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

Beedie, Chris; Barbiani, Diletta; Camerone, Eleonora Maria; Lindheimer, Jacob B.; Roelands, Bart

doi:10.1080/17461391.2019.1675765

Cited by 21 publications

(28 citation statements)

References 126 publications

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“…expectancy theory, classical conditioning), in this paper, we adopt a broader and general conception that the placebo effect of taste could be explained through an anticipation on resource allocation. Beedie et al [115], recently argued that the brain modulates and anticipates the relationship between a signal (e.g. taste) and the body, which regulates subsequent resource allocation.…”

Section: Thermal Tastants Section Summarymentioning

confidence: 99%

Can taste be ergogenic?

et al. 2020

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Taste is a homeostatic function that conveys valuable information, such as energy density, readiness to eat, or toxicity of foodstuffs. Taste is not limited to the oral cavity but affects multiple physiological systems. In this review, we outline the ergogenic potential of substances that impart bitter, sweet, hot and cold tastes administered prior to and during exercise performance and whether the ergogenic benefits of taste are attributable to the placebo effect. Carbohydrate mouth rinsing seemingly improves endurance performance, along with a potentially ergogenic effect of oral exposure to both bitter tastants and caffeine although subsequent ingestion of bitter mouth rinses is likely required to enhance performance. Hot and cold tastes may prove beneficial in circumstances where athletes' thermal state may be challenged. Efficacy is not limited to taste, but extends to the stimulation of targeted receptors in the oral cavity and throughout the digestive tract, relaying signals pertaining to energy availability and temperature to appropriate neural centres. Dose, frequency and timing of tastant application likely require personalisation to be most effective, and can be enhanced or confounded by factors that relate to the placebo effect,

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Section: Thermal Tastants Section Summarymentioning

confidence: 99%

Can taste be ergogenic?

et al. 2020

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“…However, previous investigations have suggested various mechanisms that may explain the findings of this study. First, it has been speculated that the placebo effect on exercise performance may be the result of participants adopting a more stable pacing strategy when they believed that had received an active treatment [32]. Nevertheless, this mechanism seems not applicable to the current experiment as the exercise workload and cadence were replicated in all trials.…”

Section: Discussionmentioning

confidence: 93%

“…In most of these investigations, researchers have used deceptive experiments where participants are informed of that they had received an ergogenic dose of caffeine to induce expectancy when in fact, they were administered a placebo. The performance obtained in this trial (i.e., informed caffeine) is habitually compared to a real placebo/control situation and to a trial where participants actually received caffeine (i.e., received caffeine) [32]. However, recent investigations [15,30] have introduced more complex experiments where expectancy and the physiological effect of caffeine are dissociated by using four trials combining informed caffeine/received caffeine, informed caffeine/received placebo, informed placebo/received caffeine, and informed placebo/received placebo.…”

Section: Discussionmentioning

confidence: 99%

“…Additionally, it has been suggested that the placebo effect often activates the same pathways as the drug that it purports to be [35], suggesting then the placebo effect of caffeine may increase the concentration of the same neurotransmitters as the actual ingestion of caffeine. In this regard, the endogenous opioids and endocannabinoid system are implicated in pain mechanisms and analgesia, the serotonin system is associated with anxiety while dopamine has been investigated in the context of motivation [32]. Therefore, it is possible that the expectancy of having received caffeine produces lower pain and anxiety and enhances motivation during exercise.…”

Section: Discussionmentioning

confidence: 99%

“…Last, no biological markers relating to mechanistic actions associated with the placebo effect of caffeine were measured. Recently, it has been proposed that that mechanisms associated with the placebo effect of caffeine may mimic real mechanisms associated to acute caffeine intake [32]. Therefore, the measurement of plasma glycerol and free fatty acid concentration [39], and muscle oxygen saturation [40] in future investigations may help to determine the mechanism associated with the placebo effect of caffeine on fat oxidation during exercise.…”

Section: Discussionmentioning

confidence: 99%

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Placebo Effect of Caffeine on Substrate Oxidation during Exercise

et al. 2021

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By using deceptive experiments in which participants are informed that they received caffeine when, in fact, they received an inert substance (i.e., placebo), several investigations have demonstrated that exercise performance can be enhanced to a similar degree as a known caffeine dose. This ‘placebo effect’ phenomenon may be part of the mechanisms explaining caffeine’s ergogenicity in exercise. However, there is no study that has established whether the placebo effect of caffeine is also present for other benefits obtained with acute caffeine intake, such as enhanced fat oxidation during exercise. Therefore, the aim of this investigation was to investigate the placebo effect of caffeine on fat oxidation during exercise. Twelve young men participated in a deceptive double-blind cross-over experiment. Each participant completed three identical trials consisting of a step incremental exercise test from 30 to 80% of V.O2max. In the two first trials, participants ingested either 3 mg/kg of cellulose (placebo) or 3 mg/kg of caffeine (received caffeine) in a randomized order. In the third trial, participants were informed that they had received 3 mg/kg of caffeine, but a placebo was provided (informed caffeine). Fat oxidation rates were derived from stoichiometric equations. In received caffeine, participants increased their rate of fat oxidation over the values obtained with the placebo at 30%, 40%, 50%, and 60% of V.O2max (all p < 0.050). In informed caffeine, participants increased their rate of fat oxidation at 30%, 40%, 50% 60%, and 70% of V.O2max (all p < 0.050) over the placebo, while there were no differences between received versus informed caffeine. In comparison to placebo (0.32 ± 0.15 g/min), the rate of maximal fat oxidation was higher in received caffeine (0.44 ± 0.22 g/min, p = 0.045) and in informed caffeine (0.41 ± 0.20 g/min, p = 0.026) with no differences between received versus informed caffeine. However, the intensity at which maximal fat oxidation rate was obtained (i.e., Fatmax) was similar in placebo, received caffeine, and informed caffeine trials (42.5 ± 4.5, 44.2 ± 9.0, and 41.7 ± 10.5% of V.O2max, respectively, p = 0.539). In conclusion, the expectancy of having received caffeine produced similar effects on fat oxidation rate during exercise than actually receiving caffeine. Therefore, the placebo effect of caffeine is also present for the benefits of acute caffeine intake on substrate oxidation during exercise and it may be used to enhance fat oxidation during exercise in participants while reducing any risks to health that this substance may have.

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