What's behind so-called "old man strength"?

Factual Questions
1

I’ve heard the phrase “old man strength” used several times in the past month. In spite of never having heard it before, I recognized exactly what was meant… the ability of men well beyond their prime who can pull out some strength in a crunch. I’ve often seen it while moving furniture, where grand-dad will pull out a reserve of strength on par with what younger men are doing.

What’s the phenomenon behind this? Is it years of experience in unconsciously estimating angles of mechanical advantage or tessellate objects, etc? Years of development of core muscle stability? Knowledge of economy of effort? Is it just plain stubbornness? I’m wondering if anybody has any thoughts.

2

“The old that is strong does not wither, Deep roots are not reached by frost.”
J.R.R. Tolkien

The phenomenon? The muscles are still there and can be used at need. But more experienced folks don’t use them so hard so much, as they know there will be consequences later. Nothing unnatural about it.

3

I’d call it a learning economy too.

4

Yes! A thread where Qadgop can post medical knowledge gained from Tolkien! Now, that’s what the SDMB is all about.

5

Old age and treachery will overcome youth and zeal every time.

6

Why don’t these muscles dimish with the relative lack of activity?

7

Because muscle cells don’t just vanish (or turn to fat cells).

8

Uh, yeah they do if you stop using them or at least they significantly weaken.