Abstract
PurposePrevious research shows that endurance performance can be enhanced by placebo ergogenic aids. This study investigates the ergogenic placebo response, which we define as an increase in objective and physiological effort without an increase in subjective effort, in competitive cyclists. The primary objective of this study is to explore the role of supplement salience in the ergogenic placebo response, while the secondary aim is to assess whether believing to have taken an inactive placebo supplement attenuates the desired ergogenic effect.MethodsWe employed a double-blind placebo-controlled study design and compared a high salience (pudding) to a low salience (capsules) ergogenic placebo supplement and to a no treatment control group. Thirty-four male athletes (30.0 ± 5.7 years) performed two self-regulated time trials on an isokinetic cycling ergometer, one without intervention serving as a baseline and one with intervention according to group assignment. At both time trials, power output (objective effort), blood lactate (physiological effort) and the rating of perceived exertion (subjective effort) were measured.ResultsReceiving a high salience supplement can increase physiological and objective effort without a proportional rise in subjective effort, suggesting a decoupling of perceived exertion and endurance performance. Low salience and control group both showed no such ergogenic placebo response. Athletes’ belief concerning the true nature of the ergogenic aid (inactive placebo vs. ergogenic supplement) did not influence the ergogenic placebo response.ConclusionHigh salience placebo ergogenic aids can elicit enhanced performance without the athlete noticing (exertion), and deception of athletes seems unnecessary as even believing to have received an inactive placebo supplement maintains the ergogenic placebo response.
Highlights
More than 80% of competitive athletes consume dietary supplements as ergogenic aids for performance enhancement on a daily basis [1,2,3]
Previous research has shown that exercise performance can be influenced by the ingredients of supplements and by expectancy effects caused by beliefs about the efficacy of such ergogenic aids [4,5,6]
To investigate the influence of salience on physiological effort, we conducted a repeated measures analysis of variance (ANOVA) of group (HS x Low Salience (LS) x C) and time (TTb x time trial (TTi)) on PE, which revealed a marginally significant interaction of time and group (F(2,31) = 3.26, p = .05, partial η2 = .17). Despite this marginally significant interaction we performed exploratory post-hoc t-tests, which revealed a significant increase in blood lactate from TTb to TTi in the high salience (HS) group (from M = 4.92 ± SD = 1.60 to M = 5.58 ± SD = 1.96; t (12) = -2.66, p = .02), but no significant changes in the LS (t(14) = -.60, p = .56) and control group (t(5) = 1.28, p = .26) (Fig 3)
Summary
More than 80% of competitive athletes consume dietary supplements as ergogenic aids for performance enhancement on a daily basis [1,2,3]. Previous research has shown that exercise performance can be influenced by the ingredients of supplements and by expectancy effects caused by beliefs about the efficacy of such ergogenic aids [4,5,6]. These expectancy effects are commonly known as the placebo effect, which is defined as any change in physical or physiological condition following an inert treatment [7]. Metaanalyses examining the placebo effects in various strength and endurance sports disciplines including power lifting, cycling and running found a medium effect size for overall performance enhancement [12] and placebo responses between -7.8% and +50.7% [13]
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