Lot of people seem to equate durability with physical strength.
You can have the qualities of durability and physical strength co-existing with each other. In most instances, however, they're really not the same. We'll explore the distinction here.
I'll periodically supply reference information for my entries and experiment with various size and format presentations.
This is a scene from Mark Waid's Legion of Super-Heroes, fifth volume, for instance, where Ultra Boy tries to impress one time-stranded Kara Zor-el, and fails miserably ...
Mini-end scene. Note that using his power to make himself strong did NOT protect Ultra Boy from being ROCKED by his opposition, as Kara pointed out in the previous panel.
This is an entire thread dedicated to the question, Jake.
You can be certain he won't be the only example.
I disagree that Ultra Boy would be a bad example, by the way.
Extreme examples tend to be the clearest examples, not moderate ones that feature a mix of the 2 qualities being examined.
Ultra Boy's case makes the distinction about as clear as can be.
I think what most people say is that, in order to "realistically" have/use extreme physical strength, the character's body needs to be strong enough to tolerate the tensile, compressive and other stresses imposed by deployment of that strength. Eg, you might be strong enough to military-press a building, but if your body isn't up to par, your bones will snap, ligaments will tear, and the skin (of your palms) will be crushed. (Frankly, the "one power at a time" thing noted in the scans strikes me as gimmicky.)
On the other hand, while I don't think you can have (or shouldn't, anyway) extreme strength wthout extreme durability, offhand I don't see why you couldn't have the durability w/o the strength.
Regardless, this brings up something I've wondered about : given a certain level of strength, what would be an appropriate level of durability? For example, if you can press a mountain, should you be able to withstand a nuke? Or from the other direction: if you're bulletproof, what level of strength would be proportionate?
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Shinier than a speeding bullet.
In answer to your question, Mindship, I think the following level of durability would suffice for most any modern character.
The fact that our young heroine here regards feeling pain from so many tons of steel slamming into her side as an indicator that something is WRONG with her ...
Kara versus Titanic. Image 2. Impact. Gravitygun ammo...
Eg, Superman can benchpress the Earth for 5 days straight with barely no sweat, not stopping to recharge. What should we expect his durability to be? What would be disappointing?
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Shinier than a speeding bullet.
There are characters that are more durable than they are strong (Colossus, Aquaman), and then characters who are the other way around (Superman, Hulk).
Actually, the reverse seems to be the case for Superman; he's tougher than he is strong to judge from everything I've seen to date.
Same seems to be generally true of other Kryptonians.
Maybe you've seen something different; I'll be interested to see what you present.
Superman is very, very durable. I wouldn't argue that. But his strength feats like the infinite book, pushing warworld, the five earth press and such, say to me that he's stronger than he is durable.
If you want to argue that he's more durable, that's fine; he is insanely durable.
Tendons don't contract, so they don't exert any mobile force. And what makes muscles contract -- specifically, what makes muscular contraction stronger -- is 1) the number of contractile filaments in the muscle fibers, and 2) the strength of the neural signal, ie, how deeply it reaches into the muscle (and consequently how many filaments it activates).
On the other hand, many characters have been described as having extremely dense tissue, which one could translate as having a helluva lot of contractile filaments in a muscle of given size. Also, generally, the more dense something is, the harder it is to damage.
But comicological physics, being what they are, I can see extreme durability present w/o extreme strength, maybe because, eg, the molecular bonds of all body tissues are stronger (though again, these molecular bonds are not what causes muscles to contract).
Like I said, nit-picky.
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Shinier than a speeding bullet.