Build Your Own 6-Pack

Everything you need to know about abs.



These are the muscles that the bodybuilding judges (and the ladies) are looking for when evaluating a physique — the “six-pack” and the diagonal ridges that flank them.

  • RECTUS ABDOMINIS: Muscles that originate at the bottom of the sternum and insert at the pelvis. 
    • Function: Pulling knees up to torso and vice versa.
  • SERRATUS: The fingerlike muscles running from the lats to the sides of the rib cage.
    • Function: To pull your shoulder blades forward.
  • EXTERNAL INTERCOSTALS: Muscles that run diagonally across the rib cage — below pecs and above the external obliques. Not to be confused with the serratus.
    • Function: Assist in deep respiration as they, coupled with the internal obliques, work to expand and contract the rib cage.
  • EXTERNAL OBLIQUES: Muscles that run diagonally down the sides of body, between the rectus abdominis and lats.
    • Function: Twist the body from side to side and flex the spine to the left and right.


These are the muscles colloquially referred to as the “core.” Although not visible to the naked eye, they are invaluable for the support and strength they provide not only in the gym, but also in sports activities and throughout the day.

For bodybuilders, these core muscles (sometimes referred to as the “girdle”) are also important because they enable you to vacuum up your abs — something that was prized in bodybuilding in a bygone era and which makes any pose far more impressive.

  • TRANSVERSE ABDOMINIS: Directly below the rectus abdominis.
    • Function: Acts as one of the core muscles to stabilize the spine and pelvis.
  • INTERNAL OBLIQUES: Below the external obliques, running in the opposite direction of the external obliques.
    • Function: Torque the body left and right.
  • INTERNAL INTERCOSTALS: Beneath and between the ribs.
    • Function: Assist breathing by elevating the ribs.


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