This study underscores the reactivity of sensorimotor rhythms (SMR) in EEG such as mu rhythm in connection with the imagination and voluntary movement of left and right knee extension with able-bodied subjects using the standard Graz brain-computer interface (BCI) paradigm. As the knee motor execution (ME) and motor imagery (MI) reflect the user's voluntary physical and imagination state of knee extension respectively, they have been analyzed in order to be used as control signals to restore motor function with neuro-plasticity for BCI applications. This reactivity has been evaluated using the quantification of event-related desynchronization (ERD) and event-related synchronization (ERS) patterns. Investigations on the cortical lateralization of ERD/ERS during the left and right knee MI and ME for the extension task was done. During left and right knee MI, the foot area mu rhythm was desynchronized in all subjects, whereas no enhancement of the hand area mu rhythm was observed during any task. The frequency of the most reactive components for mu rhythm was 8.8±0.5 Hz. Interestingly a contralateral dominance was visible at a central electrode position, during left knee extension MI task. This lead to the establishment of an understanding of the left-right knee MI and its associated cognitive behavior.