Quadriceps Muscle Function Research Articles

A comparison of foam rolling and vibration foam rolling on the quadriceps muscle function and mechanical properties

PurposeThe purpose of the study was to investigate the effects of using a vibration foam roll (VFR) or a non-vibration foam roll (NVFR) on maximum voluntary isometric contraction peak torque (MVIC), range of motion (ROM), passive resistive torque (PRT), and shear modulus.MethodsTwenty-one male volunteers visited the laboratory on two separate days and were randomly assigned to either a VFR group or a NVFR group. Both interventions were performed for 3 × 1 min each. Before and after each intervention, passive resistive torque and maximum voluntary isometric contraction peak torque of the leg extensors were assessed with a dynamometer. Hip extension ROM was assessed using a modified Thomas test with 3D-motion caption. Muscle shear modulus of the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) was assessed with shear wave elastography (SWE).ResultsIn both groups (VFR, NVFR) we observed an increase in MVIC peak torque (+ 14.2 Nm, + 8.6 Nm) and a decrease in shear modulus of the RF (− 7.2 kPa, − 4.7 kPa). However, an increase in hip extension ROM (3.3°) was only observed in the VFR group. There was no change in PRT and shear modulus of the VL and VM, in both the VFR group and the NVFR group. Our findings demonstrate a muscle-specific acute decrease in passive RF stiffness after VFR and NVFR, with an effect on joint flexibility found only after VFR.ConclusionThe findings of this study suggest that VFR might be a more efficient approach to maximize performance in sports with flexibility demands.

Unique Characteristics of Quadriceps Muscle Morphology and Function in Older Tennis Players.

We investigated the quadriceps muscle size and quantitative characteristics in older tennis players. Thirty-eight senior tennis players (70.8 ± 5.3years) and 38 controls (71.6 ± 5.1years) were included. To measure the muscle size and quality, we measured muscle thickness in the rectus femoris (RF), vastus lateralis, and vastus intermedius, and muscle echo intensity in the RF and vastus lateralis using B-mode transverse ultrasound, respectively. We measured knee extension peak torque for muscle function. Muscle thickness in the RF, vastus lateralis, and vastus intermedius were significantly larger in tennis players than in controls. Tennis players had a lower echo intensity in RF and a higher knee extension peak torque compared to controls. Stepwise multiple linear regression analysis implied that echo intensity and muscle thickness were predictors of knee extension peak torque. Higher muscle quality contributes to a higher knee extension peak torque in tennis players. Playing tennis may prevent age-related muscle atrophy and maintain muscle quality in older individuals.

Effects of different analgesia methods on early mobilization after knee join replacements

Rationale. Knee join replacement is accompanied by intensive pain syndrome. Prolonged blocks of branches of sciatic and femoral nerves are the most effective. Apart from sensory block and analgesia some types of blocks cause motor block of lower extremities, particularly quadriceps muscle of thigh which may prevent patients mobilization. In this connection, the choice of anesthesia strategy is significant concerning the use of prolonged blocks of the branches of sciatic and femoral nerves maintaining the motor function of the lower extremities with adequate analgesia.
 The goal of the study is to select a method of pain relief after knee replacement that provides adequate analgesia while maintaining the motor function of the lower limb muscles.
 Material and methods. The investigation was carried out in patients undergone knee join replacement according to standard procedure. The operation was performed under combined anaesthesia: spinal anaesthesia plus prolonged block of tibial nerve and femoral nerve or femoral triangle block with perineural space catheterization. The block with the use of local anesthetic in the analgesic concentration for postoperative analgesia during 3 postoperative days. All participants were divided into four groups according to the combinations of the blocks.
 Results. The combination of block of branches of sciatic and femoral nervessignificantly improves the quality of postoperative analgesia on the first postoperative day. The block in femoral triangle (subsartorial) in comparison with the block of femoral nerve is accompanied by significantly less weakness of quadriceps muscle of thigh at the equal analgesic potency.
 Conclusions. Maintaining the motor function of quadriceps muscle of thigh with the use of the prolonged block in femoral triangle for analgesia can be of certain advantage for patients mobilization in the early postoperative period (fast track).

Home-Based Functional Electrical Stimulation of Human Permanent Denervated Muscles: A Narrative Review on Diagnostics, Managements, Results and Byproducts Revisited 2020.

Spinal cord injury (SCI) produces muscle wasting that is especially severe after complete and permanent damage of lower motor neurons, as can occur in complete conus and cauda equina syndrome. Even in this worst-case scenario, mass and function of permanently denervated quadriceps muscle can be rescued by surface functional electrical stimulation using a purpose designed home-based rehabilitation strategy. Early diagnostics is a key factor in the long-term success of this management. Function of quadriceps muscle was quantitated by force measurements. Muscle gross cross-sections were evaluated by quantitative color computed tomography (CT) and muscle and skin biopsies by quantitative histology, electron microscopy, and immunohistochemistry. Two years of treatment that started earlier than 5 years from SCI produced: (a) an increase in cross-sectional area of stimulated muscles; (b) an increase in muscle fiber mean diameter; (c) improvements in ultrastructural organization; and (d) increased force output during electrical stimulation. Improvements are extended to hamstring muscles and skin. Indeed, the cushioning effect provided by recovered tissues is a major clinical benefit. It is our hope that new trials start soon, providing patients the benefits they need.

Synergetic Effect of NO Precursor Supplementation and Exercise Training.

Nitric oxide (NO) precursor supplementation has been shown to increase NO bioavailability and can potentially improve vascular function and exercise performance. It remains unclear whether the combination of NO precursor supplementation and exercise training has synergic effects on exercise performance. This study aims to assess the effect of chronic nitrate and citrulline intake on exercise training adaptations in healthy young individuals. In this randomized, double-bind trial, 24 healthy young (12 females) subjects performed vascular function assessment (blood pressure, pulse wave velocity, postischemia vasodilation, and cerebrovascular reactivity) and both local (submaximal isometric unilateral knee extension) and whole-body (incremental cycling) exercise tests to exhaustion before and after a 2-month exercise training program and daily intake of a placebo or a nitrate-rich salad and citrulline (N + C, 520 mg nitrate and 6 g citrulline) drink. Prefrontal cortex and quadriceps oxygenation was monitored continuously during exercise by near-infrared spectroscopy. N + C supplementation had no effect on vascular function and muscle and cerebral oxygenation during both local and whole-body exercise. N + C supplementation induced a significantly larger increase in maximal knee extensor strength (+5.1 ± 3.5 vs +0.2 ± 5.5 kg, P = 0.008) as well as a trend toward a larger increase in knee extensor endurance (+35.2 ± 26.1 vs +24.0 ± 10.4 contractions, P = 0.092) than placebo, but no effect on exercise training-induced maximal aerobic performance improvement. These results suggest that chronic nitrate and citrulline supplementation enhances the effect of exercise training on quadriceps muscle function in healthy active young individuals, but this does not translate into improved maximal aerobic performances.

The Immediate Effects of Transcranial Direct Current Stimulation on Quadriceps Muscle Function in Individuals With a History of Anterior Cruciate Ligament Reconstruction: A Preliminary Investigation.

Altered quadriceps activation is common following anterior cruciate ligament reconstruction (ACLR), and can persist for years after surgery. These neural deficits are due, in part, to chronic central nervous system alterations. Transcranial direct current stimulation (tDCS) is a noninvasive modality, that is, believed to immediately increase motor neuron activity by stimulating the primary motor cortex, making it a promising modality to use improve outcomes in the ACLR population. To determine if a single treatment of tDCS would result in increased quadriceps activity and decreased levels of self-reported pain and dysfunction during exercise. Randomized crossover design. Controlled laboratory. Ten participants with a history of ACLR (5 males/5 females, 22.9 [4.23]y, 176.57 [12.01]cm, 80.87 [16.86]kg, 68.1 [39.37] mo since ACLR). Active tDCS and Sham tDCS. Percentage of maximum electromyographic data of vastus medialis and lateralis, voluntary isometric strength, percentage of voluntary activation, and self-reported pain and symptom scores were measured. The 2 × 2 repeated-measures analysis of variance by limb were performed to explain the differences between time points (pre and post) and condition (tDCS and sham). There was a significant time main effect for quadriceps percentage of maximum electromyographic of vastus medialis (F9,1 = 11.931, P = .01) and vastus lateralis (F9,1 = 9.132, P = .01), isometric strength (F9,1 = 5.343, P = .046), and subjective scores for pain (F9,1 = 15.499, P = .04) and symptoms (F9,1 = 15.499, P = .04). Quadriceps percentage of maximum electromyographic, isometric strength, and voluntary activation showed an immediate decline from pre to post regardless of tDCS condition. Subjective scores improved slightly after each condition. One session of active tDCS did not have an immediate effect on quadriceps activity and subjective scores of pain and symptoms. To determine if tDCS is a valid modality for this patient population, a larger scale investigation with multiple treatments of active tDCS is warranted.

Blood Flow Restriction Training Applied With High-Intensity Exercise Does Not Improve Quadriceps Muscle Function After Anterior Cruciate Ligament Reconstruction: A Randomized Controlled Trial

Background: A major goal of rehabilitation after anterior cruciate ligament reconstruction (ACLR) is restoring quadriceps muscle strength. Unfortunately, current rehabilitation paradigms fall short of this goal, such that substantial quadriceps muscle strength deficits can limit return to play and increase the risk of recurrent injuries. Blood flow restriction training (BFRT) involves the obstruction of venous return to working muscles during exercise and may lead to better recovery of quadriceps muscle strength after ACLR. Purpose: To examine the efficacy of BFRT with high-intensity exercise on the recovery of quadriceps muscle function in patients undergoing ACLR. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: A total of 34 patients (19 female, 15 male; mean age, 16.5 ± 2.7 years; mean height, 169.0 ± 19.7 cm; mean weight, 73.2 ± 17.7 kg) scheduled to undergo ACLR were randomly assigned to 1 of 4 groups: concentric (n = 8), eccentric (n = 8), concentric with BFRT (n = 9), and eccentric with BFRT (n = 9). The exercise component of the intervention consisted of patients performing a single-leg isokinetic leg press, at an intensity of 70% of the patients’ 1-repetition maximum during either the concentric or eccentric action, for 4 sets of 10 repetitions 2 times per week for 8 weeks beginning at 10 weeks postoperatively. Patients randomized to the BFRT groups performed the leg-press exercise with a cuff applied to the thigh, set to a limb occlusion pressure of 80%. Isometric and isokinetic (60 deg/s) quadriceps peak torque, quadriceps muscle activation, and rectus femoris muscle volume were assessed before ACLR, after BFRT, and at the time that patients returned to activity and were converted to the change in values from baseline for analysis. Also, 1-way analyses of covariance were used to compare the change in values for each dependent variable between groups after BFRT and at return to activity (P ≤ .05). Results: No significant differences were found between groups for any outcome measures at either time point (P > .05). Conclusion: An 8-week BFRT plus high-intensity exercise intervention did not significantly improve quadriceps muscle strength, activation, or volume. On the basis of our findings, the use of BFRT in conjunction with high-intensity resistance exercise in patients undergoing ACLR to improve quadriceps muscle function may not be warranted. Registration: NCT03141801 (ClinicalTrials.gov identifier)

Comparison of continuous femoral nerve block with local infiltration for postoperative analgesia in unilateral total knee arthroplasty- a randomized controlled trial

Background & Objective: Local infiltration of knee joints during knee joint surgery has been used for postoperative analgesia with preservation of motor function of quadriceps muscle, which helps in early mobilization. Femoral nerve block has been incriminated with paralyses of vastus medialis muscle. We aimed to compare postoperative analgesia between femoral nerve block and local infiltration in patients undergoing unilateral total knee arthroplasty (TKA).Methodology: After obtaining institutional ethical approval and written informed consent from the patients, this randomized controlled trial was conducted at Department of Anesthesia at Teerthankar Mahaveer Medical College & Research Centre between July - December 2018. The study was conducted on 60 patients of ASA I and II, undergoing unilateral total TKA. Patients were randomly divided into two groups: Group FB patients underwent femoral nerve block, and Group LI patients underwent local infiltration analgesia. Sedation score, numeric rating scale, motor power and frequency of nausea/vomiting were recorded and statistical analysis done.Results: We observed better pain relief in patients which received femoral nerve block as compared to local infiltration analgesia (p < 0.001). Sedation score was higher in Group LI and was statistically significant between the two groups at 4th, 12th, and 48th hour (p < 0.05). Group FB patients were associated with higher muscle power grades (p < 0.001) as compared to local infiltration analgesia patients. Fentanyl demand was observed to be lesser in Group FB as compared to Group LI (p < 0.001).Conclusion: The study concludes that femoral nerve block produces better pain reliefin patients posted for unilateral knee arthroplasty as compared to local infiltration ofthe local anesthetic solution. However, there is gross reduction in range of motion withfemoral nerve block.Citation: Varshney RK, Prasad MK, Garg M. Comparison of continuous femoral nerve block with local infiltration for postoperative analgesia in unilateral total knee arthroplasty - a randomized controlled trial. Anaesth pain & intensive care 2019;23(3):268-273

Pain relieve without impairing muscle function after local infiltration anaesthesia in primary knee arthroplasty: a prospective randomized study.

Purpose of the current study was to compare early effectiveness of pain relieve of 3 in 1 regional pain catheter to local infiltration anesthesia (LIA) in primary total knee arthroplasty (TKA). Secondary endpoint was quadriceps muscle strength after both procedures. A single-center, prospective, randomized controlled trial was performed. Patients eligible to TKA were either randomized into group 3 in 1 regional pain catheter (C), or group local infiltration anesthesia (L). Pain relieve was assessed by visual analogue scale (VAS) at rest and under physical activity (PA) prior to surgery (t0) and at days one through six. In addition, quadriceps muscle strength ( = straight leg raise) was tested according to the Manual Muscle Testing Scale. Functional outcome was measured using the Oxford Knee Score (OKS) preoperatively and 6months postoperatively. 121 patients were included in the study. 59 (48.8%) patients were allocated to group C, 62 (51.2%) patients to Group L. No differences concerning pain level evaluated by VAS could be detected between the groups at any time. Comparing straight leg raise test group L was significantly superior over the complete postoperative period (p < 0.03). The mean OKS decreased significantly (p < 0.001) from preoperatively 34.2 ± 7.5 points to 16.9 ± 6.0 points at the six months final follow-up. Regarding OKS there were no intergroup differences at the final follow-up at 6months postoperative. There is no significant difference in pain relieve comparing LIA to 3 in 1 catheter in perioperative pain management in TKA. The advantage of LIA is unimpaired quadriceps muscle function in the short-term follow-up.

Quadriceps muscle function following anterior cruciate ligament reconstruction: systemic differences in neural and morphological characteristics.

Quadriceps muscle dysfunction is common following anterior cruciate ligament reconstruction (ACLR). Data considering the diversity of neural changes, in-concert with morphological adaptations of the quadriceps muscle, are lacking. We investigated bilateral differences in neural and morphological characteristics of the quadriceps muscle in ACLR participants (n = 11, month post-surgery: 69.4 ± 22.4) compared to controls matched by sex, age, height, weight, limb dominance, and activity level. Spinal reflex excitability was assessed using Hoffmann reflexes (H:M); corticospinal excitability was quantified via active motor thresholds (AMT) and motor-evoked potentials (MEP) using transcranial magnetic stimulation. Cortical activation was assessed using a knee flexion/extension task with functional magnetic resonance imaging (fMRI). Muscle volume was quantified using structural MRI. Muscle strength and patient-reported outcomes were also collected. 2 × 2 RM ANOVAs were used to evaluate group differences. Smaller quadriceps muscle volume (total volume, rectus femoris, vastus medialis, and intermedius) and lower strength were detected compared to contralateral and control limbs. Individuals with ACLR reported higher levels of pain and fear and lower levels of knee function compared to controls. No differences were observed for H:M. ACLR individuals demonstrated higher AMT bilaterally and smaller MEPs in the injured limb, compared to the controls. ACLR participants demonstrated greater activation in frontal lobe areas responsible for motor and pain processing compared to controls, which were associated with self-reported pain. Our results suggest that individuals with ACLR demonstrate systemic neural differences compared to controls, which are observed concurrently with smaller quadriceps muscle volume, quadriceps muscle weakness, and self-reported dysfunction.

Adductor Canal Nerve Versus Femoral Nerve Blockade for Pain Control and Quadriceps Function Following Anterior Cruciate Ligament Reconstruction With Patellar Tendon Autograft: A Prospective Randomized Trial

To compare femoral nerve blockade (FNB) versus adductor canal nerve blockade (ACB) for postoperative pain control and quadriceps muscle function in patients undergoing anterior cruciate ligament (ACL) reconstruction with patellar tendon autograft. A randomized therapeutic trial of 90 patients undergoing ACL reconstruction with patellar tendon autograft was conducted comparing ACB versus FNB at 24hours, 2 and 4 weeks, and 6months postsurgery. Early outcome measures included average pain score and morphine equivalent units (milligrams) consumed, quadriceps surface electromyography, straight leg raise, and ability to ambulate without assistive devices. The 6-month outcome measures included knee range of motion (ROM), isokinetic knee extension peak torque, single-leg squat, and single-leg hop performance. Complications were recorded throughout the study for the development of anterior knee pain, knee extension ROM loss, deep vein thrombosis, and graft failure. Mixed-model analysis of variance and Mann-Whitney U tests were performed using an alpha of .05. Quadriceps surface electromyography deficits were higher for FNB at 24hours (P < .001) and 2weeks (P < .001) when compared with the ACB group. There were no between-groups difference for subjective pain (P= .793) or morphine consumption (P= .358) within the first 24hours of surgery. A higher percentage of patients in the ACB group met the full ambulation criteria at 4weeks compared with the FNB group (100% vs 84.2%, P < .001). No between-group differences were observed at 6months; however, the rate of knee extension ROM loss was higher for the FNB group versus the ACB group (21.1% vs 5.0%, P= .026), respectively. ACB was as effective as FNB at providing pain control while eliciting fewer quadriceps muscle activation deficits and fewer postoperative complications. Based on previous evidence and the results of this study, we recommend the use of ACB over FNB for theanalgesic management of patients undergoing ACL reconstruction with patellar tendon autograft. Level I, prospective randomized controlled trial.

Neurostructural correlates of strength decrease following total knee arthroplasty: A systematic review of the literature with meta-analysis.

Recent literature suggests that alterations in both neural and structural components of the neuromuscular system are major determinants of knee extensor muscle weakness after total knee arthroplasty (TKA). Therefore, the goal of this study was to investigate the maximal voluntary strength (MVS), voluntary muscle activation (VMA), and the cross-sectional area (CSA) of the muscle, up to 33 months after the TKA. We searched relevant scientific databases and literature for outcomes of interest, including quadriceps MVS, VMA, and CSA. Ten studies met the inclusion criteria and involved a total of 289 patients. The quality of the studies was evaluated by Methodological Index for Non-Randomized Studies (MINORS). Results showed that quadriceps MVS markedly declines in the early postoperative period, after which it slowly and linearly recovers over time. However, the same phenomenon was not observed for VMA and CSA, which were not significantly altered after the TKA. Furthermore, a meta-regression analysis revealed that the change in VMA accounted for 39% of the relative change in quadriceps strength (R2=0.39; p=0.015) in the early postoperative period. Patients treated with TKA had considerable weakness of the quadriceps muscle, which was detectable up to 3 months after surgery. Although the change in VMA largely explains quadriceps weakness, this change and CSA differences were not significant, suggesting that other neural correlates, such as hamstrings coactivation, might alter quadriceps muscle function. Thus, more attention should be paid to address VMA failure and coactivation of antagonist muscles. More comprehensive rehabilitation approaches may be required to target the whole neural circuit controlling the motor action.

Non‐failure blood flow restricted exercise induces similar muscle adaptations and less discomfort than failure protocols

Low-load blood flow restricted resistance exercise (BFRE) performed to volitional failure is suggested to constitute an effective method for producing increases in muscle size and function. However, BFRE to failure may entail high levels of perceived exertion, discomfort, and/or delayed onset of muscle soreness (DOMS). The aim of the study was to compare BFRE performed to volitional failure (F-BFRE) vs non-failure BFRE (NF-BFRE) on changes in muscle size, function and perceptual responses. Fourteen young untrained males had one leg randomized to knee extension F-BFRE while the contralateral leg performed NF-BFRE. The training consisted of 22 exercise bouts over an 8-week period. Whole-muscle cross-sectional area (CSA) of quadriceps components, muscle function, and DOMS were assessed before and after the training period. Perceived exertion and discomfort were registered during each exercise bout. Both F-BFRE and NF-BFRE produced regional increases in muscle CSA in the range of: quadriceps (2.5%-3.8%), vastus lateralis (8.1%-8.5%), and rectus femoris (7.9%-25.0%). All without differences between leg. Muscle strength (6.8%-11.5%) and strength-endurance capacity (13.9%-18.6%) also increased to a similar degree in both legs. Less perceived exertion, discomfort, and DOMS were reported with NF-BFRE compared to F-BFRE. In conclusion, non-failure BFRE enables increases in muscle size and muscle function, while involving reduced perceptions of exertion, discomfort, and DOMS. Non-failure BFRE may be a more feasible approach in clinical settings.

The influence of different branches of sciatic and femoral nerves blocks on the postoperative analgesia quality after knee join replacement

Topicality: knee join replacement is accompanied by intensive pain syndrome. Prolonged blocks of branches of sciatic and femoral nervesare the most effective. Apart from sensory block and analgesia some types of blocks cause motor block of lower extremities, particularly quadriceps muscle of thigh which may prevent patients’ mobilization. In this connection, the choice of anesthesia strategy is significant concerning the use of prolonged blocks of the branches of sciatic and femoral nerves maintaining the motor function of the lower extremities with adequate analgesia.&#x0D; The aim of work: the choice of optimal combination of prolonged blocks of branches of sciatic and femoral nervesensuring adequate analgesia with motor function of quadriceps muscle of thigh maintenance.&#x0D; Material and methods: the investigation was carried out in patients undergone knee join replacement according to standard procedure. The operation was performed under combined anaesthesia: spinal anaesthesia and intravenous sedation with propofol and midazolam plus prolonged block of tibial nerve and femoral nerve or adductor canal with perineural space catheterization. The block with the use of local anesthetic in the analgesic concentration for postoperative analgesia during 72-hour period after the end of the operation. The patients were divided into the investigation groups according to the combinations of the blocks.&#x0D; Results and discussion: the combination of block of branches of sciatic and femoral nervessignificantly improves the quality of postoperative analgesia on the first postoperative day. The block of adductor canal in comparison with the block of femoral nerve is accompanied by significantly less weakness of quadriceps muscle of thigh at the equal analgesic potency.&#x0D; Conclusions: maintaining the motor functionof quadriceps muscle of thigh with the use of the adductor canal prolonged block for analgesia can be of certain advantage for patients’ mobilization in the early postoperative period.

Quadriceps and Patient-Reported Function in ACL-Reconstructed Patients: A Principal Component Analysis.

Assessment of physical function for individuals after anterior cruciate ligament reconstruction (ACL-R) is complex and warrants the use of diverse evaluation strategies. To maximize the efficiency of assessment, there is a need to identify tests that provide the most meaningful information about this population. To investigate underlying constructs of quadriceps muscle function that uniquely describe aspects of performance in patients after ACL-R and establish clinical thresholds for measures able to classify patients with and without ACL-R. Cross-sectional. Research laboratory. Patients (or Other Participants): Seventy-two patients with a primary, unilateral ACL-R (32 males and 40 females, age = 26.0 [9.3]y, time since surgery = 46.5 [58.0] mo) and 30 healthy controls (12 males and 18 females, age = 22.7 [4.6]y). Quadriceps function was assessed bilaterally during 1 study visit. Isokinetic strength (peak torque, total work, and average power) at 90° and 180°/s, maximal voluntary isometric contraction torque, fatigue index, central activation ratio, Hoffmann reflex, and active motor threshold. Principal component analyses were performed for the involved limb, contralateral limb, and limb symmetry. Receiver-operator characteristic curve analyses were conducted to determine the diagnostic utility of each variable. Binary logistic regression was used to predict group membership (ACL-R vs healthy). Three components of peripheral, central, and combined (peripheral and central) muscle function were identified, explaining 70.7% to 80.5% of variance among measures of quadriceps function. Total knee-extensor work at 90°/s (≥18.4J/kg), active motor threshold (≥39.5%), and central activation ratio (≥94.7%) of the involved limb were strong predictors of patient status and correctly classified 83.5% of patients with ACL-R (P < .001). Unique constructs of peripheral, central, and combined muscle function exist in patients with ACL-R. Total knee-extensor work at 90°/s, active motor threshold, and central activation ratio consistently explained a significant portion of variance in measures of quadriceps function, demonstrated acceptable to excellent diagnostic utility, and predicted group membership with 72.8% to 83.5% accuracy.

Increasing Body Weight Alters Lower Limb Muscle Balance And Foot Control

Obesity is a well established risk factor for developing osteoarthritis (OA). Population-based studies in particular have consistently shown a link between obesity and knee OA. Yet many factors for diseases and conditions associated with obesity could contribute to OA initiation and/or progression. The present study examined the effects systematically increasing subject weight and the effects on quadriceps femoris muscle function and foot balance stability during walking and squatting. METHODS: Twenty asymptomatic healthy young adults (Age = 22 ± 2; 19 kg/m(2) < BMI < 22 kg/m(2)) were studied. A three-dimensional gait analysis was conducted for all subjects. Plantar pressure distribution (the peak pressure of the eight plantar surface areas) and foot kinematics, surface electromyograms from the lateral and medial gastrocnemii, lateral and medial hamstrings, vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) were recorded during squatting and self-selected speed walking. Weight increase (10, 20 and 30% of subject body weight) was achieved by placing a belly bag on the subject’s body attached around the hip and to the shoulders. Principal component analysis was used to extract major features of amplitude and temporal pattern variability from the electromyograms of each muscle group (gastrocnemii, quadriceps, hamstrings separately). Analysis of variance models tested for weight load effects and interaction effects for these features (α = 0.05). RESULTS: Significant weight load effects were found for features that described more prolonged activation of the gastrocnemii and quadriceps muscles during the stance phase of gait (P < 0.05). Load increase selectively activated the VL compared to the VM during walking and the first 20 degrees of knee flexion during the squat. Load increase was also associated with increased mid-rear-foot pressure and delay in both the onset of the second wave of flexion at the knee joint and reduced range of motion of the ankle (P < 0.05). CONCLUSIONS: We confirm the effects of increasing body weight on lower extremity muscle activation and foot balance control, both of which may contribute to knee OA development and progression.

Early structural and functional signature of 3‐day human skeletal muscle disuse using the dry immersion model

Our study contributes to the characterization of muscle loss and weakness processes induced by a sedentary life style, chronic hypoactivity, clinical bed rest, immobilization and microgravity. This study, by bringing together integrated and cellular evaluation of muscle structure and function, identifies the early functional markers and biomarkers of muscle deconditioning. Three days of muscle disuse in healthy adult subjects is sufficient to significantly decrease muscle mass, tone and force, and to induce changes in function relating to a weakness in aerobic metabolism and muscle fibre denervation. The outcomes of this study should be considered in the development of an early muscle loss prevention programme and/or the development of pre-conditioning programmes required before clinical bed rest, immobilization and spaceflight travel. Microgravity and hypoactivity are associated with skeletal muscle deconditioning. The decrease of muscle mass follows an exponential decay, with major changes in the first days. The purpose of the study was to dissect out the effects of a short-term 3-day dry immersion (DI) on human quadriceps muscle function and structure. The DI model, by suppressing all support zones, accurately reproduces the effects of microgravity. Twelve healthy volunteers (32±5years) completed 3days of DI. Muscle function was investigated through maximal voluntary contraction (MVC) tests and muscle viscoelasticity. Structural experiments were performed using MRI analysis and invasive experiments on muscle fibres. Our results indicated a significant 9.1% decrease of the normalized MVC constant (P=0.048). Contraction and relaxation modelization kinetics reported modifications related to torque generation (kACT =-29%; P=0.014) and to the relaxation phase (kREL =+34%; P=0.040) after 3days of DI. Muscle viscoelasticity was also altered. From day one, rectus femoris stiffness and tone decreased by, respectively, 7.3% (P=0.002) and 10.2% (P=0.002), and rectus femoris elasticity decreased by 31.5% (P=0.004) after 3days of DI. At the cellular level, 3days of DI translated into a significant atrophy of type I muscle fibres (-10.6±12.1%, P=0.027) and an increased proportion of hybrid, type I/IIX fibre co-expression. Finally, we report an increase (6-fold; P=0.002) in NCAM+ muscle fibres, showing an early denervation process. This study is the first to report experiments performed in Europe investigating human short-term DI-induced muscle adaptations, and contributes to deciphering the early changes and biomarkers of skeletal muscle deconditioning.

Lower-limb muscle function is a determinant of exercise tolerance after lung resection surgery in patients with lung cancer.

This study aims to investigate the association between exercise tolerance, pulmonary function and lower-limb muscle function in patients with lung cancer who underwent lung resection surgery in the previous year. Sixty-four patients (age: 67 ± 11 years, 66% males) performed a symptom-limited incremental cycle test to define peak oxygen consumption (VO2 peak) and peak workload (Wpeak). The best of two 6-min walking distance (6MWD) tests was also included. Isometric quadriceps strength and isokinetic quadriceps endurance were measured. Post-bronchodilator spirometry, lung volumes and diffusing capacity of the lung for carbon monoxide (DLCO ) measurements were assessed. Univariate correlation analysis and multiple regression analyses were performed. VO2 peak, W peak and 6MWD showed moderate to strong correlations with quadriceps strength/endurance and DLCO while weak to moderate correlations were found with forced expiratory volume in 1 s (FEV1) , functional residual capacity (FRC) and body weight. Multiple regression showed that peak isometric quadriceps strength (P < 0.001) and DLCO (P < 0.001) were significant predictors of VO2 peak (explained variance R2 = 0.67), while quadriceps endurance (P = 0.0015) and DLCO (P < 0.0001) were significant predictors of W peak (R2 = 0.61). Quadriceps endurance capacity (P = 0.013), but not DLCO , significantly contributed to the 6MWD model (R2 = 0.29). We identified a strong significant relationship between peak aerobic capacity and quadriceps muscle function and lung diffusing capacity. 6MWD was significantly related to quadriceps muscle function but not to pulmonary function. These findings suggest that accurate assessment of lower-limb muscle strength has a role in the accurate interpretation of exercise tests and in selecting optimal candidates for resistance training interventions targeting the lower-limb muscles after resection surgery.

What is the impact of impaired left ventricular ejection fraction in COPD after adjusting for confounders?

BackgroundIt remains unknown whether and to what extent impaired left ventricular ejection fraction (LVEF) affects physical and psychological status in COPD. We aimed to compare health outcome measures between COPD patients with and without impaired LVEF after adjusting for age, sex, BMI and FEV1. MethodsImpaired LVEF was defined as values <50%. 85 COPD patients with impaired LVEF and 85 COPD patients with normal LVEF were matched for sex, age, BMI and FEV1. Exercise capacity, quadriceps muscle function, functional mobility, inflammatory status, health status, care dependency, and mood disorders were cross-sectionally assessed. ResultsPatients with impaired LVEF had shorter 6-minute walk distance (mean −59 (95% confidence interval: −94, −25)m), lower symptom-limited peak oxygen uptake (−131 (−268, 7)ml/min), weaker quadriceps muscles (−12 (−20, −3)Nm) and had more symptoms of anxiety (+2 (1, 3) points) and depression (+1 (0, 2) points) than those with normal LVEF (all P<0.05). Health status was not statistically different between groups (P>0.05). ConclusionsImpaired LVEF has a clear impact on physical and psychological status in patients with COPD, even after adjusting for confounders. This reinforces the importance of assessing and treating cardiac problems in COPD.

Immediate Effects Of Verbal Encouragement On Fatigued Quadriceps Strength, Activation, And Knee Joint Position Sense

PURPOSE: To examine the effects of verbal encouragement on quadriceps maximal voluntary isometric contraction (MVIC), central activation ratio (CAR), and knee joint position sense (KJPS). METHODS: Sixty eight active healthy male adults (age: 23.3±2.6) randomly underwent either condition (verbal: “kick, kick, harder, harder” or control: non-verbal encouragement during MVIC). Measurements were assessed at time-0 (baseline), -1, -2, and -3. Superimposed burst was delivered to the quadriceps during MVIC assessments (knee locked at 90°) for CAR calculations. For KJPS, subjects flexed their knees and stopped when they thought that their knee flexion angle was 15° or 45° (in a randomised order), then absolute error scores were calculated. Each assessment was performed on a dynamometer and assessed three times at time-0 and twice for other time intervals. Between assessments, muscular fatigue protocols (continuous knee extensions at 60°/s until three consecutive torque values dropped below 50% of the averaged MVIC value recorded during the previous assessments) were implemented. To test effects of verbal encouragement on quadriceps muscle and knee joint function over time, we performed mixed model ANOVAs and Tukey-Kramer post hoc tests (p<0.05) and calculated between-time effect sizes (ES). RESULTS: Our fatigue protocol immediately decreased both group’s MVIC (F3,198=4.42, p=0.005; verbal: a 24% reduction, ES: 1.13; control: a 27% reduction, ES: 1.44) and CAR (F3,198=10.91, p<0.0001; verbal: a 2.1% reduction, ES: 0.33; control: a 3.2% reduction, ES: 0.73) at time-1. While subjects in the control group showed a 6.8% and a 3.3% further decrease in MVIC (p=0.03, ES=0.30) and CAR (p<0.0001, ES=0.49), respectively, subjects in the verbal group did not change both values at time-2. Regardless of the conditions, absolute error scores in KJPS at 15° were began to alter at time-2 (F3,198=7.74, p<0.0001, a 17% reduction, ES=0.28) while those in KJPS at 45° were immediately altered at time-1 (F3,198=11.76, p<0.0001, a 29% reduction, ES=0.49), from the baseline values. CONCLUSIONS: (1) verbal encouragement may delay reduction of force output and activation, (2) fatigued muscle may affect adjacent joint position sense, and (3) less knee flexion, 15° appears to be more fatigue resistance.