Research Review: EMG Analysis of Transverse Abdominis and Lumbar Multifidus During Lumbar Stabilization Exercises
By Jinny McGivern, PT, DPT, CFMT, Certified Yoga Instructor
Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS
Original Citation: Okubo, Y., Kaneoka, K., Imai, A., Shiina, I., Tatsumura, M., Izumi, S., & Miyakawa, S. (2010). Electromyographic analysis of transversus abdominis and lumbar multifidus using wire electrodes during lumbar stabilization exercises. Journal of Orthopaedic & Sports Physical Therapy, 40(11), 743-750. ABSTRACT
Why the Study is Relevant: The terms "local" and "global" were used to describe the different functions of the various trunk muscles by Bergmark in 1989 (Bergmark, 1989). Local muscles were described as those that provided single segment stability and had direct attachments to the spine, whereas global muscles were categorized as those that spanned multiple spinal segments and may not have direct attachments to the spine. This 2010 study by Japanese researchers investigated the activation levels of both local and global muscles during a series of common exercises often used with the intention of improving the stability of the lumbar spine. Lumbar spine stabilization exercises are key components of exercise programs that range in purpose from reducing low back pain (LBP) to improving performance. The findings of this research place the exercises observed in context as to where and how they should be most effectively utilized to aid clients in achieving their activity goals.
Modified image from Gray's Anatomy - https://en.wikipedia.org/wiki/Transverse_abdominal_muscle
Study Summary
| Study Design | Experimental descriptive laboratory study |
| Level of Evidence | III - Evidence from non-experimental descriptive studies, such as comparative studies, correlation studies, and case-control studies |
| Subject Demographics |
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| Outcome Measures | Bilateral muscle activation was recorded via EMG for the following muscles during a single rep of each of the following lumbar stabilization exercises:
Activity levels during exercises were reported as a % of Max Voluntary Contraction (MVC) recorded against manual resistance prior to performance of exercises. The 8 Lumbar Stabilization Exercises (LSE) observed were:
*Subjects were cued to maintain neutral spine for all exercises except crunch and to hold each position for 3s. |
| Results | EMG Findings
EO
ES
*Authors displayed data in bar chart thus estimations are reported to provide context of approximate activation levels. |
| Our Conclusions | This research recorded the activity level of "local" stabilizing muscles (TVA, LM), as well as "global" muscles (RA, EO, ES) of the "core" during a wide variety of lumbar stabilization exercises. It highlights that these muscles work synergistically during these exercises, and that these exercise do not isolate the TVA nor the LM.
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| Conclusions of the Researchers | All exercises generated activity in all muscles observed. The abdominal musculature tended to be more active during exercises in the prone position and the extensors tended to be more active during supine activities. During the side plank exercise, activity of the (R) side of all muscles observed increased as compared to the (L) with varying degrees of asymmetry. The exercise that generated the highest TVA activity was the forearm plank with contralateral arm/leg reach. The exercises that generated the highest LM activation were the bridge exercises, especially when one leg was lifted. It is important to note that although TVA and LM were activated during these exercises, they activated at low-mod levels (no activity greater than 60% for either) and that there were many other muscles working as well. The exercises observed in this study may not be the most optimal activities to train isolated firing of the specific local, segmental lumbar stabilizers in individuals who are prone to over use "global" stability strategies. |
Quadruped Opposite Arm and Leg Raise - Transverse Abdominis Activation (TVA)
Review & Commentary:
This study adds to a significant body of research on trunk muscle activity during stabilization exercises. It provides information about how to classify, and potentially how to integrate the exercises observed into practice. The authors described these activities as "high load lumbar stabilization exercises" because they result in recruitment of both local and global core musculature. The authors acknowledge that these exercises may not be best for specific training of local muscles in isolation.
This study had many methodological strengths. The authors utilized validated and clearly described procedures for data collection. Surface electrodes were used to collect information from the superficial muscles (RA , EO and ES ) whereas fine wire electrodes were used to collect data from the deeper muscles (TVA and LM ). This minimized errors related to signal interference or crosstalk; which may occur when surface electrodes are used to collect information from deeper muscles. The placement of the wire electrodes was guided by ultrasound and confirmed with active muscle contraction. Electromyographic (EMG) data collected from each muscle, during each exercise, was normalized to a percentage of maximum voluntary contraction (MVC) against manual resistance for that muscle. By performing a bilateral assessment of each muscle group, the authors were able to collect information about the symmetry of muscle group activity during each exercise. Finally, the results of this study fill gaps in the literature about activation levels of different muscles considered "core stabilizers" during a variety of exercises commonly used in practice as "core stability exercises".
This research also has several limitations. The study used a small, homogeneous sample (n=9) of active, healthy, pain-free, male subjects. The results may not generalize to other populations, particularly individuals who have low back pain. Previous research has shown that this group demonstrates altered recruitment patterns of lumbar stabilizing muscles (Hides et al., 1996). The authors did not report excluding individuals who had a history of lower extremity injury or surgery. Alterations in trunk motor patterns have been noted in individuals with peripheral lower extremity injuries/pain (Dos Reis et al., 2015). The authors only collected data from a single repetition of each exercise. Collecting the mean of multiple repetitions may have provided a more accurate representation of muscle activation. The sequence of exercises was not randomized. It is possible that a muscles's activity during a specific exercise may have been influenced by earlier exercises.
How This Study is Important:
As human movement professionals, exercise is one of our primary options for addressing dysfunction. It is important that we understand the recruitment patterns of various exercises to aid in exercise selection. This study demonstrates synergy between local and global stabilizers of the core during various commonly recommended lumbar stabilization exercises.
How the Findings Apply to Practice:
This research study aids in refining exercise selection. The authors found that while the LM and TVA were active during these exercises, they were active in conjunction with, and at comparable or lower levels, than the RA , EO and ES . In the event that a client demonstrated motor patterns that implied synergistic dominance of global core muscles, these exercises (Forearm plank , Quadruped , Bridge , Forearm side plank , and Abdominal crunch ) might not be the best choice for starting a neuromuscular re-education program for local stabilizers. For performance goals, these exercises may not be the most appropriate either. With the exception of EO activity during the forearm plank with contralateral arm/leg lifting, and the forearm side plank, all muscles demonstrated activity levels of less than 60% MVC for all exercises. It is likely that resistance or more difficult progressions of these exercises would be necessary to optimize athletic performance.
How does it relate to Brookbush Institute Content?
The results of this study support core exercise selection based on consideration of the Anterior Oblique Subsystems (AOS) and Posterior Oblique Subsystems (POS) in conjunction with the Instrinsic Stabilization Subsystem (ISS) - in so much as core motor patterns almost always include a combination of musculature from both local and global stabilizers. The Brookbush Institute (BI) recommends core exercise selection based on movement assessment and the implied relative activity of core subsystems. Further BI recommends that core (lumbar stabilization) exercise follows activation techniques, with the exception of Transverse Abdominis Activation (which may be used as an activation technique). Although the Brookbush Institute may need to consider "more accurate word choice," it is worth noting that BI recommends the "Quadruped" exercise and progressions for Transverse Abdominis Activation . Although other muscles were active, of the exercises investigated this study, the transverse abdominis showed the highest relative activity during the Quadruped Opposite Arm/Leg Reach. The Brookbush Institute has published several progressions of these techniques, including specific approaches to cueing that may aid in optimizing performance. The videos below show a sample sequence (circuit) of exercises progressing from isolated activation, to core integration, to reactive activation techniques, all with the goal of improving trunk or core stability.
Transverse Abdominis TVA Isolated Activation
Ball Bridge
Side Plank
Modified Mountain Climbers:
References
- Bergmark, A. (1989). Stability of the lumbar spine: a study in mechanical engineering. Acta Orthopaedica Scandinavica, 60(sup230), 1-54.
- Dos Reis, A. C., Correa, J. C. F., Bley, A. S., Rabelo, N. D. D. A., Fukuda, T. Y., & Lucareli, P. R. G. (2015). Kinematic and Kinetic Analysis of the Single-Leg Triple Hop Test in Women With and Without Patellofemoral Pain. journal of orthopaedic & sports physical therapy, 45(10), 799-807.
- Hides, J. A., Richardson, C. A., & Jull, G. A. (1996). Multifidus Muscle Recovery Is Not Automatic After Resolution of Acute, First‐Episode Low Back Pain.Spine, 21(23), 2763-2769.
© 2016 Brent Brookbush
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