Repeat trial and breath averaging: Recommendations for research of VO2 kinetics of exercise transitions to steady-state

Multiple-breath and multiple-trial averaging have been used extensively in research of oxygen uptake kinetics to steady-state. However, specific guidelines outlining correct levels of averaging have not been discussed. The aim of this study was to assess error differences using multiple-trial and multiple-breath averaging systems, and make recommendations for future VO2 kinetics research. Eight male subjects were recruited for this study. Following a maximal cycle test to ascertain each subject’s ventilation threshold, eight identical repetition cycling exercise bouts were administered. The bouts consisted of 6-minute at 85% of the subject’s ventilation threshold. Firstly, multiple-trial and multiple-breath data were processed using traditional methods. As well, data were fit using a mono-exponential model to derive tau. Data for all levels of multiple-trial and multiple-breath methods were compared to an 8-trial and 13-breath average, respectively. Reduction in error from the 3-trial average and a 3-breath average represented ∼68% and ∼70% of total error reduction, respectively. Tau tended to increase with increasing breath averaging and decrease with increasing trial averaging. There is negligible benefit to averaging more than 3 repeat trials in VO2 kinetics research. Breath averaging beyond 3-breaths artificially increases tau.