Heloyse Uliam Kuriki

The Relationship Between Electromyography and Muscle Force

The generation of physical movement in animals involves the activation and control of muscle forces. Understanding the mechanisms behind force generation and control is essential for professionals who work to promote health. The human body can be represented as a system of articulated segments in static or dynamic balance. Within this system, movement can arise from internal forces acting outside the joint axis, causing angular displacement of these segments, or by forces external to the body. Knowledge of the contribution of muscle forces to joint position and movement is of great importance for the study of muscle activity during exercise and also for understanding the coordination of muscle activities during functional movement. However, muscles forces cannot be easily measured in vivo; rather, they must be assessed, calculated or modeled (Amadio & Duarte, 1996; Amadio & Barbanti 2000). Closely associated with the generation of force by a muscle, is the generation of an electrical signal that can be observed by placing electrodes on the skin surface to detect underlying electrical activity displaying the associated waveform on a computer monitor. This process is called electromyography (EMG) and the waveform is the electromyogram. The assumption that there is an association between EMG and underlying muscle forces is the basis for many applications of EMG, allowing inferences regarding various aspects of muscle physiology. However, it is not possible to measure muscle force directly using EMG. Since 1952 there have been studies that show some cases where there is a linear relationship between force and EMG (Lippold, 1952), however this relationship is not always simple and linear. In recent years methods for detecting and processing EMG signals have been refined considerably, with the availability of better equipment, tools, mathematical, statistical and computational techniques. Although the determination of muscle strength using EMG measurements has also evolved, it has not yet fully exploited the technological potential available. In this chapter, we describe a practical approach to the quantitative evaluation of muscle force through analysis of the EMG signal.

The surface electromyography analysis of the non-plegic upper limb of hemiplegic subjects

Many authors have studied physical and functional changes in individuals post-stroke, but there are few studies that assess changes in the non-plegic side of hemiplegic subjects. This study aimed to compare the electromyographic activity in the forearm muscles of spastic patients and clinically healthy individuals, to determine if there is difference between the non-plegic side of hemiplegics and the dominant member of normal individuals. 22 hemiplegic subjects and 15 clinically healthy subjects were submitted to electromyography of the flexor and extensor carpi ulnaris muscles during wrist flexion and extension. The flexor muscles activation of stroke group (average 464.6 u.n) was significantly higher than the same muscles in control group (mean: 106.3 u.n.) during the wrist flexion, what shows that the non affected side does not present activation in the standard of normality found in the control group.

Análise da reprodutibilidade de parâmetros no domínio da frequência do sinal EMG utilizados na caracterização da fadiga muscular localizada

The aim of this study was to analyze the reproducibility of the electromyography signals parameters (EMG) in the frequency domain used in the characterization of localized muscle fatigue. Fifteen male subjects underwent a fatigue test based on isometric knee extension, being held at three different times at intervals of seven days. To assess the reproducibility of data between the tests we calculated the correlation coefficient (ICC) for the median frequency (MF) in total exercise time (MFT), MF obtained for every 10% of exercise time (MF10%) and the powers of the frequency bands obtained by dividing the power spectrum at windows of 20 Hz. The results showed: (1) excellent reproducibility for MFT, (2) good reproducibility for MF10%, and (3) greater variation in the signal EMG bands from 20 to 120 Hz, especially at the bands of 20-40 Hz and 40-60 Hz, which showed greater sensitivity to the process of muscle fatigue. We conclude that the MF is a variable that shows good reproducibility and that the fragmented analysis of the power spectrum, by means of frequency bands, showed that significant variations occur in the EMG signal during the installation of the fatigue process, having potential to become a new method for the characterization of localized muscle fatigue.

Capacidade funcional de hemiparéticos crônicos submetidos a um programa de fisioterapia em grupo

Este estudo tem como objetivos analisar a eficacia da fisioterapia em grupo sobre a marcha, o equilibrio corporal e o risco de queda, e verificar se ha correlacao entre a capacidade funcional da marcha e o equilibrio em individuos com hemiparesia cronica. Participaram do estudo 21 adultos hemipareticos, com idade media de 58,9±10,6 anos, com sequela de no minimo 1 ano apos acidente vascular encefalico isquemico ou hemorragico. Os sujeitos foram submetidos a um programa de 1 hora de fisioterapia em grupo duas vezes por semana durante seis meses. Foram avaliados por meio da escala de equilibrio de Berg (EEB) e do teste de levantar e caminhar cronometrado TLCC (TUG, na sigla em ingles de timed up & go) antes do programa, apos 13 e ao fim de 26 semanas. Os resultados mostram uma reducao progressiva, embora nao-significativa, no tempo de execucao do TLCC e aumento progressivo, tambem nao-significativo, do escore na EEB. Foi observada forte correlacao entre as duas escalas (r=0,7, p<0,05). Assim, a terapia nao foi efetiva para produzir melhora nos escores dos testes, mas contribuiu para manter a mobilidade.The purpose of this study was to assess the effectiveness of a group therapy program on gait, body balance and risk of falling, and to search for a correlation between functional gait and balance in subjects with chronic hemiparesis. A total of 21 hemiparetic adults, mean aged 58.9±10.6 years, with sequelae (at least 1 year after stroke) of ischemic or hemorrhagic stroke, underwent a program of onehour group therapy twice a week, for six months. They were assessed using the Berg balance scale (BBS) and the timed up-and-go test (TUGT) at baseline, after 13 weeks, and at the end of six months. Results show a progressive, though nonsignificant, reduction in TUGT times, and an also non-significant increase in BBS scores. A strong correlation (r=0.7, p<0.05) was found between the two scales. The therapy was then not effective in providing improvement in subjects’ gait or balance, but allowed for maintaining them.

CHARACTERIZATION OF THE PATELLOFEMORAL PAIN SYNDROME BY FREQUENCY PARAMETERS OF EMG SIGNAL

Universidade Estadual Paulista Julio de Mesquita Filho, Departamento de Fisica Quimica e Biologia, Presidente Prudente, Rua Roberto Simonsen, 305, CENTRO EDUCACIONAL, CEP 19060-900, SP, Brasil

Terapia manual no tratamento da espondilólise e espondilolistese: revisão de literatura

Spondylolysis is a defect in the pars interarticularis of a vertebra with a disruption in the intervertebral segment. Progression of the defect leads to one vertebra slipping over another - which is called spondylolisthesis - which may cause low-back pain. Non-surgical treatment is the initial course of action in most cases of spondylolisthesis. However, few studies have assessed the efficacy of conservative treatment. The purpose of the present study is to review literature on conservative treatment for spondylolysis/listhesis, especially manual therapy, in order to guide practitioners for effective intervention. Results show that both manual therapy and conventional physiotherapy were effective in relieving low-back pain and beneficial for patients functional outcome. Manual therapy involved spine manipulation, sacroiliac joint manipulation, muscle-energy techniques and stretching affected muscles. Stabilizing lombopelvic exercises, postural muscles strengthening, and hamstring and psoas stretching were also considered important in treating spondylolysis/listhesis. Each cases clinical and radiological features must be individually considered in order to determinate therapeutic strategy. Among non-surgical options, none has proved better than others and all may be included in symptomatic treatment of patients with spondylolysis/listhesis.

CHARACTERIZATION OF BIOMECHANICAL PARAMETERS DURING STAIR ASCENT

Universidade Estadual Paulista Julio de Mesquita Filho, Departamento de Fisica Quimica e Biologia, Presidente Prudente, Rua Roberto Simonsen, 305, CENTRO EDUCACIONAL, CEP 19060-900, SP, Brasil

Análise do ângulo de rotação da coxa em indivíduos com síndrome da dor patelofemoral durante a subida de degraus

Introduction: The femur rotation can lead to increased pain in individuals with patellofemoral pain syndrome (PFPS). However, few studies are found in order to measure this rotation. Objective: Compare the angle of the femur rotation of patients with and without PFPS during stair climbing. Methods: Femur rotation was analyzed in 11 female volunteers with PFPS and 22 without PFPS using the Ariel Performance Analysis System for data acquisition and digitization, an algorithm for calculating the rotation and Student’s t-test for comparison of data, with 5% of significance. Results: Regarding external rotation, the PFPS group had a higher angle 8.86° (±7.6°) in relation to the control group 5.72° (±5.0°) (p=0.015). Conclusion: The results showed that individuals with PFPS presented a greater external rotation angle, what can be the factor that causes the pain, as further rotation leads to an increase in patellar pressure.