The Mangler

To begin with, place all of your fingers on the G string, each on their own fret. The 3rd through 6th frets is a good place to try this exercise.

Throughout the exercise, you should keep every finger fretting the G string unless it is being used.

Next, play the high E string with your index finger, then reach down and play the low E.

Keep alternating between these notes 10-20 times, or until your finger gets tired out.

Then return your index finger to the G string.

Now repeat that with your middle finger.

Alternate between playing the low and high E string 10-20 times, and then return your middle finger to the G string.

Then the ring finger....

And lastly the pinky.