Neurophysiological Mechanisms of Placebo and Nocebo Effects in Sports - a Protocol Paper
Trial statusNot yet recruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18+
SponsorCanterbury Christ Church University
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Healthy adult participants (18+)
physically active (WHO, 2020)
no medical history pf psychological disorders/mental health issues
no acute or regular medication intake
Disqualifiers
None
Trial design
Design model
Parallel
Treatments tested in this trial
Positive Expectation
Combination productThe lead researcher will deliver a short presentation (8 minutes) to participants informing them about the deceptive substance, presenting it as a performance enhancing neurostimulant,. Participants will be given the opportunity to ask questions and will receive a handout of the key points of the presentation. After the presentation, participants will be set up with a high-density EEG and given two inert pills filled with cornstarch. Participants will be reminded of the performance enhancing qualities of the deceptive substance by implicit adjectives on a screen. Afterwards, experimental performance outcomes will be collected using a dynamometer.
Negative Expectation
Combination productThe lead researcher will deliver a short presentation (8 minutes) to participants informing them about the deceptive substance, presenting it as a performance inhibiting neuro-depressant. Participants will be given the opportunity to ask questions and will receive a handout of the key points of the presentation. After the presentation, participants will be set up with a high-density EEG and given two inert pills filled with cornstarch. Participants will be reminded of the performance inhibiting qualities of the deceptive substance by implicit adjectives on a screen. Afterwards, experimental performance outcomes will be collected using a dynamometer.
Control
Other interventionThe lead researcher will deliver a short presentation (8 minutes) to participants informing them about EEG research and set ups and give general information about isometric strength testing. They will be shown neutral adjectives unrelated to performance instead of implicit adjectives related to performance (experimental groups). EEG set up and strength testing remains the same as the experimental groups.
Treatment groups
56 Participants
are divided into 4 treatment groupsGroup A: positive-expectationsExperimental treatment 1 intervention
Group B: negative-expectationsExperimental treatment 1 intervention
Group C: controlActive comparator 1 intervention
Group D: natural historyNo intervention 0 interventions
Trial outcomes
Primary outcomes
1
EEG data - performance
Temporal neurophysiological data measured by EEG. The Continuous Negative Variation (CNV), an Event Related Potential (ERP), will be used to differentiate positive and negative expectations as well as motor preparation before and at onset of isometric strength testing.
Time frame
From collection of baseline data on day one to the end of day two of data collection.2
EEG data - reinforcement of beliefs
Event related potentials (ERP) will be investigated during the reinforcement of beliefs, specifically the late positive potential (LPP) and the late positive component (LPC).
Time frame
From collection of baseline data on day one to the end of day two of data collection.3
EEG, exploratory source analysis
In addition to ERP data, Low-Resolution Electromagnetic Tomography (LORETA) will be used in an exploratory approach to identify specific neural origins associated with placebo and nocebo responses.
Time frame
From collection of baseline data on day one to the end of day two of data collectionSecondary outcomes
1
Performance Output, Isometric Forces
Peak Isometric Force: Measured in Newton-meters (Nm) as the maximum force output during a 5-second unilateral knee extension contraction. Average Isometric Force: Calculated as the mean force output in Nm maintained over a 5-second unilateral knee extension contraction. Isometric Force output data will be analysed in a within and between analysis, the latter being normalized to body mass (Nm/kg).
Time frame
From collection of baseline data on day one to the end of day two of data collection.2
Performance Output, Force Consistency
Force Consistency: Assessed by comparing peak and average force outputs in Nm across five consecutive trials of 5-second contractions.
Time frame
From collection of baseline data on day one to the end of day two of data collection.3
Performance Output, Endurance Hold and Fatigue Resistance
Fatigue Resistance and Endurance Hold: Evaluating the time to failure at the 60% maximally voluntary contraction (MVC) hold.
Time frame
From collection of baseline data on day one to the end of day two of data collection.4
Performance Output, Recovery Capacity
Recovery Capacity: Determined by examining the ability to maintain force output in Nm across trials with 1-minute rest intervals between contractions.
Time frame
From collection of baseline data on day one to the end of day two of data collection.Other outcomes
1
Questionnaires - Anxiety
Further outcomes measures include questionnaires and inventories to assess key personality traits and states, motivation and beliefs. 1\. Cognitive and Somatic State Anxiety levels measured by the Competitive Sport Anxiety Inventory-2 (CSAI-2).
Time frame
From collection of baseline data on day one to the end of day two of data collection.2
Questionnaires - Motivation and Perception of Ability
A 7-point Likert scale will be used to assess the participants' achievement motivation and their approach to performance.
Time frame
From collection of baseline data on day one to the end of day two of data collection.3
Questionnaires - Optimism
We will use the Life Orientation Test-Revised (LOT-R) to test for the level of optimism versus pessimism.
Time frame
From collection of baseline data on day one to the end of day two of data collection.4
Questionnaires - Sport supplement use and belief
We will collect data on participants' use of and beliefs on sport supplements.
Time frame
From collection of baseline data on day one to the end of day two of data collection.Sponsors and contacts
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Source ClinicalTrials.gov
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