Men training women at the gym

No. Rasulullah (sallallahu alaihi wa sallam) has said that hayaa (shame and modesty) coexists with imaan. When one leaves then the other will also leave. In another hadeeth, Nabi (sallallahu alaihi wa sallam) has explained that a woman is an object that needs to be concealed. And when she emerges from her home then Shaytaan seeks to seduce others through her. Further, looking at women and more so with lust is a poisonous arrow of shaytaan which can have devastating effects.

And Allah Ta'ala (الله تعالى) knows best.