Runner's anatomy. Artwork showing the musculature of a running human figure. The main muscles used when running are the quadriceps femoris (rectus femoris, vastus medialis, vastus lateralis, vastus intermedius), hamstrings (biceps femoris, semitendinosus, semimembranosus), the gluteus maximus, the hip flexors (iliacus and psoas major), and the calf muscles (gastrocnemius and soleus). Also used in a supporting role are the abdominal muscles, and the biceps brachii.