Has there ever been an example of a power armour in Star Trek? We know that some species like the Hirogen are wearing armour and for others, like the Klingon that like close combat, it might be useful. But I can't remember ever having seen a piece of power armour, where a power armour is a armoured and powered exoskeleton, i.e. rendering the weight of the armour insignificant and maybe even make the wearer stronger by supporting him.
And if not, has it ever been stated why they decided against power armour, even for species that wear armour or are warriors (like the Jem'Hadar / Klingons)?
I am aware that factions, like the borg, are using personal shields instead and that Starfleet has shields, see this question. But if some are using armour, why not power armour?