Quadriceps Contraction Research Articles

Influence of cognitive load on the dynamics of neurophysiological adjustments during fatiguing exercise.

We aimed to determine the neurophysiological mechanisms associated with reduced endurance performance during cognitive-motor dual task at different levels of cognitive load, compared to a motor task alone. Eighteen healthy men performed isometric quadriceps contractions at 15% of maximal voluntary contraction (blocks of 170s interspaced by neuromuscular evaluations) until exhaustion. This task was performed on three separate days: (a) in the absence of concomitant cognitive task, (b) with concomitant 1-back task, and (c) with concomitant 2-back task. Autonomic nervous system activity, perceived exertion, and cognitive performance were continuously monitored. Peripheral and central determinants of neuromuscular function were assessed at rest, between each block, and at task failure using femoral nerve stimulation. Endurance time was shorter during 2-back (982±545s) and 1-back (1,128±592s) conditions, compared with control (1,306±836s). Voluntary activation level was lower in 2-back (87.1%; p<0.001) and 1-back (88.6%; p=0.04) conditions compared to control (91.2%) at isotime (100% of the shortest test duration). Sympathetic activity showed a greater increase in 2-back condition compared to control. Perceived muscular exertion was higher during 2-back than during control. Cognitive performance decreased similarly with time during both cognitive-motor dual task but was always lower during 2-back condition. Motor performance is reduced when adding a concomitant demanding memory task to a prolonged isometric exercise. This can be explained by the interaction of various psychological and neurophysiological factors including higher perceived exertion, greater perturbations of autonomic nervous system activity, and cerebral impairments leading to earlier onset of central fatigue.

How does acute pain influence biomechanics and quadriceps function in individuals with patellofemoral pain?

ObjectivesBeside pathophysiological factors, pain is believed to play a crucial role in the progression of patellofemoral pain (PFP). However, the isolated effect of pain on biomechanics and quadriceps function has not been investigated in PFP. Thus, this study aimed to investigate the effect of pain on quadriceps function and lower limb biomechanics in individuals with PFP. MethodsTwenty-one individuals with PFP (11 males and 10 females, age: 29.76 ± 6.36 years, height: 1.74 ± 0.09 m, mass: 70.12 ± 8.56 kg) were measured at two different occasions: when not and when experiencing acute pain. Peak quadriceps torque (concentric, eccentric and isometric) and arthrogenic muscle inhibition (AMI) were assessed. Three-dimensional motion analysis and surface electromyography of the quadriceps and hamstring muscles were collected during running, a single-leg-squat and step-down task. The normality was assessed using the Shapiro–Wilk test and a MANOVA was performed at the 95% confidence interval. ResultsAMI increased significantly in acute pain. The net muscle activation of the knee extensors and flexors decreased during running in acute pain. The lower limb biomechanics and the quadriceps torque did not change in acute pain. DiscussionIt appears that even if individuals with PFP experience pain they can still deliver maximal quadriceps contractions and maintain their moving patterns without biomechanical changes. However, the overall reduced activation of the quadriceps and the increased AMI indicate the presence of quadriceps inhibition in acute pain.

Patellar Height Assessment Methods: An Update.

* Direct and indirect radiographic methods have been proposed for patellar height assessment. Direct methods relate the position of the patella to the femur, and indirect methods relate the position of the patella to the tibia.* Various knee flexion angles have been used for practicality or because obtaining a true lateral knee radiograph is difficult. Knee flexion angles and quadriceps contraction modify patellar height measurements because of proximal patellar displacement and influence patellar height ratios.* Over time, progression from a simple radiographic measurement to modern biomechanical and imaging technologies has added complexity to the techniques devised to measure patellar height. Currently, the definition of patellar height and its causal relationship to the conditions commonly associated with anterior knee pain remain controversial.

The effects of isokinetic exercise with acute blood flow restriction on isometric quadriceps strength, muscle fatigue, and muscle contraction displacement

Purpose The purpose of this manuscript was to investigate the effect of high and low speed blood flow restriction versus non-blood flow restriction isokinetic exercise on isometric muscle strength, muscle fatigue, and muscle contraction displacement. Methods The subjects were consisted of ten males without non-specific muscular skeletal disease. They were classified into four training groups: ① high speed(300°/s) without blood flow restriction, ② high speed(300°/s) under blood flow restriction, ③ low speed(90°/s) without blood flow restriction, ④ low speed(90°/s) under blood flow restriction. Before and after the intervention, all of the subjects underwent measurements of isometric quadriceps strength, muscle fatigue, and muscle contraction displacement. Results In regard to isometric quadriceps strength before &amp; after intervention, there was no significant difference between groups. For the lactic acid measurement before &amp; after intervention, there was a signigicant difference between groups(p&lt;.05). Also, there was a significant difference between groups(p&lt;.05) in muscle contraction displacement in terms of Dm but there was no significant difference between groups in terms of Tc Conclusions Isokinetic exercise with blood flow restriction had effects on lactic acid and muscle contraction displacement.

Static patellofemoral alignment in anterior cruciate ligament deficient knees; a retrospective analysis with magnetic resonance imaging

Static patellofemoral alignment in anterior cruciate ligament deficient knees; a retrospective analysis with magnetic resonance imaging

UBC-Nepal expedition: peripheral fatigue recovers faster in Sherpa than lowlanders at high altitude.

The reduced oxygen tension of high altitude compromises performance in lowlanders. In this environment, Sherpa display superior performance, but little is known on this issue. Sherpa present unique genotypic and phenotypic characteristics at the muscular level, which may enhance resistance to peripheral fatigue at high altitude compared to lowlanders. We studied the impact of gradual ascent and exposure to high altitude (5050m) on peripheral fatigue in age-matched lowlanders and Sherpa, using intermittent electrically-evoked contractions of the knee extensors. Peripheral fatigue (force loss) was lower in Sherpa during the first part of the protocol. Post-protocol, the rate of force development and contractile impulse recovered faster in Sherpa than in lowlanders. At any time, indices of muscle oxygenation were not different between groups. Muscle contractile properties in Sherpa, independent of muscle oxygenation, were less perturbed by non-volitional fatigue. Hence, elements within the contractile machinery contribute to the superior physical performance of Sherpa at high altitude. Altitude-related acclimatisation is characterised by marked muscular adaptations. Lowlanders and Sherpa differ in their muscular genotypic and phenotypic characteristics, which may influence peripheral fatigability at altitude. After gradual ascent to 5050m, 12 lowlanders and 10 age-matched Sherpa (32± 10vs. 31± 11years, respectively) underwent three bouts (separated by 15s rest) of 75 intermittent electrically-evoked contractions (12 pulses at 15Hz, 1.6s between train onsets) of the dominant leg quadriceps, at the intensity which initially evoked 30% of maximal voluntary force. Trains were also delivered at minutes 1, 2 and 3 after the protocol to measure recovery. Tissue oxygenation index (TOI) and total haemoglobin (tHb) were quantified by a near-infrared spectroscopy probe secured over rectus femoris. Superficial femoral artery blood flow was recorded using ultrasonography, and delivery of oxygen was estimated (eDO2 ). At the end of bout 1, peak force was greater in Sherpa than in lowlanders (91.5%vs. 84.5% baseline, respectively; P< 0.05). Peak rate of force development (pRFD), the first 200 ms of the contractile impulse (CI200 ), and half-relaxation time (HRT) recovered faster in Sherpa than in lowlanders (percentage of baseline at 1min: pRFD: 89%vs. 74%; CI200 : 91%vs. 80%; HRT: 113%vs. 123%, respectively; P< 0.05). Vascular measures were pooled for lowlanders and Sherpa as they did not differ during fatigue or recovery (P< 0.05). Mid bout 3, TOI was decreased (90% baseline) whereas tHb was increased (109% baseline). After bout 3, eDO2 was markedly increased (1266% baseline). The skeletal muscle of Sherpa seemingly favours repeated force production at altitude for similar oxygen delivery compared to lowlanders.

Antagonist muscle architecture and aponeurosis/tendon strain of biceps femoris long head during maximal isometric efforts

Examination of the mechanical behavior of the hamstrings when acting as antagonists provides information about loading of this muscle group and its role for joint stability during forceful quadriceps contractions. The aim of this study was to quantify biceps femoris long head fascicle length (FL), angle of pennation (PA) and distal tendon/aponeurosis strain during maximum voluntary contraction efforts of the knee extensors using real-time ultrasound. Fourteen participants performed passive joint movements and maximum voluntary knee extension and flexion efforts of the knee flexors at 0°, 45° and 90° of knee flexion. An ultrasound probe was used to visualize FL, PA and tendon/aponeurosis strain from the distal part of the muscle. Two-way analysis of variance designs indicated that: (a) antagonist BFlh tendon/aponeurosis strain increased significantly up to 2.77 ± 1.25% relative to rest (p < 0.05). The FL increased non-significantly (2.86 ± 6.81%) while the PA was unaltered during isometric MVC efforts of the knee extensors (p > 0.05) (b) FL, PA and tendon/aponeurosis strain of the BFlh when acting as antagonist were not significantly affected by knee joint angular position (p > 0.05). Antagonist hamstring function takes the form of a lengthened tendon/aponeurosis, no fascicle shortening and submaximal neural activation. Future research could examine whether exercise interventions that aim to alter tendon/aponeurosis mechanical properties of the hamstrings when acting as antagonists are beneficial for injury prevention and rehabilitation.

Estimation of quadriceps femoris muscle dysfunction in the early period after surgery of the knee joint using shear-wave elastography

ObjectivesOrthopaedic surgery of the knee joint results in functional deterioration of the quadriceps femoris muscle. However, little is known about quadriceps femoris muscle dysfunction in the early postsurgical period. Therefore,...

Effect of Caffeine Supplementation on Quadriceps Performance After Eccentric Exercise

Green, MS, Martin, TD, and Corona, BT. Effect of caffeine supplementation on quadriceps performance after eccentric exercise. J Strength Cond Res 32(10): 2863-2871, 2018-Caffeine use is common among athletes seeking to capitalize on its potential ergogenic effects. Limited research has examined caffeine's effects when used after activities that resulted in exercise-induced muscle damage (EIMD). This study examined the effect of caffeine supplementation on uninjured and injured muscle. Eight men and women (N = 16) who were physically active individuals participated in this study (age: 24.3 ± 4.3 years; height: 173.0 ± 7.0 cm, mass: 75.2 ± 11.5 kg; body fat: 18.2 ± 15.9%). One leg was assessed under uninjured and injured (100 eccentric quadriceps contractions) conditions after caffeine supplementation (6 mg·kg), with the other leg assessed under both conditions after placebo supplementation. Compared with the placebo, caffeine increased peak isokinetic torque by 6.8 ± 2.3 and 9.4 ± 2.5% in uninjured and injured muscle, respectively, but had no effect on maximal voluntary isometric torque or fatigue index in uninjured or injured muscle, with treatments exhibiting similar (p > 0.05) alterations in isometric torque (-11.9 ± 2.2%), fatigue index (-13.9 ± 3.4%), and soreness (+44.0 ± 4.7) after eccentric contractions. The results of this study suggest that caffeine possesses a similar ergogenic effect on isokinetic torque in both uninjured and injured states, but no effect on the production of isometric torque, perception of soreness, or degree of relative fatigue. Athletes should consider the potential caffeine supplementation possesses during recovery from activities that resulted in EIMD.

Eccentric cross-exercise after anterior cruciate ligament reconstruction: Novel case series to enhance neuroplasticity

ObjectivesSubstantial changes in neural function are historically present after anterior cruciate ligament reconstruction (ACLR), and are not rectified with traditional rehabilitation. Cross-exercise is a potential means to enhance neural excitability and improve recovery after ACLR. Hence our purpose, was to detail changes in brain activation, neural excitability and patient-reported outcomes in a cohort that completed an 8-week quadriceps-focused eccentric cross-exercise training program immediately following ACLR. DesignCase series. SettingUniversity. ParticpantsFive patients participated in an 8-week (24-session) eccentric cross-exercise intervention after ACLR. Main outcome measuresBrain activation, neural activity and patient-reported outcomes were evaluated within 2 weeks post-ACLR and again at 10-weeks post-ACLR after the intervention. Each cross-exercise session consisted of 4 sets of 10 isokinetic eccentric contractions at 60 deg/sec with the noninvolved limb. ResultsFollowing the intervention, patients demonstrated a facilitated spinal reflexive and muscle activity response from the motor cortex during a time when these measures are known to be depressed. Patients also demonstrated a reduce dependence on frontal cortex activity to generate quadriceps contractions. Further patients reported significant reductions in pain and symptoms and greater knee function. ConclusionsEccentric cross-exercise after ACLR helps to facilitate positive adaptations in neural function and patient reported outcomes.

Non-Operative Rehabilitation of Isolated Popliteus Tendon Rupture in a Rugby Player

Isolated rupture of the popliteus tendon is uncommon; instead, it is often seen as part of multi-ligamentous posterolateral corner injuries. In this report, we present a case of a 22-year-old professional rugby player who sustained a lateral blow to his semi-flexed knee in a tackle during a competitive game. A complete popliteus tendon rupture at its musculo-tendinous junction was diagnosed on magnetic resonance imaging despite a relatively unremarkable physical examination. The aims of this report are to highlight the diagnostic challenges with this rare injury as physical signs are often subtle and non-specific. Furthermore, we demonstrate the viability of conservative management in the setting of a direct contact mechanism. Indeed, our patient was successfully treated with a specific rehabilitation protocol via isometric quadriceps contractions, gastrocnemius-soleus and hamstring strengthening exercises and graded activity with successful return to full contact activities at 4 weeks and regular season matches shortly after.

Reliability of patellotrochlear index in patellar height assessment on MRI-correction for variation due to change in knee flexion.

To assess the reliability of patellotrochlear Index (PTI) in patellar height assessment on successive MRI scans in asymptomatic patients. Sixty-four patients with two successive MRI scans (128 studies) of the same knee for non-patellofemoral joint symptoms were identified retrospectively. PTI and knee flexion angle were assessed independently by three observers to assess interobserver reliability. The effect of knee flexion on PTI was assessed by comparing the change in values of PTI in each patient correlated with change in knee flexion. Sixty-four MRIs of patients (M:F) aged between 18 and 35years (mean 24.6) years were assessed. The mean PTI for initial scan group was 0.33% (95% CI: 0.29-0.37; SD: 0.15) and consecutive scan group was 0.30% (CI: 0.27-0.33; SD: 0.3). The difference was not significant (p= 0.097 using a paired t test) with high inter-observer correlation (0.9) in both sets. Spearman's rho for knee flexion angle and PTI was found to be positive and statistically significant (0.41; p = 0.001). A linear regression model was derived using a scatter chart of change in PTI with change in knee flexion for each patient. The gradient of the linear regression line was used to estimate a cPTI (corrected PTI) value (corrected to 0 degrees of knee flexion), defined as cPTI = PTI - 1.3a (a = knee flexion angle). This study demonstrates high inter-observer correlation of PTI on MRI and high test-retest reliability indicating unconscious quadriceps contraction does not change the index sufficiently. Knee flexion significantly alters PTI, increased patellotrochlear engagement with flexion increases the index. We propose use of the formula cPTI = PTI -1.3a to correct the index to 0 degree knee flexion in clinical practice.

Neural Network-Based Muscle Torque Estimation Using Mechanomyography During Electrically-Evoked Knee Extension and Standing in Spinal Cord Injury.

This study sought to design and deploy a torque monitoring system using an artificial neural network (ANN) with mechanomyography (MMG) for situations where muscle torque cannot be independently quantified. The MMG signals from the quadriceps were used to derive knee torque during prolonged functional electrical stimulation (FES)-assisted isometric knee extensions and during standing in spinal cord injured (SCI) individuals. Three individuals with motor-complete SCI performed FES-evoked isometric quadriceps contractions on a Biodex dynamometer at 30° knee angle and at a fixed stimulation current, until the torque had declined to a minimum required for ANN model development. Two ANN models were developed based on different inputs; Root mean square (RMS) MMG and RMS-Zero crossing (ZC) which were derived from MMG. The performance of the ANN was evaluated by comparing model predicted torque against the actual torque derived from the dynamometer. MMG data from 5 other individuals with SCI who performed FES-evoked standing to fatigue-failure were used to validate the RMS and RMS-ZC ANN models. RMS and RMS-ZC of the MMG obtained from the FES standing experiments were then provided as inputs to the developed ANN models to calculate the predicted torque during the FES-evoked standing. The average correlation between the knee extension-predicted torque and the actual torque outputs were 0.87 ± 0.11 for RMS and 0.84 ± 0.13 for RMS-ZC. The average accuracy was 79 ± 14% for RMS and 86 ± 11% for RMS-ZC. The two models revealed significant trends in torque decrease, both suggesting a critical point around 50% torque drop where there were significant changes observed in RMS and RMS-ZC patterns. Based on these findings, both RMS and RMS-ZC ANN models performed similarly well in predicting FES-evoked knee extension torques in this population. However, interference was observed in the RMS-ZC values at a time around knee buckling. The developed ANN models could be used to estimate muscle torque in real-time, thereby providing safer automated FES control of standing in persons with motor-complete SCI.

Neuromuscular reprogramming in femoro-patellar pain syndrome (FPPS) using combined muscle contractions

The main objective of this study is to measure the effect induced by combined muscle contraction of the Quadriceps and rectus femoris (by neuromuscular reprogramming) on pain phenomena and on the short-term recovery of muscle power. The goal to be achieved for these patients is to reduce the pain phenomena and to modify voluntarily and actively the orientation of their functional mechanical axes. Evaluation of isokinetic quadriceps strength before and after stretching the injured knee and the healthy knee for 27 patients with FPPS and 12 healthy control subjects (matched). No pathology on the contralateral knee. The evaluation is carried out at 60°/s concentric 120°/s concentric and 30°/s eccentric contraction by an isokinetic dynamometer. After performing the isokinetic tests and evaluating the pain (by EVA), specific contraction work of the quadriceps of the injured knee according to an identical protocol for each patient was performed (3 times). Our results show a significant effect of these contraction exercises on the pain phenomena of patients in the short-term. We obtained after quadriceps contraction a significant decrease in pain −38% and an increase in the strength of +17% for the pathological group. No significant change in the control group. There is a statistical correlation between the decrease of pain and recovery of strength after stretching. This significant decrease in pain associated with an increase in force parameters in only eccentric contraction. We confirm the effectiveness of quadriceps stretching with slow eccentric contraction in the care of FPPS. These beneficial effects are in favor of a systematic use with muscle building. These results are in favor of a new therapeutic care by using this kind of stretching. The management of stiffness and neurophysiological components that are directly associated with these phenomena of stiffness during the onset of this syndrome, encourages therapists to continue.

Intérêt de l’échographie pour l’étude du cartilage

Several imaging methods are available for the study of joint cartilage. Ultrasonography is generally used only to study the peripheral tissues. Exceptionally, ultrasonography is particularly well adapted for studying the trochanter cartilage of the knee joint that can be mobilized and exposed to the force of quadriceps contraction. We conducted a prospective study of 11 patients in order to compare the imaging performance of computed tomography versus ultrasonography for the evaluation of subchondral bone. Although it only studies the surface of the bone, ultrasonography was found to be very sensitive for analyzing subchondral irregularities, computed tomography remaining the gold standard for assessment of bone surface irregularities.

Influence of group III/IV muscle afferents on small muscle mass exercise performance: a bioenergetics perspective.

This investigation assessed the influence of group III/IV muscle afferents on small muscle mass exercise performance from a skeletal muscle bioenergetics perspective. Group III/IV muscle afferent feedback was attenuated with lumbar intrathecal fentanyl during intermittent isometric single-leg knee-extensor all-out exercise, while 31 P-MRS was used to assess skeletal muscle bioenergetics. Attenuation of group III/IV muscle afferent feedback improved exercise performance during the first minute of exercise, due to an increase in total ATP production with no change in the ATP cost of contraction. However, exercise performance was not altered during the remainder of the protocol, despite a sustained increase in total ATP production, due to an exacerbated ATP cost of contraction. These findings reveal that group III/IV muscle afferents directly limit exercise performance during small muscle mass exercise, but, due to their critical role in maintaining skeletal muscle contractile efficiency, with time, the benefit of attenuating the muscle afferents is negated. The direct influence of group III/IV muscle afferents on exercise performance remains equivocal. Therefore, all-out intermittent isometric single-leg knee-extensor exercise and phosphorous magnetic resonance spectroscopy (31 P-MRS) were utilized to provide a high time resolution assessment of exercise performance and skeletal muscle bioenergetics in control conditions (CTRL) and with the attenuation of group III/IV muscle afferent feedback via lumbar intrathecal fentanyl (FENT). In both conditions, seven recreationally active men performed 60 maximal voluntary quadriceps contractions (MVC; 3s contraction, 2s relaxation), while knee-extensor force and 31 P-MRS were assessed during each MVC. The cumulative integrated force was significantly greater (8±6%) in FENT than CTRL for the first minute of the all-out protocol, but was not significantly different for the second to fifth minutes. Total ATP production was significantly greater (16±21%) in FENT than CTRL throughout the all-out exercise protocol, due to a significantly greater anaerobic ATP production (11±13%) in FENT than CTRL with no significant difference in oxidative ATP production. The ATP cost of contraction was not significantly different between FENT and CTRL for the first minute of the all-out protocol, but was significantly greater (29±34%) in FENT than in CTRL for the second to fifth minutes. These findings reveal that group III/IV muscle afferents directly limit exercise performance during small muscle mass exercise, but, due to their critical role in maintaining skeletal muscle contractile efficiency, with time, the benefit from muscle afferent attenuation is negated.

Examining the Relationships Between the Mode of Quadriceps Contraction and Clinical Outcomes After ACL Reconstruction

Quadriceps strength is a useful clinical predictor of physical function and patient reported outcomes after anterior cruciate ligament reconstruction (ACLR). However, it remains unknown which mode of muscle contraction (isometric, concentric or eccentric) is most important for optimal physical and patient reported recovery, creating uncertainty amongst clinicians as to the most ideal strength assessment tool. PURPOSE: Examine the association between the mode of quadriceps muscle contraction (isometric, concentric and eccentric) and functional performance and patient reported outcomes. METHODS: Ten individuals with history of unilateral ACLR volunteered (22.4±1.95yrs; 1.66±0.08m; 65.62±12.10kg; years from surgery, 5.88±1.86yrs). Peak concentric and eccentric quadriceps force production at 60°/s and peak isometric force production with the knee positioned at 90° were assessed via an isokinetic dynamometer and normalized to body mass. Objective clinical hop tests were evaluated for maximal distance during the single leg hop for distance (SLHD), cross-over hop (CH) and triple hop (TrH). Patient reported outcomes were assessed using the International Knee Documentation Committee (IKDC) form. Association between quadriceps strength outcomes and all functional and patient reported outcomes were assessed using Pearson product moment correlations. RESULTS: Peak concentric strength was only associated with maximal TrH distance (mean±SD; 1.90±0.57Nm/kg, 4.61±0.67m; r=0.723, P=0.018). Peak eccentric strength was only associated with maximal SLHD (2.82±0.78Nm/kg, 1.41±0.19m; r=0.680, P=0.044). Peak isometric strength was associated with maximal CH distance (3.06±0.59Nm/kg, 4.35±0.70m; r=0.696, p=0.025) and IKDC (84.94±9.92; r=0.803, P=0.005). CONCLUSION: No single mode of quadriceps contraction was associated with all clinical outcome measures. Hence, a multimodal approach to strength re-training and evaluation may be important for the development of proper quadriceps function and progression of optimal clinical outcomes. Clinicians should consider adding a multimodal strength program during ACLR rehabilitation to promote positive outcomes across a variety of clinical measures.

ISOKINETIC ASSESSMENT OF MUSCULAR STRENGTH AND BALANCE IN BRAZILIAN ELITE FUTSAL PLAYERS

Strength asymmetries are related to knee injuries in intermittent sports players. The purpose of this study was to examine whether elite futsal players demonstrate strength asymmetries during knee isokinetic testing applying the Croisier et al.21 criteria. Forty male elite (27.9 ± 6.5 years) Brazilian futsal players participated in the study. The testing protocol required players to perform concentric contractions of both quadriceps and hamstring muscles at angular velocities of 60 °·s-1 and 240 °·s-1 and eccentric contractions of hamstring at 30 °·s-1 and 120 °·s-1. Conventional (concentric:concentric) and mixed (eccentric:concentric) hamstrings/quadriceps (H/Q) ratios were calculated. Subjects were determined to have an imbalanced strength profile if an athlete had at least two parameters that were asymmetrical across speeds and conditions. Asymmetry was operationally defined as peak torque asymmetry greater than 15% in bilateral comparison, and H/Q ratio less than 0.47 for conventional and 0.80 for mixed conditions. Significant differences were observed between preferred and nonpreferred limbs in the concentric contractions of flexors at 240 °·s-1 and eccentric contractions of extensors and flexors at 30 °·s-1 and 120 °·s-1. However, these asymmetries did not exceed 15%. The conventional and mixed H/Q ratios were greater in the preferred than in nonpreferred limbs, but only the mixed hamstringsecc/quadricepsconc in the nonpreferred limbs showed values lower than recommended (<0.80). In addition, 50% of elite futsal players had preseason strength imbalances per the developed criteria. The studied elite futsal players had preseason strength imbalances, which may increase the risk of hamstring injuries. 3.

Aptitude physique et psychologique pour la reprise du sport après reconstruction du ligament croisé antérieur du genou : score ACL-RSI et tests fonctionnels

BackgroundFor the patient returning to sport after injury, physical and psychological aptitude are crucial elements: premature return is a risk factor for new injury. The Anterior-Cruciate-Ligament Return-to-Sport-After-Injury (ACL-RSI) scale can be used to quantify the impact of psychological factors affecting a patient's aptitude for return-to-sport. MethodsA prospective single-center cohort study included a series of athletes who underwent surgical treatment in 2013–2016 for an isolated primary full-thickness ACL tear. These patients had a healthy contralateral knee. A complete clinical work-up with function tests was conducted postoperatively and at six months. Isokinetic tests were performed with Con-Trex JM® to measure knee muscle force at three angular speeds: concentric quadriceps contraction at 60° (Q 60°) and 240° (Q 240°) and excentric hamstring contraction at 30° (H 30°). Neuromuscular tests used the single-leg jump. The main outcome was the correlation between ACI-RSI score and inter-knee difference in Q 60° at six months. ResultsInclusion criteria were met by 182 patients. Mean follow-up was 6.5±1.7 months (range: 4–12). The ACL-RSI score was positively and weakly significantly correlated with jump test results (r=0.15–0.18; P=0.1–0.03). The ACL-RSI exhibited better significance among patients who had returned to sport (P=0.0001). ConclusionAt six months, the ACL-RSI is significantly and positively correlated with isokinetic and function tests, though weakly.

Ultrasonographic Morphological Changes in the Prefemoral Fat Pad Associated with Knee Osteoarthritis.

Background:In normal knees, quadriceps contraction changes the shape of the prefemoral fat pad (PFP). However, in persons with knee osteoarthritis (OA), the functional or morphological changes of the PFP are unclear. This study aimed to clarify the morphological changes in the PFP in individuals with knee OA through ultrasonography.Materials and Methods:Participants were divided into the OA (36 knees; mean age, 74 years), elderly (31 knees; mean age, 70 years), and young (26 knees; mean age, 21 years) groups. The anteroposterior (AP) length of the PFP before and during isometric quadriceps contraction at 0°, 30°, 60°, and 90° knee flexion was measured ultrasonographically. The difference between the maximum and minimum length values, change in length, was also measured. These parameters were compared among the three groups. In the OA group, correlations between the parameters and clinical features (knee pain; visual analog scale, knee range of motion [ROM], Kellgren and Lawrence (K/L) grade, and intercondylar distance) were examined by Spearman and Pearson's correlation coefficient tests.Results:The AP lengths of the PFP before contraction were significantly lower in the OA group than in elderly group and young group at 30° (6.9 ± 2.5 vs. 12.0 ± 3.6 or 11.1 ± 2.7 mm, respectively; in order P = 0.014, P = 0.006) and 60° (6.5 ± 2.0 vs. 9.7 ± 2.5 or 9.1 ± 2.7 mm, respectively; both P < 0.001). The AP lengths of the PFP during contraction were significantly lower in the OA group than in elderly group and young group at 0° (6.7 ± 2.3 vs. 8.8 ± 3.7 or 9.1 ± 1.6 mm, respectively; both P < 0.001), 30° (7.9 ± 2.6 vs. 12.9 ± 3.7 or 13.0 ± 2.6 mm, respectively; both P < 0.001), and 60° (7.1 ± 2.5 vs. 13.5 ± 2.6 or 13.6 ± 3.0 mm, respectively; both P < 0.001). The change in length before maximum isometric quadriceps contraction was significantly lower in the knee OA group than in both elderly and young groups (3.3 ± 1.9 vs. 8.4 ± 2.5 or 6.8 ± 3.0 mm, respectively; both P < 0.001). The change in length during contraction was also significantly lower in the knee OA group than in both the elderly and young groups (3.9 ± 2.3 vs. 8.7 ± 2.3 or 8.9 ± 2.0 mm, respectively; both P < 0.001). In the OA group, change in length during contraction was significantly associated with knee pain (r = −0.476, P = 0.007), knee ROM (r = 0.388, P = 0.019), and Kellgren and Lawrence grade (r = −0.357, P = 0.045).Conclusions:In knee OA, movement of PFP was decreased more than healthy participants. In the knee OA group, the decrease of the morphological change of the PFP showed the relationship between VAS score, knee extension ROM, intercondylar distance (ICD), and K/L grade. An evaluation to the PFP may be required in individuals with knee OA.