@misc{10481/68065,
year = {2021},
url = {http://hdl.handle.net/10481/68065},
abstract = {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 doubleblind cross-over experiment. Each participant completed three identical trials consisting of a step
incremental exercise test from 30 to 80% of
.
VO2max. 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
.
VO2max (all p < 0.050). In informed caffeine,
participants increased their rate of fat oxidation at 30%, 40%, 50% 60%, and 70% of
.
VO2max (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
.
VO2max, 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.},
organization = {Francisco de Vitoria University 

UFV-18/2020},
publisher = {MDPI},
keywords = {Dietary supplements},
keywords = {Ergogenic aids},
keywords = {Psychological advantage},
keywords = {Carbohydrates},
title = {Placebo Effect of Caffeine on Substrate Oxidation during Exercise},
doi = {10.3390/nu13030782},
author = {Amaro Gahete, Francisco José and Gutiérrez Hellín, Jorge},
}