Symmetry of electromechanical delay, peak torque and rate of force development in knee flexors and extensors in female and male subjects

Purpose: The aim of the study was to evaluate electromechanical delay (EMD), peak torque (PT) and rate of force development (RFD) in selected muscles of right and left lower extremities in groups of female and male subjects. Methods: The study evaluated 9 volunteer female subjects (mean ± SD: age: 21.67 ± 0.87 years; height: 168 ± 7 cm; body mass: 59.44 ± 4.8 kg) and 10 male university students (mean ± SD: age 22 ± 1.25 years; height: 179 ± 6 cm; body mass: 74.3 ± 5.1 kg) from the Faculty of Physical Education. Muscle torques and electromyographic activity were measured for knee flexors and extensors in static conditions, separately for the right and the left lower extremities. During the measurements, the subjects generated the maximum torque as fast as possible. Surface electrodes were placed on the right and left lower extremities on the following muscles: rectus femoris, vastus lateralis (m.VL), vastus medialis and biceps femoris. Results: Symmetry of EMD, RFD and “flexors-extensors” ratio was found in the muscles of the right and left lower extremities (with an exception of m.VL) in the group of male and female subjects. Statistical analysis demonstrated the presence of asymmetry in PT (297.66 vs. 272.05 N⋅m) and relative force in knee extensors in the group of men (3.90 vs. 3.54 N⋅m⋅kg–1). Conclusions: Symmetry of EMD and asymmetry of PT might suggest that the cause of asymmetry of the muscular force is mainly morphological characteristics of the muscle rather than the process of controlling its activity.