Fig. 5. Schematic diagram showing the relative timing of electromyographic activity in the biceps femoris (BF) and vastus lateralis (VL) during walking, trotting and galloping. Stance and swing phases are shaded dark and light gray, respectively. Note how the stance phase takes up a relatively small fraction of the stride during galloping. Both muscles are consistently activated prior to foot-down at the start of stance, and both become inactive during stance. The biceps is consistently activated and deactivated earlier than the vastus.