This exercise strengthens the wrists, making them (with further training) immune to wrist-locks.
TUTORIAL AND PHILOSOPHY FOR THIS TECHNIQUE: http://gyokku-ninja.com/free-online-ninja-training-002-basic-exercises-18-lizard-crawl.htm

This video is part of the Gyokku Free Online Ninja Training Program. If you are interested in starting to walk the path of the Ninja, simply go through this video playlist in sequence, mastering the videos one by one.

You can consult with the masters if you have problems or require advice (completely for free), using the form on each page of http://gyokku-ninja.com

Train well, my brothers and sisters, and be worthy of the Way.