No particular order.. Biohazard, Pantera, Slayer, Metallica, Candiria, E-town Concrete, Machine Head, Byzantine, Sepultura.. so pretty much late 80s, 90s, early 2000s, some newer, like Havok, Power Trip
To each his own on tunes to get pumped up for your next set but for me, I love putting on some Netflix drama on my I-pod when I want to bust out an hour of cardio.