Core Muscle Activation During Swiss Ball and Traditional Abdominal Exercises

image A new study was recently published in JOSPT by my friend Rafael Escamilla to assess core muscle activation during Swiss ball and traditional abdominal exercises.  This is a great research topic as the Swiss ball (or physioball, exercise ball, etc.) is widely believed to enhance core EMG.  Selecting core exercises is typically more complicated than most people think.  Sometimes I worry that too many people just try to create new exercises that look different and promote them as new “functional” techniques without any efficacy or research validation.  Articles like this help us select the most appropriate exercises as much as we can.

Abdominal Exercises

Exercises on the physioball included the pike, knee-up, skier, decline push-up, hip extension, roll-out, and sitting march.  These were compared to the traditional crunch and sit up floor exercises.

Core Muscles Examined

The muscles evaluated were the upper rectus abdominis, lower rectus abdominis, external oblique, internal oblique, lumbar paraspinals, latissimus dorsi, and rectus femoris.


  • image The pike and roll-out were the most effective exercises in recruiting core musculature.  These exercises are pretty advanced and should be considered the most aggressive.  These may be more appropriate for the advanced patient or client.
  • The pike, roll-out, knee-up, and skier exercises all showed relatively high EMG activity compared to the crunch and sit-up exercises.  These exercises also had high EMG activity of the latissimus and internal oblique, suggesting that these exercise may be good exercises to enhance core stability by tensioning the thoracolumbar fascia.
  • imageThe decline push-up and hip extension exercises produced similar amounts of rectus abdominis, external oblique, and internal oblique activity compared to the traditional crunch and sit-up.  This is interesting considering that these are upper and lower extremity exercises rather than what would be considered “core” exercises.  The use of a physioball increases the contribution from the core.  While this may be great for core training, I would hesitate to say that performing these exercises should replace traditional extremity exercises.  image While core activity may be enhanced, extremity activity is decreased.  Something to consider when your goal is to enhance extremity activation.  I see a lot of trends towards using unstable surfaces, which is fine, but needs to be used correctly in combination with traditional exercises.
  • No statistically significant difference in rectus adbominis activity was observed between the two traditional crunch and sit up exercises, however rectus femoris was significantly higher during sit ups.  While this info is not new, it does continue to demonstrate that crunches should definitely replace sit ups in any training or rehabilitation program, especially when considering the greater intradiscal pressure and lumbar compression observed with the sit up.
  • The discussion in this article is worth reading, the authors do a great job discussing core stability itself and the contributions of various core musculature.  Of note, the authors highlight the potentially disadvantageous stress at the lumbar spine during hip flexion activities.  This needs to be taken into consideration when designing core programs.  People with lumbar disk pathology may want to at least initially avoid exercises that involve hip flexion, such as the sit up, skier, knee-up, and pike.  More appropriate exercises may be the roll-out, decline push up, and crunch.

Clinical Implications

As you can see, choosing core exercises is not a simple task.  There are several factors that need to be assess in each individual.  This article examined EMG activity, but the authors do a good job relating the info to core function in the discussion.  The way I see it, we need to take 5 factors into consideration when designing core programs:

  1. image Pathology/function of the person – Injured and healthy people have two different challenges and goals for core stability.  The same program will not work for both.
  2. EMG activity of core musculature,
  3. EMG activity of surround musculature – especially the rectus femoris and psoas,
  4. Position of the lumber spine during exercises, and
  5. Function of the core musculature during movement – i.e. does the exercise produce an isometric stabilizing force or does it use concentric/eccentric forces to control core movement.

How does this article change the way you work with your patients and clients?  I know I don’t routinely use some of these but will definitely reconsider for the right person.  For those interested, I use the TheraBand exercise ball pictured above for my physioball exercises, click here for more information.

Escamilla, R. (2010). Core Muscle Activation During Swiss Ball and Traditional Abdominal Exercises Journal of Orthopaedic and Sports Physical Therapy DOI: 10.2519/jospt.2010.3073

11 replies
  1. Mike Reinold
    Mike Reinold says:

    @ Walt – Agree that these exercises are more advanced, seem to be maybe more for training the athlete than rehabbing the low back pain patient.

    @ Wrench – good progression thoughts.

    @ Garrett – Like how you brought all that together. Thanks for sharing that!

  2. Garrett
    Garrett says:

    Hi Mike!

    Great post! Certainly I agree with you in regards to "Clinical Implications". I've noticed the two post prior to me mention about these "exercises are not the best for routine LBP patient". Again, I agree with that. After reading Shirely Sahrmann's "Diagnosis and Treatment of Movement Impairment Syndrome", I think it's safe to say the key is to assess the patient's movement pattern, recognize the weak synergist muscle(s).

    In Escamilla's study and point of view for a healthy patient: CONCLUSIONS: The roll-out and pike were the most effective exercises in activating upper and lower rectus abdominis, external and internal obliques, and latissimus dorsi muscles, while minimizing lumbar paraspinals and rectus femoris activity. ……. long story short these muscles are now in different categories of Janda's LCS! Brilliant!

    What's everybody thought process on this?

  3. wrenchpt
    wrenchpt says:

    I agree with Walt above in that these exercises are not the best for the routine LBP patient we see in an outpatient setting. I usually start with (after their symptoms are controlled) NMR activities such as abdominal hollowing/isometrics, adding in heel slides, leg lifts, dbl leg lifts, etc. before progressing to anything on an unstable surface such as a swiss ball. The frustrating thing in outpatient PT clinics is becoming the problem of keeping a patient in the clinic for longer than a couple weeks due to co-pays and co-insurance. Makes it really tough on us to progress people to the level they should be functioning at. But that topic aside, i did find good benefit from this article. Thanks for bringing it to light again Mike.

  4. Walt Lingerfelt
    Walt Lingerfelt says:

    I agree w/ considering all the above factors for selecting "core" activities and reinforce a point Mike had made in the article and that is being aware of the biomechanical forces being loaded to the spine (i.e., compression, shear, rotational, etc.). Most of the above exercises would not be the best for most of my LBP pt.'s (taking into consideration the pathology), but seems like they would fit well into a program designed for a younger or more athletic individuals w/ stability related issues at whatever segment. I will say that sometimes you do have to be inventive and design exercises on your own based on good sound biomechanical knowledge whether or not research has validated the exercise. It is too easy to follow the advice of others without it making sense in your own head as to why the exercise is good, bad, or whatever. I do certainly think that Mike is correct when stating that the above factors must be considered.

  5. amy castillo
    amy castillo says:

    I found the article helpful, I am happy to have evidence to quote when discussing exercise programs with my patients. Since it is surface EMG and conducted on young, health volunteers…the application should be done with caution.

  6. Mike Reinold
    Mike Reinold says:

    In trying to follow your comment, sounds like Charlie is talking about motion, the article above discusses EMG activity of the muscles. The crunch may be an important exercise for some to work their core musculature. The intent of using it in this study was to compare Swiss ball exercises to traditional core exercises to show the difference in EMG activity. It doesnt necessarily say that any are better, just different. This info helps clinicians individualize a program based on their muscle needs. Hope this helps!

  7. Anonymous
    Anonymous says:


    I noticed the following comments in a blog post from Charlie Weingroff not all that long ago…..

    "I have no professional patience for anyone that thinks repetitive flexion is okay or that suggest that because it happens in 'real life,' we should train those positions for 'resiliency.' That is short-sighted and foul."

    "The assumption that we are going by is for example once you get the toe touch, you keep the toe touch with great advanced corrective exercise as long as needed and deadlifts in the program.

    Keep in mind that there is 45-50 degrees of lumbar flexion in a normal spine as well as about 12 degrees of rotation. These are normal ranges that should be evident. Going beyond is not appropriate, nor is repeatedly going through what is available."

    Given that crunches were one of the tested movements, I'd be curious if you feel there are any particular populations where this type of movement (or even a reverse crunch-type movement is actually warranted), or if you sentiments are more in line with those expressed by Charlie, namely that once you have regained (or maintained) the requisite ROM in the lumbar spine (outside of some pathology that may permanently preclude achieving those approximate ranges), these are motions that should not be actively sought out/should generally be avoided whenever possible in favor of maintaining a "tall spine?"

    As someone who is just a lay person and exercises enthusiast, I'm largely in the dark on this stuff compared to world-class experts like you and Charlie. Case in point, there were years earlier in my lifting career when I had included a very low volume of crunch, reverse crunch, and lateral spinal flexion movements in my programming. While I never experienced issues, I began to realize that absence of any discomfort and ostensibly optimal (or at least close to it) function was not an indication that what I was doing was warranted or even a good idea long-term. As such, I scrapped all of those in place of either pure stability exercises or rotational movements focusing on movement from the t-spine and hips. But for some reason there's always a part of me that wondered if I had too much of an over-reaction, bordering on paranoia about movement around the lumbar spine in the handful of core exercises I was using in a low-volume capacity, on the order of 2 movements 2x/week for roughly 2-3 sets of 6-12 repetitions(obviously I'd never let lumbar flexion and rotation fly on deadlifts, overhead work, or anything of that sort).While this was hardly a massive amount relative to what many folks perform, it's still far more than some highly-regarded pros would ever deem acceptable (with many saying that anything above nothing is too much).

    Just curious if you'd be able to distill a relatively complex topic down to a few major points that highlight your own feelings on this matter.

    ~Rod McLean

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