Effect of inspiratory threshold loading on ventilatory kinetics during constant-load exercise.
Details
Serval ID
serval:BIB_37621
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Effect of inspiratory threshold loading on ventilatory kinetics during constant-load exercise.
Journal
American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
ISSN
0363-6119 (Print)
ISSN-L
0363-6119
Publication state
Published
Issued date
2005
Peer-reviewed
Oui
Volume
289
Number
6
Pages
R1618-R1624
Language
english
Abstract
Humoral factors play an important role in the control of exercise hyperpnea. The role of neuromechanical ventilatory factors, however, is still being investigated. We tested the hypothesis that the afferents of the thoracopulmonary system, and consequently of the neuromechanical ventilatory loop, have an influence on the kinetics of oxygen consumption (VO2), carbon dioxide output (VCO2), and ventilation (VE) during moderate intensity exercise. We did this by comparing the ventilatory time constants (tau) of exercise with and without an inspiratory load. Fourteen healthy, trained men (age 22.6 +/- 3.2 yr) performed a continuous incremental cycle exercise test to determine maximal oxygen uptake (VO2max = 55.2 +/- 5.8 ml x min(-1) x kg(-1)). On another day, after unloaded warm-up they performed randomized constant-load tests at 40% of their VO2max for 8 min, one with and the other without an inspiratory threshold load of 15 cmH2O. Ventilatory variables were obtained breath by breath. Phase 2 ventilatory kinetics (VO2, VCO2, and VE) could be described in all cases by a monoexponential function. The bootstrap method revealed small coefficients of variation for the model parameters, indicating an accurate determination for all parameters. Paired Student's t-tests showed that the addition of the inspiratory resistance significantly increased the tau during phase 2 of VO2 (43.1 +/- 8.6 vs. 60.9 +/- 14.1 s; P < 0.001), VCO2 (60.3 +/- 17.6 vs. 84.5 +/- 18.1 s; P < 0.001) and VE (59.4 +/- 16.1 vs. 85.9 +/- 17.1 s; P < 0.001). The average rise in tau was 41.3% for VO2, 40.1% for VCO2, and 44.6% for VE. The tau changes indicated that neuromechanical ventilatory factors play a role in the ventilatory response to moderate exercise.
Keywords
Adult, Differential Threshold/physiology, Exercise Test, Humans, Inhalation/physiology, Male, Oxygen Consumption/physiology, Physical Endurance/physiology, Physical Exertion/physiology, Pulmonary Ventilation/physiology, Respiratory Function Tests/methods
OAI-PMH
Pubmed
Web of science
Create date
19/11/2007 11:12
Last modification date
20/08/2019 14:25