Metal is lifting music, some hard bass and your max lifts grow fast. Back in the day Danzig - Mother fucking weights were light with the right music even though they were new max they rose fast, it's all in the mind. Sound gay but put on something to dance alone with like aerobic and not for aerobics reasons. I got so tight just lifting and jogging it was detrimental but just letting music let you flow your muscles will move themselves no stretching into the place they feel they need to be since they're loose with the tun-age unlike the lift so they slide effortlessly to the best fit and prevents injury also since they are not fighting joints and tendons so your body self settles. Unlike aerobics or other training you get your groove so you know what feels right your body was made to fix itself when not forced into repetitions of unnatural positions to build muscle we also have to let the muscles free themselves so we are working as god intended our movements and our brains know sub consciously what feels right. I would show of the loosening up dance but it's something that really works.