Energy Regen and Attack Speed?

So I was noticing today, I think anyway, that when using like Berserk for Trolls, my energy was coming in faster?

Is that how that works? So when like someone Blood Lusts does it really increase our energy regen?

Can someone confirm this or am I just trippin?
It counts like haste for energy regen. I first learned this at like level 30 using the crowd pummeler from gnomeregan for 500 haste. At that level, it's like 200% or 300% haste; it was better than adrenaline rush. I literally could not spend the energy fast enough.