Isokinetic Knee Extensor Strength Research Articles

A RANDOMIZED CONTROLLED TRIAL INVESTIGATING PATIENT RECOVERY AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION UNDERTAKEN WITH A QUADRICEPS VERSUS HAMSTRINGS TENDON AUTOGRAFT

INTRODUCTION & AIMS Anterior cruciate ligament (ACL) tears are common. However, a lack of high-quality evidence exists comparing different graft options in patients undergoing surgical reconstruction (ACLR). This randomized controlled trial (RCT) investigated the course of recovery in patients undergoing ACLR with either a quadriceps (QT) or hamstrings (HT) tendon autograft. METHODS This study randomized 112 patients to one of the two graft reconstruction cohorts (HT=55, QT=57), subsequently undergoing ACLR and a structured rehabilitation program. Patients were assessed pre-surgery and at 6 weeks and 3, 6, 12 and 24 months, with a range of patient-reported outcome measures (PROMs) including the International Knee Documentation Committee form (IKDC) and the Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) score. Graft laxity, peak isokinetic knee extensor and flexor strength and a 6-hop performance battery were assessed. Limb Symmetry Indices (LSIs) were calculated. RESULTS All PROMs significantly improved (p<0.0001). Apart from the ACL-RSI score which was significantly better (p<0.05) in the HT group at 3, 6 and 12 months, no other group differences (p>0.05) were observed. No group differences (p=0.407) were observed for knee laxity. While the HT group demonstrated significantly greater (p<0.05) quadriceps strength LSIs at 6 and 12 months, the QT group demonstrated significantly greater (p<0.05) hamstrings strength LSIs at 6, 12 and 24 months. The HT group demonstrated significantly greater (p<0.05) LSIs for the single horizontal (6 months), lateral (6 and 12 months) and medial (6 months) hop tests. CONCLUSION The HT group reported a higher level of psychological readiness to return to sport, while demonstrating greater quadriceps strength (and hop test) LSIs. Greater hamstring strength LSIs were observed for the QT cohort. Longer-term review will continue to evaluate RTS and later-stage re-injury between the two graft constructs.

A RANDOMIZED CONTROLLED TRIAL INVESTIGATING FUNCTIONAL RECOVERY AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING A SINGLE VERSUS DOUBLE TENDON HARVEST

INTRODUCTION & AIMS Anterior cruciate ligament (ACL) tears are common. While surgical reconstruction (ACLR) is commonly advocated and a hamstring autograft is the popular choice, hamstring tendon harvest has been linked to reduced hamstring strength and ongoing donor site pain. While traditional surgical techniques required a harvest of both semitendinosus/gracilis tendons, modern harvesting and fixation methods permit a shorter, broader harvest of semitendinosus only. This study investigated donor site pain, strength and functional recovery in patients undergoing ACLR via a single (ST) versus dual (DT) tendon hamstring harvest. METHODS This prospective randomized controlled trial (RCT) allocated 138 patients to ACLR with one of the two hamstring tendon graft options (ST=71, DT=67) followed by a structured rehabilitation program. Patients were assessed pre-surgery and at 3, 6, and 12 months, with a range of patient-reported outcome measures (PROMs) including a validated donor-site morbidity score. Graft laxity, peak isokinetic knee extensor and flexor strength and a 6-hop performance battery were assessed. Limb Symmetry Indices (LSIs) were calculated. RESULTS All PROMs significantly improved (p<0.0001) and were largely similar between groups (p>0.05), apart from significantly less graft morbidity reported in the ST group (p=0.001). No group differences were observed for knee laxity or LSIs for hop measures (p>0.05), nor the LSIs for peak knee flexor (p=0.113) or extensor (p=0.286) torque. CONCLUSION While the ST ACLR group reported significantly less harvest site morbidity, no other subjective or functional differences were observed in patients undergoing ACLR with either a single or dual hamstring tendon autograft harvest.

Assessing the efficacy of the Stop OsteoARthritis (SOAR) program: A randomized delayed-controlled trial in persons at increased risk of early onset post-traumatic knee osteoarthritis

ObjectiveAssess the efficacy of an 8-week virtual, physiotherapist (PT)-guided knee health program (SOAR) to improve knee extensor strength in individuals at risk of post-traumatic knee osteoarthritis (PTOA). MethodIn this superiority, randomized delayed-control trial, persons aged 16-35 years, 1-4 years after a self-reported knee joint injury were randomly assigned (1:1) to receive the SOAR program immediately (experimental group) or after a 9-week delay (control group). SOAR includes 1) one-time Knee Camp (virtual PT-guided group education, knee assessment, 1:1 exercise and physical activity goal-setting); 2) Weekly personalized home-based exercise and physical activity program with tracking; 3) Weekly 1:1 PT counseling (virtual). The primary outcome was change in isokinetic knee extensor strength (baseline to 9-weeks). Additional outcomes included change in self-reported knee-related quality-of-life (QOL), self-efficacy, self-management and kinesiophobia, and physical activity (accelerometer) at 9 and 18-weeks. Linear regression models estimated the effect of the 8-week intervention at the primary endpoint (9-week). Results49 of 54 randomized participants completed the study (91%). Participants were a mean±SD age of 27±5.0 years, and 2.4±0.9 years post-injury. No mean between group differences for the primary (0.05; 95%CI: -0.10,0.19) or other outcomes were seen at 9 weeks except for greater improvements in perceived self-management (Partner in Health Scale; 11.3/96, 95%CI: 5.5,17.1) and kinesiophobia (Tampa Scale of Kinesiophobia; -4.4/33, 95%CI: -7.0,-1.8). ConclusionFor active persons with elevated risk of PTOA, an 8-week SOAR program did not change knee-related strength, QOL, self-efficacy, or physical activity, on average, but may benefit the ability to self-manage knee health and kinesiophobia.

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.

Feasibility of Mobile Health App-Based Home Aerobic Exercise for Physical Performance in Healthy Young Adults.

To investigate the feasibility and effects of a mobile app-based home cycling exercise program compared to home cycling exercise without additional monitoring system. Compared with fitness facilities or outdoor exercise, home-based exercise programs effectively improve physical performance in an indwelling community. However, a flexible, informal environment may decrease motivation and impair adherence to physical exercise. Mobile devices for aerobic exercise and mobile applications provide real-time monitoring, immediate feedback, and encouragement to increase motivation and promote physical performance. We investigated the feasibility and effects of a mobile app-based home exercise program on body composition, muscular strength, and cardiopulmonary function. Between February and May 2023, 20 participants were randomly allocated to the intervention (mobile application with a tablet) and control groups, and they performed aerobic exercise using a stationary bicycle for ≥150 minutes per week for 6 weeks (≤30-minute exercise session, with 3-minute warm-up and 3-minute cool-down). Karvonen formula-based heartrate defined the weekly increase in exercise intensity. Outcome measures included body-composition parameters, isokinetic knee flexor and extensor strength tests, cardiopulmonary exercise test results, and rate of target heart rate (HR) achievement. Participants were assessed at baseline and after the intervention. Unrelated personal events led two participants to drop out. The intervention and control groups had similar baseline characteristics. Compared with the control group, in the post-intervention isokinetic strength test, bilateral knee flexor and extensor power, and time to target HR achievement significantly increased each week in the intervention group. Home-based exercise to achieve long-term cardiovascular fitness with portable electronic/mobile devices facilitates individualized exercise using real-time feedback to improve motivation and adherence.

10-Year Prospective Clinical and Radiological Evaluation After Matrix-Induced Autologous Chondrocyte Implantation and Comparison of Tibiofemoral and Patellofemoral Graft Outcomes

Background: Long-term outcomes in larger cohorts after matrix-induced autologous chondrocyte implantation (MACI) are required. Furthermore, little is known about the longer-term clinical and radiological outcomes of MACI performed in the tibiofemoral versus patellofemoral knee joint. Purpose: To present the 10-year clinical and radiological outcomes in patients after MACI and compare outcomes in patients undergoing tibiofemoral versus patellofemoral MACI. Study Design: Case series; Level of evidence, 4. Methods: Between September 2002 and December 2012, 204 patients who underwent MACI were prospectively registered into a research program and assessed preoperatively and at 2, 5, and 10 years postoperatively. Of these patients, 168 were available for clinical review at 10 years, with 151 (of a total of 182) grafts also assessed via magnetic resonance imaging (MRI). Patients were evaluated using the Knee injury and Osteoarthritis Outcome Score, a visual analog scale for pain frequency and severity, satisfaction, and peak isokinetic knee extensor and flexor strength. Limb symmetry indices (LSIs) were calculated for strength measures. Grafts were scored on MRI scans via the MOCART (magnetic resonance observation of cartilage repair tissue) system, with a focus on tissue infill and an overall MRI graft composite score. Results: All patient-reported outcome measures improved (P < .0001) up to 2 years after surgery. Apart from the significant increase (P = .004) in the peak isokinetic knee extensor LSI, no other patient-reported outcome measure or clinical score had changed significantly from 2 to 10 years. At the final follow-up, 92% of patients were satisfied with MACI to provide knee pain relief, with 76% satisfied with their ability to participate in sports. From 2 to 10 years, no significant change was seen for any MRI-based MOCART variable nor the overall MRI composite score. Of the 151 grafts reviewed via MRI at 10 years, 14 (9.3%) had failed, defined by graft delamination or no graft tissue on MRI scan. Furthermore, of the 36 patients (of the prospectively recruited 204) who were not available for longer-term review, 7 had already proceeded to total knee arthroplasty, and 1 patient had undergone secondary MACI at the same medial femoral condylar site because of an earlier graft failure. Therefore, 22 patients (10.8%) essentially had graft failure over the period. At the final follow-up, patients who underwent MACI in the tibiofemoral (vs patellofemoral) joint reported significantly better Knee injury and Osteoarthritis Outcome Score subscale scores for Quality of Life (P = .010) and Sport and Recreation (P < .001), as well as a greater knee extensor strength LSI (P = .002). Even though the tibiofemoral group demonstrated better 10-year MOCART scores for tissue infill (P = .027), there were no other MRI-based differences (P > .05). Conclusion: This study reports the long-term review of a prospective series of patients undergoing MACI, demonstrating good clinical scores, high levels of patient satisfaction, and acceptable graft survivorship at 10 years. Patients undergoing tibiofemoral (vs patellofemoral) MACI reported better long-term clinical outcomes, despite largely similar MRI-based outcomes.

Bilateral differences of isokinetic knee extensor strength are velocity- and task-dependent

ABSTRACT The purpose of this study was to investigate the concordance of isokinetic bilateral strength differences of the knee extensors in single- and multi-joint movement tasks. One hundred and nineteen male athletes performed isokinetic legpresses at 0.1 m/s and 0.7 m/s as well as isokinetic knee extensions at 60°/s and 180°/s. Bilateral differences and directed bilateral differences (sign indicating the direction of the difference) were calculated for all measurements. Bland-Altman-Plots were plotted to investigate if the different conditions detect bilateral differences of the same magnitude. Additionally, concordance correlations for the directed bilateral differences of the different tests were calculated to investigate magnitude and direction. The results indicate poor to fair concordance between the bilateral differences in the legpress conditions as well as between single- and multi-joint tasks. The single-joint knee extensions displayed a moderate level of agreement. Bilateral strength differences in isokinetic movement tasks are dependent on movement velocity and the nature of the task (single- or multi-joint movement) in the lower extremities. Both the value and the direction of the strength differences show no clear pattern across the investigated measurements and cannot be used interchangeably. Therefore, to assess interlimb strength balance, multiple different tests should be performed.

Relationships of lower extremity and trunk asymmetries in elite soccer players.

In light of previous research highlighting the prevalence of asymmetries in soccer players and possible links to injury risks, there is a crucial gap in the biomechanical understanding of complex relationships between lower extremity and trunk asymmetries in elite soccer players. The purpose of this study was to investigate the level, relationships, and differences among twelve different parameters of strength, morphological, and neuromuscular asymmetries in elite soccer players. Methods: Elite male soccer players (n = 25, age 21.7 ± 3.9years) were tested in the following tests: bilateral fluid distribution, hip flexor range of motion, postural stability, isokinetic strength of knee extensors and flexors, isometric lateral trunk rotation strength, eccentric strength of knee flexors, isometric bilateral strength of hip adductors, and vertical ground reaction force in counter-movement jump-free arms, counter-movement jump, squat jump, and drop jump tests. One-way ANOVA, Pearson's coefficient (r), and partial eta squared (η p 2) were used for data analysis. Results: Significant differences in asymmetries were found in elite soccer players (F11,299 = 11.01, p < .01). The magnitude of asymmetry over 10% was in postural stability and drop jump parameters. The lowest magnitudes of asymmetries were in the fluid distribution of the lower limbs and the vertical ground reaction force during the take-off phase in squat jumps. The highest asymmetries between the dominant and non-dominant sides were found in postural stability and drop jump. A total of eleven significant correlations (p < 0.05, r = 0.41-0.63, R2 = 0.17-0.40) were detected between the analyzed asymmetries in elite soccer players. The lateral trunk rotation asymmetries were significantly correlated to vertical ground reaction force asymmetries and knee extensors. Conclusion: Long-term exposure in elite soccer leads to unilateral biomechanical loading that induces abnormal strength and morphological adaptations in favor of the dominant side while linking lower limb and trunk strength asymmetries. By unraveling these complex relationships, we strive to contribute novel methods that could inform targeted training regimens and injury prevention strategies in the elite soccer community. The data should encourage future researchers and coaches to monitor and develop trunk strength linked to lower body kinematics.

A Prospective Randomized Controlled Trial Investigating Quadriceps Versus Hamstring Tendon Autograft in Anterior Cruciate Ligament Reconstruction

Background: Numerous graft options are available when undertaking anterior cruciate ligament (ACL) reconstruction (ACLR), although a lack of high-quality evidence exists comparing quadriceps (QT) and hamstring (HT) autografts. Purpose: To investigate patient outcomes in patients undergoing HT versus QT ACLR. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: After recruitment and randomization, 112 patients (HT = 55; QT = 57) underwent ACLR. Patients were assessed pre- and postoperatively (6 weeks and 3, 6, 12, and 24 months), with a range of patient-reported outcome measures (PROMs), graft laxity (KT-1000 arthrometer; primary outcome variable), active knee flexion and extension range of motion (ROM), peak isokinetic knee extensor and flexor strength, and a 6-hop performance battery. Limb symmetry indices (LSIs) were calculated for strength and hop measures. Secondary procedures, ACL retears, and contralateral ACL tears were reported. Results: All PROMs and knee ROM measures significantly improved (P < .0001), and no other group differences (P > .05) were observed—apart from the Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) score, which was significantly better in the HT group at 3 (P = .008), 6 (P = .010), and 12 (P = .014) months. No significant changes were observed in side-to-side laxity from 6 to 24 months (P = .105), and no group differences were observed (P = .487) at 6 (HT mean, 1.2; QT mean, 1.3), 12 (HT mean, 1.1; QT mean, 1.3), and 24 (HT mean, 1.1; QT mean, 1.2) months. While the HT group demonstrated significantly greater (P < .05) quadriceps strength LSIs at 6 and 12 months, the QT group showed significantly greater (P < .05) hamstring strength LSIs at 6, 12, and 24 months. The HT group showed significantly greater (P < .05) LSIs for the single horizontal (6 months), lateral (6 and 12 months), and medial (6 months) hop tests for distance. Up until 24 months, 1 patient (QT at 22 months) had a retear, with 2 contralateral ACL tears (QT at 19 months; HT at 23 months). Secondary procedures included 5 in the HT group (manipulation under anesthesia, notch debridement, meniscal repair, and knee arthroscopy for scar tissue) and 6 in the QT group (notch debridement, meniscal repair, knee arthroscopy for scar tissue, tibial tubercle transfer, and osteochondral autologous transplantation). Conclusion: Apart from the ACL-RSI, the 2 autograft groups compared well for PROMs, knee ROM, and laxity. However, greater hamstring strength LSIs were observed for the QT cohort, with greater quadriceps strength (and hop test) LSIs in the HT cohort. The longer-term review will continue to evaluate return to sports and later-stage reinjury between the 2 graft constructs. Registration: ACTRN12618001520224p (Australian New Zealand Clinical Trials Registry).

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

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

Cadmium exposure is associated with decreased muscle strength in middle-aged and older adults.

Cadmium, a toxic heavy metal, is ubiquitous in the environment. No previous research has evaluated the relationship of blood and urine cadmium levels with muscle strength measured by isokinetic knee extensor strength. This analysis included participants who were aged 50 years or older and had measurements of cadmium in blood (n = 2052) and urine (n = 811) from the National Health and Nutrition Examination Survey. Blood and urine cadmium levels were assessed by atomic absorption spectrometry and inductively coupled plasma-mass spectrometry, respectively. Isokinetic dynamometry was used to assess knee extensor strength (peak force). Linear regression models were used to examine the association between cadmium exposure and peak force, with adjustment for potential confounders. The median values (25-75th percentiles) of blood cadmium and creatinine-corrected urine cadmium were 0.50 μg/L (0.40-0.70) and 0.43 μg/g (0.27-0.71), respectively. After adjusting for potential confounders, linear dose-response relationships of peak force with blood and urine cadmium concentrations were observed in the present study. Compared to participants in the highest quartile of blood cadmium and urine cadmium, the peak force decreased by 6.99 Newton (95% CI: -21.96, 7.98) and 26.84 Newton (95% CI: -44.34, -9.34) in participants in the lowest quartiles, respectively. The observed associations were more evident among men participants. Our findings suggest that the cadmium levels have a dose response relationship with decreased muscle strength measured by isokinetic knee extensor strength in middle aged and older adults. Further longitudinal investigations are required to disentangle these complexities on this issue.

Paper 54: Long Term Clinical and Radiological Review of Matrix-Induced Autologous Chondrocyte Implantation

Objectives: Long-term outcomes following matrix-induced autologous chondrocyte implantation (MACI) are required to better demonstrate later-stage clinical outcomes, patient satisfaction and longevity of repair tissue. This prospective study sought to present the long-term (minimum 10 year) clinical and radiological outcomes of the largest prospectively assessed MACI dataset yet to be reported and compare outcomes in patients undergoing tibiofemoral (TF) versus patellofemoral (PF) MACI. Methods: Between September 2002 and December 2012, 204 patients that underwent MACI were prospectively registered into a research program and assessed pre-surgery and at 2, 5 and 10 years. Of these, 168 patients (182 grafts) were available for clinical review at a minimum 10 years (range 10 to 16 years), of which 151 also underwent MRI. Included in the 182 MACI grafts with minimum 10-year review were: 83 medial femoral condyle (MFC), 32 lateral femoral condyle (LFC), 35 trochlea and 32 patella. Clinically, patients were evaluated with the Knee Injury and Osteoarthritis Outcome Score (KOOS), the 36-item Short Form Health Surveys (SF-36), a visual analogue scale for pain frequency (VAS-F) and severity (VAS-S), satisfaction and peak isokinetic knee extensor and flexor strength. Limb symmetry indices (LSIs) were calculated for strength measures. Grafts were scored on MRI via the magnetic resonance observation of cartilage repair tissue (MOCART) system, with a focus on tissue infill and an overall MRI graft composite score. Results: All PROMs significantly improved (p&lt;0.0001) over the pre- and post-operative period to 2-years post-surgery (Figure 1), with no statistical change (p&gt;0.05) from 2-years to final 10-year follow-up. While the peak isokinetic knee extensor LSI improved significantly over time (p=0.016), at final follow up the mean LSI for peak isokinetic knee flexor and extensor strength was 99.1% and 92.8%, respectively. At final follow-up, 93% of patients were satisfied with MACI to provide knee pain relief, 77% were satisfied with their ability to participate in sports and 89% were satisfied overall. A statistically significant decline was observed from 5 years post-surgery to final follow-up in the MOCART variable of subchondral lamina (p=0.002), while a non-statistical decline was observed in tissue infill (p=0.066) and the overall MRI composite score (p=0.072) (Figure 2), with the MRI-based progression of one patient over the period demonstrated in Figure 3. Of the 151 grafts reviewed via MRI at 10 years or beyond, 14 (9.3%) had failed as defined by graft de-lamination or a graft bed devoid of any repair tissue. Furthermore, of the 36 patients (out of the prospectively recruited 204) that were not available for longer term review, 7 had already proceeded to total knee arthroplasty (TKA) and 1 patient had undergone secondary MACI at the same MFC site due to earlier graft failure. Therefore, a total of 22 patients (10.8%) had essentially failed at or before the final review time. At final follow-up, patients that underwent MACI in the TF (versus PF) joint reported significantly better KOOS sub-scale scores for Pain (p=0.013, TF mean 86.5, PF mean 80.1), Sport (p&lt;0.001, TF mean 71.5, PF mean 60.5) and Quality of Life (p=0.010, TF mean 65.8, PF mean 58.7), as well as a greater knee extensor strength LSI (p=0.002, TF mean 96.0%, PF mean 85.8%). While the TF group demonstrated better 10-year MOCART scores for tissue infill (p=0.027, TF mean 3.2, PF mean 2.9), there were no other differences in MRI-based scores including the overall MRI composite score (p=0.481, TF mean 3.0, PF mean 3.1). Conclusions: This study reports the largest prospective series of patients with long-term review, demonstrating good clinical scores, levels of patient satisfaction and graft survivorship beyond 10 years. Patients undergoing TF (versus PF) MACI reported better long-term clinical outcomes, despite largely similar MRI-based outcomes.

Multidirectional Landing Kinetics, Stabilisation Times, and Associated Isokinetic Knee Torques of High-Level Female Netball Players

Netball is a multidirectional sport afflicted by a relatively high proportion of lower-extremity injuries. The purpose of this study was to evaluate the relationships between multidirectional landing stabilisation times, unilateral landing kinetics, and isokinetic knee joint torques in elite female netball players. A total of 15 players volunteered for the study (age: 20.80 ± 1.42 years; height: 1.75 ± 0.06 m; body mass: 71.69 ± 13.58 kg). All players completed a minimum of 25 multidirectional, unilateral landing tasks, as well as isokinetic dynamometry, to evaluate both concentric and eccentric knee flexion and extension torques. Players showed rapid stabilisation times upon landing (2.02 ± 0.69 s) coupled with moderately high landing forces (4.06 ± 0.82 BWs) and comparatively low isokinetic knee extensor (2.01 ± 0.49 N·m·kg−1) and flexor (1.33 ± 0.30 N·m·kg−1) strength. Moderate positive (r¯ = 0.61) and negative (r¯ = −0.63) correlations were observed between peak isokinetic knee joint strength and the force–time waveform during the early and late weight-acceptance phases of multidirectional jump landings prior to stabilisation. Multidirectional landing kinetics can potentially provide valuable insights related to TTS and possible associations with isolated knee joint musculature during the weight-acceptance phase of jump landings.

How limb dominance influences limb symmetry in ACL patients: effects on functional performance

BackgroundTiming for return to sport (RTS) after anterior cruciate ligament (ACL) injury is paramount for the avoidance of a secondary injury. A common criterion in RTS decision-making is the limb symmetry index (LSI) which quantifies (a)symmetries between the affected and unaffected limb. Limb dominance is one of many factors that may contribute to the recovery of the LSI after ACL reconstruction. The purpose of this study was to examine how limb dominance affects the LSI of functional performance tasks nine months following ACL reconstruction (time of RTS).MethodsAt time of return to sport, n = 100 patients (n = 48 injured the dominant limb, n = 52 injured the non-dominant limb, n = 34 female, n = 66 male) with ACL reconstruction surgery performed isokinetic strength measurements of the knee extensors and flexors, and drop jumps (DJ), single leg hop for distance (SHD) and 6 m timed hop (6MTH) testings.ResultsThe findings indicated that injury of the dominant leg led to significantly higher LSI values in maximal isokinetic knee extensor strength (p = 0.030). No significant differences were observed for maximal isokinetic knee flexor strength, DJ, SHD or 6MTH performance. Stratifying for sex revealed no significant differences. Simple regression analyses demonstrated that LSI in maximal knee extensor strength significantly predicted LSIs in DJ and SHD while explaining 14% and 18% of the respective variance.ConclusionsGiven that limb dominance affects the LSI of muscle strength suggests that a differentiated interpretation of the LSI with respect to limb dominance should be considered for a safe return to sport. Monoarticular knee extensor strength and multiarticular hop test performance are interrelated and thus can show asymmetries which are not maladaptive but established during years of habituation or training.

Running interval training combined with blood flow restriction increases maximal running performance and muscular fitness in male runners

We investigated the effects of 8 weeks (3 days per week) of running interval training (RIT) combined with blood flow restriction (RIT-BFR) on the maximal running performance (RPmax), isokinetic muscle strength, and muscle endurance in athletes. Twenty endurance-trained male runners were pair-matched and randomly assigned to the RIT-BFR and RIT groups. The RIT-BFR group performed RIT (50% heart rate reserve, 5 sets of 3 min each, and 1-min rest interval) with inflatable cuffs (1.3× resting systolic blood pressure), and the RIT group performed the same RIT without inflatable cuffs. RPmax, isokinetic muscle strength, and muscle endurance were assessed at pre-, mid-, and post-training. Compared with the RIT group, the RIT-BFR group exhibited a significantly (p < 0.05) greater increase in RPmax, isokinetic knee extensor and flexor strength, and knee extensor endurance after 24 training sessions. These results suggested that RIT-BFR may be a feasible training strategy for improving muscular fitness and endurance running performance in distance runners.

A structured accelerated versus control rehabilitation pathway after anterior cruciate ligament reconstruction using autologous hamstrings demonstrates earlier improvement in physical outcomes without increasing graft laxity: A randomized controlled trial

ObjectivesTo investigate whether an accelerated rehabilitation pathway could enhance strength and functional symmetry after ACLR, without affecting laxity. DesignRandomized Controlled Trial. SettingPrivate rehabilitation clinic. Participants44 patients randomized to an ‘Accelerated’ (n = 22) or ‘Control’ (n = 22) rehabilitation intervention. Main outcome measuresGraft laxity (primary outcome), isokinetic knee extensor and flexor strength, hop tests, surveys, sport participation, re-injuries and re-operations. ResultsNo knee laxity differences (p > 0.05) were observed. A significantly greater (p = 0.006) percentage of Accelerated (77.3%) versus Control (59.1%) patients were participating in Level 1 or 2 pivoting sports at 12 months. Greater limb symmetry indices were observed in the Accelerated group for knee extensor strength at 6 (p < 0.0001), 12 (p = 0.010) and 24 (p = 0.005) months, as well as the triple hop at 6 (p = 0.015) and 9 (p = 0.008) months, and the triple crossover hop at 6 (p < 0.0001) and 9 (p = 0.009) months. One ipsilateral re-tear was observed (Control group, 17 months). No differences (p˃0.05) existed in surveys apart from the Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) score, better (p = 0.001) in the Accelerated group at 12 months. ConclusionsAccelerated rehabilitation produced earlier improvement in strength and hop LSIs, without increasing graft laxity.

Influence of lower-limb muscular and tendon mechanical properties and strength on countermovement jump performance.

The aim of the study is to examine the relationship between measures of muscle and tendon mechanical properties and strength on countermovement jump (CMJ) performance. Twenty-six physically active participants (males; N.=16: females; N.=10) were tested. Testing comprised of measuring the mechanical properties of lower limb muscles and tendons using myotonometry, isometric and isokinetic knee extensor strength through dynamometry, and CMJ's with a force platform. Large positive correlations were observed between CMJ jump height and Achilles tendon stiffness (N/m) (r=0.56) and Achilles tendon tone (Hz) (r=0.553). Large negative correlations were found between CMJ height and Achilles tendon elasticity (r=-0.658), and Achilles tendon relaxation (r=-0.572), and Achilles tendon creep (r=-0.589). Large correlations (r=0.592 to 0.659) were observed between CMJ height and all measures of isometric and isokinetic dynamometry measures. Achilles tendon stiffness, elasticity level and relaxation, and isokinetic peak concentric torque (N.m) explained 63% of this variance. Greater stiffness of the Achilles tendon may improve CMJ performance due to the improved transfer of concentric and eccentric force of the knee extensor muscles. Practitioners need to implement specific interventions to target increasing Achilles tendon stiffness to improve countermovement jump performance.

Relationship Between Isokinetic Knee Strength and Single-Leg Drop Jump Performance 9 Months After ACL Reconstruction.

Background:Deficits in knee strength after anterior cruciate ligament reconstruction (ACLR) surgery are common. Deficits in the single-leg drop jump (SLDJ), a test of plyometric ability, are also found.Purpose:To examine the relationship between isokinetic knee strength, SLDJ performance, and self-reported knee function 9 months after ACLR.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Knee isokinetic peak torque, SLDJ jump height, contact time, and reactive strength index (RSI), as well as International Knee Documentation Committee (IKDC) scores were assessed in 116 male, field-sport athletes at 9.2 months after ACLR. SLDJ testing took place in a 3-dimensional biomechanics laboratory. Linear regression models were used to analyze the relationship between the variables.Results:A significant relationship was found between ACLR-limb isokinetic knee extensor strength and SLDJ jump height (P < .001, r 2 = 0.29) and RSI (P < .001, r 2 = 0.33), and between ACLR-limb isokinetic knee flexor strength and SLDJ jump height (P < .001, r 2 = 0.12) and RSI (P < .001, r 2 = 0.15). A significant positive relationship was also found between knee extensor asymmetry and SLDJ jump height asymmetry (P < .001, r 2 = 0.27) and SLDJ reactive strength asymmetry (P < .001, r 2 = 0.18). Combined ACLR-limb jump height and contact time best predicted IKDC scores (P < .001, r 2 = 0.12).Conclusion:Isokinetic knee extension strength explained approximately 30% of SLDJ performance, with a much weaker relationship between knee flexion strength and SLDJ performance. Isokinetic strength and SLDJ performance were weak predictors of variation in IKDC scores.

Double-bundle anterior cruciate ligament reconstruction using autologous hamstrings with LARS augmentation demonstrates comparable outcomes to hamstrings alone, without evidence of synovitis or early osteoarthritis.

To compare the clinical and radiological outcomes in patients undergoing anterior cruciate ligament reconstruction (ACLR) with, or without, LARS augmentation. One-hundred and thirty-six patients that underwent double-bundle ACLR with (DB Hams/LARS, n = 67), or without (DB Hams, n = 69), LARS augmentation, were assessed clinically and with Magnetic Resonance Imaging (MRI) at a minimum of 7-years post-surgery. Patients were assessed via patient-reported outcome measures (PROMs), KT-1000 (laxity), isokinetic knee extensor and flexor strength and a 4-hop test battery. Limb symmetry indices (LSIs) were calculated. The Whole-Organ Magnetic Resonance Imaging Score (WORMS) evaluated knee status via MRI. Sport participation, secondary operations, ACL re-tears and contralateral ACL tears were reported. No differences (n.s.) were observed in demographics, PROMs, KT-1000 scores or strength and hop LSIs. Normal (< 3mm side-to-side differences) KT-1000 scores were observed in 64 (92.8%) and 59 (88.1%) of DB Hams and DB Hams/LARS patients, respectively. Comparative rates of satisfaction were reported. Knee flexor strength and hop test LSIs were all ˃95% in both groups, which was 94.2% and 96.7% for knee extensor strength in the DB Hams and DB Hams/LARS cohorts, respectively. While 53 (76.8%) and 52 (77.6%) of the DB Hams and DB Hams/LARS patients had returned to pivoting sports, 42 (60.9%) and 41 (61.2%) were participating in pivoting sports at the minimum 7-year review. No difference (n.s.) was observed in the WORMS (12.3 DB Hams, 16.7 DB Hams/LARS). Of the cohort assessed, 8 (11%) DB Hams and 11 (16%) DB Hams/LARS patients had undergone secondary surgery. In addition to one patient in each group that demonstrated ACL rupture on MRI, an additional cohort of patients were excluded from the current analysis due to prior re-tear (DB Hams n = 6, DB Hams/LARS n = 8) or contralateral ACL tear (DB Hams n = 4, DB Hams/LARS n = 4). Comparable outcomes were observed after double-bundle ACLR using autologous hamstrings with, or without, LARS augmentation. Therefore, while these outcomes do not justify the additional use of synthetic augmentation given the lack of further benefit and additional cost, higher rates of graft failure, synovitis and early osteoarthritic change previously reported were not observed. III.

Six methods for classifying lower-limb dominance are not associated with asymmetries during a change of direction task.

Quantifying asymmetries between dominant and non-dominant limbs is a common research objective aimed at identifying systematic differences between limbs and establishing normative ranges of asymmetry. Multiple methods for classifying limb dominance exist, and it is unclear how different methods relate to directional asymmetries during change of direction (CoD). This study aimed to determine whether different methods of classifying limb dominance, including a novel CoD task-specific method, identified significant inter-limb asymmetries during a 90° CoD task. Fifty participants completed a testing battery consisting of jumping, hopping, CoD, and isokinetic dynamometry. Limb dominance was classified for each participant according to preferred kicking limb, vertical jump height, horizontal hop distance, initial force plate contact during landing, max isokinetic knee extensor strength, and turning velocity. Asymmetries in whole-body and joint-level mechanics were defined using each method. No method for classifying limb dominance was associated with consistent inter-limb biomechanical asymmetries during CoD, and no method was related to any other method. The magnitude of asymmetry relative to the magnitude of absolute asymmetry present within the cohort suggests that using these tasks to classify the dominant limb in this CoD is akin to assigning dominance to a randomly selected limb. Previous observations of group symmetry during CoD may be statistical artifacts as opposed to a true indication of normative movement. Until an appropriate means of classifying limbs during CoD is established, quantifying normative asymmetry based on limb dominance should be done with caution.