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Oxygen-conserving effects of apnea in exercising men.
KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).ORCID iD: 0000-0001-6361-8965
1999 (English)In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 87, no 6, 2122-2127 p.Article in journal (Refereed) Published
Abstract [en]

We sought to determine whether apnea-induced cardiovascular responses resulted in a biologically significant temporary O(2) conservation during exercise. Nine healthy men performing steady-state leg exercise carried out repeated apnea (A) and rebreathing (R) maneuvers starting with residual volume +3.5 liters of air. Heart rate (HR), mean arterial pressure (MAP), and arterial O(2) saturation (Sa(O(2)); pulse oximetry) were recorded continuously. Responses (DeltaHR, DeltaMAP) were determined as differences between HR and MAP at baseline before the maneuver and the average of values recorded between 25 and 30 s into each maneuver. The rate of O(2) desaturation (DeltaSa(O(2))/Deltat) was determined during the same time interval. During apnea, DeltaSaO(2)/Deltat had a significant negative correlation to the amplitudes of DeltaHR and DeltaMAP (r(2) = 0.88, P < 0.001); i.e., individuals with the most prominent cardiovascular responses had the slowest DeltaSa(O(2))/Deltat. DeltaHR and DeltaMAP were much larger during A (-44 +/- 8 beats/min, +49 +/- 4 mmHg, respectively) than during R maneuver (+3 +/- 3 beats/min, +30 +/- 5 mmHg, respectively). DeltaSa(O(2))/Deltat during A and R maneuvers was -1.1 +/- 0.1 and -2.2 +/- 0.2% units/s, respectively, and nadir Sa(O(2)) values were 58 +/- 4 and 42 +/- 3% units, respectively. We conclude that bradycardia and hypertension during apnea are associated with a significant temporary O(2) conservation and that respiratory arrest, rather than the associated hypoxia, is essential for these responses.

Place, publisher, year, edition, pages
1999. Vol. 87, no 6, 2122-2127 p.
National Category
URN: urn:nbn:se:kth:diva-123248OAI: diva2:625574
NR 20140805Available from: 2013-06-05 Created: 2013-06-05 Last updated: 2014-01-20Bibliographically approved

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Sundblad, Patrik
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