Determinants of the Intention to Use Performance-Enhancing Substances Among Portuguese Gym Users.

The purpose of this study is to examine the determinants of the intentions to use prohibited performance-enhancing substances (PES) and to test the Theory of Planned Behavior's usefulness in predicting self-reported PES use in both genders. A convenience sample of Portuguese gym users ( = 453) completed an anonymous web-based survey. Structural equation modeling, multigroup analysis, and -test with the Welch correction for heterokedastic variances were used.