The dumbbell row should be a back training staple. Include it in your back and upper body training days for 3 sets of 8 to 12 reps per arm. Once you're more accustomed to the movement, you can pick up ...

If your goal is building a bigger back to fill out your t-shirt, then the traditional single ... extra helping hand through the concentric portion of the lift (where you row the dumbbell up).