I think some call that “old man strength”.

Might not be as strong or fast as he used to be, but knows how to do it smartly.

Sometimes the problem truly requires strength and brute force, but not usually.

Even something like taking up concrete. It seems straight forward but you can waste a lot of energy hitting the wrong places.

> Might not be as strong or fast [..] knows how to do it smartly.

Friend of mine worked in Prisons for a while, and has a way of telling the difference between people with a lot of muscle and people who know how leverage their musculature to high effect.

Also using all your motor units to their full capacity (the "invisible" strength) helps. Which usually requires at least some training.