Archive for the ‘Ask Bret Contreras (ABC)’ Category

Dear BC,

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


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.

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Dear Heavenly Glute Man,

I try to keep a good arch when I deadlift, but when the weight gets really heavy, say around 95% of my 1RM and higher, I find myself rounding my back in order to complete the lift? Why am I stronger when I round?


Mark, you’re in luck. I feel that I’m very qualified to answer this question for several reasons.

First, I live by the deadlift and die by the deadlift. If all goes well I’ll leave this world immediately after performing a heavy set of deadlifts (hopefully when I’m around 88). That’s how much I love deadlifting. Second, I’ve thought about this phenomenon for many years. And third, I’ve spoken to researchers and powerlifters regarding this concept.

Many beginners round their back because they have crappy hamstring flexibility or poor glute strength so they’re forced to deadlift with a combination of hip and spinal extension. However, since you hinted that you only round when you go heavy, this indicates that you possess the hip mobility and core stability to lift properly.

I can think of two main reasons why one would be able to lift heavier when rounding the low back:

1) First, powerlifters often use their glutes and hip extensors to “roll” their pelvis which allows them to hang on their ligamentous structures in the spine as well as the thoracolumbar fascia. This gives them a tremendous boost in strength. This is probably the most important factor.

2) Second, by rounding the back you change the kinematics and kinetics of the lift. You slightly decrease the angle of hip flexion when initiating the lift (your hips aren’t bent forward as much), the hips are moved closer to the bar in the sagittal plane (your butt doesn’t stick out as far), the barbell’s range of motion is slightly diminished (when you lockout the bar hangs lower with a rounded upper back in comparison to an arched back), and you use the erector spinae as prime movers rather than stabilizers. These factors definitely add up and allow for heavier lifting.

Now let’s address the safety aspect.

First, it’s never a good idea to round the low back in a deadlift. Under such heavy loading it’s very easy to herniate a disc or damage other structures in the spine when the lumbar spine is flexed forward significantly.

It’s not as big of a deal to round the upper back in a deadlift. It is quite possible to control the spinal segments and allow the thoracic spine to flex while keeping the lumbar spine in neutral (or better yet slightly arched). Obviously the safest way to deadlift is to keep a slight arch in the lumbar and thoracic spines, while keeping the cervical spine in neutral with the chin tucked.

So powerlifters and strongmen can round all they want, as can recreational lifters who understand the risks versus the rewards. But if you’re a strength coach or a personal trainer, it’s best to avoid round-back deadlifts (or squats, good mornings, bent over rows, t-bar rows, and bent over rear-delt raises) and keep an arch when deadlifting.

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Here’s another question that I’ve received several times over the past few months that warrants a blogpost.


Hey Bret,

I would love to hear your thoughts on the HCG Diet. I have a couple of friends who have lost a bunch of weight on it, and I’m thinking about doing it myself.





Here’s a quick overview of the HCG Diet:

Participants take 125 iu’s of HCG (Human Chorionic Gonadotropin – a hormone that naturally occurs in the body in large quantities during pregnancy) per day while consuming 500 calories per day and not exercising. Here is a page from a popular HCG website that discusses some of the diet’s claims.

The HCG diet has been out since the 1930’s when it was pioneered by Dr. ATW Simeons. It is claimed that overweight patients who follow the Simeons therapy will a) lose weight quickly, b) not feel weak, c) not be hungry, and d) lose fat from those parts of the body where it tends to remain longest during normal dieting (i.e. stomach, hips, thighs, upper arms).

Below is link to a full paper meta-analysis conducted in 1995 by Lijesen et al.

The effect of human chorionic gonadotropin (HCG) in the treatment of obesity by means of the Simeons therapy: a criteria-based meta-analysis

Here are the researcher’s conclusions:

We conclude that there is no scientific evidence that HCG causes weight-loss, a redistribution of fat, staves off hunger or induces a feeling of well-being.

For more information, read this great article by Anthony Colpo.

I also think that the recommendations to avoid exercise are absurd. If it were up to me I’d have participants strength train for thirty minutes three days per week so they kept more muscle and lost more fat. The theory behind the diet is that since you’re only consuming 500 calories per day you don’t need to exercise and the HCG will cause the weightloss to come in the form of fat loss, but this theory just doesn’t seem to hold true.

The diet is very popular here in Scottsdale and I know of several individuals who are on the diet. Although they’ve achieved impressive amounts of weight loss due to consuming only 500 calories per day, their physiques paint a different story as they appear to be losing an equal amount of muscle and fat according to my observation. For optimal physique-enhancement, you want to do whatever you can to keep your muscle and shape and lose mostly fat for weight loss. Strength training and progressive overloading in particular would be of great benefit in this regard, despite the diet’s claims.

On a side note, many male bodybuilders take HCG during or following a cycle of anabolic steroids (AAS) to maintain and restore testicular size and testosterone production. When exogenous AAS are taken, negative-feedback loops cause the body to shut down its production of testosterone via shutdown of the hypothalamic-pituitary-gonadal axis (HPGA), which causes testicular atrophy. High levels of AAS trigger the hypothalamus to shut down its production of gonadotropin-releasing hormone (GnRH) from the hypothalamus. Without GnRH, the pituitary gland stops releasing luteinizing hormone (LH). LH travels from the pituitary gland to the testes, where it triggers the production of testosterone. Without LH, the testes fail to produce testosterone. In males, HCG helps restore testosterone production and testicular volume by mimicking LH and triggering the production of testosterone.

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Here’s a question I just received from one of my female readers. This question crops up quite often so I believe it’s best to address it in a blogpost.


Dear Wonderful Glute God (Okay I made that part up),

May I ask you a question? Whenever I do glute bridges or supine hip thrusts, my hamstrings cramp up and ache like hell! I mean, I can feel my glutes working, but it seems like my hammies are working overtime, like they are firing a lot more than the glutes. Is this right? If not, do you have any suggestions on how to stop it – should I be doing other exercises to get my glutes stronger first (so that my hammies don’t hog all the hip extension work) before doing these particular exercises? Or should I just harden the f*ck up LOL and keep hip thrusting!

Thanks so much,



Nadine, this is very common. One of the reasons why this happens is because your hamstrings are relatively strong in comparison to your glutes. When you shorten a muscle (as in keeping the knees bent in bridging which shortens the hamstrings) you interfere with the length-tension relationship of the muscle (it can’t contract as hard because fewer sarcomeres are in proper alignment). If your hamstrings are your dominant hip extensor, then they will still try to take the brunt of the load during hip thrusts, whereas the glutes should fulfil this role. This will cause them to cramp. Over time you can ameliorate this problem but here’s what you need to do:

1. Regress to bodyweight glute bridges and focus on “feeling the glutes.” Think of your posterior chain as a river with three waterfalls; one goes to the erector spinae, one goes to the glutes, and one goes to the hamstrings. Right now you might have 30% of the water going to the erectors, 20% going to the glutes, and 50% going to the hamstrings. You want around 33% going to each. Research indicates that it is possible to increase and/or decrease the relative contribution of various prime movers and synergists through proper training. In fact, there was a terrific article in February of this year’s Journal of Orthopaedic and Sports Physical Therapy entitled, Strengthening and Neuromuscular Reeducation of the Gluteus Maximus in a Triathlete With Exercise-Associated Cramping of the Hamstrings, which addressed bilateral differences and hamstring-cramping during running but showed that through sound training hamstring contribution can decrease while glute activation increases during movement and new and more efficient motor programs can be created. However, I like my methodology better than the researchers for your scenario.

2. Also focus on “feeling the glutes” during back extensions (remember you want all hip motion and no lumbar motion) and Romanian deadlifts, and make sure you utilize hip-dominant strategies and not just quad-dominant strategies (share the loading between the knee joint and hip joint) when you squat and lunge. You need to develop what bodybuilders call a “mind-muscle connection” with the glutes and learn how to better-activate the musculature.

3. In addition to bridging for glute activation, also add in exercises such as side lying clams, side lying abductions, x-band walks, quadruped hip extensions, and bird dogs. Make sure you keep the lumbar spine in neutral and move solely at the hips.

4. Once you feel your glutes working very well with bodyweight bilateral glute bridges, you’ll start progressing to more difficult variations. Here’s a good progression scheme for those:

bodyweight glute bridges
shoulder-elevated bodyweight glute bridges (hip thrusts)
barbell glute bridges
single leg glute bridges
barbell hip thrusts
single leg hip thrusts

Different trainers might progress in a different order but I’ve found that this progression-scheme works very well for most people.

5. Right before you work on glute activation, I want you to stretch your hip flexors (to make sure you decrease any reciprocal inhibition that you might have in the glutes), and I also want you to stretch your hamstrings (to slightly lengthen/weaken them so the glutes might do more of the work). When you do your bridges, rather than dorsiflex your ankles and push through your heels (which is the preferred method with most trainers which I find perfectly acceptable), instead I want you to keep your feet flat and push through your forefeet. Although this may increase quad activity, it will slightly decrease hamstring activity so you can hopefully get the glutes to contribute more to the movement.

6. Take your time and give yourself a couple of months to work your way into barbell hip thrusts. Remember, you didn’t become a champion squatter or deadlifter overnight, nor will you be a champion hip thruster overnight either.

When your glutes are really kicking in you can stop doing so much glute-activation prior to your workouts and you can focus more on pure strength training. Getting your glutes to work more during various movements is very wise as rarely do individuals “pull” their glutes. Conversely, often individuals strain the synergists (helpers) of the glutes – the low back, the hammies, the adductors, etc. Strong glutes spare the spine and the knees so I’m glad you’re taking this seriously.

Last thing – make sure you’ve watched these videos! Best of luck!

Squat Technique

Deadlift Technique

Hip Thrust Technique

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