There are a lot of standard exercises that are great for building your arms. There is also a less commonly known one that is outstanding at getting a crazy pump. It is called “21's.” This is bar-none my favorite bicep finisher exercise. I like to cap off my arm workouts with this exercise to drive as much blood into the muscle as possible and get an excruciating and intense pump. While using heavy weights goes hand in hand with packing on new foundations of muscle, flushing tons of blood and getting a crazy pump to induce fascial stretching is what works best for growing arms. This is exactly what 21's do. To perform the exercise it is quite simple. First, you need to know that you will be doing 21 reps in total per set. Hence, the name of the exercise “21's.” Second, you need to use a lighter barbell curl weight than you would typically because you'll be doing almost twice as many reps than your standard 12 rep set. The genius in this exercise is how it exhausts the biceps in a way where it fatigues the strongest part of the bicep curl first, followed by the second, and finishing with the third. To perform it, your first 7 reps will only be the bottom half of the standing barbell bicep curl. I like to use an EZ grip bar and advise you do as well because the angle works great for this exercise. After completing 7 reps of the bottom half of the bicep curl, bend your elbows to 90 degrees and then do 7 reps of the top half of the curl. After doing those 7 reps (14 total), bust out 7 more reps, this time using a full range of motion and doing the entire movement from top to bottom. For a visual demonstration of this exercise in its' entirety, refer to the video below: To learn about building more mass to your back by using dumbbell rows, click here.