<p>The root-mean-square (RMS) values of electromyographic activities of the three superficial knee extensor muscles during maximal voluntary isomeric contractions of knee extension (open bar) and hip flexion (closed bar). A: absolute RMS values (RMS<sub>MVC</sub>), B: RMS values normalized to the peak-to-peak amplitude of the maximal compound muscle action potential of each region (RMS<sub>MVC</sub>/AMP<sub>Mwave</sub>), C: RMS values normalized to the RMS values of the maximal compound muscle action potential of reach region (RMS<sub>MVC</sub>/RMS<sub>Mwave</sub>). Results are presented as the mean ± SD (n = 12). *Significant difference (P<0.05) between the two tasks. †Significant difference (P<0.05) from distal region.</p
