The effects of an injected placebo on endurance running performance

Ross, R., Gray, C. M. and Gill, J. M.R. (2015) The effects of an injected placebo on endurance running performance. Medicine and Science in Sports and Exercise, 47(8), pp. 1672-1681. (doi:10.1249/MSS.0000000000000584) (PMID:25412293)

102299.pdf - Accepted Version



PURPOSE: To quantify the placebo effect magnitude on endurance running performance, in 'real-world' field-based head-to-head competition settings, of an injected placebo ('OxyRBX') purporting to have similar effects to recombinant human erythropoietin (r-HuEPO). METHODS: 15 endurance-trained club-level men (age: 27.5+/-6.8 years, BMI: 22.9+/-2.0 kg[middle dot]m-2), with personal best 10 km times of 39.3+/-4.4 min (mean+/-SD), completed the randomised cross-over study design of 3 km races before and after 7-day 'control' and 'placebo' phases. During the placebo phase participants self-administered subcutaneous saline injections daily, believing it to be OxyRBX, with no intervention during the control phase. At the start and end of each 7-day phase 3 km running performance was assessed. Qualitative assessments of participants' perceptions and experiences were recorded throughout and in semi-structured interviews on completion. RESULTS: Race time improved significantly more in response to the placebo intervention (9.73+/-1.96 s faster, P=0.0005), than in response to control (1.82+/-1.94 s faster, P=0.41) (P interaction = 0.02). In response to the placebo, participants reported reductions in physical effort, increased potential motivation and improved recovery. Beliefs and congruence between positive expectations of the effects of the placebo and perceptions of physical change during training also appeared to impact on competitive performance. CONCLUSIONS: Compared to control, the injected placebo improved 3 km race time by 1.2%. This change is of clear sporting relevance, but is smaller than the performance improvement elicited by r-HuEPO administration. The qualitative data suggest that placebo may have improved performance by both reducing perception of effort and increasing potential motivation, in accord with the psychobiological model for exercise performance, and that cognitive and non-cognitive processes appear to have influenced placebo response.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Gray, Professor Cindy and Gill, Professor Jason and Ross, Mr Ramzy
Authors: Ross, R., Gray, C. M., and Gill, J. M.R.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
College of Medical Veterinary and Life Sciences > Institute of Health and Wellbeing > Social Scientists working in Health and Wellbeing
College of Medical Veterinary and Life Sciences > School of Life Sciences
College of Social Sciences
College of Social Sciences > School of Social and Political Sciences > Sociology Anthropology and Applied Social Sciences
Journal Name:Medicine and Science in Sports and Exercise
Publisher:Lippincott Williams & Wilkins
ISSN (Online):1530-0315
Copyright Holders:Copyright © 2014 American College of Sports Medicine
First Published:First published in Medicine and Science in Sports and Exercise 47(7):1672-1681
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.

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