Neurophysiological Mechanisms of Placebo and Nocebo Effects in Sports - a Protocol Paper

This clinical trial aims to investigate the neurophysiological mechanisms of placebo and nocebo effects on sports performance, using Electroencephalography (EEG) and isometric strength testing of the lower extremities.

The primary objective of this trial is to identify temporal mechanisms and cortical regions and networks involved in generating placebo and nocebo effects before (expectation) and at onset of athletic performance (perception).

The trial will include four groups, two of them experimental, one an active control and one natural history, meaning participants in this group will receive no intervention and won't be EEG controlled. Data will be collected on two occasions with baseline data for EEG, expectations and performance as well as key participant characteristics being collected on day one. On day two, in a deceptive process, participants in the two experimental groups will take an inert substance presented as either performance enhancing or inhibiting and subsequently experience a reinforcement of beliefs via exposure to explicit adjectives. EEG data will be collected during reinforcement of beliefs. In the active control group, participants will receive no substance, but this group will follow the same procedure as the experimental groups with neutral adjectives. Participants will then perform isometric strength and fatigue resistance tests on an isometric dynamometer. EEG data as well as subjective data on expectations and rating of perceived exhaustion will be collected.