Reps Tip! In addition to flexing the arm, the biceps is also responsible for turning the wrist up. Supinating your wrist while curling makes the biceps work harder than if you use an underhand grip throughout.
Reps Tip! With your upper arms locked in position at your sides, the basic barbell curl hits both heads of the biceps brachii fairly evenly. This is a good move to do first in your workout as you can go fairly heavy with it.