Placebo in sports nutrition: a proof‐of‐principle study involving caffeine supplementation

Saunders, Bryan; Oliveira, Luana Farias de; Silva, R. P. da; Painelli, Vítor de Salles; Gonçalves, Lívia de Souza; Yamaguchi, Guilherme; Mutti, Tomás Argentino; Maciel, Érika da Silva; Roschel, Hamilton; Artioli, Guilherme Giannini; Gualano, Bruno

doi:10.1111/sms.12793

Cited by 146 publications

(169 citation statements)

References 17 publications

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“…Lastly, this study utilized a dichotomous questionnaire to determine the perceived effect of the supplement, which did not capture non-decisive responses (i.e., "don't know" or "not sure"). Because of this, the effects of supplement identification cannot be explored, which may improve performance when participants correctly identify the supplement with an active ingredient or incorrectly identify the placebo [56]. However, 50% of the participants in the current investigation perceived an effect from the supplement in the caffeine condition (i.e., correct identification), which failed to produce a significant effect on CrossFit ® performance.…”

Section: Discussionmentioning

confidence: 89%

Acute Caffeine Supplementation Does Not Improve Performance in Trained CrossFit® Athletes

Stein

Ramirez

Heinrich

2020

Sports

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Caffeine's ergogenic effects persist during various exercise modalities; however, information establishing its efficacy during CrossFit ® protocols is limited. This study aimed to determine the effects of caffeine supplementation on CrossFit ® performance. Twenty CrossFit ® -trained men (age = 26.7 ± 6.2 years, experience = 3.7 ± 2.9 years) were randomized in a double-blind, crossover design. Participants completed two sessions separated by a seven-day washout period, 60 min after consuming 5 mg/kg body mass of caffeine or a placebo. In each session, participants completed as many rounds as possible in 20 min of five pull-ups, 10 push-ups, and 15 air squats. CrossFit ® performance was the total number of repetitions completed in 20 min. Paired-samples t-tests were used to compare CrossFit ® performance between caffeine and placebo conditions and to test for a potential learning effect between the first and second sessions. CrossFit ® performance was not significantly different during the caffeine condition compared to the placebo (468.6 ± 114.7 vs. 466.7 ± 94.3 repetitions, p = 0.861). A significant learning effect was identified between the first and second sessions (452.4 ± 101 vs. 483.8 ± 106.5 repetitions, p = 0.001), with no significant effect of treatment order (p = 0.438). Caffeine's ergogenic effect were not present during the CrossFit ® workout "Cindy"; however, future research should include familiarization sessions and examine other CrossFit ® workouts in novice and women participants.

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Section: Discussionmentioning

confidence: 89%

Acute Caffeine Supplementation Does Not Improve Performance in Trained CrossFit® Athletes

Stein

Ramirez

Heinrich

2020

Sports

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“…As noted previously, only two studies explored the effectiveness of the blinding to the caffeine and placebo conditions. Recently, Saunders et al [28] presented data that suggest that correct supplement identification may influence the outcome of a given exercise task and, therefore, could be a source of bias in the sports supplement line of research. Given these results, we would like to highlight to researchers examining the effects of caffeine on exercise performance to assess the effectiveness of the blinding.…”

Section: Discussionmentioning

confidence: 99%

“…Given these results, we would like to highlight to researchers examining the effects of caffeine on exercise performance to assess the effectiveness of the blinding. Preferably, this assessment should be done both pre-and post-exercise, given that the opinion and response might change from pre-to post-exercise [28].…”

Section: Discussionmentioning

confidence: 99%

The Effects of Caffeine Ingestion on Measures of Rowing Performance: A Systematic Review and Meta-Analysis

et al. 2020

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The purpose of this paper was to conduct a systematic review and a meta-analysis of studies examining the acute effects of caffeine ingestion on measures of rowing performance. Crossover and placebo-controlled experiments that investigated the effects of caffeine ingestion on measures of rowing performance were included. The PEDro checklist was used to assess the methodological quality of the included studies. Seven studies of good and excellent methodological quality were included. None of the included studies examined on-water rowing. The majority of studies that were included in the meta-analysis used a 2000m rowing distance with only one using 1000m distance. Results of the main meta-analysis indicated that caffeine enhances performance on a rowing ergometer compared to placebo with a mean difference of −4.1 s (95% confidence interval (CI): −6.4, −1.8 s). These values remained consistent in the analysis in which the study that used a 1000m distance was excluded (mean difference: −4.3 s; 95% CI: −6.9, −1.8 s). We also found a significant increase in mean power (mean difference: 5.7 W; 95% CI: 2.1, 9.3 W) and minute ventilation (mean difference: 3.4 L/min; 95% CI: 1.7, 5.1 L/min) following caffeine ingestion. No significant differences between caffeine and placebo were found for the rating of perceived exertion, oxygen consumption, respiratory exchange ratio, and heart rate. This meta-analysis found that acute caffeine ingestion improves 2000m rowing ergometer performance by~4 s. Our results support the use of caffeine pre-exercise as an ergogenic aid for rowing performance.

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“…Both in the caffeine and the placebo trials, before and after the exercise session, participants responded to the following question: "Which supplement do you think you have ingested?" [24]. The question had three possible responses: (a) "caffeine", (b) "placebo" and (c) "I do not know" [24].…”

Section: Assessment Of Blindingmentioning

confidence: 99%

CYP1A2 genotype and acute effects of caffeine on resistance exercise, jumping, and sprinting performance

Grgić

Pickering

Bishop

et al. 2020

Journal of the International Society of Sports Nutrition

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Background: It has been suggested that polymorphisms within CYP1A2 impact inter-individual variation in the response to caffeine. The purpose of this study was to explore the acute effects of caffeine on resistance exercise, jumping, and sprinting performance in a sample of resistance-trained men, and to examine the influence of genetic variation of CYP1A2 (rs762551) on the individual variation in responses to caffeine ingestion.Methods: Twenty-two men were included as participants (AA homozygotes n = 13; C-allele carriers n = 9) and were tested after the ingestion of caffeine (3 mg/kg of body mass) and a placebo. Exercise performance was assessed with the following outcomes: (a) movement velocity and power output in the bench press exercise with loads of 25, 50, 75, and 90% of one-repetition maximum (1RM); (b) quality and quantity of performed repetitions in the bench press exercise performed to muscular failure with 85% 1RM; (c) vertical jump height in a countermovement jump test; and (d) power output in a Wingate test.Results: Compared to placebo, caffeine ingestion enhanced: (a) movement velocity and power output across all loads (effect size [ES]: 0.20-0.61; p < 0.05 for all); (b) the quality and quantity of performed repetitions with 85% of 1RM (ES: 0.27-0.85; p < 0.001 for all); (c) vertical jump height (ES: 0.15; p = 0.017); and (d) power output in the Wingate test (ES: 0.33-0.44; p < 0.05 for all). We did not find a significant genotype × caffeine interaction effect (pvalues ranged from 0.094 to 0.994) in any of the analyzed performance outcomes.Conclusions: Resistance-trained men may experience acute improvements in resistance exercise, jumping, and sprinting performance following the ingestion of caffeine. The comparisons of the effects of caffeine on exercise performance between individuals with the AA genotype and AC/CC genotypes found no significant differences.

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Placebo in sports nutrition: a proof‐of‐principle study involving caffeine supplementation

Cited by 146 publications

References 17 publications

Acute Caffeine Supplementation Does Not Improve Performance in Trained CrossFit® Athletes

Acute Caffeine Supplementation Does Not Improve Performance in Trained CrossFit® Athletes

The Effects of Caffeine Ingestion on Measures of Rowing Performance: A Systematic Review and Meta-Analysis

CYP1A2 genotype and acute effects of caffeine on resistance exercise, jumping, and sprinting performance

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