Dont forget the square-cube law. As a person gets bigger, his area increases slower than his volume, so his relative strength always goes down. Imagine a simple shape like a cube with side length equals 1". Assuming constant density, its strength is a function of its cross sectional area, or 1^2=1 square inch. Its weight (at constant density), is a function of its volume, or 1^3= 1 cubic inch. Its relative strength is a function of its area to volume ratio, or 1^2 / 1^3 = 1.
Now imagine this same cube starts lifting weights and swinging kettlebells, and achieves SINISTER! Now the length of the cube is 2"! Double the size! Assuming constant density, its strength is a function of its cross sectional area, or 2^2=4 square inch. Its weight (at constant density), is a function of its volume, or 2^3= 8 cubic inch. Its relative strength is a function of its area to volume ratio, or 2^2 / 2^3 = 0.5.
So this 2nd cube is 4 times (2^2 / 1^2=4) stronger than the 1st cube, on an absolute basis. But the 2nd cube is only half as strong as the 1st cube, on a relative basis ((2^2/2^3)/(1^2/1^3)=0.5).
Example, they claim insects can lift like 50+ times their bodyweight. Impressive! But if an insect were the size of an elephant, it wouldnt be able to even walk on those skinny legs. It would instantly die and be crushed by the force of gravity.
Or a powerlifter or weightlifter. A 2 times bodyweight deadlift of someone weighing 120 lb is less impressive then someone weighing 400 lb. This is why strength sports use scoring like Wilkes scored to compare athletes of different weight.
A child is relatively strong vs the average adult. A child is light and can easily maneuver monkey bars and climb trees. The average adult cannot do this (I realize a fit adult can). But virtually every healthy, normal child can do this.
Everyone should be fit and strong and healthy. That is a no brainer. But what is strength, how do you define it?
1) Do you define being strong as being able to maximize your ability to manipulate external objects in space? Such as lifting a refrigerator or wrestling another human being or pushing a car out of the mud. Then you need to lift more and more weight. Then bulk up and get big!
2) Or do you define strength as being able to maximize your ability to manipulate internal (yourself) objects in space such as being able to jump, run, pushup, pullup, climb a rope, or march from point A to point B, etc...? Then try and stay as small as possible.
3) For most people it is somewhere in the middle of (1) and (2), they want both! Although they may lean 1 way or the other.
Regards,
Eric