Isokinetic Flexion Research Articles

High-Intensity Conditioning Activity Causes Localized Postactivation Performance Enhancement and Nonlocalized Performance Reduction

Abstract Kolinger D, Stastny P, Pisz A, Krzysztofik M, Wilk M, Tsoukos A, and Bogdanis GC. High-intensity conditioning activity causes localized postactivation performance enhancement and nonlocalized performance reduction. J Strength Cond Res 38(1): e1–e7, 2024—This study aimed to examine whether a conditioning activity (CA) performed by the legs (barbell back squat) may cause postactivation performance enhancement (PAPE) on muscle groups other than leg extensors in isokinetic (eccentric [ECC] and concentric [CON]) and dynamic movement. Twelve male basketball players (age: 21.3 ± 3.2, body mass: 89.6 ± 14.1 kg, height: 187.4 ± 4.6 cm, and 1 repetition maximum (1RM) barbell back squat: 113 ± 21 kg) with previous resistance-training experience of at least 2 years, performed 3 sets of 3–4 repetitions of back-squats with submaximal load (60, 90, and 90% 1RM) as CA. Before and after the CA, they performed pretest and post-test in the form of countermovement jumps (CMJs) (localized) or explosive push-ups (EPUs) (nonlocalized) along with isokinetic flexion and extension at the knee (localized) or at the elbow (nonlocalized). The localized and nonlocalized protocols were divided into 2 days in a randomized order. The back squat as CA significantly increased peak torque (PT) (p < 0.05) in all CON and ECC muscle actions and average power per repetition (APPR) (p < 0.05) (all muscle actions except ECC flexion) of the localized isokinetic tests with large (>0.8) and medium (0.4–0.79) effect sizes and significantly decreased (p < 0.01) the PT and APPR (p < 0.01) of the nonlocalized isokinetic test in the ECC flexion. The CMJ and EPU tests showed no significant differences (p > 0.05) between premeasures and postmeasures of take-off height. The effect of PAPE seems to be specific to the muscles most involved in the CA, and the CA inhibits PT of subsequent muscle ECC contractions in muscles not involved in the CA.

No Deficits in Functional Outcomes of the Contralateral Limb Are Seen When the Hamstring Is Harvested for Augmentation of Small Diameter Ipsilateral Hamstring Autograft

To evaluate clinical outcomes of the contralateral, nonoperative limb in patients undergoing contralateral hamstring (HS) autograft harvest compared with patients undergoing ipsilateral HS autograft harvest alone. This study included 96 patients who underwent isolated anterior cruciate ligament reconstruction (ACLR) using 4-stranded HS autograft (n= 85) or 4-stranded HS autograft augmented with contralateral HS (n= 13) due to inclusion of ipsilateral graft diameter <8 mm. Isokinetic flexion and extension strength and dynamic performance of the ipsilateral and contralateral limbs and limb symmetry index (LSI) were evaluated at 6 months' postoperatively. Rates of contralateral native ACL tear at minimum 2 years also were compared. For all comparisons, P < .05 was considered statistically significant. Normalized isokinetic knee flexion and extension strength of the contralateral limb did not differ between cohorts (P= .34; P= .21, respectively). LSI for knee extension peak torque and knee flexion peak torque did not differ between cohorts (P= .44; P= .67, respectively). No difference in LSI was seen for any dynamic performance testing (single leg hop, P= .97; triple leg hop, P= .14; 6-m timed hop, P= .99). No difference was observed in International Knee Documentation Committee (P= .99) or Knee Injury and Osteoarthritis Outcome Score subscale measures (P= .39-.86). No difference in rates of contralateral knee native ACL tears were seen between cohorts (HS autograft+ contralateral HS augmentation, n= 2, 15.4%; HS autograft, n= 7, 8.4%; P= .26). In this study, at the time of return to sport, we found no differences in contralateral limb functional performance or limb symmetry measurements between patients undergoing contralateral HS autograft harvest for augmentation of smaller (<8 mm) diameter HS autografts harvested from the injured extremity. Level III, retrospective cohort study.

Research on the Recognition of Various Muscle Fatigue States in Resistance Strength Training.

Instantly and accurately identifying the state of dynamic muscle fatigue in resistance training can help fitness trainers to build a more scientific and reasonable training program. By investigating the isokinetic flexion and extension strength training of the knee joint, this paper tried to extract surface electromyogram (sEMG) features and establish recognition models to classify muscle states of the target muscles in the isokinetic strength training of the knee joint. First, an experiment was carried out to collect the sEMG signals of the target muscles. Second, two nonlinear dynamic indexes, wavelet packet entropy (WPE) and power spectrum entropy (PSE), were extracted from the obtained sEMG signals to verify the feasibility of characterizing muscle fatigue. Third, a convolutional neural network (CNN) recognition model was constructed and trained with the obtained sEMG experimental data to enable the extraction and recognition of EMG deep features. Finally, the CNN recognition model was compared with multiple support vector machines (Multi-SVM) and multiple linear discriminant analysis (Multi-LDA). The results showed that the CNN model had a better classification accuracy. The overall recognition accuracy of the CNN model applied to the test data (91.38%) was higher than that of the other two models, which verified that the CNN dynamic fatigue recognition model based on subjective and objective information feedback had better recognition performance. Furthermore, training on a larger dataset could further improve the recognition accuracy of the CNN recognition model.

Discharging the medial knee compartment: comparison of pressure distribution and kinematic shifting after implantation of an extra-capsular absorber system (ATLAS) and open-wedge high tibial osteotomy—a biomechanical in vitro analysis

PurposeYoung and active patients suffering early degenerative changes of the medial compartment with an underlying straight-leg axis do face a therapeutical gap as unloading of the medial compartment cannot be achieved by high tibial osteotomy. Extracapsular absorbing implants were developed to close this existing therapeutical gap. Purpose of the present cadaveric biomechanical study was to compare the unloading effect of the knee joint after implantation of an extra-articular absorber system (ATLAS) in comparison to open-wedge high tibial osteotomy (OW-HTO) under physiological conditions. The hypothesis of the study was that implantation of an extra-capsular absorber results in an unloading effect comparable to the one achievable with OW-HTO.MethodsEight fresh-frozen cadaveric knees were tested under isokinetic flexion–extension motions and physiological loading using a biomechanical knee simulator. Tibiofemoral area contact and peak contact pressures were measured using pressure-sensitive film in the untreated medial compartment. The tibiofemoral superior–inferior, latero-medial translation and varus/valgus rotation were measured with a 3D tracking system Polaris. Pressures and kinematics changes were measured after native testing, ATLAS System implantation and OW-HTO (5° and 10° correction angles) performed with an angular stable internal fixator (TomoFix).ResultsThe absorber device decreased the pressure in the medial compartment near full extension moments. Implantation of the ATLAS absorbing system according to the manufacturers’ instruction did not result in a significant unloading effect. Deviating from the surgery manual provided by the manufacturer the implantation of a larger spring size while applying varus stress before releasing the absorber resulted in a significant pressure diminution. Contact pressure decreased significantly Δ0.20 ± 0.04 MPa p = 0.044. Performing the OW-HTO in 5° correction angle resulted in significant decreased contact pressure (Δ0.25 ± 0.10 MPa, p = 0.0036) and peak contact pressure (Δ0.39 ± 0.38 MPa, p = 0.029) compared with the native test cycle. With a 10° correction angle, OW-HTO significantly decreased area contact pressure by Δ0.32 ± 0.09 MPa, p = 0.006 and peak contact pressure by Δ0.48 ± 0.12 MPa, p = 0.0654 compared to OW-HTO 5°. Surgical treatment did not result in kinematic changes regarding the superior–inferior translation of the medial joint section. A significant difference was observed for the translation towards the lateral compartment for the ATLAS system Δ1.31 ± 0.54 MPa p = 0.022 and the osteotomy Δ3.51 ± 0.92 MPa p = 0.001. Furthermore, significant shifting varus to valgus rotation of the treated knee joint was verified for HTO 5° about Δ2.97–3.69° and for HTO 10° Δ4.11–5.23° (pHTO 5 = 0.0012; pHTO 10 = 0.0007) over the entire extension cycle.ConclusionOW-HTO results in a significant unloading of the medial compartment. Implantation of an extra-capsular absorbing device did not result in a significant unloading until the implantation technique was applied against the manufacturer’s recommendation. While the clinical difficulty for young and active patients with straight-leg axis and early degenerative changes of the medial compartment persists further biomechanical research to develop sufficient unloading devices is required.

Effectiveness of whole-body vibration exercise and core stabilization exercise in chronic non-specific low back pain: A randomized-controlled study.

Objectives The aim of this study was to investigate the effectiveness of whole-body vibration exercise (WBVE) and core stabilization exercise (CSE) on pain, muscle strength, and functional recovery in patients with chronic non-specific low back pain (NLBP). Patients and methods Between June 2016 and July 2017, a total of 74 patients with NLBP (12 males, 62 females; mean age: 44.7±8.9 years; range, 24 to 64 years) were included in this prospective, randomized-controlled study. The patients were randomly assigned to WBVE group (WBVEG, n=25), CSE group (CSEG, (n=25), and home exercise group as the control group (CG, (n=24). All groups performed 24 sessions of exercise for a total of eight weeks. Clinical outcome was measured using the Visual Analog Scale (VAS), Roland-Morris Disability Questionnaire (RMDQ), computerized isokinetic muscle strengths (IMS) and progressive isoinertial lifting evaluation (PILE) test. Results The VAS and RMDQ scores in WBVEG and CSEG statistically significantly decreased (p<0.05). The difference between the pre-treatment and at three-month VAS scores during intense activity were significantly different in both WBVEG and CSEG than the CG (p<0.05). The IMS values, except for the isokinetic flexion total work (IKFTW), increased significantly in all three groups (p<0.05). The IKFTW values increased significantly in the WBVEG and CSEG (p<0.05). A statistically significant increase in the functional work performance with PILE was observed in all three groups (p<0.05). The differences between the pre-treatment and three-month PILE test (ground to back and back to shoulder) were significantly different in both WBVEG and CSEG than the CG (p<0.05). Conclusion In the treatment of chronic NLBP, WBVE and CSE appear to be effective in pain and functionality. Although there was a significant improvement in muscle strength and functional work performance in all three groups, greater improvements were observed in the WBVEG and CSEG than the CG.

The efficacy of intermittent pneumatic compression and negative pressure therapy on muscle function, soreness and serum indices of muscle damage: a randomized controlled trial

BackgroundThe study aimed to assess whether intermittent pneumatic compression (IPC) and intermittent negative pressure (INP) would attenuate the muscle damaging effects of eccentric exercise.MethodsForty-five healthy males were recruited. Immediately post, 24 and 48 h post eccentric exercise consisting of 100 drop jumps, volunteers randomly received 30-min sessions of intermittent pneumatic compression (IPC, n = 15) or intermittent negative pressure (INP, n = 15), or sham microcurrent (PT, n = 15). Creatine kinase (CK), lactate dehydrogenase (LDH), isokinetic muscle strength, soreness and active flexion of the knee joint were measured after every therapy session.ResultsNo significant intergroup differences were observed in biochemical or functional measurements. However, there was an increase in muscle soreness (P < 0.05), CK and LDH activity (P < 0.05), and a reduction in muscle strength (P < 0.05) and range of active knee flexion (P < 0.05).ConclusionsThe prescription of IPC and INP did not attenuate the reduction of markers to muscle function or pain perception up to 48 h after muscle damaging exercise. Future research should focus on the potential impact of treatment frequency and duration on muscle recovery.Trial registration The study was retrospectively registered in the Australian New Zealand Clinical Trials Registry (ANZCTR); The trial registration number: ACTRN12621001294842; date of registration: 24/09/2021.

Minimal graft site morbidity using autogenous semitendinosus graft from the uninjured leg: a randomised controlled trial

PurposeTo quantify the effect on strength of semitendinosus (ST) graft harvest by comparing isokinetic and isometric muscle strength.MethodsA cohort of 140 patients underwent anterior cruciate ligament (ACL) reconstruction (ACLR) and were randomized to ipsilateral or contralateral ST graft harvest. Isokinetic and isometric muscle strength testing using a dynamometer were collected for the operated and non-operated leg. Patients were assessed pre-surgery and at 6, 12 and 24 months after reconstruction.ResultsST graft harvest reduced isokinetic flexion muscle strength for 6 months. At 12 months follow up there was no significant difference between the two groups and they were all stronger than pre-injury. No other significant differences were found in any primary or secondary outcome measurements.ConclusionSolitary ST graft harvest does not appear to result in a permanent reduced isometric or isokinetic quadriceps muscle strength on the side where the graft is harvested. A reduction in hamstring muscle strength of less than 10% can be seen at short-term follow-up with full recovery by 12 months. Most patients report little or no donor site pain. Given these findings, ST autograft is an alternative graft choice that could be used for various reconstructions in terms of donor site morbidity.Level of evidence Level II.

Internal Risk Factors for Low Back Pain in Pole Vaulters and Decathletes: A Prospective Study.

Background:Pole vaulters and decathletes frequently experience several types of injuries to their lower back, often resulting in mechanical low back pain (LBP). However, the risk factors for the occurrence of LBP in these athletes have not been defined.Purpose:To determine the physical factors that relate to LBP occurrence for collegiate pole vaulters and decathletes.Study Design:Cohort study; Level of evidence, 2.Methods:We observed 31 pole vaulters and decathletes for 1 year. At the start of the observation period, isokinetic flexion and extension muscle strength of the knee and hip joints were recorded along with active and passive range of motion (ROM) and muscle tightness. Participants were then divided into 2 groups using the median value of each measurement: those below the median (low group) and those above the median (high group). The log-rank test was used to compare LBP occurrence between the low group and high group for all measurements. Multivariate regression analyses were thereafter applied using the Cox proportional hazards regression.Results:Log-rank tests revealed a statistically significant change in the survival curve for the occurrence of LBP in the participants with chronic LBP (P = .037), the low group for hip flexion peak torque per body weight on the non-takeoff leg (P = .047), and the low group for passive hip flexion angle on both legs (takeoff leg: P = .034; non-takeoff leg: P = .023). In addition, log-rank tests revealed a statistically significant change in the survival curve for the occurrence of LBP in the low group for passive hip extension angle on the takeoff leg only for the participants without chronic LBP (P = .014).Conclusion:It may be necessary to acquire sufficient ROM and hip flexion to prevent LBP occurrence in pole vaulters and decathletes.

Detection of effort maximality in adults performing isokinetic wrist flexion and extension

BACKGROUND: The difference between isokinetic eccentric to concentric strength ratios at high and low velocities (DEC) is a powerful tool for identifying submaximal effort in other muscle groups but its efficiency in terms of the wrist extensors (WE) and flexors (WF) isokinetic effort has hitherto not been studied. OBJECTIVE: The objective of the present study is to examine the usefulness of the DEC for identifying suboptimal wrist extensor and flexor isokinetic efforts. METHODS: Twenty healthy male volunteers aged 20–40 years (28.5 ± 3.2) were recruited. Participants were instructed to exert maximal and feigned efforts, using a range of motion of 20∘ in concentric (C) and eccentric (E) WE and WF modes at two velocities: 10 and 40∘/s. E/C ratios (E/CR) where then calculated and finally DEC by subtracting low velocity E/CR from high velocity ones. RESULTS: Feigned maximal effort DEC values were significantly higher than their maximal effort counterparts, both for WF and WE. For both actions, a DEC cutoff level to detect submaximal effort could be defined. The sensitivity of the DEC was 71.43% and 62.5% for WE ad WF respectively. The specificity was 100% in both cases. CONCLUSION: The DEC may be a valuable parameter for detecting feigned maximal WF and WE isokinetic effort in healthy adults.

The Relationship between Isokinetic Trunk, Leg Strength and Isometric Mid-Thigh Pull Test, Counter Movement Jump in National Rowing Athletes

OBJECTIVES The purpose of this study was to analyze the relationship between isokinetic leg strength and maximum Isometric Med-Thigh Pull Test(IMTP) and maximum height of Counter Movement Jump (CMJ) in Korean national rowers.METHODS Each eight male and female athletes were participated in the study. Isometric IMTP, CMJ, and isokinetic trunk, hip, and knee strength were measured to analyze the relationship between the IMTP, CMJ and isokinetic strength. The correlation between variables was analyzed by the step-wise method of multiple regression analysis after analyzing the correlation between dependent and independent variables.RESULTS Knee, Hip and trunk isokinetic flexion and extension strength showed high correlation with maximum IMTP with the all participants. Knee extension and trunk flexion isokinetic strength showed higher correlation with IMTP. Knee extension isokinetic strength showed high correlation with CMJ.CONCLUSIONS For strengthening exercise of National rowers, ipsilateral strength balance and agonistantagonist strength balance of leg and trunk should be considered to improve performance efficiently.

Evaluation of regeneration of semitendinosus tendon using ultrasound imaging and isokinetic strength testing after graft harvest for arthroscopic anterior cruciate ligament reconstruction

BackgroundA lot of the research has been done worldwide evaluating the capacity of the semitendinosus tendon to regenerate which has not been conducted in the Indian population. Study design31 patients who underwent unilateral ACL reconstruction with hamstrings were taken into study. All patients underwent ultrasonography imaging of both knees and bilateral isokinetic flexion strength assessment at a one-year postoperative period. Images were obtained at three levels and their dimensions are compared with normal side. Isokinetic testing of the knee is done to evaluate the flexion deficit and is compared to the uninvolved knee. ResultsOut of a total of 31 patients, 14 patients showed no regeneration, 17 showed regeneration at various levels. On isokinetic testing patients with no regeneration showed the highest mean flexion deficit. ConclusionThe semitendinosus tendon and its regeneration can be visualized well using ultrasonography. After semitendinosus harvesting, the flexion strength will be decreased as compared to the normal knee. The flexion strength in patients who have a regenerated tendon will be higher as compared to those who have no regeneration.

The Effect of Shortwave Diathermy Treatment on Muscle Power in Patients with Chronic Low Back Pain

Objective: The goal of this study was to investigate the effects of shortwave diathermy therapy combined with exercise on lumbar muscle strength. Patients and methods: Our study was an interventional study involving 90 patients with chronic low back pain who were admitted to our clinic between 2007-2008. Patients were randomized into 3 groups (each group had 30 patients). The same exercise programs were given to all groups. Patients in the first group were applied placebo shortwave diathermy treatment, the second group was applied continuous shortwave diathermy and the third group received pulsed shortwave diathermy. Isokinetic muscle strength measurements of the patients were performed before and three months after the treatment. Results: In our study, the only significant difference observed between the groups was in isometric flexion strength and interestingly the first group had higher improvement compared to the other groups. In regard to within group comparisons, Group 1 was found to have significant improvements in strengths for:isometric flexion, isokinetic flexion (60°/sec and 120°/sec), isokinetic extension (60°/sec and 120°/sec). Group 2 had significant improvements in isokinetic flexion and extension (60°/sec) and also isokinetic extension (120°/sec). In Group 3, none of the improvements were found to be significant. Conclusion: Our findings indicate that there are no significant differences between exercise therapy alone and exercise therapy in combination with diathermy (either continuous or pulsed) in terms of their effects on lumbar muscle strength, even though marginal differences in some of the measurements were observed.

No functional differences in anatomic reconstruction with one vs. two suture anchors after non-simultaneous bilateral distal biceps brachii tendon rupture: a case report and review of the literature

BackgroundSurgical reattachment of the tendon is still the gold standard for ruptures of the distal biceps brachii tendon. Several fixation techniques have been described in the literature, with suture anchors being one of the most common fixation techniques. Currently, there is no data available on how many anchors are required for a safe and stable refixation. In this case report clinical data of a patient with non-simultaneous bilateral distal biceps tendon ruptures treated with a different number of suture anchors for each side (one vs. two) are demonstrated.Case presentationA 47-year-old factory worker suffered a rupture of the distal biceps tendon on both arms following two different occasions. The left side was fixed using a single suture anchor, while refixation on the right side was performed with two anchors.The patient was prospectively followed for one year. Functional outcome was assessed using the Andrews Carson Score (ACS), the Oxford Elbow Score (OES), and the Disabilities of Arm, Shoulder and Hand (DASH) Score after six, twelve, 24 and 48 weeks. Furthermore, an isokinetic strength measurement for flexion strength was performed after 24 and 48 weeks.After 48 weeks the patient presented with excellent functional outcome scores and no follow-up complications. During the follow-up period, no differences in the functional scores nor in the isokinetic flexion strength measurement could be detected. Furthermore, no radiological complications (like heterotopic ossifications) could be detected in the postoperative radiographs after one year.ConclusionsAnatomic reattachment of the distal biceps tendon is a successful operative treatment option for distal biceps tendon ruptures. Suture anchor fixation remains one of the most common techniques, as it allows fast surgery and provides good results with respect to range of motion (ROM) and functional scoring according to the current literature. However, the number of anchors required for a stable fixation remains unclear. As indicated by our presented case, we hypothesize, that there are no significant differences between a one-point or a two-point fixation. In the presented case report, no intraindividual differences between the usage of one versus two suture anchors were evident in the short-term follow-up.

Isokinetic Strength of the Dominant and Non-dominant Elbow in Elite Male Volleyball Players

The purpose of this research is to compare the elbow isokinetic strength applied at different angular velocities on the dominant and non-dominant side in elite male volleyball players. Fifteen elite volleyball players participated in the research. Isokinetic elbow flexion and extension strength were separately obtained on concentric/concentric dominant and non-dominant side as 5 repetitions at 60˚.s-1 angular velocity, 10 repetitions at 180˚.s-1 and 15 repetitions at 300˚.s-1. In the research, the peak torque (PT), peak torque/body weight (PT/BW), flexion/extension ratio (B/T), angle of PT, work and power parameters were compared between the dominant and non-dominant elbows. No significant difference was found between the dominant and non-dominant side in the elbow isokinetic strength parameters of the subjects at three different velocities. A significant difference was found at three different velocities only in the angle of PT flexion (p &amp;lt; 0.05). It is thought that this difference may result from the muscle shortening that may occur on muscle length (longitudinal effect) as a result of the more concentric contraction of the muscle on the dominant side compared to the non-dominant muscle. Consequently, there is not any isokinetic strength difference between the dominant and non-dominant elbow in elite male volleyball players. Isokinetic elbow test can provide important information regarding the potential risk factors for elbow injuries. For this reason, it is recommended to include this test in the functional screening of volleyball players.

The effect of power-specific weight training on the muscle function for the athletes in Korean national freestyle wrestling team

Purpose The purpose of this study was to identify the effect of a power-specific weight training program in order to improve the muscle strength of Korean national team’s freestyle wrestlers. Methods Participants were 13 male athletes in the national freestyle wrestling team. The period of the program was 6 weeks. Muscle strength, muscular endurance, muscle power, flexibility, agility, cardiorespiratory endurance, anaerobic power and isokinetic muscle function were measured. Data were analyzed using IBM SPSS Statistics ver. 23.0 (IBM Co., Armonk, NY, USA). Paired t-test was conducted for comparison between pre-test and post-test score. Results There were significant difference and tendency in the leg isokinetic power and trunk isokinetic flexion strength. However, there was no significant difference in muscle strength, muscular endurance, muscle power, flexibility, agility and cardiorespiratory endurance. Conclusion The 6-week program focusing on the power-specific weight training indicated a significant difference not in every variable but in isokinetic muscle power, speed power and core strength. It is suggested that the training program was applied to the athletes less continuously and not in the long term because of frequent international games abroad and the need for losing weight. Consequently, a year-long training program with personalized methods should be developed to bring about more significant outcomes.

FEMORAL NERVE BLOCK VERSUS ADDUCTOR CANAL BLOCK FOR ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION IN PEDIATRIC AND ADOLESCENT PATIENTS

Background Adductor canal block (ACB) is an alternative method to femoral nerve block (FNB) for post-operative analgesia for anterior cruciate ligament reconstruction (ACLR) in pediatric and adolescent patients. Prior studies have suggested that FNB is associated with persistent strength deficits at 6 months after ACLR in this population. Proponents of the ACB consider that this method may result in a decreased incidence of quadriceps strength deficits during post-operative rehabilitation. The purpose of this study was to compare knee strength and function at 6 and 9 months after ACLR in pediatric and adolescent patients who received FNB versus ACB peri-operatively. Methods Patients 18 years or younger who underwent primary ACLR between 2002 and 2017 at a single institution were identified. ACLR was performed with either a patellar tendon autograft or hamstring autograft. A transphyseal ACLR was performed in patients with open physes. All patients participated in a comprehensive rehabilitation program which included isokinetic strength testing and functional testing at 6 and/or 9 months postoperatively. Patients were excluded if they underwent multiligamentous knee reconstruction, concomitant cartilage restoration procedures, did not receive perioperative FNB or ACB, or if they did not complete isokinetic strength and functional testing at 6 or 9 months. The included cohort was separated into FNB group and ACB group for comparison. Isokinetic extension and flexion strength deficits and functional deficits in vertical jump, single hop, and triple hop between the two groups were compared at both time points. A strength deficit of 15% or less and a functional deficit of 10% or less compared to the contralateral side were considered satisfactory. Univariate analysis was performed to assess for differences in patient demographics and surgical variables. A 1:1 matched subgroup analysis between the two groups was performed to account for possible differences in outcomes associated to graft types, concomitant meniscus repair, and BMI. Results Of the 240 patients identified, 85 patients (64 FNB, 21 ACB) with a mean age of 15.9 years (Range: 11-18) met inclusion criteria for comparison at 6 months and 76 patients (40 FNB, 36 ACB) with a mean age of 15.5 years (Range: 12-17) met inclusion criteria for comparison at 9 months. Univariate analysis showed significantly greater deficits at 6 months in the FNB with respect to fast isokinetic flexion strength (7.7% vs. -4.9%; p = .03). There were no differences in slow isokinetic flexion (10.5% vs. 6.8%; p = .79) and fast isokinetic extension (11.9% vs. 13.9%; p = .68) strength deficits between the groups. There were clinically relevant greater deficits in the FNB group with respect to slow isokinetic extension (19.3% vs. 12.0%; p = .24), but this did not reach statistical significance. This clinical difference in satisfactory scores between the groups with respect to slow isokinetic extension was accentuated with the 1:1 matched outcome trial (23.9% vs. 12.1%; p = .20). With respect to function, there were no differences in deficits for vertical jump (8.4% vs. 4.3%; p = .55), single hop (7.4% vs. 9.3%; p = .65), or triple hop (6.0% vs. 7.1%; p = .77) between the two groups. Univariate analysis showed significant greater deficits at 9 months in the FNB with respect to slow isokinetic flexion strength (9.6% vs. 0.4%; p = .01). There were no differences in fast isokinetic flexion (-0.2% vs. 0.7%; p = .87) and fast isokinetic extension (6.0% vs. 2.7%; p = .51) strength deficits between the groups. There were clinically relevant greater deficits in the FNB group with respect to slow isokinetic extension (17.3% vs -14.0%, p = .19), but this did not reach statistical significance. With respect to function, there were no differences in deficits for vertical jump (5.2% vs. 6.5%, p = .85), single hop (7.7% vs. 6.2%; p = .79), or triple hop (1.9% vs. 3.9%; p = .35) between the two groups. Conclusion Because previous studies have shown a significant delay in return of strength with FNB, ACB began to be employed at our center for post-operative pain control following ACLR in pediatric and adolescent patients. This study showed that pediatric and adolescent patients treated with FNB as a method of post-operative analgesia after ACLR had significantly greater deficits in fast isokinetic flexion at 6 months and slow isokinetic flexion at 9 months compared to those who received ACB. These differences may or may not have clear clinical relevance. However, patients treated with FNB showed clinically relevant greater deficits in slow isokinetic extension strength at 6 and 9 months postoperatively compared to those who received ACB if 85% strength return is used as criteria to return to sport. Pediatric and adolescent patients could benefit from undergoing perioperative analgesia with ACB instead of FNB, but comparison between these two methods of regional anesthesia may require a prospective trial. Level of Evidence Retrospective cohort study, Level IV [Table: see text][Table: see text]

Side-to-side asymmetry in lower limb strength and hamstring-quadriceps strength ratio among collegiate American football players.

[Purpose] The present study aimed to investigate the lower limbs injury risk factors that are based on conventional Hamstring to Quadriceps ratio and limb asymmetry index in varsity American football players. [Participants and Methods] Twenty-six varsity American football players aged 19–27 years and with 2.31 ± 1.29 years of American football experience from Dogu Akdeniz University volunteered to undergo measurements of average peak torque for isokinetic flexion and extension of dominant limb and non-dominant limb at 60°·s−1 and 300°·s−1. Hamstring to Quadriceps ratio and limb asymmetry index were also calculated for Hamstring and Quadriceps muscles. [Results] Statistical analysis revealed that dominant Quadriceps is stronger than non-dominant Quadriceps at 60°·s−1 speed. No statistical difference was found between dominant and non-dominant Hamstring peak torque at 60°·s−1 . Hamstring to Quadriceps ratio determined as normal both for 60°·s−1 and 300°·s−1according to the currently reported cut off value (H:Q ratio >60). Hamstring and Quadriceps limb asymmetry index also determined as normal (cut off value for LSI 10%) at 60°·s−1. However, for both Hamstring and Quadriceps, side- to- side strength asymmetry at 300°·s−1 was observed. [Conclusion] To prevent possible lower limb injury and to increase performance, varsity American football players who are actively training and competing might consider taking strength asymmetry into account to tailor their strength training program accordingly.

Bio-signal based elbow angle and torque simultaneous prediction during isokinetic contraction

It is of great importance to decode motion dynamics of the human limbs such as the joint angle and torque in order to improve the functionality and provide more intuitive control in human-machine collaborative systems. In order to achieve feasible prediction, both the surface electromyography (sEMG) and A-mode ultrasound were applied to detect muscle deformation and motor intent. Six abled subjects were recruited to perform five trails elbow isokinetic flexion and extension, and each trail contained five repetitions, with muscle deformation and sEMG signals recorded simultaneously. The experimental datasets were categorized as: the ultrasound-EMG combined datasets, ultrasound-only datasets and EMG-only datasets. The support vector machine (SVM) regression model was developed for both elbow joint angle and torque prediction, based on the above three kinds of datasets. The root-mean-square error (RMSE) and the correlation coefficients (R) were applied to evaluate the prediction accuracy. The results across all the subjects for different datasets indicated that the combined datasets and the ultrasound datasets were superior to the sEMG datasets both on elbow joint angle and torque prediction, and there were no significant differences between the combined datasets and the ultrasound datasets. It turns out that elbow angle and torque can be reconstructed by A-mode ultrasound, and the significant findings pave the way towards the application of musculature-driven human-machine collaborative systems.

Isokinetic flexion strength recovery after ACL reconstruction: a comparison between all inside graft-link technique and full tibial tunnel technique

ABSTRACTIntroduction: Recently, a new minimally invasive single bundle technique for anatomic ACL reconstruction has been described, called the ‘All-Inside graft-link technique’. One of the advantages of this procedure is the reduced morbidity at the donor site as the graft choice is the quadrupled semitendinosus, thus sparing the gracilis tendon. The aim of this study was to evaluate isokinetic flexion strength recovery in patients who underwent a gracilis sparing technique compared to those with a full-tibial tunnel technique using a doubled gracilis and semitendinosus tendons (DGST) graft.Methods: Patients were divided into two groups: Group A (22 patients) who underwent ACL reconstruction performed with an All-Inside graft-link technique; Group B (22 patients) who underwent ACL reconstruction with an Out-In technique and DGST graft. At a mean follow-up of 13 months, quadriceps and hamstring isokinetic peak torque deficits were recorded.Results: In group A, the mean side to side peak torque flexion difference between the operated and non-operated limbs was −3% and the mean torque at 30° was −7.5% at high angular velocity (180°/sec); the mean peak flexion torque was 7.2% and the mean torque at 30° was 3.1% at low angular velocity (60°/sec).In group B, the mean side to side peak flexion torque was −3.5% and the mean torque at 30° was −7.6% at high angular velocity (180°/sec); the mean peak flexion torque was −7.2% and the mean torque at 30° was −11% at low angular velocity (60°/sec).A statistically significant difference was found between the two groups at lower angular velocity both for the mean peak flexion torque and the mean torque at 30° (p = 0.009), with better results in the study group.Discussion/conclusion: Gracilis sparing technique is a minimally invasive technique for ACL reconstruction and yielded a significantly better flexion strength recovery at lower angular velocity compared to a full tibial tunnel technique with DGST for ACL reconstruction.

Single-Shot Femoral Nerve Block Does Not Cause Long-Term Strength and Functional Deficits Following Anterior Cruciate Ligament Reconstruction

To determine if patients treated with a single-shot femoral nerve block have strength and functional deficits at 9-month follow-up. Forty-three patients who underwent primary anterior cruciate ligament reconstructions were randomized to receive either a preoperative single-shot femoral nerve block or local infiltration anesthesia for primary pain control. All patients underwent a standardized comprehensive rehabilitation program postoperatively. Isokinetic strength and function was tested using a Biodex machine at 9months or more postoperatively comparing the operative and nonoperative extremity. No significant difference in strength was found at an average of 10.6months postoperatively (range, 9-15months) between the femoral nerve block and control groups. In comparing strength deficits, we found no difference in slow isokinetic extension strength (22.4% vs 27.8%, P= .51), fast isokinetic extension strength (18.5% vs 12.5%, P= .41), slow isokinetic flexion strength (11.0% vs 15.1%, P= .55), and fast isokinetic flexion strength (8.2% vs 4.9%, P= .56) in the femoral nerve block versus control groups, respectively. In terms of functional outcomes, there also was no difference in deficits for single-leg hop distance (P= .12), timed single-leg hop (P= .74), and single-leg triple hop distance (P= .94). Maximal strength noted to be within 15% of the contralateral limb was achieved in 40% of patients and maximal function in 63% of patients at an average of 10.6months postoperatively. A 13% complication rate was found in patients who received a femoral nerve block (1 with prolonged quadriceps inhibition and 2 with prolonged sensory disturbances). Our study found a 13% motor/sensory complication rate in patients who underwent femoral nerve block for pain control after anterior cruciate ligament reconstruction. Although these deficits may persist, they are not permanent and are not different when compared with controls at 9-month follow-up. However, maximal strength and function are not fully restored at normal return to play time and rehabilitation should continue long term to maximize recovery. Level I, prospective randomized trial.