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The aim of the study was to confirm the hypothesis that the longer a contraction is sustained, the larger are the changes in the spatial distribution of muscle activity. For this purpose, surface electromyographic (EMG) signals were recorded with a 13 x 5 grid of electrodes from the upper trapezius muscle of 11 healthy male subjects during static(More)
During a sustained contraction, electromyographic signals (EMGs) undergo a spectral compression. This fatigue behaviour induces a shift of the mean and the median frequencies to lower frequencies. On the other hand, several studies conclude that the mean/median frequency can increase, decrease or remain constant with an increasing force level. Such(More)
Mean firing rate estimation is an important step in elec-tromyographic (EMG) signals analysis. Its application is of great interest for the conception and implementation of algorithms in various research domains, ranging from neuromus-cular diseases diagnosis to biomechanics. The proposed work is focused on the study of the intrinsic cyclostationary(More)
It is known that the conduction velocity (CV) is a relevant estimator for fatigue and disease electromyographic (EMG) studies. CV estimation, which is linked to the time delay of an EMG signal propagation between two or more sensors, is particularly interesting in dynamic studies to detect local changes along the time. In this paper, we investigate three(More)
A group of 24 subjects performed on a cycle ergometer a fatigue test consisting of four successive all-out sprints against the same braking torque. The subjects were not allowed time to recover between sprints and consequently the test duration was shorter than 30 s. The pedal velocity was recorded every 10 ms from a disc fixed to the flywheel with 360(More)
The aim of this study was to compare the muscle oxygenation between trained and untrained subjects during heavy exercise until exhaustion at two extreme pedaling cadences using a NIRS system. Nine untrained male subjects and nine male competitive triathletes cycled until exhaustion at an intensity corresponding to 90 % of the power output achieved at peak(More)
Pathological or physiological state of the muscle can be assessed from the velocity of propagation of surface action potentials (conduction velocity-CV). The estimation of CV from surface electromyography (sEMG) implies an estimation of time delay between signals detected by two or more sensors along the muscle length. In this paper we investigate the(More)
The present study was aimed at investigating differences of maximal strength (F(max)) of the elbow flexors and characteristics of the surface electromyogram (EMG) between six gymnasts (G) and six untrained (UT) 10-year-old boys during brief and maintained maximal voluntary isometric contraction (MVC). The F(max) was estimated during 5 s MVC (maximal test,(More)