AUTHOR=Arce-Álvarez Alexis , Veliz Carlos , Vazquez-Muñoz Manuel , von Igel Magdalena , Alvares Cristian , Ramirez-Campillo Rodrigo , Izquierdo Mikel , Millet Gregoire P. , Del Rio Rodrigo , Andrade David C. 

TITLE=Hypoxic Respiratory Chemoreflex Control in Young Trained Swimmers

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.632603

DOI=10.3389/fphys.2021.632603

ISSN=1664-042X

ABSTRACT=<p>During an apnea, changes in PaO<sub>2</sub> activate peripheral chemoreceptors to increase respiratory drive. Athletes with continuous apnea, such as breath-hold divers, have shown a decrease in hypoxic ventilatory response (HVR), which could explain the long apnea times; however, this has not been studied in swimmers. We hypothesize that the long periods of voluntary apnea in swimmers is related to a decreased HVR. Therefore, we sought to determine the HVR and cardiovascular adjustments during a maximum voluntary apnea in young-trained swimmers. In fifteen trained swimmers and twenty-seven controls we studied minute ventilation (V<sub><italic>E</italic></sub>), arterial saturation (SpO<sub>2</sub>), heart rate (HR), and autonomic response [through heart rate variability (HRV) analysis], during acute chemoreflex activation (five inhalations of pure N<sub>2</sub>) and maximum voluntary apnea test. In apnea tests, the maximum voluntary apnea time and the end-apnea HR were higher in swimmers than in controls (<italic>p</italic> &lt; 0.05), as well as a higher low frequency component of HRV (<italic>p</italic> &lt; 0.05), than controls. Swimmers showed lower HVR than controls (<italic>p</italic> &lt; 0.01) without differences in cardiac hypoxic response (CHR). We conclude that swimmers had a reduced HVR response and greater maximal voluntary apnea duration, probably due to decreased HVR.</p>