Metalhead here, and I love that you said MANOWAR...cheesy as all hell, but I love them.
Even though IRON MAIDEN is my favorite band, that's not my go-to for lifting. HATEBREED gets that honour. Other good ones off the top of my head: AMON AMARTH, DYING FETUS, GOATWHORE, DEVILDRIVER, BELPHEGOR, LAMB OF GOD (live Killadelphia album), & SKELETONWITCH.
Oh, and...if you're not into metal, you are not my friend!