Isometric index finger abduction (1st dorsal interosseous) (Finger (index) abduction strengthening isometric, palm down - 1st dorsal interosseous)

Sit upright in a chair.
Place your affected arm on a table with your palm facing down and your fingers flat.
Place your index finger from your unaffected hand on the thumb side of your affected finger.
Try to move your affected finger towards your thumb, using your opposite hand to resist the movement.
Remember to keep your palm and forearm flat on the table throughout the exercise.