Incorporating methods and findings from neuroscience to better understand placebo and nocebo effects in sport

Abstract

Placebo and nocebo effects are a factor in sports performance. However, the majority of published studies in sport science are descriptive and speculative regarding mechanisms. It is therefore not unreasonable for the sceptic to argue that placebo and nocebo effects in sport are illusory, and might be better explained by variations in phenomena such as motivation. It is likely that, in sport at least, placebo and nocebo effects will remain in this empirical grey area until researchers provide stronger mechanistic evidence. Recent research in neuroscience has identified a number of consistent, discrete and interacting neurobiological and physiological pathways associated with placebo and nocebo effects, with many studies reporting data of potential interest to sport scientists, for example relating to pain, fatigue and motor control. Findings suggest that placebos and nocebos result in activity of the opioid, endocannabinoid and dopamine neurotransmitter systems, brain regions including the motor cortex and striatum, and measureable effects on the autonomic nervous system. Many studies have demonstrated that placebo and nocebo effects associated with a treatment, for example an inert treatment presented as an analgesic or stimulant, exhibit mechanisms similar or identical to the verum or true treatment. Such findings suggest the possibility of a wide range of distinct placebo and nocebo mechanisms that might influence sports performance. In the present paper, we present some of the findings from neuroscience. Focussing on fatigue as an outcome and caffeine as vehicle, we propose three approaches that researchers in sport might incorporate in their studies in order to better elucidate mechanisms of placebo/nocebo effects on performance.

Key words:

• Neurobiology
• nocebo effects
• fatigue
• caffeine
• research methods
• experimental design

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Christopher Beedie http://orcid.org/0000-0003-0106-3479

Fabrizio Benedetti http://orcid.org/0000-0003-4057-1150

Diletta Barbiani http://orcid.org/0000-0001-8703-6687

Eleanora Camerone http://orcid.org/0000-0002-4771-2836

Jacob Lindheimer http://orcid.org/0000-0002-1581-3210

Bart Roelands http://orcid.org/0000-0002-2808-044X

Notes

1 Whilst the potential for neurobiological processes to modulate pain is intuitively logical to many in sport, the effects on respiratory depression of the endogenous opioids, for a long time associated with the ‘runner’s high’ (Boecker et al., 2008) is less intuitive. However, given that many neuroscience studies have demonstrated that placebo opioid drugs mimic the effects and pathways of real opioid drugs (Benedetti, Pollo, et al., 2007), this not only makes sense, but has implications for performance in hypoxia.

2 We recognize that RPE responses vary, caffeine/placebo caffeine might produce a reduction in RPE at the same power output or no change in RPE at increased power output.

3 The authors discussed findings in the context of the ethics of sports competition, indicating that these raised important questions as to whether conditioned placebo responses to illegal treatments have to be considered a doping procedure.