The Effects of an Injected Placebo on Endurance Running PerformanceRamzy Ross, Cindy M. Gray and Jason M. R. Gill

Terminology

Recombinant Human

Erythropoietin (r-HuEpo)

Hematocrit

Placebo

Background• The placebo effect is acknowledged as a key factor in medical research and,

as a consequence, its effect has been controlled in clinical trials for over 50 years

• The placebo effect has also been recognized in the context of sports performance, with a number of studies reporting statistically significant improvements in endurance, sprint or strength performance with placebo interventions

• Orally administered placebos have been typically shown to improve endurance performance by ~2% in participants who are at least moderately well-trained

Background• Previous studies have assessed performance using either cycle ergometer or

running time-trial performance assessments • Such tests were performed on individual performing alone, and unaware of the

performances of others, rather than assessment during head-to-head field-based competition scenarios

• It’s known that performance is often improved in head-to-head competition settings, compared to settings without a competitive element

• Motivational Intensity Theory predicts that maximum exercise tolerance will be increased when either perception of effort is reduced or ‘potential motivation’ (i.e. the greatest effort an individual is prepared to exert) is increased.

Effects and Benefits of Competition

• Consistent with increased potential motivation, there is evidence that competition results in the following:

• Increased:• Potential motivation• Allocation of effort to an exercise task• Positive emotions• Heart rate• Peak oxygen uptake• Enhanced sympatho-adrenal system activation

• Reduced:• Internal attentional focus

Recombinant Human Erythropoietin (r-HuEpo)

Stimulates renal erythrocyte production

r-HuEpo administration increases hematocrit (Hct)

A key feature of r-HuEpo administration is that it is given

by injection.

Studies on the effects of r-HuEpo administration on

sporting performance in field-based tests are limited, and no study has assessed its effects on performance in a placebo-

controlled trial using field-based head-to-head competition setting.

Recombinant Human Erythropoietin (r-HuEpo)

Aim• 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

Methods

Preliminary Study Brief

3 km Races

Data Collection

Quantitative and

Qualitative Data Analysis

Participants

Methods

Methods

Preliminary Study Brief

3 km Races

Data Collection

Quantitative and

Qualitative Data Analysis

Participants

Methods

Methods

Preliminary Study Brief

3 km Races

Data Collection

Quantitative and

Qualitative Data Analysis

Participants

Methods

Methods

Preliminary Study Brief

3 km Races

Data Collection

Quantitative and

Qualitative Data Analysis

Participants

Methods

Methods

Preliminary Study Brief

3 km Races

Data Collection

Quantitative and

Qualitative Data Analysis

Participants

Experimental Design

Quantitative Results

Ross et al. 2014

Quantitative ResultsFigure 3

Ross et al. 2014

Quantitative ResultsFigure 4

Ross et al. 2014

Quantitative Results

Ross et al. 2014

Quantitative Results

Ross et al. 2014

Quantitative Results

Ross et al. 2014

Quantitative Results

Ross et al. 2014

Quantitative Results

Ross et al. 2014

Qualitative Results• Reduction in perceived physical effort

both during training and the competitive races was also evident in the post-study interviews, where some participants described how ‘taking OxyRBX’ had increased their enjoyment of training sessions

• Another noticeable physical effect that many participants experienced during the placebo week (including those whose race times showed no improvement) was enhanced recovery both following training sessions and after the races

• Many participants also described enhanced potential motivation, particularly during the competitive races.

• Almost all of the participants reported that they thought they were taking a real performance enhancing substance during the study, providing further evidence that the briefing procedures used were highly effective in inducing participants’ beliefs that the substance would enhance their performance.

• A few participants reported minor

negative effects (changing sleep patterns, slight pain at the injection site, nausea), almost all mentioned at least some positive effects

Conclusion

The study provided novel insights into the effects of

an injected placebo (OxyRBX), purporting to be

performance enhancing agent similar to r-HuEPO, on endurance performance in a

head-to-head competitive setting.

Further study is needed to determine whether the magnitude of the

placebo effect is similar in athletes at the elite

level

The magnitude of benefit, at 1.2%, is of

clear sporting relevance, but is substantially smaller than the

performance improvement elicited by r-HuEPO administration.

Take Home Messages

Placebo improves competitive

performance by both reducing perception of effort and increasing potential motivation,

in accord with the psychobiological

model for exercise performance

The benefits elicited by a placebo are of

clear sporting relevance

Further study is needed to determine

whether the magnitude of the placebo effect is

similar in athletes at the elite level

Ask and You shall Receive