A massive group encompassing the quadriceps , hamstrings , glutes , and calves (often cited as the hardest muscle to grow due to high-frequency daily use).

Exercises like the incline dumbbell press or cable flyes target the upper, middle, and lower regions of the pectoralis major.

Effective bodybuilding splits are typically organized around seven primary muscle groups, each requiring specific mechanical tension to grow:

To transform anatomy, bodybuilders rely on several scientific and practical pillars: Bodybuilding Anatomy epub - Human Kinetics