Knee and elbow extensors fatigability
The subjects performed a 90-s sustained isometric con- traction at 25% MVC in order to evaluate the muscle fat- igability of the main knee and elbow extensor muscles. Visual feedback about force was provided to the subject during the sustained contraction. Electromyographic sig- nals (EMG) of the superficial heads of the knee extensors (vastus lateralis, vastus medialis and rectus femoris) and the triceps brachii muscle (medial and lateral heads) were recorded throughout the 90-s sustained contraction. EMG was quantified in the time domain using the Root Mean Square value (RMS). All the RMS values recorded during the 90-s contraction were normalized to a percentage of maximal Root Mean Square value (RMSmax) of the best MVC trial for each muscle.