Method for obtaining a functional parameter of a muscle

Device for obtaining at least one functional parameter of a muscle having at least one part, the device comprising:

• an applying unit adapted to apply ultrasound waves to the muscle,
• a collecting unit adapted to collect the ultrasound waves retrodiffused by the muscle at a plurality of times, to obtain collected ultrasound waves,
• a calculator being adapted to carry out the steps of:
• determining a first plurality of values representative of stiffness values of at least one part of the parts of the muscle at a first plurality of times by using the collected ultrasound waves, the first plurality of times being included in the plurality of times, each value representative of stiffness is selected from the group consisting of a shear modulus of the muscle, a Young's modulus of the muscle, and a propagation speed of shear waves in the muscle,
• determining a second plurality of values representative of deformation values of said part at a second plurality of times by using the collected ultrasound waves, the second plurality of times being included in the plurality of times and being associated with the first plurality of times in a one-to-one relationship, each value representative of deformation is selected from the group consisting of a cumulative deformation, a length of the muscle, a normalized length of the muscle and a volume of the muscle, and
• deducing at least one functional parameter based on the first plurality of values and the second plurality of values, wherein the first plurality of values and the second plurality of values form a stiffness-deformation loop.