(The above rendering comes from the RJPS translation, an adaptation of the NJPS translation. Before accounting for the added footnote, I will analyze the plain sense of the אִישׁ term, by employing a situation-oriented construal as outlined in “Notes on Gender in Translation,” pp. 11–16.)
Prototypically, as here, the noun אִישׁ designates a participant who is essential for grasping the depicted situation. A pair of cities are under threat from the Israelite invaders. In that context, it goes without saying that only able-bodied men of military age are in view.
As for rendering into English, I have preserved the NJPS rendering. Gender is germane, in that a gender-neutral rendering would falsely imply that both men and women left the city in pursuit. Yet nowadays man is also misleading, implying that all of the towns’ adult males were involved. So I have added a new footnote, to encourage the construal of man in its classical usage (as a situating noun, like אִישׁ) to designate a situation-defining participant as such—and situationally constrained in its scope—rather than pointing to the qualities of “adult” and “male.”