Barbell front squat. A major compound exercise that's easier on the lower back than the barbell squat. Must hold barbell properly, unlike illustration (sorry!). Target muscle: Quadriceps (Vastus Lateralis, Vastus Intermedius, Vastus Medialis, and Rectus Femoris). Synergists: Gluteus Maximus, Adductor Magnus, and Soleus. Dynamic stabilizers (not highlighted): Hamstrings and Gastrocnemius.