External & Internal Obliques Working Together

External & Internal Obliques Working Together

Did you know that you have two layers of oblique muscles that work together when you move?

We previously explained the fiber orientation of these muscle. So, how can we train them optimally based on this information?

  • They both contribute to flexion of the trunk (picture a sit up) & lateral flexion (side bending), however, there are other muscles that more optimally contribute to these actions. Thus, these actions will not optimally contract the obliques.
  • If we want optimal contraction, then the name of the game is ROTATION! Let’s break down an example to understand why the fiber orientation matters:

Example – Rotation to the Left

  • EO – on the RIGHT of our body contracts
  • IO – on the Left of our body contracts

Therefore, we are working both our EO on the right & the IO on the left with one motion! The opposite would be true for rotating to the right. There are also no other major muscles on the front of our body that contribute to rotation, so the EO & IO will be the primary movers that get worked the hardest!

Our favorite exercises are Banded or Cable, Cross, Chop & Lift Rotations. Work these exercises into your core days in order to get optimum oblique gains!


  • Neumann, Donald A. Kinesiology Of the Musculoskeletal System : Foundations for Physical Rehabilitation. 2016.

Featured Image By: Balance In Motion

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