Sit next to elevated surface, approximately arm pit height. With hand of upper arm, grasp unilaterally loaded dumbbell; pinkie positioned near weighted side. Bend elbow approximately 90-degrees and place upperarm on elevated surface. Position thumb upward (supinated).
Rotate dumbbell so thumb turns downward (pronation). Return and repeat.
If unilaterally loaded dumbbell, or "half dumbbell" is not available, grasp conventional dumbbell to one side of handle with thumb against inside surface.