Weight to Strength relation

[progressiveman1]

In the last chart in PPST, you guys estimate strength levels according to bodyweight. I couldn't help but notice that at the heaviest end of the spectrum the strength levels were very much higher than the lowest end, even in untrained people. Is this solely because a surplus of calories drives strength progression, or is there another function derived from bodyweight that relates to strength levels?

[Mark Rippetoe]

Your question is unclear. What do you mean by "heaviest end of the spectrum"?

[progressiveman1]

The heaviest end of the spectrum in the charts in your book; ie, the heaviest bodyweight compared to the lowest bodyweight.

For example, in the Squat chart the heaviest bodyweight you list is 320 and the untrained strength level for that weight is 147. The lowest bodyweight you list is 114 and the untrained strength level for that weight is 78. Basically, my question is: Why does an untrained person who weighs more have more strength than someone who weighs less?

[Mark Rippetoe]

I was afraid that's what you were going to say. The answer is: because his muscles are bigger, and bigger muscles produce more force than smaller muscles.

[progressiveman1]

1. So the answer to my first question would be, "Yes, the reason a heavier untrained person is stronger than a lighter one is solely because eating a surplus of calories drives strength progression."?

2. For trained people, I don't understand how you can make an estimation for strength based on bodyweight without making a distinction between bodyfat percentage. For example, based on the charts an intermediate man who weighs 220 has an estimated 301 squat, and a man who weighs 198 has a 185 squat. If a man is currently at the former stage and decides to rid 20 off his bodyweight to reach the latter bodyweight, he wouldn't lose 15 off his squat if he continued training, would he?

[Baldr]

You have to realize that every time a heavier person lifts their legs, moves their arms, jumps, etc. it requires more strength than it would for a lighter person, so naturally the heavier person has bigger muscles, and is stronger.

[Mark Rippetoe]

1. No, the answer to your first question is in my second reply.

2. My chart says the intermediate man has a 285 squat. Given that typo, it is understood that these are averages, and that an average 198 lb. guy that is squatting 285 does not have 30% bodyfat anyway. Average bodyfat for that level of advancement is assumed.

[Brandon Oto]

I think a better question would be the opposite; why are the strength-to-mass ratios LOWER at higher bodyweights? That is, it appears that a very light lifter is able to lift RELATIVELY more than a very heavy lifter at the same level of training. Why is lower bodyweight associated with greater pound-for-pound strength?

[Mark Rippetoe]

Finally, a sensible question. This is because strength is related to the cross-sectional area of the muscle mass, not its total mass. The contractile mechanism of muscle depends on the total number of fibers in a cross-section, not the length of those fibers, and a short guy will have the same cross sectional area as a taller guy, while the taller guy will have more muscle mass due to the fact that his muscle bellies are heavier because they are twice as long at the same cross-sectional area. Therefore, taller/bigger people have more muscle mass per unit of cross-sectional area than do shorter/lighter people. So on a pound-for-pound basis, shorter/lighter people will be stronger.