Neuromuscular compartmentalization of the vastus medialis muscle: comparison of the activity of the vastus medialis obliquus and the vastus medialis longus by high density electromyography / Compartimentación neuromuscular del músculo vasto medial: comparación de la actividad del vasto medial oblicuo y del vasto medial largo mediante electromiografía de alta densidad

SUMMARY: Anatomical studies describe the vastus medialis (VM) as being subdivided into two morphologically distinct components, the vastus medialis obliquus (VMO) and the vastus medialis longus (VML). However, there are discrepancies regarding the functional differentiation of these components. The aim of this study was to compare the levels of activation of the VMO and the VML by high density surface electromyography. Twelve healthy young women (age: 21.4 ± 2.0 years; weight: 58.1 ± 7.5 kg; height: 1.6 ± 0.1 m), performed an open kinetic chain knee exercise during which the EMG activity of the VMO and the VML was recorded with two- dimensional matrices of 32 surface electrodes. The exercises were performed with three levels of resistance (5, 10 and 15 % of the body weight (BW)), considering three phases: concentric, isometric and excentric. In the isometric phase the VMO had greater activation than the VML with the three levels of resistance (p<0.05). In the excentric phase, the VMO also showed greater activation than the VML with the 10 and 15 % BW resistance levels, while in the concentric phase, the VMO showed greater activity than the VML with only the 15 % BW resistance. The results indicated significant differences in the activation level of the two components of the VM. This bears importance in the development of exercises intended to achieve a greater or more selective activation of the VMO. In the sample subjected to evaluation, the EMG recordings describe a greater activation of the VMO in comparison to the VML, which is more important in the isometric and excentric phases of the flexion/extension of the knee in an open kinetic chain. These findings suggest a functional compartmentalization of the VM.

RESUMEN: Los estudios anatómicos describen que el músculo vasto medial (VM) se subdivide en dos componentes morfológicamente distintos, el vasto medial obliquus (VMO) y el vasto medial largo (VML). Sin embargo, existen discrepancias con respecto a la diferenciación funcional de estos componentes. El objetivo de este estudio fue comparar los niveles de activación del VMO y el VML mediante electromiografía de superficie de alta densidad. Doce mujeres jóvenes sanas (edad: 21,4 ± 2,0 años; peso: 58,1 ± 7,5 kg; altura: 1,6 ± 0,1 m), realizaron un ejercicio de rodilla de cadena cinética abierta durante el cual se registró la actividad EMG de la VMO y la VML con dos matrices dimensionales de 32 electrodos de superficie. Los ejercicios se realizaron con tres niveles de resistencia (5, 10 y 15% del peso corporal (PC)), considerando tres fases: concéntrica, isométrica y excéntrica. En la fase isométrica el VMO tuvo mayor activación que el VML con los tres niveles de resistencia (p <0,05). En la fase excéntrica, el VMO también mostró mayor activación que el VML con los niveles de resistencia de 10 y 15% BW, mientras que en la fase concéntrica, el VMO mostró mayor actividad que el VML con solo el 15 % de resistencia al BW. Los resultados indicaron diferencias significativas en el nivel de activación de los dos componentes de la VM. Esto tiene importancia en el desarrollo de ejercicios destinados a lograr una activación mayor o más selectiva del VMO. En la muestra sometida a evaluación, los registros EMG describen una mayor activación del VMO en comparación con el VML, que es más importante en las fases isométrica y excéntrica de la flexión / extensión de la rodilla en cadena cinética abierta. Estos hallazgos sugieren una compartimentación funcional de la VM.

Effects of Different Interventions on Activation Mode of Trapezius Muscle during Exercise / 中国康复理论与实践

Objective:To analyze the activation characteristics of trapezius muscle in normal people, and explore whether different interventions could restore the activation pattern of people with abnormal trapezius muscles to normal during subsequent exercises. Methods:From September to October, 2017, 20 persons with normal shoulder joints (control group) and 20 persons with mild discomfort in shoulder joints (observation group) participated in the study. All of them were treated randomly with four steps, including no intervention, static traction of upper trapezius muscle (UT), isometric contraction of lower trapezius muscle (LT) and combined intervention. Then, they were asked to complete three actions, including straight arm side lifting, sitting in rowing and flying birds. Myoelectric signal was recorded before and after test. Results:Compared with the control group, the UT activation degree increased (P < 0.05), and the activation time shortened (P < 0.05); the activation degrees of middle trapezius muscle (MT) and LT decreased (P < 0.05), and the activation time delayed (P < 0.05); the ratios of UT/LT and UT/MT increased (P < 0.05) in the observation group with no intervention. After static traction of UT, isometric contraction of LT, and both interventions, the MVE%, activation time and the ratios of activation varied in different muscles under different actions in both groups (P < 0.05). Conclusion:In different actions, the activation degree and activation time of three trapezius muscles are different. Static traction of UT and isometric contraction of LT before exercise could improve the activation pattern of trapezius muscles of people with shoulder joint discomfort during exercise, which is conducive to the normal function of the shoulder joint.

Prediction of Motor Function Recovery after Subcortical Stroke: Case Series of Activation PET and TMS Studies

OBJECTIVE: To examine whether the pattern of brain activation induced by a motor task and the motor responses to transcranial magnetic stimulation (TMS) have prognostic implications for motor recovery after stroke. METHOD: Ten patients with first-ever subcortical stroke (55.7+/-17.3 years, 5 ischemic and 5 hemorrhagic) underwent 2 FDG PET studies under different conditions (1: rest, 2: activation with a specific motor task) at 37.7+/-25.2 days after stroke. The regions showing more than a 10% increase in glucose metabolism on subtraction images during activation and rest were considered to be significantly activated. Cortical excitability of intracortical inhibition (ICI) and intracortical facilitation (ICF) were assessed using the TMS from both abductor pollicis brevis muscles within 7 days of PET scans. Recovery of motor function was assessed at the point of the neurological plateau. RESULTS: The presence of a motor response at the plegic site to TMS and normal intracortical inhibition, and facilitation patterns in the unaffected hemisphere were found to be related to good recovery. An association between an ipsilesional activation on PET and good motor recovery was also observed, but this was significantly weaker than that between TMS measured cortical excitability and motor recovery. CONCLUSION: Integrity of the ipsilesional corticospinal pathway, normalized contralesional intracortical excitability, and task-related activation in the ipsilesional hemisphere were found to predict post-stroke motor recovery significantly.