Comparison of Oxygen Uptake Kinetics During Severe-intensity Laboratory and Field Cycling

The O₂-kinetic response to constant work rate exercise provides an insight into the adjustment of systemic oxygen transport and muscle metabolism. Whether O₂-kinetics measured in laboratory conditions reflect O₂-kinetics in field conditions has not yet been analysed. The aim of this study was to compare O₂-kinetics between field and laboratory conditions. Thirteen competitive male cyclists (mean±SD age 23.3±4.1 years; V̇O_2peak 68.2±4.7 mL^.min^-1.kg^-1) completed two 6-min severe-intensity trials at 60 and 90 rev^.min^-1 in both conditions. Power output was measured with an SRM power meter and V̇O₂ was measured with a portable gas analyser. The time constant (τ), the time delay (TD) and the amplitude (Amp) were resolved by least square regression, and the V̇O₂ slow component (SC) was calculated as the difference between the end-exercise V̇O₂ and Amp. To determine differences between the trials, a repeated-measure ANOVA was conducted. The Amp and end-exercise V̇O₂ were significantly higher during field cycling whereas the SC were significantly higher during laboratory cycling (all at p<0.001). No significant differences were found for τ (p=0.24). Laboratory measures tend to underestimate the oxygen demand in field cycling. A higher cadence leads to greater oxygen demand in laboratory and field cycling.