It was originally thought that you could not effectively train for both strength and endurance at the same time because they required different adaptations which were not compatible with each other. It was claimed that ‘an interference effect’, blunted the adaptations for strength if you simultaneously trained for endurance. However, recent developments in sports which require both strength and endurance have really challenged this idea, with hybrid athletes producing impressive performances in both strength and endurance sports together. This had led scientists, coaches, and athletes to rethink what is humanly possible and suggests the interference effect is not as influential as originally thought. But what is a hybrid athlete? What is the ‘interference effect’? And how can we maximize our training to improve at the same time our strength and endurance performance? In this book, Dr Phil Price provides insight into the misconceptions surrounding strength and endurance training by distilling the past 50 years of research and drawing on the conversations he had with great scientists, coaches, and athletes on The Progress Theory podcast. This book is essential reading for hybrid athletes and coaches who are looking to understand the key training variables and their effect on the simultaneous development of strength and endurance performance.