Strength & Bodyweight Lifting Comparisons

[Tannhauser]

Originally Posted by kitarpyar

Apart from the absolute value of the weight lifted, beyond a point of time there's also a diminishing strength return with increasing bodyweight (although strength DOES increase) - this makes it easier for lighter guys to lift x times their bodyweight than bigger guys. Therefore for "best lifter" comparisons, Wilks coefficients are widely used in a powerlifting meet.

Mathematically, Wilks coefficient (comparing relative strength of PL) is given by the following formula:

coeff = Wt lifted / (a + b*x + c*x^2 + d*x^3 + e*x^4 + f*x^5)

Here x is the bodyweight and a-f are constant values (different for men and women). As you can see, the variation is non-linear. The normalized weight is this factor multiplied by the weight lifted.

Here's a graph I plotted out (lol, I have nothing better to do at lunch time), which shows the variation of normalized weight with bodyweight if the lifters lift 2x bodyweight.

Lifting 2x stronger at a higher bodyweight would have you much stronger compared to a lower bodyweight using the normalized scale.



In your example, normalized weight lifted by the 180 lb lifter lifting 360 lbs would be 242.712. The same value for the 350 lb guy lifting 600 would be 327.9

Interesting. I was trying to figure out why this should be. Is this something to do with scaling? I'm not at all sure I can explain myself, but let's try some (very) hypothetical figures:

Let's say a lifter is like a cube with 0.5 m sides, and a density of 1000kg/m cubed. And he has a thigh muscle 0.1m * 0.1m (= 0.01 m sq) that can lift 200kg.

His mass is 125kg, he can lift 200kg, so strength/ mass is 1.6

Now double him in size in every dimension. He is now 1m * 1m * 1m = 1 metre squared, which means he now has a mass of 1000kg (well, I said it was hypothetical).

However, his thigh, if it has increased in proportion to his other dimensions, is now 0.2m * 0.2m = 0.04 m sq. in cross-sectional area. It's four times bigger than it was.

Now, strength of muscle is directly proportional to cross sectional area (other factors being equal), so therefore he can now lift four times as much = 800kg.

An eightfold increase in mass has resulted in a four fold increase in muscle cross sectional area, so his strength/mass ratio is now 800/1000 = 0.8, half what it was before.

The ratio will change because mass is proportional to the cube of length, whereas strength is only proportional to the square. Poorly expressed, but that's my best shot.

[5kgLifter]

Originally Posted by Rich Knapp

OK so straight and to the point. No one cares about your body weight just what you move. That's all I needed to know so if it comes up again I answer correctly.

I don't need to wright a dictionary to them on why.
Point blank "No one care's about what you weight." The End. lol

Thats what I figured but just wanted to make sure I had my ducks in a row on it.

Thanks all.

I think some are all about absolute strength, maybe because they like to see exactly how far we can go as a species in terms of the weights we lift; personally, though, I prefer to compare equally weighted individuals...not necessarily even weight classes where there may be 9+ lbs of difference permitted and so forth but quite literally people of equal weight...but it's also great to watch people just lifting heavy as well.

Maybe I'm just strange

[Fazc]

[Tannhauser]

Originally Posted by Fazc

Made me laugh. It certainly is.

[BendtheBar]

My can of worms is heavier.

[Fazc]

Deleted.

[BendtheBar]

Seriously though, good info in this post. Needs to go into the training resources section.

[Rich Knapp]

Originally Posted by Fazc

Deleted.

True fazc, The NPC wheelchair bodybuilders are 2x as popular as I am.
Just as the people here say "They want to see what I can do against some real competition." What make NPC any more real than natty? So great point. Why did you delete your post?

[IronManlet]

I actually disagree. I believe impressive/heavy lifting is completely relative.

[Kyle Aaron]

Smaller people lift larger multiple of their bodyweight. Larger people lift larger weights.

Smaller people think that lifting large multiples of their weight is "real strength", larger people think that lifting larger weights is "real strength." There's no ego in it, they're being completely objective, of course.

Luckily in competitions we have weight classes to accommodate all egos.