Coupling of [Formula: see text] and [Formula: see text] kinetics: insights from multiple exercise transitions below the estimated lactate threshold.

Autor: Ward AMM; School of Kinesiology, The University of Western Ontario, 1151 Richmond Street, London, ON, N6A 3K7, Canada., Guluzade NA; School of Kinesiology, The University of Western Ontario, 1151 Richmond Street, London, ON, N6A 3K7, Canada., Kowalchuk JM; School of Kinesiology, The University of Western Ontario, 1151 Richmond Street, London, ON, N6A 3K7, Canada.; Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada., Keir DA; School of Kinesiology, The University of Western Ontario, 1151 Richmond Street, London, ON, N6A 3K7, Canada. dkeir@uwo.ca.; Toronto General Research Institute, Toronto General Hospital, Toronto, ON, Canada. dkeir@uwo.ca.
Jazyk: angličtina
Zdroj: European journal of applied physiology [Eur J Appl Physiol] 2023 Mar; Vol. 123 (3), pp. 509-522. Date of Electronic Publication: 2022 Nov 12.
DOI: 10.1007/s00421-022-05073-4
Abstrakt: During a step-change in exercise power output (PO), ventilation ([Formula: see text]) increases with a similar time course to the rate of carbon dioxide delivery to the lungs ([Formula: see text]). To test the strength of this coupling, we compared [Formula: see text] and [Formula: see text] kinetics from ten independent exercise transitions performed within the moderate-intensity domain. Thirteen males completed 3-5 repetitions of ∆40 W step transitions initiated from 20, 40, 60, 80, 100, and 120 W on a cycle ergometer. Preceding the ∆40 W step transitions from 60, 80, 100, and 120 W was a 6 min bout of 20 W cycling from which the transitions of variable ∆PO were examined. Gas exchange ([Formula: see text] and oxygen uptake, [Formula: see text]) and [Formula: see text] were measured by mass spectrometry and volume turbine. The kinetics of the responses were characterized by the time constant (τ) and amplitude (Δ[Formula: see text]/Δ[Formula: see text]). Overall, [Formula: see text] kinetics were consistently slower than [Formula: see text] kinetics (by ~ 45%) and τ[Formula: see text] rose progressively with increasing baseline PO and with heightened ∆PO from a common baseline. Compared to τ[Formula: see text], τ[Formula: see text] was on average slightly greater (by ~ 4 s). Repeated-measures analysis of variance revealed that there was no interaction between τ[Formula: see text] and τ[Formula: see text] in either the variable baseline (p = 0.49) and constant baseline (p = 0.56) conditions indicating that each changed in unison. Additionally, for Δ[Formula: see text]/Δ[Formula: see text], there was no effect of either variable baseline PO (p = 0.05) or increasing ΔPO (p = 0.16). These data provide further evidence that, within the moderate-intensity domain, both the temporal- and amplitude-based characteristics of V̇ E kinetics are inextricably linked to those of [Formula: see text].
(© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
Databáze: MEDLINE
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