Motivation is the key to keeping you primed to keep pushing heavy weight in the gym. And what better motivator is there than music? We asked the experts—our dedicated Muscle & Fitness fans—what music makes their heart rate rise and gets them pumped to hit new PRs, and you answered. If you like listening to growling vocals and superhuman guitar riffs to get you pumped up to push superhuman weight, here are some metal, hard rock and hardcore workout songs for your playlist.