Following almost three decades of research, doping has now raised the attention of health professionals beyond the sporting arena, voicing concerns about doping use on the grounds of protecting physical and psychological well-being of athletes and non-athletes alike . This view is mirrored in publications on doping in sport emphasizing the growing need for effective prevention , making a much needed shift from moral reasoning to general health concerns [3, 4], or, at least, implementing harm reduction strategies [4–7] as realistic and sustainable solutions, with a strong focus on athletes' health .
The World Anti-Doping Agency (WADA) was established in 1999 to promote drug-free sport and to coordinate and monitor the fight against doping. To date, the prevailing approach to ensuring drug free sport is based on the three key documents (The World Anti-Doping Code, International Standards, and Models of Best Practice and Guidelines), each aiming to ensure harmonised detection and sanctions in nations that are signatories of the WADA anti-doping programme . In recent years, this detection-based deterrence has been complemented with educational initiatives and social marketing campaigns. Despite the clearly stated organisational philosophy declaring that "a long-term solution to preventing doping is through effective values-based education programs that can foster anti-doping behaviours and create a strong anti-doping culture" , advances in this area are seriously lagging behind those made on the analytical side for drug testing. This discrepancy may partly arise from the magnitude of investment made into each area independently (approximately 3:100 benefitting 'science' over education and social science research together ), but also from the facts that i) the link between the goals and means of the education and awareness campaigns, by default, is less straightforward than it is for the analytical tests and ii) the desirable outcome (i.e. drug free sport) cannot be accurately ascertained.
Athletes are mainly thought to be vulnerable to doping in situations where much depends on sporting success . However, the notion of assisted performance enhancement is not confined within the boundaries of highly competitive sport. As a direct result of this demand, the number of Internet retailers and range of products has mushroomed over the years and is now causing great concerns for safety [12–14]. Experimenting with various supplements is natural to most athletes as it is evidenced by the significant proportion of athletes reporting regular use; in many cases, polypharmacy [15–19]. The use of prohibited performance enhancements is an unwanted extension of this avenue [20–22] on which athletes have been progressing for quite a long time. It has been suggested that an effective and sustainable anti-doping approach may succeed if comparable acceptable means are offered along with the prohibition approach, intervening by changing outcome expectancies pertaining to doping and non-prohibited alternatives . In this paper we take the first step in exploring the viability of this 'alternative means' approach.
When members of the exercise and athletic community decide which genre of supplements to use, they tend to make choices via said expected outcomes. If the outcome is perceived to be positive then it increases the likelihood of following with action whereas if the outcome is perceived as negative, the likelihood of making that choice is reduced. Therefore the process of choice involves weighing up positive outcome perceptions against negative ones. Positive and negative outcomes can be direct, for example physical enhancements or detrimental effects; as well as indirect outcomes such as fame and fortune or damnation.
Although social marketing, which uses commercial marketing techniques and strategies to influence people's behaviour for a greater public good, is still in its relative infancy, it has been effective across a wide range of public health areas including healthy lifestyle and health promotion, nutritional habits, obesity, drug use, smoking, alcohol consumption, road safety: speeding and risk/drink driving, condom use and HIV [23–34]. A fairly recent assessment of social marketing in anti-doping campaigns has reported the absence of social marketing but expressed a view in which social marketing would enhance the current detection-sanction as well as educational approaches to drug free sport . This view is supported by a Europe-wide survey prepared for the European Commission on fighting doping  and a recent analysis of the anti-doping campaigns of UK Olympic Federations  indicating that whilst a considerable variation exists in anti-doping provisions, these campaigns tend to rely on information booklets, information service and workshops/seminars focusing on the moral aspect of doping with appropriate market segmentation and targeted messages mostly missing. Tailored and interactive campaigns designed and implemented by highly trained professionals have been recommended .
The ways in which social marketing strategies are best used in relation to doping are open to debate. Despite the use of secondary sourced information by various campaigns to deter athletes as well as the exercise population from using performance enhancing drugs (PED) , little is known about the most effective way to communicate messages that promote abstinence from PED use, whether it is for health, moral or legal reasons, although the latter one has been shown to have a lesser effect on athletes' decisions in hypothetical scenarios . In the past anti-doping messages were typically produced in two forms: i) moralising sport competition or ii) employing scare campaigns, involving informing only the negative outcomes so that they outweigh the positives. The effectiveness of this approach depends on a plethora of external and internal factors, such as level of fear, framing, vivid presentation, physical versus social consequences, specificity, referencing, argument strength, source credibility, number of exposures, individual differences, emotions and goals . With regard to PEDs, this approach has been shown not to yield any significant benefit in terms of deterrence whereas campaigns which provide secondary information in a more balanced manner have been shown to significantly increase agreement on adverse effects of PEDs . These campaigns may help inform athletes of benefits and risks but fail to suggest acceptable alternatives.
Intervention strategies used in public health domains range from promoting positive examples to evoking fear, often using a combination of media. Reviews and meta-analyses [26, 34, 41, 43–48] suggest that, among many other factors, the credibility of the source appears to be important for those that have no direct involvement in the target behaviour. Whilst there appears to be a consensus regarding the importance of 'framing', the type of framing that leads to the desired behaviour or behaviour change is much debated. It was noted that 'negative' messages are better recognised, regardless of the content or effect. Involvement and relevance certainly mediated the effectiveness, as well as the process between the type of message (e.g. gain or loss framing, fear arousal, comparative alternatives, perceived vulnerability, health, legal and social consequences) and outcome. Interestingly, some studies have found that fear appeal and negative perception of the message had reverse effects (hence were counterproductive) but this was not always the case.
In summary, in order to be effective, social marketing for anti-doping should use strategies developed and successfully employed in commercial marketing for decades, namely: deep understanding and consideration of information processing, inter-individual and developmental differences in decision making, appropriate segmentation for targeted messages. It is timely that anti-doping prevention and intervention incorporate media messages that, in addition to promoting drug-free sport for the sake of fairness or health, also propagate comparable and acceptable alternatives to doping. To facilitate this process, we test the effectiveness of a knowledge-based information intervention in changing beliefs regarding performance enhancements.