With nearly two decades of elite-level training experience and advanced degrees in both exercise science and physical therapy, Dr. Rusin has developed performance, regeneration, and aesthetics programs for some of the world's best strength, power, and endurance athletes. His client list--past and present--includes MLB All-Stars, NFL All-Pros, Olympic gold medalists, world-record-holding powerlifters, and professional athletes from eight major American sports leagues.

Named a "Top 50 Health & Fitness Expert" by Men's Health magazine, Dr. Rusin took the methods proven at the highest levels of sport and adapted them specifically for everyday people--making elite-level injury prevention, sustainable health, and lifelong physical performance accessible to everyone. This approach evolved into the Pain-Free Performance Specialist Certification (PPSC), the largest and fastest-growing fitness education company in industry history, certifying over 20,000 coaches, trainers, physical therapists, physicians, and allied healthcare providers since its inception in 2018.

Today, hundreds of thousands of clients across all ages, abilities, and experience levels have successfully transformed their bodies, rebuilt their health, and reclaimed their lives, demonstrating the unmatched real-world effectiveness of the pain-free performance training system.

Glen Cordoza is a New York Times and Wall Street Journal best-selling author. He is one of the most published writers in the world on the topics of MMA, jiu-jitsu, Muay Thai, exercise, and fitness with twenty-six books to his credit.