Why Side Bends Do Not Target Your Obliques!

Why Side Bends Do Not Target Your Obliques!


Are side bends actually doing what you want them to do?



When most people think about targeting their External & Internal Oblique muscles their exercise of choice is side bends with DBs. I admit that I used to think the same way. However, this thought process is flawed because of our lower back muscles, specifically our Erector Spinae. We have already describe the anatomy & actions of the internal & external obliques in the previous posts. So, let’s check out the Erector Spinae to show the flaws of side bends for targeting our obliques:

Image result for erector spinae

The Erector Spinae is a very large group of 3 muscles in our back that help contribute to the action of side bending. In order to determine the amount of contribution, we need to evaluate 2 factors:

  1. Size of the Muscle

    • Compared to the obliques, they are much larger
  2. Internal Moment Arm (amount of work the muscle does with side bends based on its location)  

    • Compared to the obliques, they have slightly less leverage

Both these factors together, determine to total contribution of the muscle to side bending. Since the size of the Erector Spinae are so much larger than the size of the obliques, they overcome the slightly less leverage based on their location.


Thus, the Erector Spinae contribute more to side bending and, as a result, will be worked harder when performing this action. The oblique will be worked in this exercise, however, they will not be optimally targeted because the erector spinae will be worked harder. If you’re trying to target your obliques, then ditch the side bends in favor of the rotations from our previous post!


Resources:

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

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