When do men reach their physical prime?

18-20 years

Yes normally mean reach physical and mental prime at around 18-20

but each human is different some may not reach physical prime until 25

other could reach it sooner.

Nevertheless it not when you reach i tit how long you hold on to it.

Depending on health a man can stay at their peak of physicall health for many years

it all depends on how often they exercise and what exercises they do.

Some byciallist have kept their prime up though their 50s. But every body is different.

Ultimatly 18-20 years is the average, once you get their try to stay there. ^_^