Líliam Fernandes de Oliveira

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EMG-driven models can be used to estimate muscle force in biomechanical systems. Collected and processed EMG readings are used as the input of a dynamic system, which is integrated numerically. This approach requires the definition of a reasonably large set of parameters. Some of these vary widely among subjects, and slight inaccuracies in such parameters(More)
This paper uses a EMG-driven Hill-type muscle model to estimate individual muscle forces of the triceps surae in isometric plantar flexion contractions. A uniform group of 20 young physical-active adult males was instructed to follow a specific contraction protocol with low (20%MVC) and medium-high (60%MVC) contractions, separated by relaxing intervals. The(More)
BACKGROUND This paper describes the "EMG Driven Force Estimator (EMGD-FE)", a Matlab® graphical user interface (GUI) application that estimates skeletal muscle forces from electromyography (EMG) signals. Muscle forces are obtained by numerically integrating a system of ordinary differential equations (ODEs) that simulates Hill-type muscle dynamics and that(More)
This work aims at testing the influence of peripheral and central fatigue, after maximal oxygen uptake test (Test1) and prolonged (Test2) cycle ergometer exercises, respectively, on sway density curve (SDC) parameters of postural control. Sixteen healthy male subjects were submitted to stabilometric tests, before and after the exercises. The Test1 was(More)
Posture control is mediated by the integration between the environment information (coming from the visual, somatosensory and vestibular systems) and the efferent organs (motoneurons and muscles). The influence of the first systems on body sway signals is already documented in the literature. Few studies are focused in the relationship between stabilometric(More)
Age-related changes in postural control during quiet standing likely result from underlying pathological conditions or from the low specificity of classical stabilometric parameters, which are vulnerable to base of support configurations and anthropometric differences. This study focuses on the identification of changes in postural control with natural(More)
The skeletal muscle system can adapt to an external stimulus from either physiological or pathological conditions. This plasticity is measured by imaging techniques such as magnetic resonance imaging or ultrasound. The anatomical cross-sectional area of a muscle is one of the muscle architecture parameters that relates to the maximum muscle strength. The(More)
The authors collected and compared mechanomyo-graphic (MMG) signal behavior from the biceps brachii of left and right arms of right-handed men (n = 19) and women (n = 20) who performed isometric contractions at 5 contraction levels. Mean frequency (MF) and RMS values were calculated from the MMG signals that arose from lateral oscillations of muscle fibers.(More)
EMG is a useful tool for quantifying muscle forces and studying motor control strategies. However, the relationship between EMG and muscle force is not trivial, and depends in part on muscle dynamics. This work has the following objectives: the first, to find muscle excitations and partial joint torque contribution patterns in isometric plantar flexions,(More)
The occurrence of fatigue in triceps surae (TS) muscles during sustained plantar flexion contraction is investigated by means of the RMS electromyogram (EMG) and the instantaneous median frequency (IMF) of the short time Fourier transform (STFT). Six male subjects realized a 40% maximal plantar flexion isometric voluntary contraction until fatigue in two(More)