The purpose of this study was to test whether believed versus actual acute creatine ingestion impacted resistance exercise performance.
Fifteen male participants were required to complete four bouts of exercise consisting of three sets of squats and bench press exercises towards a 10 repetition maximum effort with 1min rests between exercise intervals. The average age of the participants was 21.9 years old.
Thirty minutes prior to each exercise bout, each participant received the following treatments in a randomized order: First, nothing (control); second, 0.3 g·kg−1 dextrose placebo, identified to participants as placebo; and third, 0.3 g·kg−1 dextrose, labeled as creatine (Cr- False); and fourth, 0.3 g·kg 20 −1 creatine, identified as creatine (Cr-True).
Comparisons of total exercise repetitions were performed statistically, and data was collected on the rate of perceived exertion (RPE) for each participant in the study.
Statistical results showed that significantly higher repetitions of both the squat exercise and bench press were performed for all treatments (placebo; Cr-True; Cr-False) when compared to no ingestion (control):
• In the squat exercise, significantly more repetitions were performed with Cr-True and Cr-False in comparison to control and placebo treatments.
• Using a Bayes Factor analyses, results supported the study hypothesis, thus favouring the positive effects for both creatine conditions (Cr-True; Cr-False) over the placebo for the squat exercise.
• Additionally, statistical analysis reinforced that any applied pre-workout supplement enhances exercise performance, but the effect seems to be caused, or at least boosted, by the suggestion of a “powerful” intervention, as creatine ingestion. As such, the hypothesis of a psychological effect is considered true as researchers found a significantly lower RPE/number of repetition ratio in supplemented conditions, but especially supplemented or suggested to have received creatine, imparting the notion that the enhanced performance was accompanied, or associated, to a lower RPE. In other words, the rate of perceived exertion was found to be lower after creatine ingestion (whether Cr-True, Cr-False, or placebo).
• For squats, the suggestion of creatine supplementation seems to boost the exercise performance by psychological way, since Cr-False provided a significantly greater number of repetitions and lower RPE/ number of repetition ratio, when compared to placebo, despite the same pre-workout supplement (i.e. dextrose) offered in both conditions.
In conclusion, when subjects ingested both actual (Cr-True) and merely believed (Cr-False) pre-workout creatine, they performed a significantly higher volume of resistance exercise toward fatigue than when under a control condition. Ingestion of dextrose, identified to research participants as a placebo, also led to the completion of a slightly higher resistance exercise volume than a control condition.
Collectively, these data tells us that there are significant psychological influences on acute exercise performance and that the efficacy of acute supplement ingestion may be more attributable to belief (i.e. psychological effect) than physiological mechanisms.
Reference: Matheus S Aguiar, Rafael Pereira, Alexander J Koch & Marco Machado (2022) Psychological effect of acute creatine pre-workout supplementation induces performance improvement in resistance exercise, Research in Sports Medicine, DOI: 10.1080/15438627.2022.2090253
