In sports involving sprinting, a key concern is the reduction of hamstring strain injuries. There is a significant body of research concerning the nature and rehabilitation of hamstring injury and it is important that this research should inform the practice of strength and conditioning professionals. The purpose of part 1 of this article is to present the theoretical basis that should underpin the training of the hamstring musculature. Practical evidence based recommendations for the prevention of hamstring injuries have been advanced by previous authors and part 2 of this article will build on previous work in order to present a comprehensive system for training the hamstrings