 If you're a skinny person who wants to put on muscle mass, especially in your upper body, the number one exercise for massive arms is the deadlift. It seems counterintuitive, but if you think about just a barbell curl, maybe a normal curl, let's say I might be able to do 95 for six reps or something like that. I don't know, six clean ones at least. The force involved there is not that substantial, right? I don't get this hormonal response throughout my entire body because there's no axial loading. It's just I put some weight in my arms, right? And there is a purpose to that. It's okay to fatigue the actual muscle that you want to train and it does help, but you need to prioritize the big bang things, the things that are going to get you a larger growth response from everything. And if you think about the deadlift as our example here, when I try the deadlift, that bar is literally trying to rip your arms off, okay? And if your bicep lets go, then it makes it much more likely that your arms will indeed rip off. So to stabilize your shoulder joint throughout this heavy deadlift that you're doing, you need a little bit of bicep to position your shoulder, right? You need a little bit to control the bar, so it's not just drifting all over the place. You need to glue your hands to the bar, right? You don't want to drop it out of your hands. So that's my little bit of advice. If you are a young lifter and you're trying to put on a lot of muscle mass in your upper body, consider deadlifting.