Quadriceps Muscle

AimDespite males typically exhibiting greater muscle strength and fatigability than females, it remains unclear if there are sex-based differences in neuromuscular recruitment strategies e.g. recruitment and modulation of motor unit firing rate (MU FR) at normalized forces and during progressive increases in force.MethodsThe study includes 29 healthy male and 31 healthy female participants (18-35 years). Intramuscular electromyography (iEMG) was used to record individual motor unit potentials (MUPs) and near-fibre MUPs from the vastus lateralis (VL) during 10% and 25% maximum isometric voluntary contractions (MVC), and spike-triggered averaging was used to obtain motor unit number estimates (MUNE) of the VL.ResultsMales exhibited greater muscle strength (P ConclusionIn the vastus lateralis, females produce muscle force via different neuromuscular recruitment strategies to males which is characterized by smaller MUs discharging at higher rates. However, similar strategies are employed to increase force production from low- to mid-level contractions. These findings of similar proportional increases between sexes support the use of mixed sex cohorts in studies of this nature.

BackgroundA nationwide, prospective, multicenter, cohort study (the Disease-Related caloric-protein malnutrition EChOgraphy (DRECO) study) was designed to assess the usefulness of ultrasound of the rectus femoris for detecting sarcopenia in hospitalized patients at risk of malnutrition and to define cut-off values of ultrasound measures.MethodsPatients at risk of malnutrition according to the Malnutrition Universal Screening Tool (MUST) underwent handgrip dynamometry, bioelectrical impedance analysis (BIA), a Timed Up and Go (TUG) test, and rectus femoris ultrasound studies. European Working Group on Sarcopenia in Older People (EWGSOP2) criteria were used to define categories of sarcopenia (at risk, probable, confirmed, severe). Receiver operating characteristic (ROC) and area under the curve (AUC) analyses were used to determine the optimal diagnostic sensitivity, specificity, and predictive values of cut-off points of the ultrasound measures for the detection of risk of sarcopenia and probable, confirmed, and severe sarcopenia.ResultsA total of 1000 subjects were included and 991 of them (58.9% men, mean age 58.5 years) were evaluated. Risk of sarcopenia was detected in 9.6% patients, probable sarcopenia in 14%, confirmed sarcopenia in 9.7%, and severe sarcopenia in 3.9%, with significant differences in the distribution of groups between men and women (p 2 and 3.66 cm2 for CSA, 32.57 mm and 40.21 mm for the X-axis, and 7.85 mm and 10.4 mm for the Y-axis. In general, these cut-off values showed high sensitivities, particularly for the categories of confirmed and severe sarcopenia, with male patients also showing better sensitivities than women.ConclusionsSarcopenia in hospitalized patients at risk of malnutrition was high. Cut-off values for the better sensitivities and specificities of ultrasound measures of the rectus femoris are established. The use of ultrasound of the rectus femoris could be used for the prediction of sarcopenia and be useful to integrate nutritional study into real clinical practice.

BackgroundIn aging, muscle stiffness is considered as one of the factors associated with the reduction of force generation capability. There have been inconsistent findings on age-related alteration in the passive stiffness of quadriceps muscle in the female adults. Thus, the aim of this study was to determine the effect of aging on the shear moduli of the superficial muscle heads of the quadriceps and to explore its relationship with knee extension force.MethodsPassive shear moduli of the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) were measured at rest using shear wave elastography in 20 young and 20 senior female adults. Measurements were repeated at four knee joint positions, that is, 30°, 60°, 90°, and 105° of knee flexion. Maximal isometric voluntary knee extension force was assessed at 30°, 60°, and 90° of knee flexion.ResultsAs per our findings, senior adults were determined to have significantly higher passive muscle shear moduli in the RF (by 34% - 68%; all p ConclusionsSenior female adults had greater passive stiffness at the superficial muscle heads of the quadriceps muscles when measured at long muscle length. Among the senior female adults, the passive stiffness of RF has been determined to have a negative association with the knee extensor force only at 60° knee flexion. No significant association was noted for other angles and muscles.

BackgroundMultiligament knee injuries (MLKIs) are serious and heterogeneous injuries that often lead to long-term functional limitations. There is limited literature regarding objective muscle strength and functional recovery after surgical treatment of MLKIs.PurposeTo investigate long-term quadriceps and hamstring muscle strength and functional recovery after surgical treatment of MLKI and to compare postoperative outcomes between single cruciate MLKI and bicruciate MLKIs.Study designCross-sectional study; Level of evidence, 3.MethodsPatients surgically treated for an MLKI at a single level 1 trauma center between January 2013 and December 2020 were included. Isokinetic quadriceps and hamstring muscle strength were assessed using a Biodex dynamometer, and physical function was measured by single-leg hop, triple hop, crossover hop, and 6-m timed hop tests, with the limb symmetry index (LSI) calculated.ResultsOf 124 eligible patients, 90 (72%) participated at a mean follow-up time of 7 years (SD, 2.1) since surgery to evaluation. The median age at the time of testing was 49 years (range, 21-72) and 59% were male. In total, 54% of the patients had not regained full quadriceps strength (LSI P = .01). The mean LSI for quadriceps PT/BW was 88% at 60 deg/s and 90% at 240 deg/s, while for the hamstrings, the mean LSI was 93% at 60 deg/s and 97% at 240 deg/s. Median LSIs for the hop tests ranged from 93% (range, 41%-187%) for single leg to 99% (42%-141%) for crossover; however, 44% of patients failed to reach the 90% threshold for the single-leg hop. The 6-m timed hop test and quadriceps muscle strength were significantly lower for patients with bicruciate injuries than those with single cruciate injuries (P ConclusionPersistent deficits in quadriceps and hamstring muscle strength were observed 7 years after MLKI surgery, with a substantial proportion of patients failing to regain full functional symmetry in muscle strength and hop test performance. Patients with bicruciate injuries demonstrated significantly more pronounced deficits in muscle strength and hop test scores as compared with those with single cruciate injuries.