Dietary supplement use is related to doping intention via doping attitudes, subjective norms, and perceived behavioural control

The use of dietary supplements (e.g., caffeine, creatine, dietary nitrate) has shown to be related to the intention to dope (e.g., amphetamines, anabolic steroids, erythropoietin). In this study, we integrated elements of the theory of planned behaviour to better understand the relationship between dietary supplement use and doping intention. Specifically, we tested whether dietary supplement use is indirectly related to doping via doping attitudes, doping subjective norms, and doping perceived behavioural control. Competitive athletes (N = 443; 46 % female, age = 27.0 +/- 8.6 years old, years competing = 8.3 +/- 3.5) completed measures of dietary supplement use, doping attitudes, doping subjective norms, doping perceived behavioural control, and doping intention. Parallel mediation analysis indicated that dietary supplement use was not directly related to doping intention, but instead was indirectly related via doping attitudes (effect size = 0.15), doping subjective norms (effect size = 0.17), and doping perceived behavioural control (effect size = 0.15). Contrast analyses reported no differences between each indirect effect. Our results suggest that athletes who use dietary supplements report stronger intentions to dope, which is related to more favourable doping attitudes, a greater social pressure to dope, and a perceived ease in which to dope.