Test-retest reliability of pulmonary oxygen uptake and muscle deoxygenation during moderate- and heavy-intensity cycling in youth elite-cyclists

Abstract

To establish the test-retest reliability of pulmonary oxygen uptake ( O2), muscle deoxygenation (deoxy[heme]) and tissue oxygen saturation (StO2) kinetics in youth elitecyclists. From baseline pedaling, 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. O2 was measured breath-by-breath alongside deoxy[heme] 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 O2 and between 6.6-13.7% and 3.5-10.4% for deoxy[heme], respectively. The 95% confidence interval for estimating the kinetic parameters significantly improved for ensemble-averaged transitions of O2 (p<0.01) but not for deoxy[heme]. 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 0.81-0.99 for all measures. Test-retest reliability data provides limits within which changes in O2, deoxy[heme] and StO2 kinetics may be interpreted with confidence in youth athletes.