Electrical muscle stimulation: Two carbon electrode pads were placed distally over the motor point of the medial (vastus medialis) and lateral (vastus lateralis) heads of the quadriceps muscle. The motor point was defined as the location that corresponded to the lowest possible threshold current and the motor threshold current was defined as the lowest train stimulation current that resulted in visible muscle contraction. Another pair of electrodes (5x9 cm) was placed 5 cm distal to the inguinal fold (10). To optimize electrical conduction, the skin was shaved and rinsed before applying the electrodes. This approach was similar to previous studies (11).