Development of a scale to assess knowledge levels about sports supplements in individuals exercising at fitness centers and the evaluation of general-sports nutrition knowledge and supplement use: The case of Eskisehir

In the first stage of the study, an assessment tool Sports Supplements Knowledge Scale (SSKS) was developed to evaluate the knowledge levels regarding sports supplements (SS) among individuals exercising in fitness centers. Subsequently, the study aimed to determine the frequency of SS usage among individuals exercising in fitness centers in Eskişehir and to examine some associated variables. This methodological and cross-sectional study was conducted between September 2023 and February 2024. Data were collected using questionnaires aligned with the study's objectives. The validity and reliability of the SSKS were tested through item analysis, exploratory factor analysis, concurrent criterion validity, group differentiation, confirmatory factor analysis (CFA), and internal consistency coefficient determination. The second stage, the study group consisted of 499 individuals. Chi-square tests, Spearman correlation analysis, and logistic regression analysis were performed. The factor loadings of the SSKS items ranged between 0.32 and 0.62, and the Cronbach's alpha was calculated as 0.889. The fit indices obtained from the CFA were acceptable. The mean age was 28.17±9.32 years. The frequency of SS use was found to be 55.5%. The most commonly used SS products were those with insufficient-no evidence of efficacy. Higher SS usage frequency was observed among university graduates, employees, smokers, alcohol consumers, those reporting SS use in their close circles, those engaging in high-intensity exercise, overweight-obese individuals, and those primarily performing bodybuilding exercises. SS usage likelihood decreased with higher knowledge levels regarding general nutrition and increased with higher knowledge levels regarding sport supplements. In conclusion, the SSKS is a valid and reliable scale that can be used to assess knowledge levels related to SS. Awareness-raising, educational, and informational activities targeting individuals exercising in fitness centers and the staff could be beneficial to improve knowledge levels related to nutrition and SS.