Testing Your Core: Part 4
Testing Muscle Balance
It is no secret that proper health and function of the muscles that surround the back is critical for spine health. The past three articles in this series have looked at this concept in more detail, and as part of this process we have discussed simple tests that you can administer yourself to help determine if your muscle are working the way they should.
So far these tests have looked at specific muscle groups. While proper function of individual muscle groups is important, the individual scores may be less important that the relationship between the groups. In fact, even if all your test scores are adequate, but there is an imbalance between muscle groups (we will discuss how to test this below), you may still be at risk for back pain as the system is out of balance.
This fourth and final article will discuss the concept of muscle balance. In other words, how do the specific muscle groups (i.e., the back muscles, the lateral trunk muscles, and the abdominal muscles) compare with each other.
Testing Muscle Balance
To test muscle balance you will need to have your test scores from the previous three tests (you can review each test in Article 1, Article 2, and Article 3). As you have each score, you will need to calculate the ratio between each test score.
To do this we will use the Trunk Extensor Endurance score (see Article 2) as our measuring stick as typically people will have (or at least should have) the highest endurance time for this test. Now you simply have to divide each score from the Side Bridge Endurance Test (see Article 1) and Trunk Flexor Endurance Test (see Article 2) to calculate a ratio for each score.
Finally, you can also calculate a ratio between your right and left Side Bridge Endurance Score. This should give you four scores. Just as we did in the previous articles, we can then compare these ratios to ‘normal’ values as look for any deficiencies.
In the table below you can review the normal ratios when comparing endurance scores between the Trunk Extensors, Trunk Flexors (abdominals), and Lateral Trunk Muscles. Keep in mind that these numbers are not exact, but provide a ballpark as to where findings should be. As a guide, if your calculated ratios are close to the ones reported here you are in good shape. If there are way off (say by more that 0.10-0.20) you will want to do something to correct these ratios. To do this you can review the exercise recommendations presented in the previous 3 articles. (Table is adapted From McGill et al. Endurance times for low back stabilization exercises. Arch Phys Med Rehabil; 80; 1999).
Lastly, we must discuss the endurance scores between the right and left side bridge. This ratio is not included in the table above, but simply stated, the endurance scores should be very close between the right and left sides. If there is a large discrepancy between right and left sides this should also be corrected.