ABC (Ask Bret Contreras) – Is it Possible to Isolate the Upper or Lower Abs?

Dear BC,

Is it possible to isolate my upper or lower abs with different ab exercises?

Thanks!

I hear this debate all of the time. Many say that it’s not possible to contract one part of the rectus abdominis over another, while others claim that you can.

Part of this is semantics…you can’t “isolate” one part or another. In other words, you cannot contract one portion while keeping the other completely dormant. However, I believe that you can “target” one part, or steer more activation toward one portion or another. When you look at the nerve supply for the abdominal muscles you will find that they are innervated by multiple nerves (i.e. the ventral rami of T7-T11, T12 (subcostal nerve), and L1 (iliohypogastric, ilioinguinal). This is nothing new; you can also target portions of the the gluteus maximus, deltoids, pecs, etc.

I’m not particularly passionate about this topic because 1) Getting 6-pack abs is 90% about reaching low bodyfat levels and 10% about having muscular abs, and 2) The differences in activation between upper and lower rectus abdominis (RA) activity aren’t so drastic that they’ll lead to huge differences in functional strength adaptations.

Around a year ago I was a bit curious about this topic so I conducted a bunch of comprehensive EMG analyses on the abdominals. While one of my core studies can be found on a TNation article here, I didn’t measure upper vs. lower RA activity in that experiment. I conducted two experiments where I measured upper vs. lower abdominal activity, the tables for which can be found in my glute eBook. I performed tons of the best and most challenging abdominal exercises, and I found that you can indeed target the upper or lower abdominals. “Shoulder to hips” flexion, or abdominal exercises that have you bringing your shoulders toward your hips such as crunches, activate higher levels of upper RA than lower RA. “Hips to shoulder” flexion, or abdominal exercises that have you bringing your hips toward your shoulders such as reverse crunches, activate higher levels of lower RA than upper RA. In regards to my EMG experiments and other EMG experiments, the hip flexors are too far away to interfere with the readings of the lower abdominals – the amplitude is proportional to the inverse square of the distance from the source. So I don’t believe that that is an issue. And my EMG data was normalized, so that’s not an issue either.

If we go by “the feel test,” I’ve performed various abdominal/core exercises for many years and I believe that I can feel my lower abdominals working harder when I do exercises like reverse crunches in comparison to exercises like crunches. And as I’m sitting here typing, I believe that I can segmentally contract the different portions of the abdominals to different degrees. I find it easy to alternate between flexing the lower abs pretty hard while keeping the upper abs slightly more relaxed, and tensing the upper abs pretty hard while keeping the lower abs slightly more relaxed – but I’m not sure how much this has to do with turning on other core muscles such as the transverse abdominis or diaphragm to create this effect. Maybe if I study Shakira hard enough the answer will come to me….

In addition, I’m taking a Graduate level Biomechanics course right now, I’ve read the literature on the topic, I’ve discussed the matter with professors and Biomechanists, and I’ve studied the anatomy. So I believe that I’m pretty qualified to address this matter.

Here are six different studies that indicate that you can preferentially activate one portion over the other:

Relative activity of abdominal muscles during commonly prescribed strengthening exercises.

Electromyographic analysis of upper body, lower body, and abdominal muscles during advanced Swiss ball exercises.

Core muscle activation during Swiss ball and traditional abdominal exercises.

Electromyographic analysis of traditional and nontraditional abdominal exercises: implications for rehabilitation and training.

Muscle activity in upper and lower rectus abdominus during abdominal exercises.

Electromyographic analysis of abdominal muscle activity using portable abdominal exercise devices and a traditional crunch.

There are some studies in the literature that fail to demonstrate the same pattern and therefore contain different conclusions, but most studies do show differences in upper and lower RA activity. I know that Dr. Stuart McGill feels otherwise and believes that these readings are incorrect due to issues with normalization, but I know some professors who are adamant that he’s incorrect on the matter. Furthermore, if you read McGill’s full paper on the topic you’ll see that hips to shoulder spinal flexion still gets you slightly higher lower than upper RA activity, and when you do shoulder to hip spinal flexion you get slightly higher upper than lower RA activity – it’s just not significant in his study – though I’d argue that he may have seen different results had he tested other exercises.

I don’t believe that this is that big of a deal in terms of selecting the best exercises – in addition to EMG, I look at other things like joint safety, specificity, tension in stretch position, ability to produce a pump, ability to produce hypertrophy, ability to transfer to another lift, ability to transfer to an athletic endeavor, joint ROM, ability to increase joint mobility or stability, how the exercise “feels,” etc. When choosing core exercises, I like to stabilize in all directional vectors, and I like to perform exercises that strengthen the hip flexors from time to time – a muscle group that should be strengthened in advanced athletes.

12 thoughts on “ABC (Ask Bret Contreras) – Is it Possible to Isolate the Upper or Lower Abs?

  1. Clement

    Hey Bret,

    I am having a really strange problem with the body part in question, and it’s quite related to working the lower abs.

    I’m reasonably lean, much leaner than any of my friends, but I have a lower belly that protrudes. It just sticks out, although I have reasonable arm definition and am not fat at all. When I lie down, it goes flat, but when I sit up or stand up it pokes out. How do I test if it’s due to bloating (air in the stomach) or visceral fat? Have you had any such problems with your clients? Is it what they call the skinny-fat syndrome?

    Reply
  2. Thy.

    Bret, when you tested hanging leg raises for the T-nation article, did you perform them by lifting the legs all the way to the bar? I find that this exercise if probably the toughest on the whole abdominal region and a true test of ab strength. Few ab exercises can match it in difficulty, besides some more advanced gymnastic variations of this exercise. If you make it harder by controlling the descent forcefully and starting each rep from a dead stop to avoid swinging, it becomes a true hell. Also, hanging L position held for time is brutal as well.

    Reply
  3. Bianca

    Hi Bret,

    thanks for this interesting article.

    I have a question, which is not directly related to this specific article but it’s a more general one. Is muscle soreness an indicator that a certain excercise has been effectful for certain muscles? What I mean is: if after a certain workout (let’s say, targeting glutes) my glutes don’t get sore the same day or the day after the work-out, does it mean that the particular excercise that I did was not that effectful for my glutes?

    I had never done hip thrusts and glute bridges before (because I was concentrating on lunges, squats, deadlifts, bulgarian squats, etc) and have only started doing them recently but my glutes don’t seem to get sore….Is this normal or am I one of the very few people whose glutes don’t get a high activation out of hip thrusts and glute bridges?

    I started doing them only bodyweight first and then loaded them a little more with a 14 kg kettlebell placed on my belly… and I did 3 sets of 15 reps.
    But no soreness, not even the day after. And it’s strange because normally when I do something new I always tend to get a little sore.

    Any suggestion?

    Thanks

    Bianca

    Reply
  4. Anoop

    Hi Bianca,

    Soreness is not always an indicator that you have worked the muscles well enough. You can be sore and grow muscle and you can be without any soreness and still grow muscle. Soreness might be indicative of muscle damage, connective tissue damage, pain receptors being more sensitive, and so on.

    Instead of muscle soreness why not strength and muscle gains be an indicator to see if it worked the muscle or not?

    Reply
    1. Bianca

      Hi Anoop,

      first of all thanks for answering my question.

      Your comment is right: strength and muscle gains are the ideal indicators.
      Nevertheless, I was looking for an “almost immediate” indicator that a certain excercise is useful or is not so useful for my glutes (and I wanted an almost immediate indicator because I wanted to know if it was worth continuing with this particular excercise, together with the other ones as well).

      Thanks :)

      Bianca

      Reply
  5. anoopbal

    Hi Bianca

    Instead of soreness, why not go for the burn or the feel?

    Try squeezing the glutes hard , focus on using the glutes, do high reps and do drop sets or rest pause. If you are feel the burn in your glutes, you are using them. That’s an immediate indicator if that exercise is good for you or not.

    Reply
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