how can a man use the one ring?

[The Saucepan Man]

As I recall, there is a suggestion that the Ring, with time and effort, could enhance the powers of its bearer. Which would presumably extend to physical, as well as mental powers.

Don't forget also that the Nine Rings gave the Men who became the Nazgul great power, wealth and sorcery, while ultimately binding them to Sauron's will. If the Nine could do that, then the One could surely bestow even greater power.

However, since Sauron, through the Ring, would be the Master in the end, the long-term effects would be reduced power (at least in the sense of free will/will power). So, short-term boost but long-term enslavement.

Edit: Cross-posting with morm. Thanks, that's the quote I had in mind.