, TMS was used to examine SICI, silent period, silent period: MEP ratios and area under the stimulus response curve in the biceps femoris and medial hamstrings. Comparisons were made between participants with (n = 10) and without (n = 10) previous hamstring strain injury. Motor threshold and isometric knee flexor strength were also compared between participants and the relationship between strength and SICI in control and previously injured participants was examined. Isometric knee flexor strength was lower in previously injured limbs compared with control limbs (mean difference = -41 Nm (-26%) [95% CI = -80 to -2 Nm], p = 0.04, Cohen's d = -1.27) and contralateral uninjured limbs (mean difference = -23 Nm (-17%), [95% CI = -40 to -6 Nm], p = 0.01, Cohen's d = -0.57). Previously injured limbs exhibited smaller responses to paired pulse stimulation (i.e. greater levels of SICI) in the biceps femoris compared with control limbs (mean difference = -19%, [95% CI = -34 to -5%], p = 0.007, Cohen's d = -1.33). Isometric knee flexor strength was associated with the level of SICI recorded in the biceps femoris in previously injured participants (coefficient = 23 Nm [95% CI = 7-40 Nm], adjusted R2 = 0.31, p = 0.01). There were no differences in markers of corticospinal excitability between previously injured and control limbs (all p > 0.24, all Cohen's d < 0.40). Athletes with previous injury in the biceps femoris exhibit increased SICI in this muscle compared with control participants. Increased SICI is related to lower levels of hamstring strength, and rehabilitation programs targeting the removal of intra-cortical inhibition should be considered.

Associations of fitness, motor competence, and adiposity with the indicators of physical activity intensity during different physical activities in children

We investigated the associations of peak oxygen uptake (V̇O2peak), ventilatory threshold (VT), muscle strength, motor competence (MC), and adiposity with the indicators of PA intensity during different physical activities used to create absolute PA intensity cut-offs among 35 children 7–11-years-of-age. V̇O2peak was defined as the highest V̇O2 achieved in the maximal cardiopulmonary exercise test (CPET) on a cycle ergometer, self-paced running, or running on a treadmill at 8 km/h. VT was defined from the CPET data. Peak isometric knee extensor and flexor strength was assessed by a dynamometer, MC by the Körperkoordination test für Kinder tests, and body composition by the bioelectrical impedance analysis. PA intensity was assessed using V̇O2 as a % of V̇O2reserve or V̇O2 at VT, mean amplitude deviation (MAD) measured by accelerometry, metabolic equivalent of task (MET), and muscle activity measured by textile electromyography during walking or running on a treadmill at 4, 6, and 8 km/h, playing hopscotch, walking up and down the stairs, self-paced walking, and self-paced running. Children with lower V̇O2peak, V̇O2 at VT, and MC operated at higher intensity level during given physical task than their peers with higher fitness and MC when PA intensity was expressed using relative PA intensity using V̇O2 as a % of V̇O2reserve or V̇O2 at VT (p < 0.05). MAD and METs during different tasks were not able to discriminate PA intensity between children with varying levels of physical fitness or MC. Traditionally used absolute measures of PA intensity based on accelerometry or MET underestimated PA intensity in children with lower V̇O2peak, V̇O2 at VT, and MC.

Performance-based physical function correlates with walking speed and distance at 3 months post unilateral total knee arthroplasty.

After total knee arthroplasty (TKA), walking speed and distance are main concerns of patients. Which physical functions affect walking speed and distance after TKA? Cross-sectional data from 149 patients who underwent unilateral primary TKA and completed performance-based physical function tests. Instrumental gait evaluation for spatiotemporal parameters, isometric knee extensor and flexor strength of both knees, 6-minute walk test (6MWT), timed up-and-go (TUG) test, timed stair climbing test (SCT), and knee flexion and extension range of motion (ROM) of surgical knee were examined. Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and EuroQol five dimensions (EQ-5D) questionnaires were also performed. Univariate analyses revealed that post-operative walking speed showed significant positive correlations with cadence, stride length, propulsion index of surgical and non-surgical knee, peak torque (PT) of the extensor of surgical and non-surgical knee and flexor of surgical and non-surgical knee, 6MWT, EQ-5D, and significant negative correlations with gait cycle duration, TUG, SCT-ascent and descent, and WOMAC-pain scores. Post-operative walking distance had significant positive correlations with walking speed, cadence, stride length, swing phase duration, propulsion index of surgical and non-surgical knee, PT of the extensor of surgical and non-surgical knee, EQ-5D, and significant negative correlation with gait cycle duration, double support duration, TUG, SCT-ascent and descent. In the multivariate linear regression analyses, TUG, cadence, stride length and propulsion index of non-surgical knee were factor correlated with post-operative walking speed. The SCT-ascent and descent, TUG and propulsion index of surgical knee were factor correlated with post-operative walking distance. Physical performance factors correlated with walking speed and distance at 3 months after surgery. Based on these observations, rehabilitation of bilateral muscle strength and functional mobility would be important for functional recovery after unilateral TKA.

Knee flexor strength and rate of torque development deficits in women with patellofemoral pain are related to poor objective function

BackgroundDeficits in knee flexor strength and rate of torque development (RTD) might be present in women with patellofemoral pain (PFP). In addition, maximal strength and RTD of the knee flexors and extensors might be related with subjective and objective function in women with PFP. However, both conjectures are still poorly understood. Research questionDo women with PFP have deficits in the maximal strength and RTD of the knee flexors and extensors during isometric, concentric, and eccentric contractions? Is there a relationship between maximal strength and RTD of the knee flexors and extensors with subjective and objective function in women with PFP? MethodsFifty-six women with, and 46 women without, PFP participated. Maximal strength and RTD (to 30% and 60% maximal torque) during isometric, concentric, and eccentric contractions of the knee flexors and extensors were assessed using an isokinetic dynamometer. Objective assessment included single leg hop test (SLHT) and forward step-down test (FSDT). Subjective assessment involved the anterior knee pain scale. ResultsWomen with PFP had small to large deficits in maximal strength and RTD of the knee flexors and extensors during isometric, concentric and eccentric contractions (Effect sizes: -0.43 to -1.10; p ≤ 0.016). Small to moderate correlations of maximal concentric and eccentric knee flexor strength and RTD with SLHT and FSDT (r = 0.28 to 0.41; p ≤ 0.037) were identified. Subjective or objective function were not correlated with maximal isometric knee flexor strength and RTD, or any knee extensor measures (p > 0.05). SignificanceMaximal strength and RTD deficits of the knee flexors and extensors were identified in this female PFP cohort, but they were unrelated to subjective function. The relationship of concentric and eccentric knee flexor strength and RTD deficits with poor objective function should be considered in future exercise trials for women with PFP.

Strength, Jumping and Change of Direction Speed Asymmetries in Soccer, Basketball and Tennis Players

Despite growing research in the field of inter-limb asymmetries (ILAs), little is known about the variation of ILAs in different populations of athletes. The purpose of this study was to compare ILAs among young basketball, soccer and tennis players. ILAs were assessed in three different types of tests (strength, jumping and change of direction (CoD) speed), each including different tasks: (1) bilateral and unilateral counter movement jump, (2) isometric strength of knee extensors (KE) and knee flexors (KF), and (3) 90° and 180° CoD. Generally, the absolute metrics showed strong reliability and revealed significant differences (p &lt; 0.05) among the three groups in KE maximal torque, KE and KF rate of force development and in both CoD tests. For jumping ILAs, power and force impulse metrics exhibited significant between-limb differences between groups, compared to jump height. For strength and CoD speed ILAs, only KF maximal torque and 180° CoD exhibited significant differences between groups. Greater KF strength ILAs in soccer players and counter-movement jump ILAs in tennis players are most probably the result of sport-specific movement patterns and training routines. Sport practitioners should be aware of the differences in ILAs among sports and address training programs accordingly.

Hamstring strength and architectural adaptations following inertial flywheel resistance training

ObjectivesTo investigate the architectural and strength adaptations of the hamstrings following 6-weeks of inertial flywheel resistance training. DesignRandomised, stratified training intervention MethodsTwenty healthy males undertook 6-weeks of a conventional (n=10) or eccentrically biased (n=10) flywheel leg-curl training intervention as well as a subsequent 4-week detraining period. Biceps femoris long head (BFlh) architecture was assessed weekly, whilst assessments of eccentric and isometric knee flexor strength and rate of force development (RFD) were conducted prior to and following the intervention and detraining periods. ResultsThe participants who undertook the eccentrically biased flywheel intervention showed a significant 14±5% (p<0.001, d=1.98) increase in BFlh fascicle length after 6-weeks of training. These improvements in fascicle length subsequently declined by 13±4% (p<0.001. d=-2.04) following the 4-week detraining period. The conventional flywheel leg-curl training group saw no changes in BFlh fascicle length after the intervention (-0.5%±0.8%, p=0.939, d=-0.04) or detraining (-1.1%±1%, p=0.984, d=-0.03) periods. Both groups saw no changes in any of the strength or RFD variables after the intervention or the detraining period. ConclusionsFlywheel leg-curl training performed with an eccentric bias led to significant lengthening of BFlh fascicles without a change in RFD, eccentric or isometric strength. These increases in fascicle length were lost following a 4-week detraining period. Conventional flywheel leg-curl training resulted in no changes in fascicle length, strength and RFD. These findings suggest that additional eccentric bias is required during inertial flywheel resistance training to promote fascicle lengthening in the BFlh, however this may still be insufficient to cause alterations to strength and RFD.

Knee extensor and flexor strength in elderly women after recent hip fracture: assessment by the Cybex 6000 dynamometer of intra-rater inter-test reliability

The reliability of knee extensor and flexor strength measurements was assessed in 20 women (aged 68-88 years) who had experienced a hip fracture two to four weeks before but who were otherwise healthy. Using the Cybex 6000 isokinetic dynamometer, isokinetic knee extensor and flexor strength (peak torque, total work and power) at 30 and 120 degree/second and isometric knee extensor and flexor strength (peak torque) were measured by the same examiner in both legs, successively, on four separate days within one week. Compared with the non-involved leg, the median reduction in peak extensor and flexor torque of the involved leg was 50% (p

The role of body mass index on dynamic balance and muscle strength in Saudi schoolchildren

The aim of this study is to investigate the effects of increased body mass on the performance of the dynamic balance (LQYBT) and isometric muscle strength (peak torque) in healthy weight (HW), overweight (OW), and obese (O) schoolchildren. Cross sectional design. Participants included 51 male schoolchildren, aged 12 to 15 years from King Saud educational complex-The Middle School, Riyadh. Dynamic balance was analyzed by Lower quarter Y balance test (LQYBT) and isometric muscle strength of knee extensors and flexors with Handheld Dynamometry (HHD). The dynamic balance scores of HW children, in the right anterior (AT) direction, were significantly different from OW and O children ( P = 0.010), but no differences were found between O and OW children. Significant differences were shown in the strength of the extensor and flexor muscles of both limbs in HW, OW, and O children (extensors left: F = 11.853, right: F = 7.660; P = 0.001; flexors left: F = 16.417, right: F = 4.576; P = 0.001). Knee extensors and flexors in the HW group were significantly positively correlated with the reach scores of right AT direction, but none with the other directions. There was a significant positive correlation between BMI and Hamstring strength, while this correlation is far less obvious with the quadriceps. The findings imply that increased BMI reduces balance ability in anterior reach direction (LQYBT) and none in other directions. The isometric strength of obese children was different from the healthy weight children. Le but de cette УЉtude est dт€™УЉtudier les effets de lт€™augmentation de la masse corporelle sur la performance de lт€™УЉquilibre dynamique (LQYBT) et la force musculaire isomУЉtrique (pic de couple de force) chez des УЉcoliers de poids normal (HW), en surpoids (OW) et obУЈses (O). У‰tude transversale. Parmi les participants figuraient 51Т УЉcoliers de 12Т У 15Т ans du complexe УЉducatif King SaudТ т€“Т The Middle School , Riyadh. La stabilitУЉ dynamique a УЉtУЉ analysУЉe avec le test Balance Y pour les membres infУЉrieurs (LQYBT) et la force musculaire isomУЉtrique des extenseurs et des flУЉchisseurs du genou par dynamomУЉtrie manuelle (HHD). Les scores dт€™УЉquilibre dynamique des enfants HW, dans la direction antУЉrieure droite (AT), УЉtaient significativement diffУЉrents de ceux des enfants OW et O ( p = 0,010), mais aucune diffУЉrence nт€™a УЉtУЉ constatУЉe entre les enfants OW et O. Des diffУЉrences significatives ont УЉtУЉ mises en УЉvidence dans la force des muscles extenseurs et flУЉchisseurs des deux membres chez les enfants HW, OW et O (extenseurs У gaucheТ : F = 11,853, У droiteТ : F = 7,660Т ; p = 0,001Т ; flУЉchisseurs У gaucheТ : F = 16,417, У droiteТ : F = 4,576Т ; p = 0,001). Les extenseurs et les flУЉchisseurs du genou du groupe HW УЉtaient significativement corrУЉlУЉs positivement avec les scores dт€™atteinte de la bonne direction, mais pas avec les autres directions. Il y avait une corrУЉlation positive significative entre lт€™IMC et la force des ischio-jambiers, alors que cette corrУЉlation est beaucoup moins УЉvidente avec le quadriceps. Les rУЉsultats impliquent quт€™une augmentation de lт€™IMC rУЉduit la capacitУЉ dт€™УЉquilibre dans la direction de la portУЉe antУЉrieure (LQYBT) et pas dans les autres directions. La force isomУЉtrique des enfants obУЈses УЉtait diffУЉrente de celle des enfants en bonne santУЉ.

Pain-Free Versus Pain-Threshold Rehabilitation Following Acute Hamstring Strain Injury: A Randomized Controlled Trial.

The primary aim was to compare time from acute hamstring strain injury (HSI) to return-to-play (RTP) clearance following a standardized rehabilitation protocol performed within either pain-free or pain-threshold limits. Secondary aims were to compare isometric knee flexor strength, biceps femoris long head (BFLH) fascicle length, fear of movement, and reinjury occurrence at the 6-month follow-up between pain-free and pain-threshold groups. Randomized controlled trial. Forty-three men with acute HSIs were randomly allocated to a pain-free (n = 22) or pain-threshold (n = 21) rehabilitation group. Days from HSI to RTP clearance, isometric knee flexor strength, BFLH fascicle length, fear of movement, and reinjury occurrence at the 6-month follow-up were reported. Median time from HSI to RTP clearance was 15 days (95% confidence interval [CI]: 13, 17) in the pain-free group and 17 days (95% CI: 11, 24) in the pain-threshold group, which was not significantly different (P = .37). Isometric knee flexor strength recovery at 90° of hip and 90° of knee flexion was greater in the pain-threshold group at RTP clearance by 15% (95% CI: 1%, 28%) and by 15% (95% CI: 1%, 29%) at 2-month follow-up, respectively. Improvement in BFLH fascicle length from baseline was 0.91 cm (95% CI: 0.34, 1.48) greater at 2-month follow-up in the pain-threshold group. Two reinjuries occurred in both the pain-free and pain-threshold groups between RTP clearance and the 6-month follow-up. Pain-threshold rehabilitation did not accelerate RTP clearance, but resulted in greater recovery of isometric knee flexor strength and better maintenance of BFLH fascicle length, compared to pain-free rehabilitation. J Orthop Sports Phys Ther 2020;50(2):91-103. Epub 28 Jun 2019. doi:10.2519/jospt.2020.8895.