Resting shear elastic modulus as a marker of peripheral fatigue during maximal isometric contractions in humans.xlsx

The aim of this study was to investigate whether the resting Vastus Lateralis (VL) muscle shear elastic modulus (µ), evaluated by shear wave elastography, represents peripheral fatigue during repetition of isometric maximal voluntary contractions (MVCs) of the knee extensor (KE) muscles.
Eight healthy well-trained males volunteered to repeated 60 isometric MVCs of the KE muscles (6 × 10 MVCs; 5 s on/5 s off). Single and double electrical stimulations were delivered to the femoral nerve every ten MVCs during contraction and at rest. The amplitude and properties of the potentiated torque following single (Twpot) double electrostimulation and the amplitude of the concomitant VL compound action potential were considered to be indicators of peripheral fatigue. The resting VLµ was measured during a 5-s rest period after each MVC and electrical stimulation series.