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

Saunders, B., de Oliveira, L.F., da Silva, R.P., de Salles Painelli, V., Gonçalves, L.S., Yamaguchi, G., Mutti, T., Maciel, E., Roschel, H., Artioli, G.G. ORCID: 0000-0001-8463-2213 and Gualano, B., 2016. Placebo in sports nutrition: a proof-of-principle study involving caffeine supplementation. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188

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Abstract

We investigated the effects of supplement identification on exercise performance with caffeine supplementation. Forty-two trained cyclists (age 37 ± 8 years, body mass [BM] 74.3 ± 8.4 kg, height 1.76 ± 0.06 m, maximum oxygen uptake 50.0 ± 6.8 mL/kg/min) performed a ~30 min cycling time-trial 1 h following either 6 mg/kgBM caffeine (CAF) or placebo (PLA) supplementation and one control (CON) session without supplementation. Participants identified which supplement they believed they had ingested (“caffeine”, “placebo”, “don't know”) pre- and post-exercise. Subsequently, participants were allocated to subgroups for analysis according to their identifications. Overall and subgroup analyses were performed using mixed-model and magnitude-based inference analyses. Caffeine improved performance vs PLA and CON (P ≤ 0.001). Correct pre- and post-exercise identification of caffeine in CAF improved exercise performance (+4.8 and +6.5%) vs CON, with slightly greater relative increases than the overall effect of caffeine (+4.1%). Performance was not different between PLA and CON within subgroups (all P > 0.05), although there was a tendency toward improved performance when participants believed they had ingested caffeine post-exercise (P = 0.06; 87% likely beneficial). Participants who correctly identified placebo in PLA showed possible harmful effects on performance compared to CON. Supplement identification appeared to influence exercise outcome and may be a source of bias in sports nutrition.

Item Type: Journal article
Publication Title: Scandinavian Journal of Medicine & Science in Sports
Creators: Saunders, B., de Oliveira, L.F., da Silva, R.P., de Salles Painelli, V., Gonçalves, L.S., Yamaguchi, G., Mutti, T., Maciel, E., Roschel, H., Artioli, G.G. and Gualano, B.
Publisher: Wiley-Blackwell
Date: 23 November 2016
ISSN: 0905-7188
Identifiers:
NumberType
10.1111/sms.12793DOI
Divisions: Schools > School of Science and Technology
Depositing User: Jonathan Gallacher
Date Added: 20 Feb 2017 15:23
Last Modified: 23 Nov 2017 03:00
URI: http://irep.ntu.ac.uk/id/eprint/30232

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