The potential to change pacing and performance during 4000m cycling time trials using hyperoxia and inspired gas-content deception

Posted on October 21, 2019 by

The aim of this study was to determine if a series of trials manipulating FiO2 content and belief (through deception) might change pacing and performance during 4000m cycling time trials.

At a glance:

  • Hyperoxic and oxygen deception time trials have the potential to build belief and improve performance in subsequent normoxic trials or competitive events.
  • The order of hyperoxic and deception time trials may encourage athletes to deviate from their routine pacing template.
  • Future studies manipulating the FiO2 should consider the effects trial order and participants’ knowledge of the FiO2 may have on exercise regulation.


To determine if a series of trials with fraction of inspired oxygen (FiO2) content deception could improve 4000-m cycling time-trial (TT) performance.

A total of 15 trained male cyclists (mean [SD] body mass 74.2 [8.0] kg, peak oxygen uptake 62 [6] mL·kg-1·min-1) completed six 4000-m cycling TTs in a semirandomized order. After a familiarization TT, cyclists were informed in 2 initial trials they were inspiring normoxic air (NORM, FiO2 0.21); however, in 1 trial (deception condition), they inspired hyperoxic air (NORM-DEC, FiO2 0.36). During 2 subsequent TTs, cyclists were informed they were inspiring hyperoxic air (HYPER, FiO2 0.36), but in 1 trial, normoxic air was inspired (HYPER-DEC). In the final TT (NORM- 1NFORM), the deception was revealed and cyclists were asked to reproduce their best TT performance while inspiring normoxic air.

Greater power output and faster performances occurred when cyclists inspired hyperoxic air in both truthful (HYPER) and deceptive (NORM-DEC) trials than NORM (P< .001). However, performance only improved in NORM-INFORM (377 W; 95% confidence interval [CI] 325—429) vs NORM (352 W; 95% Cl 299-104; P< .001) when participants (n = 4) completed the trials in the following order: NORM-DEC, NORM, HYPER-DEC, HYPER.

Cycling performance improved with acute exposure to hyperoxia. Mechanisms for the improvement were likely physiological; however, improvement in a deception trial suggests an additional placebo effect. Finally, a particular sequence of oxygen deception trials may have built psychophysiological belief in cyclists such that performance improved in a subsequent normoxic trial.

Full reference and abstract:
Davies, M., Clark, B., Lewis, L., Gore, C., Welvaert, M., Thompson, K.G. (2019) The potential to change pacing and performance during 4000-m cycling time trials using hyperoxia and inspired gas-content deception. International Journal of Sport Physiology and Performance, 2019, 14(7):949-957.

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