Muscular Potential and Reality

Stephan over at put together the Maximum Lean Body Mass Calculator (no longer online). The formula used to make the calculation includes wrist and ankle size, which is a wise thing as ectomorphs tend to have smaller wrists and less muscle potential than someone with thicker wrists. But the formula is still incomplete. I’ll explain later.

My numbers are:

Height74.5 in
Ankle9.0 in
Wrist6.75 in
Bodyfat (est)16%
Lean Muscle Potential190 lbs

I have no idea what my body fat percentage is. Since college, I’ve had numerous body fat tests done using a number of different methods. They are all over the map. I’ve had higher percentages when I was visibly lean and lower percentages when I clearly wasn’t. But the interesting part of the calculation is not what your current body fat is, but what your lean mass potential might be.

Today I weigh 206. If my body fat percentage is 16%, then my lean mass is 173. Subtract that from 190 and according to the calculator I still have the potential to gain 17 more pounds of muscle. I’m highly skeptical. Not because I am a beast. I’m clearly not. I’m skeptical because the formula doesn’t capture enough data points.

Let us revisit the work of Ellington Darden Ph.D. In the post Fitness Role Models Revisited, I included two charts of muscular potential based on his research and work with thousands of athletes. Go check out that post now. What we learned is that there are two other variables.

  1. Distance Between Elbow and Edge of Contracted Bicep
  2. Distance Between Elbow Tip and Top of Inside Horseshoe

Using both these metrics, my muscular potential is “very minimal”. After playing with the calculator on Biohacks, I went looking for more formulas. The article The WeighTrainer: Your Maximum Muscular Bodyweight and Measurements by Casey Butt, Ph.D. has several more formulas including ones to calculate maximum measurements.

I’m not going to list all my maximum potential numbers, just the two most ridiculous ones. According to the formulas, I have the potential to have a 13.9-inch forearm and a 17.3-inch bicep. Unless I foolishly decided to inject Synthol, that is not going to happen with the 2.25-inch gap between my elbow and contracted bicep. With very few exceptions, almost every jacked ectomorph you see carrying significant muscle, you will see a small gap there.


Anthony Ellis

Probably the most memorable body transformation of an ectomorph I’ve seen was Anthony Ellis from the original Body For Life contest (~ 1996). Notice how tight the space is between his elbow and contracted bicep. His accomplishments are to be praised, but for a majority of ectomorphs, I would say he represents an unrealistic role model.

Today I weigh 50 pounds more than I did the day I enlisted in the military at the age of 17. Most of those pounds are muscle. I also didn’t start weight training until I was 24, missing the golden window of youth. So all things considered, I am very pleased with what I’ve accomplished.

For most of my lifting years, I had unrealistic role models and goals. I was rarely satisfied with what I had accomplished and I had a poor body image. Thankfully I am wiser today and can look back at that scrawny 156-pound 17-year-old and see what I have gained and maintained. I only wish I was aware of Darden’s data earlier. I would have saved myself from several injuries by pushing myself to reach some vision of myself that was never possible.

Part 2


Add yours

  1. I don’t think that particular formula works for women. Mine told me I could have 149 lbs of lean body mass at 5′ 1.5″ (unless I made a major error in the calculations). It’s true that I am very big boned (ankle 9″, wrist 6″) and could stand to pack on more muscle, especially above the waist, but even if I do, I can’t see myself going over 130 lbs total. My mother who is also big boned, strong, and the same height, and quite a bit fatter, tends to be around 160 lbs total. I estimated 22% body fat for myself, which is low average for women and probably where I was before my weight destabilized, so probably where I’ll end up again when I restabilize. Though looking at the formula the body fat percentage doesn’t seem to affect the final number much. 10% body fat would only add a few pounds.

    Now I’m trying to imagine myself with 149 lbs of lean body mass. And curves on top of that. It would be kind of fun. But figuring out how to dress would be difficult.

  2. @Anemome, I agree. mine said 140. the most I have ever weighed is 125 and I did weight train as a teenager and young adult. the arm measurement chart charted me as “very minimal”

  3. *** Norlee’s comment was the 10,000th comment for my blog. (drop balloons from ceiling, Yeah!) ***

    Both of you are correct. I went to Casey’s site and dug around. The Muscular Potential formulas represent the upper limits for drug free males.

  4. Equations like those puzzle me. Your potential isn’t defined by a formula. At best a formula is just an approximation developed over a large and diverse sample size and, as you point out, it needs to capture the proper variables and the proper relationships among them. It’s a fool’s game to use them to predict anything. To me, that skepticism applies equally to Dr. Darden’s guidelines. Perhaps you really do have the potential to gain 17 pounds of muscle under all the right circumstances (possibly to include winding back the clock to a younger you).

    Rather than let your goals be defined by a formula or an arbitrary set of measurements, it seems more productive to focus on implementing a sane, healthy training system and a sane, healthy way of eating, and then just having the patience to let them work and the wisdom to know when a change in circumstances necessitates a different approach. Gee, as I type those words it seems like the kind of thing it could take a lifetime to master! Anyway, who cares what your muscular potential is right now? Aren’t you trying to lose weight?

  5. @Geoff – The timing of this post was because of 2 posts on BioHacks. Stephan asked me to test the calculator and I decided to share my results here in a post.

    The entire point of the entry was the max formula is unrealistic for a large number of ectomorphs. No where in the post did I state I used those numbers as a goal. In fact I tried to make the case for the opposite, by poking holes in the formula as being incomplete and over stating the muscular potential of ectomorphs.

    And no I don’t think I could ever have 17 inch biceps even if I turned back the clock. To believe that is to believe I am somehow an outlier in Darden’s dataset which is over one thousand. Chasing outliers is the biggest problem with fitness. Too many bro-tards out there look at the exception and then try to extrapolate back. When I was younger and dumber I did and I saw my failure to achieve those metrics as my shortcoming and not genetic.

    I wouldn’t easily dismiss Darden’s work. When you work with thousands of athletes and gather metrics – that information can be a valuable tool. I think of what Darden did as important to body composition goals as Ed Easterling’s work in investing.

    Given a set of factors what is the likelihood of an outcome.

    I’m sure someone at some point will leave a comment about some ectomorph with wide spacing that got jacked. They will have totally missed the point of this post.

  6. MAS – I apologize. My writing was poor and re-reading my comment I see that it comes across as flip. My bad.

    I agree that the formulas are unrealistic – I am a 6’1″ ecto, as well. The idiocy (and danger) of chasing outliers is also a place where we agree. My point was simply that formulae shouldn’t serve as a limiter on our expectations of what is possible any more than they should serve as a goal. A formula might guide our ideas of what is reasonable, but that guidance will always need to be viewed through the lens of real-world experience in our n=1 lives, as you did. It’s through experience that we learn what’s possible for us.

    To me, the chase for my ultimate human potential isn’t about formulae or objective measurements of bicep size, its about the process of becoming a better (healthier, smarter, wiser, more compassionate) human being. One of the big reasons I like your blog is that I think you are on a similar quest.

    Again my apologies for a hasty and flippant comment earlier.

  7. @Geoff – Cool. I figured we were in agreement, but just coming at our conclusions from two different sides.

    My goal for this post is that some younger version of me reads it and decides to take my approach or your approach instead of seeking a numerical validation, especially when that number isn’t statistical likely.

  8. Stephan Raczak

    Jun 2, 2014 — 2:55 am

    @Anemone, @Norlee:
    Casey Butt also mentions that his formulae are most accurate for drug-free males with a bodyfat percentage between 4%-12%.

    I agree that a simple mathematical formula will never be able to accurately predict a human being’s maximum muscle potential. I also don’t see my calculated value as an ultimate goal to aspire to. But being 24 years old, I think that I can still put on a decent amount of muscle in the coming years if I stay injury-free. Of course, the rate of growth will be minimal each passing year, but being aware of my muscular upper limit serves me as a motivational tool as well as a reminder not to stress out too much about how big I can get. 🙂

    It would be interesting to combine the variables Darden uses with Casey Butt’s measurements in his formula to yield a combo-formula. Obviously, it wouldn’t be perfect yet but closer to painting an even more accurate picture of how much muscle you can potentially build.

  9. @Stephan – I wonder if Darden has done something like that? He has been thinking and writing about this topic for decades now.

    You could also add in the type of research that went into the book The Sports Gene and come up with a model. Many investors are aware of the work of Ed Easterling of Crestmont Research. He used historical data to predict expected returns based off a number of factors.

    Something like could be extended to all forms of athleticism.

  10. In Casey Butt’s book on the subject, he has a formula that accounts for ectomorphs/hardgainers. It’s a very realistic peak, something attainable with years of diligent work.

  11. @Stephan – Based off Skyler’s comment, perhap you could create a 2nd online calculator? 🙂

  12. Stephan Raczak

    Jun 10, 2014 — 3:42 am

    @MAS, @Skyler:

    it’s ready! Here’s the online calculator for hard gainers/ectomorphs:


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