Lie on bench or mat. With hand of upper arm, grasp unilaterally loaded dumbbell; thumb next to side with weight. Bend elbow approximately 90-degrees and place forearm on hip, or side of waist. Position thumb downward (pronated).
Rotate dumbbell so thumb turns upward (supination). Return and repeat.
Pad or firm pillow may be placed between hip and arm. Elevation of elbow allows resistance during final range of motion. If unilaterally loaded dumbbell, or "half dumbbell" is not available, grasp conventional dumbbell to one side of handle with pinkie against inside surface. Also see Dumbbell Lying Supination with arm down. This exercise can also be performed seated by corner of table higher than shoulder height (See Seated Supination).