Video Blog: Skype Q&A with Brad Schoenfeld about Skeletal Muscle Hypertrophy

Like my last post, this one will also be in the form of a video. This time, Brad Schoenfeld is the featured guest and he answers a series of questions from the fitness community regarding muscle hypertrophy.

For those of you who don't know him, Brad Schoenfeld, MSc, CSCS, CSPS, CPT is an internationally renowned fitness expert and widely regarded as one of the leading authorities on body composition training (muscle development and fat loss). The 2011 NSCA Personal Trainer of the Year is a lifetime drug-free bodybuilder who has won numerous natural bodybuilding titles, including the All Natural Physique and Power Conference (ANPPC) Tri-State Naturals and USA Mixed Pairs crowns. As a trainer, he has worked with numerous elite-level physique athletes including many top pros.

Brad is a best-selling author of eight fitness books including his latest “The M.A.X. Muscle Plan.” He has been published or featured in virtually every major fitness magazine (including Muscle and Fitness, MuscleMag, Ironman, Oxygen, and Shape) and has appeared on hundreds of television shows and radio programs across the United States. Certified as a strength and conditioning specialist by the NSCA and as a personal trainer by the ACSM, ACE, and CanFitPro, Brad was awarded the distinction of master trainer by IDEA Health and Fitness Association.

Brad is a lecturer in exercise science at Lehman College in the Bronx, NY, is the director of their human performance lab. As a scholar, Brad has published over 40 peer-reviewed journal articles in exercise and sports nutrition and serves as the Assistant Editor-in-Chief to the Strength and Conditioning Journal. He is currently pursuing his PhD in health science at Rocky Mountain University where his research focuses on the mechanisms of muscle hypertrophy and their application to resistance training.

In addition to his impressive CV, Brad will be coming to the UK early next year to deliver two seminars (one in Bath and one in London). See here for more information and to purchase a ticket!


What is my natural muscular potential? Part 2

In part 1 of “what is my natural muscular potential?” I introduced two models of natural muscular development, which were both derived from natural bodybuilders. In this second and final part, I’ll use a real-world example and see how my stats measure up to both models. I’ll also talk about limitations to these formulae, as well as giving a brief outline of what it takes for someone to reach their muscular potential.

A real-world example

To give you an idea of what these numbers actually mean, I’ll run my own stats through both models to see how close to my genetic potential I am.

My stats:

Stature – 181 cm (5’111/3”)

Body mass – 76.5 kg (168.3 lbs.)

Body fat percentage – 8% (ish)

Lean body mass – 70.4 kg (154.8 lbs.)

Ankle circumference – 8.25”

Wrist Circumference – 6.7”

Bicep circumference – 15”

Using my stature, wrist and ankle circumferences the Casey Butt model predicted my maximal natural lean body mass to be 75.9 kg (167 lbs.).

Since my current lean body mass is roughly 70.4 kg (155 lbs.), this equates to 92-93% of my genetic potential based on this equation.

Using the Martin Berkhan model, my predicted maximal natural body mass at 4-6% is 81 kg (178.2 lbs.). When body fat is taken into account, this equates to a lean body mass of between 76.1 kg (167.5 lbs.) and 77.8 kg (171 lbs.).

Again, since my current lean body mass is roughly 70.4 kg (155 lbs.), this put me at 90-93% of my genetic potential based on this equation, which is remarkably similar to that of the previous equation.

Taken together, these predictions sound about right, as I’ve been weight training for about eight years; the last three or four of which have specifically been aimed at muscular development. Given the extremely slow rate of muscle gain following years of dedicated weight training, I don’t expect to be gaining the predicted 5-7 kg (12-16 lbs.) anytime soon. Assuming I could gain on average 3-4 lbs. per year (if I’m very lucky!) this would take me at least another four to five years or so to reach my apparent genetic limit (unless I turn to steroids, then it would be within a year).

Are there exceptions?

Like any predictive measure, there are always outliers. However, these genetic freaks are few and far between and were purposefully left out of Casey’s model since their drug-free status cannot be verified. Furthermore, as stated in part one, these equations were developed using data collected from elite drug-free bodybuilders (i.e. the people who have won the genetic lottery to begin with and have been training extremely hard and consistently for a decade or more). So, if it were possible to surpass these predictions, it would no doubt be a natural bodybuilder and it would hardly be by a meaningful degree. The average gym-goer going through the motions a few times per week can forget about reaching such stats, at least without drugs. That’s not to say these individuals cannot attain visually impressive physiques.

So, for all intents and purposes, these predictions cannot be surpassed. As such, any individual that can be verified to exceed such stats, and isn’t a pro natural bodybuilder with at least eight years of training behind them, is clearly using drugs (whether they admit to it or not). While I have nothing against people who take steroids, I dislike people who claim to be natural when they’re clearly not.

Aside from the dishonesties of some steroid users, some people are genuinely drug-free and “appear” to surpass such predictions. For example, people are notorious for severely underestimating their true body fat percentage. As such, these individuals may think they surpass the predictions (particularly Martin Berkhan’s due to the fixed body fat reference point), whereas in fact, the extra fat that they are not accounting for is assumed to be muscle. Therefore, if this individual actually reduced their body fat to the 4-6% body fat range, they would notice a substantial loss in body fat, which will no doubt put them within their predicted muscular potential.

I should mention that this might not be due to the person lying about their body fat measurement; rather, it is more often than not due to the inaccuracies of the various body composition techniques. For example, after measuring skinfold thickness (assuming the measurements are taken by a competent person), these skinfold measurements are entered into one or more of many equations available for predicting body fat percentage. Such equations are only as valid as the sample they originated from, so it is not uncommon to see body fat estimates for lean individuals deviate by as much as 5% or more, depending on which equation is used, despite using the same skinfold measurements.

So, using a fictional example, say that a person is 6” tall and weighs 87 kg (191 lbs.) and their chosen skinfold equation incorrectly puts them at 6%, this would equate to a lean body mass of 81.8 kg (180 lbs.), which surpasses their predicted natural potential. In reality, their true body fat percentage could easily be 10% due to the lack of validity of the chosen skinfold equation. 87 kg (191 lbs.) at 10% body fat would then equate to a lean body mass of 78.3 kg (172.3 lbs.), putting them within their predicted genetic potential.

Leigh Peele wrote an excellent article about this, which allows people to verify their body composition results via real-life examples of a range of body fat percentages. For example, a bodybuilder at contest condition should set the benchmark for minimum attainable body fat percentages (3-5%), which should make for a more accurate estimation of their own body fat percentage in spite of what the skinfold equation spits out. The picture to the right shows what a minimum attainable level of body fat actually looks like on a natural bodybuilder.

 Limitations of the formulae

These equations were developed using males, for males. As far as I’m aware no such predictions exist for women. However, if they did, they would be WAY below the values outlined here.

Martin Berkhan highlights a limitation to his formula in that it only “assumes average genetics” (which is also the case for Casey’s equation). There are true cases of non-responders to weight training meaning that the notion of a “hard gainer” is indeed correct. As the term hard gainer implies, these individuals have a more difficult time gaining muscle mass, despite appropriate training and nutrition. Because of this, these people may not ever come close to the limits of the predictions outlined in part 1.

This sparks the question, “if there are hard gainers, surely there are easy gainers?”. While there are genetically gifted individuals, in Martin Berkhan’s experience, “high-responders simply gain muscle mass faster than someone of average genetics; the cap for maximum muscular potential (height - 100) does not seem to be raised by much”.

How do I go about reaching this potential?

Now that the limits of natural muscular development are understood, I will briefly outline the steps someone should take in order to get there, or as close as possible.

Perhaps the most important factor in realising this potential is consistency. Despite all the ridiculous marketing claims, the only way to gain muscle quickly is through the use of drugs. It is possible for naturals to gain weight quickly with the use of weight gainers etc. but the majority of this mass will be fat. Any natural who has achieved such stats has been training consistently week in week out, month in month out, year after year, for at least a decade, or close to it. Given the diminishing rate of muscle growth over a training career, a year’s worth of hard work in the gym can bring about a 1-2 lb. gain in muscle tissue after five or so years of training, which can be disheartening even to the most dedicated trainees. Nutrition and training author, Lyle McDonald of has estimated the potential for muscle gain on a yearly basis in table 3 to give people realistic expectations of rates of muscle growth in order to set appropriate training goals.

Table 3. Potential rate of muscle gain per year

Years of proper training Potential rate of muscle gain per year Per month
1 9-11 kg (20-25 lbs.) 1 kg (2 lbs.)
2 4.5-5.5 kg (10-12 lbs.) 0.5 kg (1 lb.)
3 2.3-2.7 kg (5-6 lbs.) 0.25 kg (0.5 lb.)
4 0.9-1.2 kg (2-3 lbs.) Not worth calculating
5+ 0.45 kg (1 lb.) Not worth calculating

Speaking of training goals, a good way to plan for progress is to keep a training log. That way, you can objectively track your progress as opposed to just going in the gym and lifting based on how you feel that day. Following the FITT principle, this progression can be in the form of frequency (how many times per week), intensity (typically the load lifted), type (addition or rearrangement of exercises) and time (volume; set and rep schemes). The concept of tracking progress can also instil a degree of motivation, especially when you see your lifting numbers going up on a consistent basis.

Regardless of the other points above, you can never come close to your predicted muscular potential unless you have a solid training and nutrition regime in place.

Nutrition sets the potential for muscle growth. If adequate calories and protein are insufficient, you can forget about gaining muscle optimally. Calories should be set at just above maintenance for optimally gaining muscle, whereas protein should be a minimum of 2 g per kg of bodyweight, ideally more (e.g. 2.5–3 g/kg). In this article I discussed protein requirements in more depth.

In terms of training, the focus should be on gaining strength in the following lifts and/or their variations at least once per week (preferably in the 6-8 rep range, on average): deadlifts, squats, bench press, press, barbell row and chin-ups; muscle gains will follow. Some direct calf work wouldn’t hurt either. Isolation exercises such as bicep and wrist curls, made popular by drug-fuelled bodybuilders (and what most people seem to do in the gym!), aren’t necessary for the first one or two years of training; the focus should be on the outlined exercises which give the trainee the biggest reward for their time invested in weight training. Isolation exercises may be introduced after this period in order to bring up lagging body parts, but they shouldn’t interfere with progress in the main lifts; they should enhance it, if used correctly.

There is obviously much more to it than this (e.g. optimal set and rep schemes, training frequency, volume, periodisation etc), but this is a good start for beginner/intermediate trainees (and the vast majority of gym-goers) in order to develop good strength and muscle gains.

To conclude, I’ll reiterate that the point of this article is not to appear negative and state what someone will or will not achieve, rather, it aims to provide a realistic expectation of what actually is achievable without the use of drugs. Casey summarised his findings rather nicely, “The equations presented in this text accurately and precisely estimate the weights and muscular measurements of practically every elite-level drug-free bodybuilding champion of the past 61 years…. If the equations were not valid, for any theoretical reason, this simply would not be true. Considering bone structure size and muscle belly lengths they also apply to the average aspiring bodybuilder. It is not my intention to imply that no one will ever surpass the predictions of this text. It is, however, my intention to put what such an accomplishment would represent into proper context and likelihood”.

What is my natural muscular potential? Part 1


In this two-part article I’m going to discuss a question that comes up quite often among weight trainees, that is: what is my genetic muscular potential? Or, in other words, how ‘big’ can someone expect to get naturally (without the use of drugs such as anabolic steroids) with years of training under their belt.

The point of this article is not to appear negative and state what someone will or will not achieve, rather, it aims to provide a realistic expectation of what actually is achievable without the use of drugs. You only need to look at men’s health or other fitness magazines that make claims like, “gain 20lbs of muscle in two months!”, and other such nonsense like, “you’re not ‘big’ until you’re over 200lbs”. Such claims give trainees hugely unrealistic expectations before they start weight training, and ultimately, those people end up disheartened and frustrated when they aren’t reaching their impossible goals. It’s the equivalent of someone expecting to run a sub 2.5-hour marathon with a couple of years training; not to mention the majority of people aren’t genetically endowed in the first place to ever achieve such a feat.

In fact, it would be pretty much impossible for a natural to reach 200lbs (91 kg) at an appreciable amount of leanness, unless they are really tall (>185 cm). Yet somehow, this mentality seems engraved in a lot of lifters minds, which is further solidified by “apparently” drug-free achievements of athletes and models, as well as notable film star transformations (does the cast of the film ‘300’ ring a bell?).

What I’m trying to get at is the fact that we are led to believe that something is attainable when in fact it often isn’t. You can make the argument that “any physique is achievable as long as you have the right work ethic” or that “film stars have access to the best trainers and nutritionists”. Of course, both statements are utter nonsense. I’d also note that the vast majority of these “celebrity trainers” are shit (for lack of a better term). While it may sound somewhat patronising of me to outline what you may or may not achieve ahead of time, I’m basing my opinions on data collected from hundreds of drug-free bodybuilders; the very people you’d expect to have the greatest natural muscular development! The following paragraphs will briefly outline these data and how such predictions of genetic muscular potential were derived.

The Casey Butt model for maximum muscular development

Casey Butt is a natural bodybuilder and owner of the website Casey holds degrees in mathematics and physics as well as a Ph.D. in artificial intelligence; so it’s safe to assume he knows his numbers. Over six years of his training career, he collected the statistics of hundreds of drug-free bodybuilders. From these measurements, he came to the conclusion that height; bone size (namely, the wrist and ankle circumferences) and muscle belly length were the best predictors of an individual’s potential drug-free muscular development. Following this, he developed equations based on height, ankle circumference and wrist circumferences to allow someone to calculate how “jacked” he could potentially get. The culmination of this work, in the form of an e-book, can be bought from his website for those of you with more than a passing interest in the topic.

For those of you who want to calculate your muscular potential right away without sifting through an equation-laden book, there is a calculator on his website in which you can quickly type in your height, wrist and ankle girths and desired body fat percentage.

In table 1, I have used this calculator, along my wrist and ankle measurements (6.7” wrist and 8.25” ankle) to generate muscular potentials for lifters of varying heights and degrees of leanness.

Table 1. Estimated maximum muscular potential using Casey Butt’s model


Lean body mass

Body mass at 5% body fat

Body mass at 10% body fat

Estimated maximal bicep circumference at 8-10% body fat








































As previously stated, these are estimations based on my wrist and ankle girths, and variations in these will alter the predicted numbers. As such, for a more accurate estimation of your muscular potential you can always go and enter your measurements into the online calculator. I’ve also included the estimated bicep measurements since a lot of people tend to have delusions about what realistic measurements are. This has probably due to a combination of people inaccurately measuring their biceps (leaving the tape measure slack) or blatantly exaggerating the size of their arms. The latter factor has certainly been a case among many competitive bodybuilders. I’ve also overheard several gym conversations in which trainees claim that they have 17” "guns", whereas in reality, they were much closer to 14”!

From this table, it is also evident that body masses > 200lbs when extremely lean, are only attainable by very tall individuals. For the majority of people, a lean body mass is excess of 165lbs (75kg) would be extremely visually impressive, even for a drug-fuelled athlete.

It is worth mentioning that Casey intentionally left out some statistical outliers in his analysis that he termed “genetic freaks”. They were left out as “these trainees do not represent a typical level of development even for elite [natural bodybuilding] champions”. Another reason for leaving these statistical outliers out of the original analysis is that the drug-free status of some of these genetic freaks has not been verified, only assumed. And “given the ease at which drug tests can be passed by drug using athletes these days this gives me further reason to be skeptical of some of the natural freaks’ drug free claims”. Therefore, “it cannot be stated strongly enough that it is completely unreasonable for the genetically typical trainee to think that he can reach [the] level of development [of these “genetic freaks”]…. Few world-champion drug-free bodybuilders do so, nor do even the majority of anabolic drug users”.

The Martin Berkhan model for maximum muscular development

Martin Berkhan owns the website, and has developed a more simple, yet accurate formula (as verified on his clients), again based on natural bodybuilders at competition leanness (i.e. 4-6% body fat). The formula is as follows:

(Height in centimeters - 100) = Body weight in kg at a shredded state (4-6% body fat).

For example, using an example of someone who is 5’11” (180 cm), body weight at a shredded state = “180” – 100 = 80 kg (176 lbs.). Martin also acknowledges the possibility that many bodybuilders are dehydrated or glycogen depleted to a degree on contest day as a “dry” appearance is desired. Therefore, when the effects of dehydration are accounted for (which equates to roughly a 2% drop in total body weight independent of body composition), the equation becomes “Height in centimeters – 98” when hydrated.

Like table 1, table 2 shows the genetic muscular potentials for lifters of varying heights and degrees of leanness. I’ve used the same heights and body fat percentages as table 1 for comparative reasons.

Table 2. Estimated maximum muscular potential using Martin Berkhan’s model


Lean body mass (+2%



Body mass at 5% (contest condition) body fat (+2%



Body mass at 10% body fat (+2%










69    (70.4)

152   (155)

72.5    (74)

160   (163)

76.6    (78)

169   (172)


73.6    (75)

162   (165)

77.5    (79)

171   (174)

81.7    (83)

180   (183)


78.9 (80.5)

173   (177)

83    (84.7)

183    (186)

87.6    (89)

193   (197)


83.6    (85)

184   (188)

88    (89.8)

194   (197)

92.8 (94.7)

204   (208)

* 2% corrects for the effects of dehydration

Though not identical, the values calculated in table 2 are very similar to that obtained in table 1, especially when corrected for the effects of dehydration. Furthermore, Martin’s formula seems to be more in line with Casey’s predictions at heights of 5’10” and above, with values at 6” and 6’2” being almost identical. Martin Berkhan states that a limitation to his formula is that while it is “very accurate for guys smack dab in the middle of that range (180 cm)…. shorter guys (below 170 cm) seem to skew the formula towards being heavier”. Therefore, for shorter people (<175 cm/ 5’9”) the formula becomes:

Height in centimeters – 98-99 = Body weight in kg at a shredded state (4-6% body fat). (The 2% is also added on to this value). Following this adjustment, and that for the effects of dehydration, predicted values at all heights become extremely similar in both models.

This article is getting pretty lengthy now and I’m not close to finishing, so I’ll have to split it into two parts. In part 2 of “what is my natural muscular potential?” I’ll see how I measure up to both models and talk about limitations to these formulae, as well as giving a brief outline of what it takes for someone to reach their muscular potential.