The paper introduces a 6-tiered Participant Classification Framework to systematically classify individuals across a spectrum of exercise backgrounds and athletic abilities. The framework, designed to address the lack of standardized terminology in sports science and sports medicine, categorizes participants into Tier 0 (Sedentary), Tier 1 (Recreationally Active), Tier 2 (Trained/Developmental), Tier 3 (Highly Trained/National Level), Tier 4 (Elite/International Level), and Tier 5 (World Class). Each tier is defined based on training volume, performance metrics, and specific criteria relevant to the sport. The authors emphasize the importance of this framework for both prospective and retrospective studies, providing guidelines for its implementation and discussing its application across different sports, including considerations for depth of participation, nationality differences, gender parity, and age groups. The framework aims to enhance the uniformity and reliability of research in exercise, sport, performance, health, and fitness outcomes.The paper introduces a 6-tiered Participant Classification Framework to systematically classify individuals across a spectrum of exercise backgrounds and athletic abilities. The framework, designed to address the lack of standardized terminology in sports science and sports medicine, categorizes participants into Tier 0 (Sedentary), Tier 1 (Recreationally Active), Tier 2 (Trained/Developmental), Tier 3 (Highly Trained/National Level), Tier 4 (Elite/International Level), and Tier 5 (World Class). Each tier is defined based on training volume, performance metrics, and specific criteria relevant to the sport. The authors emphasize the importance of this framework for both prospective and retrospective studies, providing guidelines for its implementation and discussing its application across different sports, including considerations for depth of participation, nationality differences, gender parity, and age groups. The framework aims to enhance the uniformity and reliability of research in exercise, sport, performance, health, and fitness outcomes.