Assessing the need to use sport supplements: The mediating role of sports supplement beliefs

Aim: Sports supplement use by athletes can lead to unintentional anti-doping rule violations (ADRVs) due to the contamination of prohibited substances. This phenomenon underscores the need for athletes to reconsider their supplement use, assessing its safety, efficacy, and necessity—a process referred to as ‘reconsideration of supplement use’ in this study. Additionally, ingesting sports supplements may escalate to doping when athletes believe they improve performance, a notion measured by the Sports Supplement Belief Scale (SSBS), which assesses the degree to which athletes expect supplements to enhance their performance. Understanding the factors that may encourage and prevent an athlete from using supplements is crucial. This study explores the mediating influence of the perceived risk of ADRV due to supplements, reconsideration of supplement use, and sports supplement beliefs as factors influencing athletes’ decisions to use supplements as factors influencing athletes' decisions to use supplements.

Methods: In Study 1, a Japanese version of the Sports Supplement Belief Scale (SSBS-J) was created using back-translation. In order to evaluate the reliability and validity of the scale, we utilized data from 356 university athletes, which were divided into two distinct cohorts. A two-step statistical analysis was implemented involving Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA). The survey included questions about the frequency and number of supplements used. Internal consistency and fit of the SSBS-J were evaluated using EFA and CFA, and the scale’s ability to determine supplement use was assessed using linear regression analysis and t-tests. In Study 2, 525 university athletes (64.6% men, Mage = 18.7 ± 0.7 years) were asked to complete measures related to the perceived risk of committing an ADRV due to supplementation.

Results: The SSBS-J showed high internal consistency (Cronbach’s α = 0.876), a one-factor structure similar to the original version in the EFA, and a good model fit in the CFA, thereby supporting construct validity. Linear regression results indicated that the SSBS-J scores were significantly associated with the frequency and number of supplements used. Significant differences were found between the scores of supplement users (21.51 ± 6.54) and non-users (16.48 ± 6.14) (p < 0.001). Next, discriminant analysis correctly classified 64.7% of supplement users and 61.0% of non-users. In examining the direct effect of ADRV awareness on supplement use, a significant negative path coefficient of -0.44 was observed (p < 0.001). The path coefficients from ADRV awareness to the reconsideration of supplement use and from a reconsideration of supplement use to supplement use through SSBS-J were all significant (p < 0.001), with an indirect effect path coefficient of 0.06.

Conclusions: These findings suggest that ADRV awareness can influence reconsideration of supplement use and subsequently deter supplement use mediated by sport supplement beliefs. These insights emphasize the importance of promoting doping risk awareness, revisiting supplement use, and mitigating sport supplement beliefs to reduce inappropriate or unnecessary supplement use among athletes. From an anti-doping perspective, this insight could be valuable in guiding athlete education regarding supplement use.

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