The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


How Effective Is Your Core Workout?

Written by
Sue Beckham, PhD
Posted in

Thursday, Aug 28, 2014

Lots of core exercises we do challenge the global core muscles like the abdominals and back muscles. These muscles tend to be larger, more superficial muscles like the rectus abdominis, obliques, erector spinae, and hip muscles. Other muscles, called local core muscles are typically smaller and deeper than the global muscles. These muscles don’t produce much movement but primarily contract statically to stabilize the spine during lower and upper body movements. The local core muscles include the transversus abdominis, piriformis, pelvic floor, and multifidi, as well as other muscles in the hip and core.

The local core muscles which stabilize the spine during movement are not automatically engaged when the global core muscles are activated. Fibers of the transversus abdominis (TA) run horizontally and are located beneath the abdominals. When the transversus abdominis contracts, it flattens the abdominal wall and compresses the viscera (organs). It acts like a weight belt, increasing pressure in the abdominal cavity. This is like putting more air into a balloon, making it more rigid and stable. Individuals with weak TA muscles often exhibit a bulge in the abdominal wall when standing4 which can increase lumbar lordosis (arching of the low back). Weak TA muscles have been associated with long-term low back pain5. For optimal spine stabilization, the TA should engage before upper and lower body limb movements. However, TA contraction is delayed in persons with low back pain3.

Another important spine stabilizer, the multifidi muscles, span across two to four vertebrae, attaching on the spinous processes. They assist with spine rotation and extension, controlling the motion between adjacent vertebrae. The multifidi muscles are also weak in persons with chronic low back pain2,6. A study by Hides and colleagues1 showed that the ability to engage the multifidi is related to the ability to contract the TA. They reported that patients who showed good contraction of the TA were 4.5 times more likely to have good contraction of the multifidi. This suggests that engaging the TA is critical to engaging other local core muscles like the multifidi.

If traditional core exercises like crunches, planks, and back extensions are not performed properly, the local core muscles like the TA and multifidi are not engaged. An effective technique to learn to engage the TA is the abdominal hollowing maneuver. This maneuver can be performed in a variety of positions – supine (on the back), on all fours, prone (face down), seated, or standing with the back against the wall. To perform this in the supine position, bend the knees and place the spine in a neutral position (natural arch). Inhale while pulling your abdomen toward your spine. Slowly exhale as you perform the abdominal hollowing technique, holding for 5-6 seconds. Repeat 10-30 times. Check that your low back stays in a neutral position throughout the exercise. If your back flattens, other muscles besides the TA are contracting.

This is a great exercise to activate the TA. After becoming proficient in this position, practice activating the TA in other positions as well. To learn other techniques to engage the TA and techniques for recruiting and assessing the level of TA activation, register for the Corrective Exercises for Injury Prevention course at The Cooper Institute.



1Hides, J., Stanton, al. (2011). The relationship of transversus abdominis and lumbar multifidus clinical muscle tests in patients with chronic low back pain. Manual Therapy, 16(6), 573-577.

2Hides, J., Gilmore, C., Stanton, W., & Bohlscheid, E. (2008). Multifidus size and symmetry among chronic LBP and healthy asymptomatic subjects. Manual Therapy, 13(1):43-49.

3Hodges, P.W. & Richardson, C.A. (1998). Delayed postural contraction of transversus abdominis in low back pain associated with movement of the lower limb. Journal of Spinal Disorders, 11(1): 46-56.

4Kendall, F., McCreary, E. & Provance, P. (1993). MUSCLES Testing and Function (4th ed.). Philadelphia, PA: Lippincott, Williams & Wilkins.

5Moseley, G. L. (2004). Impaired trunk muscle function in sub-acute neck pain: etiologic in the subsequent development of low back pain? Manual Therapy, 9(3): 157-163.

6Wallwork, T.S., Stanton, W.R., Freke, M. & Hides, J.A. (2009). Manual Therapy, 14(5), 469-500.