The extensor digit minimi is stretched with flexion of the little finger at the metacarpophalangeal and interphalangeal joints, and flexion of the wrist joint, and flexion of the elbow joint.
Note: The stretching protocol for the extensor digitorum muscle is shown here. To better focus the stretch on just the extensor digiti minimi, maintain the same position of the elbow and wrist joints, but flex only the little finger. But this will still stretch the portion of the extensor digitorum that goes to the little finger.