This book is a great starting place to gain an understanding of how to perform splits. It is designed for use in the gym or at home, and for coaches, parents, and gymnasts.
Splits are all about flexibility, and it takes a great deal of training to become flexible enough to execute them. This flexibility is achieved by doing different types of stretches that focus on the hamstrings, quadriceps, thighs, and hip flexors. Your warm-up will include a lot of stretching exercises that will help you become flexible enough to execute splits.
Splits are used not only in gymnastics but also in dancing, cheerleading, martial arts, synchronized swimming, and more.