Affiliations: [a] Unité de Recherche: Adaptations
Cardio-circulatoires, Respiratoires, Métaboliques et Hormonales,
Faculté de Médecine Ibn El Jazzar, Sousse, Tunisia | [b] Unité de Recherche: Neurophysiologie de la
Vigilance, de l'Attention et des Performances, Service d'Explorations
Fonctionnelles du Système Nerveux, CHU Sahloul, Sousse, Tunisia | [c] Université de Nantes, Laboratoire: Motricité,
Interactions, Performance, Nantes, France
Note: [] Corresponding author: Nidhal Zarrouk, Institut Supérieur de
Sport et de l'Education Physique de Sfax, Route de l'Aéroport, Km 3.5, BP
384, Sfax 3000, Tunisia. E-mail: nidhal.zarrouk@yahoo.com
Abstract: This study aimed at quantifying maximal voluntary force-generating
capacity of the quadriceps femoris and its EMG output after an isokinetic
concentric intermittent exercise. Another objective was to find out whether the
amount of neuromuscular fatigue was velocity-dependent. Eight males judo
players (age: 18.4 ± 1.4 years; height: 1.80 ±
0.03 m; body mass: 77.0 ± 4.2 kg) performed a
fatiguing exercise composed of five sets of ten maximal knee extension at
120°/s, with 3min recovery in between. Peak torque
(PT) at three angular velocities (60, 120 and 180°/s)
and EMG from the vastus lateralis, rectus femoris and vastus medialis were
evaluated before and after the fatiguing exercise. EMG was analyzed for root
mean square (RMS) and median frequency (MF). The fatiguing exercise induced PT
decrement (P< 0.01) irrespective of the test velocity, in
conjunction with decreased RMS (P< 0.001) and a decrease in
MF (P< 0.01). In addition, although EMG activity
demonstrated no velocity effect, the loss of PT after the fatiguing isokinetic
intermittent exercise was more pronounced at the lower velocity
(P< 0.05). The combination of decreased PT, RMS and MF
suggests a reduction of the neural drive under the present fatiguing protocol.
