The Placebo Effect in Sport: How Practitioners Can Inject Words to Improve Performance.

Placebo effects are a complex interplay between an intervention* and factors associated with the administration of that intervention, such as expectations, previous experiences and interactions between participant and researcher.1 While researchers often regard the placebo effect as a nuisance to control for in randomized control trials, for practitioners (e.g. sport scientists, coaches, physiotherapists), the placebo effect can be a powerful tool to augment the beneficial effects of an intervention. In the last two decades, a growing body of research has identified various neurobiological mechanisms of the placebo effect, with a significant number of studies investigating the mediating role of the opioid, endocannabinoid, serotonin and dopamine systems.2 In sport and exercise science, understanding the full range of placebo effects, and the underpinning mechanisms, is important in how they are likely to influence the effectiveness of interventions athletes use (e.g. caffeine, cold-water immersion, altitude training). Researchers have therefore used the balanced placebo design,3 which allows an assessment of each possible combination of what the participant believes they have taken and what they have actually taken. Research using this design has shown that interventions need an interaction with placebo mechanisms to show their full potential.4 This highlights that researchers should assess the potential contributions of the placebo effect to determine the extent this phenomenon has in the outcome of their results. Placebo effect research indicates that the words used by coaches, support staff and researchers about the effectiveness of an intervention significantly affect the outcome on performance. For example, after ingesting caffeine, athletes’ run faster when they are told it is caffeine than when they are told it is a placebo.5 Similarly, when athletes ingest a placebo, they run faster when they are told it will improve performance than when they are told that it will worsen performance.6 Thus, if athletes are told that they received an intervention that significantly improves performance, they are more likely to exhibit greater improvements in performance than if they are told it is benign. The placebo effect is underpinned by beliefs that an intervention will, or will not exert an effect. Athletes are often administered numerous interventions to support various aspects relating to recovery, injury and peak performance (e.g. cold-water immersion, altitude training and protein supplements). Sport practitioners should be cognisant of the words they use when administering these interventions to develop their athletes’ belief that the intervention is effective. Consider, for example, the case of a physiologist introducing altitude training into an athlete’s training program. The physiologist might provide the following disclosure to their athlete: “I recommend that we include altitude training in your program. Several studies have shown that altitude training can be effective for increasing the volume of red blood cells, resulting in the ability to carry more oxygen to the muscles, improving endurance performance and muscle buffering capacity. Collectively, the use of altitude training is very beneficial for your training and performance”. This disclosure is honest, based on evidence, and aimed at engendering a positive belief in the effectiveness of altitude training. The physiotherapist applies an understanding of altitude training and the placebo effect through words to potentiate the response. At the 2017 Inaugural International Symposium on Placebo Effects in Sport & Exercise, Professor Fabrizio Benedetti stated that to elicit changes in people’s physiology, we do not necessarily inject drugs, but words. While Benedetti was referring to the methods used by placebo effect researchers, this statement holds true for all practitioners working with athletes. Practitioners do not work with their athletes in a vacuum, but in a complex environment of physiological and psychological states that vary from athlete to athlete and from situation to situation. Almost every aspect of the administration of an intervention moderates the placebo effect. It is therefore important practitioners recognise that the placebo effect can significantly affect the outcome of an intervention. Through an injection of words about the effectiveness of an intervention, practitioners can use knowledge and understanding of the placebo effect to maximize the likelihood of improvements in performance.