Testing You Core: Part 1

The Lateral Trunk

The muscles of the spine play an important role in protecting you back from injury.  In fact, studies have clearly shown that problems in these muscles such as a lack of endurance and poor muscle balance between these ‘core’ muscles are much more common in people with back pain.

And it is not just because people are in pain that their muscle don’t work properly. Some studies have even shown problems in these muscles can predict those who are at risk for future back pain!

So it is clear that adequate endurance and muscle balance is a critical for spine health and back pain treatment and prevention.  But this leads to the questions…… ‘How much strength and endurance is adequate?’ and ‘How do know if I have a problem?’

Fortunately, back pain researchers have studied these questions.  So in this 4 part article series we are going to discuss these key issues.  Each of the first three articles will look at one of the three critical trunk muscles groups and discuss, including what is considered adequate, how to test yourself, and finally, some recommended exercise progressions you can use to correct any problems you might find. In the fourth article we will discuss the concept of muscle balance and how it relates to the muscles of the spine.

So let’s get started…..

Testing the Lateral Trunk Muscles

The lateral trunk muscles are located on either side of your trunk and  include primarily the Quadratus Lumborum (located deep right next to your spine), as well as the lateral abdominal muscles known as the internal and external obliques.

To test the endurance of these muscles you can perform a test known as the ‘Side Bridge Endurance Test’.  Here is how you do it.

  • Begin lying on your side with your legs fully extended (if needed you can place your top foot in front of the other for balance) with your upper body proper up you bent arm that is positioned directly below your shoulder.  The uninvolved arm can be held across your chest.
  • From this position lift your hips off the floor to bring your legs back in line with your trunk. Hold this position as long as possible and record how long you can keep the hips off the floor.  Repeat on both sides.



What is Normal?

Studies looking at normal (i.e., healthy people with no back pain) people have found that men can hold the position for about 90 seconds, and women for about 70 seconds.   If your test falls below this mark it is an indication that you are lacking adequate endurance in your lateral trunk muscles.  As such, exercises to correct this problem are warranted.

Improving Endurance

The most common, and probably the easiest way to improve endurance in your lateral trunk muscles is through a side bridge (often called a side plank) exercise.  This is a variation of the test that is done as an exercise, but as is the case with any other strengthening exercise you want to get the dose right.  In other words, the exercise should be challenging enough the stimulate muscle adaptation, but not so hard as to overload the back to cause injury.

In our office we use a series of side bridge exercise of varying degrees of difficulty to retrain the lateral trunk muscles.  Instead of regurgitating this information here, simply review the side bridge exercise tract on our website to review the various exercise progressions (here is the link – Side Bridge Exercise Tract).