ABSTRACT
To establish the test–retest reliability of pulmonary oxygen uptake (V̇O2), muscle deoxygenation (deoxy[haem]) and tissue oxygen saturation (StO2) kinetics in youth elite-cyclists. From baseline pedalling, 15 youth cyclists completed 6-min step transitions to a moderate- and heavy-intensity work rate separated by 8 min of baseline cycling. The protocol was repeated after 1 h of passive rest. V̇O2 was measured breath-by-breath alongside deoxy[haem] and StO2 of the vastus lateralis by near-infrared spectroscopy. Reliability was assessed using 95% limits of agreement (LoA), the typical error (TE) and the intraclass correlation coefficient (ICC). During moderate- and heavy-intensity step cycling, TEs for the amplitude, time delay and time constant ranged between 3.5–21.9% and 3.9–12.1% for V̇O2 and between 6.6–13.7% and 3.5–10.4% for deoxy[haem], respectively. The 95% confidence interval for estimating the kinetic parameters significantly improved for ensemble-averaged transitions of V̇O2 (p < 0.01) but not for deoxy[haem]. For StO2, the TEs for the baseline, end-exercise and the rate of deoxygenation were 1.0–42.5% and 1.1–5.5% during moderate- and heavy-intensity exercise, respectively. The ICC ranged from 0.81 to 0.99 for all measures. Test–retest reliability data provide limits within which changes in V̇O2, deoxy[haem] and StO2 kinetics may be interpreted with confidence in youth athletes.
Acknowledgments
We gratefully acknowledge the commitment and loyalty of the participants and the logistic support of Mr Roland Wafler, coach of the Austrian Cycling Federation.
Author contributions
AN, BCB and CAW conceived and designed the study and drafted the manuscript. AN, BP, MZ and CR performed the experiments and data analysis. All authors revised and approved the final version of the manuscript.
Disclosure statement
No conflicts of interest, financial or otherwise, are declared by the authors.
Supplementary material
Supplemental data for this article can be accessed online https://doi.org/10.1080/02640414.2020.1792115.