About the Author

Brian Mackenzie is the author of the New York Times bestseller Unbreakable Runner, as well as the book Power, Speed, Endurance and the program that inspired it at PowerSpeedEndurance.com. He is a world-renowned strength and conditioning expert and a co-founder of XPT Life. Mackenzie and his program have been featured in Runner's World, Men's Journal, The Economist, Tim Ferris's New York Times bestseller The 4-Hour Body, and many other leading publications. Brian works with several CrossFit Games athletes, including champions Rich Froning, Jr., and Annie Thorisdottir. He also has coached and is married to Erin Cafaro-Mackenzie (a two-time Olympic Gold Medalist in rowing - W8+) and has guided world and Olympic champions and performance innovators like Laird Hamilton, Taylor Ritzel (2012 Olympic Gold Medalist - W8+), Sara Hendershot (2012 Olympian - W2), Jamie Mitchell, Koa Rothman, Koa and Alex Smith, Nathan Florence, and Elliot Sloan. Dr. Andy Galpin is a professor of kinesiology at the Center for Sport Performance at California State University, Fullerton. He has a PhD in human bioenergetics and is the founder and director of the Biochemistry and Molecular Exercise Laboratory. Galpin works directly with professional athletes in the NFL, MLB, and UFC and played a major role in Helen Maroulis's run to gold in wrestling at the 2016 Rio Olympics. He is a co-host of the popular training podcast Barbell Shrugged, which has more than 300,000 followers, and has been featured in countless magazine articles, television shows, and other podcasts. One interviewer called him "the Tony Stark of human performance." Phil White is an Emmy-nominated writer and the coauthor of the forthcoming books Waterman 2.0 with Dr. Kelly Starrett, and Game Changer with Fergus Connolly. He is also a frequent contributor to The Inertia and SUP the Mag.