[kyllo]

Words have consensus meanings, and when you try to redefine them unilaterally you make it harder to communicate. Strength in this context is defined as the ability to exert physical force (as in Newton's Second Law, force = mass x acceleration).

https://en.m.wikipedia.org/wiki/Physical_strength

[uououuttt]

The word isn't being redefined. Endurance is the ability to continue exerting physical force over a long duration.

[kyllo]

Do you disagree that it's useful to distinguish between strength and endurance?

codingdave asserted, "I think legs that can carry a 50 pound pack to the top of a mountain are "stronger" than a guy who can lift twice as much as me, but can't even run a 5K."

The former is an example of great endurance (without necessarily having great strength), and the latter is an example of great strength without endurance. You can have one without the other, so they're different, and it's plainly incorrect to say that a person with high endurance/low strength is "stronger" than a person with high strength/low endurance.

[uououuttt]

Endurance is the ability to retain strength over an extended period of time, that's all I'm saying.