Years ago I wrote an article in an old issue of the WeighTrainer magazine that dealt with the maximum strength levels a typical drug-free trainee was ever likely to achieve. They weren't meant as absolute limitations, but rather as a comparison of how you'd personally stack up against other lifters of your body weight. Recently, there's been some interest on the Strength and Size Forum regarding strength levels based on bone structure and body weight. I thought it was time for an update.
The equations below were derived by performing regressions on data of world record lifts in the Bench Press, Squat and Deadlift from the late 1940s up to current drug-free, raw Powerlifting records as of April 2010. In essence, if you plug in a body weight they'll tell you what the world record lifts would be at that weight (without drugs or lifting equipment). The fits are very accurate, but some outliers exist with the Bench Press in particular (those people who are built to Bench Press even among fellow world record holders).
Bench Press = 2.6536e-5 x BW^3 - 0.02590 x BW^2 + 8.7356 x BW - 439.90
Full Squat = 2.5122e-5 x BW^3 - 0.02993 x BW^2 + 11.2575 x BW - 676.60
Deadlift = 1.6940e-4 x BW^3 - 0.12449 x BW^2 + 30.3879 x BW - 1776.51
BW = body weight in pounds, and all lifts are expressed in pounds.
Lifts are done with no support equipment except a lifting belt. Bench Presses are with a complete stop on the chest, no bounce. Squats are to full parallel or below. Deadlifts can be Sumo or conventional style.
The equations are based on world record holders in the individual lifts - history's best "specialists", you might say. It isn't really realistic to expect that you'll be able to match the predictions - after all, only a handful of people in history have. If you eventually do, then fine, you are a world champion; if not, you're one of the rest of us. Typical trainees may reach approximately 67% of the Bench Press prediction and 72% of the Squat and Deadlift predictions. Extreme "hard gainers", in a particular lift or in general, may max out as low as 53% or less of the Bench Press and about 58% of the Squat and Deadlift. Whatever may be the case, accept yourself for who you are and never stop trying to improve yourself - that's the real measure of success, not only were you ultimately go, but where you came from as well.
The data used in formulating these equations included record holders from 110 lbs to 242 lbs, so the equations are accurate in these weight ranges. Body fat is also factored into the equations to a degree because competitors in the lower weight classes tend to have lower body fat than lifters in the heavier classes. Above 242 lbs or so lifters get significantly fatter, but the equations still hold reasonably well.
As an example of how to use the equations, let's take a look at say Marvin Eder's Bench Press. Eder was 198 pounds when he was at his best, so...
Eder's Bench Press = 2.6536e-5 x 198^3 - 0.02590 x 198^2 + 8.7356 x 198 - 439.90 = 480.3 lbs
In reality, Eder was credited with a 515 lb Bench Press, so he was one of those freaks I mentioned above. His record would likely still stand today. Interestingly, other absolute records on the Powerlifts have not increased significantly since the introduction of steroids in the late 1950s. For instance, Reg Park's Bench Press and Squat would be within 20 lbs of the current raw, drug-free Powerlifting records (set by specialists at that), as would Doug Hepburn's major lifts. Paul Anderson's Squat would most certainly be significantly above the current world record in any drug-tested, raw federation. What that tells us is that these lifts are not increasing over time and these equations can be reliably taken to approximately represent the limits of human strength without drugs or equipment (other than a lifting belt).
If you're a drug-free bodybuilder who's interested in utlimately getting as big as you can without drugs, you may want to use the equations to predict how strong you could be at your biggest (biggest, not fattest) muscular condition. In that case, use the following equations from my e-book, YOUR MUSCULAR POTENTIAL: HOW TO PREDICT YOUR MAXIMUM MUSCULAR BODYWEIGHT AND MEASUREMENTS. These equations predict how big you're likely to get after a lifetime of drug-free bodybuilding and are based on an analysis of over 300 drug-free bodybuilding champions from the 1940s up to present day.
Maximum Lean Body Mass = H(W/7.2546 + A/5.9772)(%bf/450 + 1)
Overall Bodyweight = (Lean body mass/(100-%bf)) x 100
H = height in inches
W = wrist circumference in inches
A = ankle circumference in inches
%bf = body fat percentage
As an example of how to use the equations, let's say you're a typical lifter of 5’9” (69 inches) in height, with 7.0” wrists, 8.8” ankles and 12% body fat. You would have the following potential lean body mass:
Maximum Lean Body Mass = 69.0 x (7.0/7.2546 + 8.8/5.9772)(12/450 + 1) = 172.6 lbs
Your total body weight would be,
Body weight = (172.6 / (100 – 10) ) x 100 = 196.1 lbs
At a body weight of 196.1 lbs, your world record level raw lifts would be:
Bench Press = 2.6536e-5 x 196.1^3 - 0.02590 x 196.1^2 + 8.7356 x 196.1 - 439.90 = 477 lbs
Full Squat = 2.5122e-5 x 196.1^3 - 0.02993 x 196.1^2 + 11.2575 x 196.1 - 676.60 = 569 lbs
Deadlift = 1.6940e-4 x 196.1^3 - 0.12449 x 196.1^2 + 30.3879 x 196.1 - 1776.51 = 673 lbs
Again, those would be world record level lifts. It's much more likely that you'll tap out at about 67% of the Bench Press and 72% of the Squat and Deadlift or so. That would be a Bench Press of 320 lbs, a Full Squat of 410 lbs, and a deadlift of 484 lbs. If you just weren't born to lift you might only get to about 53% and 58% of those numbers - a Bench Press of 253 lbs, Full Squat of 330 lbs and a Deadlift of 390 lbs. In that case, however, you probably wouldn't reach the predicted maximum body mass either. True "hard gainers" only achieve about 95% of the maximum body mass predictions - which in itself still represents a fine physique and an impressive accomplishment.