Using a keyboard and mouse all day overuses your forearm flexor muscles. You can counteract this pattern by doing exercises to engage your forearm extensor muscles.
The quickest, simplest way to exercise your forearm extensors is to:
- hold a light dumbbell in each hand, palm facing downward,
- rest your forearm on a weight bench or similar surface,
- extend your wrist upward.
This video demonstrates this dumbbell exercise for your forearm extensors, exercising one arm at a time.
This video shows how to do forearm extension using a barbell.
This video shows how to use a weight hanging from a roller handle to work your forearm extensors. You can both raise and lower the weight by rotating the handle.