The purpose of the study is to validate the 54-item Fitness Switching Costs Scale (FSCS). The FSCS consists of a third-order formative construct with four second-order formative constructs and 11 first-order reflective constructs. Although there was support for the reliability and validity of higher-order constructs, validity of the 11 first-order subscales has not been systematically investigated. Study 1 (n = 441) evaluates the factor structure of the first-order subscales using exploratory factor analysis and ensures the factorial validity of the subscales. Study 2 (n = 415) examines the measurement precision of the 11 first-order subscales using item response theory and shows high levels of measurement precision, while identifying some areas for improvement at the item level. Overall, the findings suggest that health and fitness researchers and practitioners can use the FSCS as a diagnostic tool to identify areas for a potential investment.