There’s no physical equivalent to knowledge checks or spot checks, so that’s one thing we don’t have to worry about.
Dexterity sometimes functions like Intelligence and Wisdom when avoiding bad situations, like avoiding slipping off a ledge. The discussion of Bad Conditions in the previous post applies here, too, perhaps doubly so. Not only do most physical actions not require a roll, and the rolls I use are usually “5+ on 1d6” unmodified by ability scores, but also high Dex for me usually means skipping a roll, rather than rolling a Dex check. Inching along a dangerous narrow ledge has a chance of falling, unless a PC has a very high Dex.
Strength may occasionally react the same way. If a PC is stuck in a bad situation and a player suggests a strength-based way of avoiding it or getting out of trouble, Again, not treated as an ability check. But the strength-based actions most people think of are Open Doors, Bend Bars, and Feats of Strength like winning a tug-of-war or rolling aside a boulder.
I use the straight 1d6 open doors roll from Underworld & Wilderness Adventures, not the strength table from Greyhawk, so it’s definitely not an ability check the way I use it. And for bending bars, I’d probably require a 12 on 2d6. I might disallow bending bars for very low strength, or improve it to a 6 on 1d6 for very high strength, but that’s as close as I get to an “ability check”… and I’m tempted to do something else entirely.
For feats of strength, a contest of strength like a tug-of-war is the only place where I might consider actual Strength scores. Even there, I’d most likely use a 50-50 die roll if the sides are evenly matched, a 5+ on 1d6 chance of winning if the PC side is weaker, or a 5+ chance of losing if the PC side is stronger, with an extreme disparity between sides meaning an automatic win for the stronger team. But the number of people on each side of a contest matters just as much, if not more, just as it matters more for things like moving boulders. “It takes three people to move the boulder” works a lot better for me than some kind of Strength check, because it eliminates the roll.
If I really wanted a roll for feats of strength, including bending bars, I’d be more likely to use damage as the mechanic. People do 1d6 damage. Set a damage value for the boulder or iron bars and let characters do damage when they try to push or bend. More people does more damage. More time, in some cases, also does more damage. And as I suggested before, monster hit dice or Fighter level can increase the amount of damage… and yes, even Strength, based on that 1d6 damage per 8 points of Strength equivalence I mentioned before.
The vast majority of physical ability checks involve actions, but Constitution checks are a passive ability. It’s certainly physical, but I’d like to cover it in yet another post, seeing as this one has become quite long.