The byline of Unbreakable Runner (T.J. Murphy and Brian Mackenzie) deceived me from the start. The book reads as though written entirely by Murphy, punctuated by references to what Mackenzie says and does for himself and the athletes he coaches. Given his experience as editor of Triathlon and Competitor magazines and author of Inside the Box, Murphy’s writing abilities are up to the task, but an introductory text to Crossfit Endurance would seem more credible coming firsthand from its founder Mackenzie. Compared to Mackenzie’s Power, Speed, Endurance, which offers a comprehensive guide to strength and conditioning for the endurance athlete, Unbreakable Runner deals mainly with the rationale for Mackenzie’s innovative approach. Again, Murphy is not the best source to make these arguments, but the numerous studies cited in support of the book’s claims lend them a great deal of credence. The training plans which comprise the second half of the book are fairly bare bones, which is understandable for a book which will be read by athletes with a variety of different goals and abilities. Far more illuminating is the highly detailed two-week plan Mackenzie programmed for one of his own athletes, found in Appendix B. For those with experience in coaching and training, this plan can be adapted to fit an athlete’s needs in a way that more closely parallels MacKenzie’s philosophy. Read Unbreakable Runner for the source material and the training plan outlines; read Power, Speed, Endurance for a complete picture of Crossfit Endurance and the technical aspects of this program.