The author has an extraordinary grasp of both the theory and practice of strength training. It is not, however, for those frightened of a bit of science. One of the more enlightening aspects is his explanation of the relationship between force and speed and the consequences of coaches failing to understand that relationship. Zatsiorsky has a depth of knowledge related to the strength requirements for many sports and activities gained from his many years experience in the former Soviet Union. This is probably the best book I have yet read relating to strength training.
Gymnic balls are terrific for playtime, gymnastics and balance conditioning exercies.