The pronator teres is stretched with supination of the forearm at the radioulnar joints. Be sure to keep the (upper) arm stabilized.
Notes:
- It is important that the client is not simply laterally/externally rotating the arm at the shoulder joint.
- Supination of the forearm with the elbow joint flexed will move this stretch to the pronator quadratus.

The pronator teres is stretched with supination of the forearm at the radioulnar joints, with full extension at the elbow joint. Be sure to keep the (upper) arm stabilized.