Vibrational Percussion Massage Improves Rectus Femoris Mechanical Properties and Sports Performance in Physically Active Adults

Muscle tension represents the resting tone of the rectus femoris muscle, quantified by oscillation frequency. Higher values indicate greater resting muscle tension.

Dynamic stiffness represents the resistance of the rectus femoris muscle to external deformation, with higher values indicating greater muscle stiffness and lower tissue compliance.

Muscle elasticity represents the ability of the rectus femoris muscle to restore its original shape after deformation. Lower values indicate better elasticity and lower energy dissipation.

Mechanical stress relaxation time represents the time required for the rectus femoris muscle to recover from deformation after an external mechanical impulse. Longer values indicate more compliant (softer) tissue, whereas shorter values indicate increased muscle stiffness.

Creep represents the viscoelastic deformation of the rectus femoris muscle under a constant mechanical load. Higher values indicate greater tissue elongation capacity and viscoelastic deformation, whereas lower values suggest reduced compliance.

Maximal isometric knee extensor strength was assessed using a handheld dynamometer. Participants performed a 6-second maximal voluntary isometric contraction of the knee extensors in a seated position, and the peak force was recorded. Three trials were performed and averaged for analysis.

The triple-hop test was used to assess functional lower-limb performance. Participants performed three consecutive maximal forward hops on the same limb and were required to maintain balance for 3 seconds after the final landing. The total hopping distance from the starting line to the final landing position was measured. Three trials were performed and averaged for analysis.