Differences In Peak Torque Research Articles

Effect of Menstrual Cycle on Neuromuscular Efficiency and Muscular Strength in Runners

PURPOSE: The aim of this study was to examine the influence of the menstrual cycle (MC) stages on neuromuscular efficiency and muscular strength in female runners. METHODS: Three runners (females) underwent testing using a BIODEX isokinetic dynamometer concurrently with a BioPac EMG, during which peak torque, peak torque/body weight, time to peak torque, mean amplitude, median amplitude, minimum amplitude, maximum amplitude, frequency, and the p-p value were collected throughout the test. During the test, the performance variables were assessed on the quadriceps (rectus femoris) muscle and collected at speeds of 60 degrees/second and 180 degrees/second. STATISTICAL ANALYSIS: A paired-sample t-test was used to determine the correlation between neuromuscular efficiency and peak torque of the quadriceps during extension in the two MC phases. A paired-sample t-test was also used to determine the difference in neuromuscular efficiency between the MC phases, as well as peak torque between the MC phases. RESULTS: Muscular strength testing did not reveal statistical significance between neuromuscular efficiency and peak torque of the quadriceps during MC phases. Furthermore, there was no statistical significance between the differences in peak torque of the MC phases. Maximum amplitude at 60 degrees/second on the left leg between the MC phases revealed statistical significance (p = 0.026). EMG wave frequency at 60 degrees/second on the right leg between the MC phases revealed statistical significance (p = 0.007). CONCLUSION: Results show a significant difference in maximum amplitude and wave frequency at 60 degrees/second during knee extension between the MC phases.

Conservative treatment outcome for Achilles tendon re-rupture occurring in the subacute phase after primary repair.

Until now, a treatment protocol for Achilles tendon re-rupture (ATRR) occurring in the postoperative period 5-12weeks following primary Achilles tendon repair has not been established. We refer to this time frame as the subacute postoperative phase, and the objective of this study was to assess the efficacy of conservative treatment for subacute ATRR in this phase. We conducted a retrospective review of 390 cases (385 patients) who had undergone primary Achilles tendon repair using the 4-strand Krachow method between January 2010 and August 2021. All patients were subjected to more than 12months of follow-up and were categorized into two groups based on the presence of subacute ATRR: Group 1 comprised 370 cases without ATRR, while Group 2 comprised 20 cases with ATRR. Following confirmation of ATRR, we immediately applied a below-knee cast in an ankle plantar flexed position (25°-30°), followed by bracing according to the same rehabilitation plan used for the primary repair. After administering conservative treatment to the patients with ATRR, we compared several outcome parameters between the two groups, including isokinetic plantar flexion power measured using a dynamometer, time required for a single heel raise (t-SHR), time needed for ten repetitive SHRs (t-SHR10), Achilles Tendon Total Rupture Score (ATRS), and Foot and Ankle Ability Measure (FAAM) scores. The baseline timepoints for Groups 1 and 2 were the dates of the primary repair and the re-injury event. After primary Achilles tendon repair, subacute ATRR occurred in 5.1% of patients. There were no significant differences between the groups in terms of t-SHR and t-SHR10 (P = 0.281, 0.486). Similarly, the isokinetic dynamometer measurements revealed no significant differences in peak torque for plantar flexion at angular velocities of 30°/s and 120°/s, both in absolute values and as a percentage of the contralateral side, between the groups (P > 0.05 for each). However, ATRSs were significantly lower in Group 2 compared to Group 1 before 6months (P < 0.05), as were FAAM-Activities of Daily Living scores at 6months (P < 0.05). After 12months, there were no significant differences in these scores between the two groups (both P > 0.05). Conservative treatment for subacute ATRR following primary Achilles tendon repair yields clinical outcomes comparable to those without ATRR. Therefore, we recommend that surgeons consider relying on the patient's natural healing capabilities rather than opting for aggressive surgical interventions, as expediting such operations may be unnecessary for subacute injuries.

The effect of rotational velocity on rotational traction across a range of artificial turf surface systems

Mechanical testing by sporting governing bodies ensures artificial turf surfaces conform with performance standards. Rotational traction is measured using two equivalent devices: a rotational traction tester (RTT) and a lightweight rotational traction tester (LRTT). The devices differ in target rotational velocity; 72 deg/s for the RTT and 30 deg/s for the LRTT. The purpose of this study was to investigate the influence of rotational velocity on peak torque during rotational traction testing. An automated rotational traction tester examined nine rotational velocities between 10 and 210 deg/s, and ten artificial turf surface systems with a range of performance infill materials, infill depths and carpet specifications. Rotations at 10 deg/s produced the lowest peak torques on nine of the ten surfaces. Infill materials with intrinsic viscoelastic properties produced significantly higher peak torques at higher rotational velocities, whereas less elastic infill materials saw no significant increase in peak torque. A mean difference in peak torque of 2.6 Nm was found between the target velocities of the RTT and LRTT. The results support the synchronisation of target velocities for the RTT and LRTT. During standards testing, trials completed below a particular velocity should be repeated to negate velocity effects on peak torque.

The Role of Strength-Related Factors on Psychological Readiness for Return to Sport Following Anterior Cruciate Ligament (ACL) Reconstruction.

Psychological readiness following anterior cruciate ligament reconstruction (ACLR) correlates with different return to sport outcomes. However, the relationship between strength and power and psychological readiness remains unexplored. The aim of this study was to investigate the relationship between anterior cruciate ligament return to sport after injury (ACL-RSI) scores and various hamstrings and quadriceps strength and power variables. Twelve participants (20.7 ± 2.5 years old; 174.2 ± 7.5 cm; 70.2 ± 8.5 kg; 18.2 ± 8.3% of body fat) who had an ACLR nine months or more before the study completed the ACL-RSI questionnaire and isokinetic strength testing of the hamstrings and quadriceps (60°·s-1 and 180°·s-1). Based on ACL-RSI scores, they were divided into "cases" and "controls", deemed not psychologically ready and psychologically ready to return to previous sport performance (PILOS), respectively. The main findings are that quadriceps' and hamstrings' rate of torque development (RTD) and time since surgery were determinants of psychological readiness following ACLR. Furthermore, compared to controls, cases showed significantly lower quadriceps torque at angles close to full knee extension (40 deg and 30 deg from extension). They also showed lower RTD than controls, but no difference in peak torque. These results suggest that physiotherapists should facilitate athletes' return to sport (RTS) by focusing on the restoration of RTD and strength at angles close to full knee extension.

Recovery of leg strength based on isokinetic testing after tumor resection and reconstruction with a modular rotating hinge knee system: Prospective cross-sectional study with a minimum follow-up of 24 months

BackgroundWhile modular reconstruction implants can be used to replace the bone lost after bone tumor resection, tumor excision from the neighboring soft tissues can lead to loss of strength and joint range of motion (ROM), which results in worse knee function. Functional recovery after total knee arthroplasty for osteoarthritis has been extensively documented. But few studies have evaluated the recovery after total knee reconstruction following tumor excision despite the fact that most of these patients are young and have high functional demands. We did a prospective cross-sectional study to: 1) compare muscle strength recovery around the knee with an isokinetic dynamometer after tumor excision and reconstruction with a modular implant to the healthy contralateral knee; 2) determine if the differences in peak torque (PT) in the knee extensors and flexors had a clinical impact. HypothesisResection of soft tissues during tumor excision around the knee causes strength loss that cannot be fully recovered. MethodsThe 36 patients who underwent extra- or intra-articular resection of a primary or secondary bone tumor in the knee area followed by reconstruction with a rotating hinge knee system between 2009 and 2021 were eligible for this study. The primary outcome was the ability to actively lock the operated knee. The secondary outcomes were the concentric PT during isokinetic testing at slow (90°/sec) and fast (180°/sec) speeds, flexion-extension ROM, Musculoskeletal Tumor Society (MSTS) score, the IKS, Oxford Knee Score (OKS) and KOOS. ResultsNine patients agreed to participate in the study, all of whom had regained the ability to lock their knee postoperatively. PT in flexion and extension on the operated knee was less than the healthy knee. The PT ratio for the operated/healthy knee at 60°/sec and 180°/sec in flexion was 56.3%±16.2 [23.2–80.1] and 57.8%±12.3 [37.7–77.4], respectively, which corresponded to a slow-speed strength deficit of 43.7% in the knee flexors. The PT ratio for the operated/healthy knee at 60°/sec and 180°/sec in extension was 34.3%±24.6 [8.6–76.5] and 43%±27.2 [13.1–93.4], respectively, which corresponded to a slow-speed strength deficit of 65.7% in the knee extensors. The mean MSTS was 70%±20 [63–86]. The OKS was 29.9/48±11 [15–45], the mean IKS knee was 149.6±36 [80–178] and the mean KOOS was 67.43±18.5 [35-88.7]. DiscussionDespite all patients having the ability to lock out their knee, there was an imbalance in the strength between opposite muscle groups: 43.7% strength deficit at slow-speed and 42.2% at fast speed for the hamstring muscles, and 65.7% at slow-speed and 57% at fast speed for the quadriceps muscles. This difference is considered pathological with an increased risk of knee injury. Despite this strength deficit, this joint replacement technique, which is free of complications, can preserve good knee function with acceptable knee joint ROM and satisfactory quality of life. Level of evidenceIII; prospective cross-sectional case-control study.

The Effect of Location of a Unicortical Defect on the Mechanical Properties of Rabbit Tibiae: A Model of the Distal Jig Pin Hole in Tibial Plateau Levelling Osteotomy.

The aim of this study was to determine the effect of a unicortical defect at either the mid-diaphysis (MD) or distal metaphysis (DM) on the torsional properties of tibiae in an in vitro rabbit model, and to further examine optimal distal jig pin position for the canine tibial plateau levelling osteotomy (TPLO) procedure. Thirty-eight tibiae from 19 skeletally mature female New Zealand White rabbits were assigned to one of three groups; Group 1: intact, Group 2: MD defect and Group 3: DM defect. Defects were created using a 1.6 mm Ellis pin. Pure torsion was applied to each sample and peak torque and angular displacement recorded. All tibiae fractured in a spiral configuration. Fracture lines involved the defect in 33% of the MD samples and 0% of the DM samples. No differences were detected for peak torque and stiffness between groups. However, energy (mean ± standard deviation) was significantly reduced (p = 0.028) in the MD group (0.18 ± 0.07) relative to the intact tibia group (0.31 ± 0.14). Angle was also significantly reduced (p = 0.040) in the MD group (0.17 ± 0.05) compared with the intact group (0.23 ± 0.07). Placement of a DM defect had no significant effect on mechanical properties of the rabbit tibiae. Defects placed in the MD significantly reduced energy and angle in comparison to intact samples. No significant difference in peak torque or stiffness was observed between groups. If canine tibiae were similarly affected, our findings suggest jig pin placement in the DM to have a lesser effect on the torsional properties of the tibiae.

Correlation analysis of national elite Chinese male table tennis players' shoulder proprioception and muscle strength.

BACKGROUNDShoulder is the most injured part in table tennis players, and it takes multiple roles in transmitting power and striking the center of the ball during the stroke. Proprioception is strongly correlated with high level of athletic performance. It is customary to assume that there is a correlation between proprioception and muscle strength and therefore proprioceptive assessment and rehabilitation is often neglected.AIMTo investigate the correlation between isokinetic muscle strength and proprioception in the internal and external rotation muscle groups of elite Chinese male table tennis players, to provide reference for physical training and rehabilitation of elite table tennis players.METHODSA total of 19 national elite table tennis players from the Chinese National Table Tennis Team were recruited in this research. All of them had more than 10 years training experience and had participated major competitions such as the National Games and World Youth Championships. IsoMed 2000 was used to test the peak torque of internal and external rotation isokinetic concentric contraction of the athletes' bilateral shoulder joints at low speed (60°/s) and high speed (180°/s) respectively; IsoMed 2000 was used to conduct the Joint Position Reproduction test to evaluate the athletes' proprioceptive ability capacity at low speed (60°/s) and high speed (180°/s) respectively. If the data satisfied the normal distribution, the correlation between the differences in peak torque s and angles in different directions was analyzed using a Pearson simple linear model; otherwise, Spearman correlation analysis was used. The comparison of proprioceptive ability between the table tennis racket-holding hand and non-racket-holding hands was performed using independent samples t-test if the data satisfied a normal distribution; otherwise, the Mann-Whitney U test was used.RESULTSThere was no direct linear correlation between the strength and proprioceptive correlation analysis at slow speed (60°/s) and fast speed (180°/s) in the racket-holding hand; At the slow speed (60°/s) and fast speed (180°/s), there was no correlation between muscle strength and proprioception in the non-racket-holding hand except for the internal rotation variable error (VE) and external rotation relative peak torque, which showed a moderate positive correlation (r = 0.477, P < 0.05), (r = 0.554, P < 0.05). The internal rotation’s constant error (CE) and VE were 1.06 ± 3.99 and 2.94 ± 2.16, respectively, for the racket-holding hand, and -3.36 ± 2.39 and 1.22 ± 0.93, respectively, for the non-racket-holding hand; the internal rotation’s CE, VE of the racket-holding hand was lower than that of the non-racket-holding hand, and there was a highly significant difference (P < 0.01).CONCLUSIONThere was no correlation between muscle strength and proprioceptive function in the internal and external rotation of the racket-holding hand’s shoulder in elite Chinese male table tennis players. These results may be useful for interventions for shoulder injuries and for the inclusion of proprioceptive training in rehabilitation programs.

Psoas weakness following oblique lateral interbody fusion surgery: a prospective observational study with an isokinetic dynamometer

BACKGROUND CONTEXTAlthough the surgical corridor used for oblique lateral interbody fusion (OLIF) protects the intrapsoas nerves by causing minimal compression, transient weakness remains the most commonly reported postoperative complication. PURPOSEUsing a dynamometer to evaluate how the hip flexor strength changes following OLIF. STUDY DESIGN/SETTINGA prospective observational study. PATIENT SAMPLEForty-six patients who underwent single or multi-level OLIF for lumbar spondylolisthesis. OUTCOME MEASURESIsokinetic dynamometer values (peak torque, total work, average power), visual analogue scale (VAS) scores for leg pain, hypoesthesia, subjective weakness of the left hip flexor muscle, Oswestry disability index, body mass index, bone mineral density, radiologic findings of the psoas muscle (cross-sectional area, Hounsfield unit (HU), fat portion grade), and psoas retraction time. METHODSThe isokinetic muscle strength of the hip flexor was measured five times (preoperatively and postoperatively at 2 days, 1 week, 1 month, and 3 months) for both legs. The peak torque was defined as the postoperative strength of the left hip flexor muscles, and was compared to the preoperative baseline value. The strength of the left and right hip flexor muscles were also compared at each time point. For logistic regression analysis, when the peak torque was below the median value, it was defined as lower peak torque. RESULTSUp to 1 week after surgery, the strength of the left hip flexor muscle decreased significantly (paired difference in peak torque was 22.6%, p<.001). In the results of multivariate logistic regression analysis, diabetes (odds ratio [OR]=8.43, p=.020) and the HU of the psoas muscle (OR=0.916, p=.034) were associated with lower peak torque 1 week after surgery. From 1 month after surgery, postoperative weakness of the psoas muscle was not significant. In the questionnaire survey, subjective left hip flexion weakness was reported in 8.5% (4/47) of patients 1 week after surgery, and it remained in only 2.1% (1/47) of patients after 3 months of operation. The frequency of left anterior thigh pain and hypoesthesia decreased from 85.1% (40/47) at 1 week to 2.1% (1/47) at 3 months after surgery. The mean VAS score for left anterior thigh or groin pain decreased significantly at 1 month after surgery (PO2D: 4.04±1.84, PO1M: 1.67±1.10, p<.001). CONCLUSIONSDynamometer measurement showed that psoas strength declined significantly up to 1 week after OLIF surgery. Patients with diabetes or lower HU of the psoas muscle showed delayed recovery from postoperative weakness of the psoas muscle. However, the weakness was insignificant from 1 month after surgery. At 3 months after surgery, the other psoas-related problems (left anterior thigh pain and hypoesthesia) also disappeared.

Effect of Dynamic Stretching versus Proprioceptive Neuromuscular Facilitation Stretching of Antagonist Muscle on Knee Extensor Torque and Dynamic Balance in Young Male Collegiate

Introduction: Many athletes perform stretching exercises as part of a warm-up prior to physical activity in order to prevent injuries and enhance their performance by an increase in flexibility. The significance of this study was that it may provide information about the better stretching method between dynamic and PNF stretching immediately before the sports events which may help to enhance the strength of knee extensor, thereby helping in improving performance and injury prevention.Method: An experimental design was used in the study. 51 subjects were randomly divided and statistically analysed for results. Group 1 had to under go dynamic stretching, Group 2 had to undergo PNF stretching for a period of four, and Group 3 (control group) did not undergo any kind of stretching. Results: It was observed that there was no significant difference in peak torque and average torque at 60⁰/s and 180⁰/s and SEBT scores after 4 weeks of dynamic vs PNF stretching. No significant difference was found in dynamic balance after 4 weeks of dynamic vs PNF stretching. Conclusion: We may infer that dynamic stretching and proprioceptive neuromuscular facilitation stretching of antagonist muscle have the same effect on knee extensor torque and dynamic balance in young collegiate males.

Effects of Robot-assisted Gait With Body Weight Support on Torque, Work, and Power of Quadriceps and Hamstring Muscles in Healthy Subjects

Background: Robot-assisted gait training (RAGT) is an effective method for walking rehabilitation. Additionally, the body weight support (BWS) system reduces muscle fatigue while walking. However, no previous studies have investigated the effects of RAGT with BWS on isokinetic strength of quadriceps and hamstring muscles. Objects: The purpose of this study was to investigate the effects of torque, work, and power on the quadriceps and hamstring muscles during RAGT, using the BWS of three conditions in healthy subjects. The three different BWS conditions were BWS 50%, BWS 20%, and full weight bearing (FWB). Methods: Eleven healthy subjects (7 males and 4 females) participated in this study. The Walkbot_S was used to cause fatigue of the quadriceps and hamstring muscles and the Biodex Systems 4 Pro was used to measure the isokinetic torque, work, and power of them. After RAGT trials of each of the three conditions, the subjects performed isokinetic concentric knee flexion and extension, five at an angular velocity of 60°/s and fifteen at an angular velocity of 180°/s. One-way repeated analysis of variance was used to determine significant differences in all the variables. The least significant difference test was used for post-hoc analysis. Results: On both sides, there were significant differences in peak torque (PT) of knee extension and flexion between the three BWS conditions at an angular velocity of 60°/s and 180°/s conditions. A post-hoc comparison revealed that the PT in the BWS 50% was significantly greater than in the BWS 20% and the FWB and the PT in the BWS 20% was significantly greater than in the FWB. Conclusion: The results of this study suggest that the lower BWS during RAGT seems to lower the isokinetic torque, work, and power of the quadriceps and hamstring muscles because of the muscle fatigue increase.

Wound closure position in total knee arthroplasty: flexion versus extension-a meta-analysis of randomized controlled trials.

Total knee arthroplasty (TKA) is one of the most commonly used procedures in orthopedics. However, whether different would closure positions affect the clinical outcomes after TKA remains controversial. We conducted a meta-analysis of randomized controlled trials (RCT) to assess the effect of wound closure position on clinical TKA outcomes. Embase, PubMed, and the Cochrane Library databases were systematically searched. A systematic review and meta-analysis of all RCTs were performed to prove the role of different wound closure positions on TKA. Five RCTs containing 389 patients were included. Surgical closure of 90° flexion in TKA was associated with higher post-operative range-of-motion (ROM) at post-operative 4weeks, lower VAS post-operative pain scores 4weeks and 3months, better peak torque difference of flexor muscle strength at 60 and 180°/s angular velocities between the flexion and the extension groups, and better total work difference of flexor muscle strength at 180°/s angular velocity. The American Knee Society Score did not show any significant difference between two closure techniques. No complications were described in the literature review. Wound closure in 90° flexion during TKA may provide better postoperative ROM, higher pain relief, preferable muscle strength improvement in short-term follow-up, and no increase in the risks of wound complications. Level II.

Biomechanical muscle stiffness measures of extensor digitorum explain potential mechanism of McArdle sign

BackgroundMcArdle sign is a phenomenon of impaired gait and muscle weakness that occurs with neck flexion, immediately reversible with neck extension. A recent report measured the specificity of this sign for multiple sclerosis by measuring differences in peak torque of the extensor digitorum between neck extension and flexion. MethodsThis substudy included 73 participants (29 multiple sclerosis, 20 non-multiple sclerosis myelopathies, 5 peripheral nerve disorders, and 19 healthy controls). The effect of neck position was assessed on muscle stiffness and neuromechanical error of the extensor digitorum. FindingsPatients with multiple sclerosis had greater neuromechanical error (sum of squared error of prediction) compared to controls (P = 0.023) and non-multiple sclerosis myelopathies (P = 0.003). Neuromechanical error also provided improved sensitivity/specificity of McArdle sign. Peak torque, muscle stiffness, and neuromechanical error could distinguish multiple sclerosis from other myelopathies with 80% specificity and 97% sensitivity (AUC = 0.95). InterpretationA decrease in muscle stiffness and neuromechanical error in neck flexion compared to extension are additional indicators for a diagnosis of multiple sclerosis. Analysis of muscle stiffness may provide insights into the pathophysiology of this specific clinical sign for multiple sclerosis. Furthermore, muscle stiffness may provide an additional accurate, simple assessment to evaluate multiple sclerosis therapeutic interventions and disease progression.

The effects of acute beetroot juice supplementation on lower and upper body isokinetic strength of the wrestlers

Background and objective: Peak torque, as measured by the gold standard method of isokinetic dynamometry, is affected by consumed of dietary nitrate (NO3−) in the form of beetroot juice (BRJ). The increasing strength performance effect of BRJ has also started to arouse interest in combat sports. This study aims to investigate the effects of acute dietary nitrate supplementation on lower and upper body isokinetic strength of trained Greco-Roman wrestlers.Materials and methods: The study is a double-blind, randomized, crossover design in which eight trained male Greco-Roman wrestlers (21.87 ± 2.3 years; height 176.87 cm ± 4.1 cm; body weight 76.75 kg ± 5.4 kg) consumed beetroot juice (140 mL) or placebo (140 mL, cherry juice with lemon juice) 150 min before performing isokinetic strength. Participants performed knee extensors and flexors and shoulder internal and external rotator isokinetic strength test (in the dominant limbs) concentrically at 60◦ with by Cybex device (Cybex NORM®, Humac, CA, USA). The same trial procedure was repeated with the other supplement (BRJ or Placebo) in a second testing session five days later. BRJ and Placebo trials' isokinetic strength values were compared with parametric testing (paired sample T-test).Results: Although there was a significant difference in peak torque of shoulder internal and external rotator values in favor of BRJ (P < 0.05), there was no significant difference in the knee strength test. Additionally, all average isokinetic strength values were significantly increased in the BRJ trial (P < 0.05).Conclusions: These results suggest that BRJ can be used as an ergogenic effect for improving strength values in Greco-Roman wrestling.

Intra-articular arthroscopic biceps tenodesis with interference screw: clinical and isokinetic evaluation

BackgroundAlthough biceps tenodesis has been widely used to treat its pathologies, few studies looked at the objective evaluation of elbow strength after this procedure. The purpose of this study is to clinically evaluate patients submitted to long head of the biceps (LHB) tenodesis with interference screws through an intra-articular approach and analyze the results of an isokinetic test to measure elbow flexion and forearm supination strengths.MethodsPatients who had biceps tenodesis were included in the study if they had a minimum follow-up of 24 months. Patients were excluded if they had concomitant irreparable cuff tears or previous or current contralateral shoulder pain or weakness. Postoperative evaluation was based on University of California–Los Angeles (UCLA) shoulder score and on measurements of elbow flexion and supination strength, using an isokinetic dynamometer. Tests were conducted in both arms, with velocity set at 60º/s with 5 concentric-concentric repetitions.ResultsThirty-three patients were included and the most common concomitant diagnosis were rotator cuff tear (69%) and superior labrum anterior to posterior (SLAP) lesions (28%). The average UCLA score improved from 15.1 preoperatively to 31.9 in the final follow-up (P < .001). Isokinetic tests showed no difference in peak torque between the upper limbs. One patient had residual pain in the biceps groove. None of the patients had Popeye deformity. UCLA score and follow-up length did not demonstrate correlation with peak torque.ConclusionArthroscopic proximal biceps tenodesis with interference screw, close to the articular margin, yielded good clinical results. Isokinetic tests revealed no difference to the contralateral side in peak torque for both supination and elbow flexion.

Comparison of isokinetic knee torque and bioelectrical activity for hamstrings, quadriceps and erector spinae muscles in elite rowers

ABSTRACT In sweep rowers, the lower extremities muscle strength translates into the driving force of the boat. Therefore, isokinetic assessment of muscle torque is used by coaches as an indicator of the level of athletes’ preparation for competitions. A total of 22 elite sweep rowers performed an isokinetic test of knee joint flexors and extensors, and a test on an asymmetric ergometer with the electromyography measures. Significantly higher quadriceps peak torque was shown during the beginning than the end of the preparatory period (p < 0.05). However, there was no significant knee peak torque difference between the lower extremities (p = 0.398). In the case of the electromyography test of quadriceps, hamstrings and lumbar erector spinae, analysis demonstrated significant bioelectrical activity differences between the sides (p < 0.05). Lower values of quadriceps peak torque at the end of the preparatory period may result from a decrease in the number of power training units during the entire preparatory period. A similar muscle strength between both lower extremities seems to be the correct result in the context of injury prevention. In turn, significant bioelectrical activity differences between the sides possibly are associated with the asymmetric movement pattern in sweep rowers.

The role of isokinetic muscle strength training in rehabilitation after rotator cuff repair

Objective To explore the effect of isokinetic strength training on post-operative rehabilitation of rotator cuff injury after arthroscopy. Methods Forty patients who had received arthroscopic repair of a rotator cuff tear no less than 3 months previously and who had normal joint movement were selected and randomly divided into a routine training group (the control group) and an isokinetic strength training group (the experimental group), each of 20. Both groups did internal and external rotation strength training with Thera-Band elastic bands, 10-20 times/session, 3 sessions/day. The experimental group additionally underwent isokinetic strength training of the shoulder for 15-20 minutes twice a week. Isokinetic strength tests were performed after 3 and 6 months at test speeds of 60°/s and 180°/s. The evaluation indexes included the internal and external rotation peak torque, peak TQ/BW, the deficit of the affected shoulder joint, the peak torque difference and peak TQ/BW difference before and after training. Results Both groups had improved significantly after the treatment, but the improvement in the experimental group was significantly greater than in the control group, on average. Conclusion Isokinetic muscle strength training is helpful to recover strength after arthroscopic repair of a rotator cuff injury, especially the rapid external rotation muscle strength. It is worthy of clinical application. Key words: Rotator cuff injury; Isokinetic training; Rehabilitation

Impact of Surgical Timing on Clinical Outcomes in Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using Hamstring Tendon Autografts.

Background:To date, no studies have analyzed the influence on clinical outcomes of the interval between an anterior cruciate ligament (ACL) injury and double-bundle (DB) reconstruction with hamstring tendon autografts.Hypotheses:(1) Performing ACL reconstruction sooner after an injury will reduce postoperative anterior and rotatory knee instability, (2) postoperative range of knee motion or functional results will not be affected by different intervals between injury and surgery, and (3) preoperative isokinetic peak torque of the quadriceps and hamstring muscles will be lower in patients undergoing surgery earlier, while postoperative muscle strength will not be affected by surgery timing.Study Design:Cohort study; Level of evidence, 3.Methods:This study was conducted on a total of 171 patients who had undergone anatomic DB ACL reconstruction with hamstring tendon autografts. The patients were divided into 3 groups based on the time to surgery: (1) ≤1 month after the injury (group E; n = 25), (2) between 1 and 3 months after the injury (group M; n = 72), and (3) >3 months after the injury (group D; n = 74). Patients were assessed for a minimum of 2 years after surgery.Results:Concerning postoperative anterior laxity, 1-way analysis of variance demonstrated a significant difference (P = .0274) among the 3 groups. Anterior laxity was significantly less in group E than in group D (P = .0206). Spearman rank correlation analysis showed a significant correlation (ρ = 0.200; P = .0327) between anterior knee laxity and time to surgery. Also, a significant correlation (P = .0461) was found between the degree of the pivot-shift phenomenon and time to surgery. There were no significant differences in loss of knee extension or flexion among the 3 groups, nor were there any differences in the Lysholm knee score or International Knee Documentation Committee grade. Postoperatively, there were no significant differences in peak torque of the quadriceps or hamstring muscles among the 3 groups.Conclusion:Early DB reconstruction led to significantly less anterior laxity compared with delayed reconstruction. There were no significant differences in postoperative range of knee motion or functional results among the 3 time intervals between injury and surgery in this study.

Passive Stiffness and Maximal and Explosive Strength Responses After an Acute Bout of Constant-Tension Stretching.

Constant-tension (CT) stretching has been used to reduce hamstrings passive stiffness; however, the time course of hamstrings stiffness responses during a short bout of this type of stretching and the effects on maximal and explosive strength remain unclear. To examine the time course of hamstrings passive-stiffness responses during a short, practical bout of manual straight-legged-raise (SLR) CT passive stretches and their effects on maximal and explosive strength in healthy young women. Descriptive laboratory study. Research laboratory. Eleven healthy women (age = 24 ± 4 years, height = 167 ± 4 cm, mass = 65 ± 8 kg) participated. Participants underwent four 15-second SLR CT passive stretches of the hamstrings. Hamstrings passive stiffness was calculated from the slopes of the initial (phase 1) and final (phase 2) portions of the angle-torque curves generated before and after the stretching intervention and at the beginning of each 15-second stretch. Hamstrings peak torque and rate of torque development were derived from maximal voluntary isometric contractions performed before and after the stretching intervention. The slope coefficients (collapsed across phase) for the third and fourth stretches and the poststretching assessment were lower than the prestretching assessment (P range = .004-.04), but they were not different from each other (P > .99). In addition, no differences in peak torque (t10 = -0.375, P = .72) or rate of torque development (t10 = -0.423, P = .68) were observed between prestretching and poststretching. A short bout of SLR CT passive stretching may effectively reduce hamstrings stiffness without negatively influencing maximal and explosive strength.

Effects of occlusal splints on shoulder strength and activation

Introduction: The use of oral appliances to enhance sports performance has been advocated by some authors, however, studies addressing the effectiveness of these strategies are inconclusive. Methods: Here we investigate the effects of dental occlusions on shoulder strength. Fourteen healthy male subjects (age = 21.67 ± 0.86 years) without temporomandibular joint (TMJ) disorder participated in this study. Isokinetic strength was evaluated in shoulder abduction/adduction and arm external/internal rotation tests. Three randomised conditions were assessed: (1) occlusal splint (OS), which repositioned the TMJ in centric relation; (2) placebo splint (PS); and (3) no-splint (N). The strength tests were performed at a speed of 60°/sec in concentric mode. Muscle activity was measured by surface electromyography (EMG) in the main muscles engaged in the movements. Results: Significant differences in peak torque between OS and both of the other experimental conditions were found in some of the analyzed variables. Moreover, there was significantly higher muscular EMG activation in the OS condition when compared to the other conditions for some of the tested muscles. These data suggest that splints may have a positive ergogenic effect on shoulder muscular strength in healthy male subjects. Conclusion: OS may provide an advantage for healthy subjects engaged in sports whereby shoulder and arm strength are important for performance. Key messages Occlusal splints in centric relation position have an ergogenic effect, by increasing strength and muscle activation on shoulder in healthy subjects. These results could have implications for sports or other physical activities were arm and shoulder strength are important.

Return-to-Sport Testing After Medial Patellofemoral Ligament Reconstruction in Adolescent Athletes.

Background:Return to sport (RTS) after patellar stabilization surgery involves the return of strength and dynamic knee stability, which can be assessed using isometric strength and functional performance testing.Purpose:To investigate the results of isometric strength and functional RTS testing between the surgical and uninvolved limbs in adolescent patients who underwent medial patellofemoral ligament (MPFL) reconstruction for patellar instability.Study Design:Case series; Level of evidence, 4.Methods:A retrospective review of adolescent patients who underwent MPFL reconstruction identified 28 patients (20 female, 8 male) who also underwent isometric and functional RTS testing. Data were compared with the uninvolved limb. The recovery of muscle strength was defined by a limb symmetry index (LSI) ≥90%. Differences in peak torque were compared using the Wilcoxon signed-rank test. Correlations were examined between dependent and independent variables using the Spearman correlation.Results:The mean age of the patients was 14.9 years (range, 12-16 years). Reconstruction was performed with a hamstring autograft in 17 (60.7%) patients. Concomitant tibial tubercle osteotomy was performed in 10 (35.7%) patients. Testing was performed at a mean 7.4 months (range, 5.5-11.9 months) postoperatively. The mean LSIs for quadriceps and hamstring strength were 85.3% and 95.1%, respectively. For knee extension, there was a statistically significant difference between isometric peak torque measured in the surgical and uninvolved limbs (P = .001). Only 32.0% of patients passed all 4 hop tests. Also, 63.0% of patients achieved an anterior reach asymmetry of <4 cm on the Lower Quarter Y-Balance Test (YBT-LQ). There were no statistically significant differences in isometric strength testing, hop tests, or the YBT-LQ based on graft type or concomitant procedures. There was no correlation between isometric strength and performance on the YBT-LQ or hop tests.Conclusion:Adolescent athletes undergoing MPFL reconstruction may need prolonged rehabilitation programs beyond 8 months to allow the adequate recovery of muscle strength for safe RTS. There is a significant deficit in isometric quadriceps strength in the surgical limb after surgery. Further investigation is needed to determine safe RTS criteria after MPFL reconstruction in the pediatric and adolescent population.