Here is a stretching routine done by
a martial arts instructor in order to improve the height of side
kicks (or other similar lateral kicks such as roundhouse kicks).
Also visit our
stretching page for written and video instructions
regarding other Taekwondo stretches.
My favorite Taekwondo stretching book is
Ultimate Flexibility: A Complete Guide to Stretching for Martial Arts.
Hundreds of great stretches (with pictures). Or check out these
other popular stretching books.