Synergists: Biceps Brachii (especially the long head), Brachioradialis
Lie prone (face down) on an inclined bench. You can kneel on the seat or lower the seat to produce a ramp-like flat surface to lean against.
Get a training partner to hand you a loaded barbell. You can also dismount the barbell from a low rack.
Hold the barbell using a shoulder-width supinated (underhand) grip, and allow the barbell to hang downward.
Keeping your upper arms fixed, exhale as you curl the barbell upward until your elbows are fully flexed.
Hold for a count of two and squeeze your biceps.
Inhale as you lower the barbell to the starting position in a controlled manner.
Comments and tips
You may use an EZ-curl bar if it is easier on your wrists. However, the camber (bend) of the bar must be minimal to ensure that your forearms remain supinated.
Arm curling exercises in which you use a supinated grip and keep your elbows in front of your body (e.g. the prone incline barbell curl, the preacher curl, and the concentration curl) target the brachialis, not the biceps brachii. What’s more, the long (outer) head of the biceps brachii is activated much more than is the short (inner) head. Generally speaking, the reason is that the long head is stretched and the short head is loose, and when a muscle is loose, it can’t contract sufficiently to produce the full range of motion. In kinesiology, this is known as active insufficiency.
The prone incline barbell curl is also known as the barbell spider curl.