Growing evidence for neurophysiological mechanisms of placebo effects does not legitimise the use of complementary and alternative medicines by athletes

Complementary and alternative medicines (CAM) are treatments proposed to prevent, manage or cure symptoms of ill health, but which lack scientific evidence for efficacy and/or mechanisms. It has been suggested that many forms of CAM are effective, albeit via the placebo effect. Furthermore, it has been argued that the fast developing neurological, biochemical and physiological evidence base for the placebo effect provides a mechanism for, and therefore legitimizes, the use of CAM. CAM treatments are widely used to enhance performance in sport, and range from the relatively harmless such as magnetic bracelets, the potentially harmful such as natural and synthetic ergogenic aids, to high-risk such as medicines and/or procedures developed for clinical applications (arguably CAM also includes treatments proven in one context but applied without evidence to another). Research has demonstrated significant placebo effects associated with several such forms of CAM in sport. In this paper it is argued that a range of factors, for example professional ethics relating to deliberate deception, pragmatic factors such as the variability and instability of placebo responding between and even within individuals, and humanistic factors such as the potential limits to human performance associated with the reliance on unstable external as opposed to stable internal cues, determine that placebo mechanisms do not legitimise CAM. Practitioners should seek treatments on the basis of valid and reliable evidence of mechanisms as well as potential efficacy, and accept that placebo effects, whilst often augmenting treatment effects, should not constitute the entire effect of a treatment.