Reduced arterial O2 saturation during supine exercise in highly trained cyclists

Acta Physiologica Scandinavica
P K PedersenK Madsen

Abstract

Performance of intense dynamic exercise in highly trained athletes is associated with a reduced arterial haemoglobin saturation for O2 (SaO2) and lower arterial PO2 (PaO2). We hypothesized that compared with upright exercise, supine exercise would be accompanied by a smaller reduction in SaO2 because of a lower maximal O2 uptake (VO2max) and/or a more even ventilation-perfusion distribution. Eight elite bicyclists completed progressive cycle ergometry to exhaustion in both positions with concomitant determinations of ventilatory data, arterial blood gases and pH. During upright cycling VO2max averaged 75 +/- 1.6 mL O2 min-1 kg-1 (+/-SEM) and it was 10.6 +/- 1.7% lower during supine cycling (P < 0.001). Also the maximal pulmonary and alveolar ventilation were lower during supine cycling (by 15 +/- 2% and 21 +/- 3%, respectively; P < 0.001) which related to a 0.8 +/- 0.1 L lower tidal volume (P < 0.001). In all subjects and independent of work posture PaO2 and SaO2 decreased from rest to exhaustion (from 99 +/- 3 to 82 +/- 2 Torr and 98.1 +/- 0.2 to 95.2 +/- 0.4%, respectively; P < 0.001); alveolar-arterial PO2 difference increased from 6 +/- 2 to 37 +/- 3 Torr in both body positions. At exhaustion arterial PCO2 was lower in upri...Continue Reading

Citations

Jul 2, 2011·High Altitude Medicine & Biology·Christoph SiebenmannMarco Maggiorini
Nov 19, 2010·Scandinavian Journal of Medicine & Science in Sports·J ElersV Backer
Nov 18, 2003·Scandinavian Journal of Medicine & Science in Sports·Henning Bay Nielsen
Oct 20, 1998·Acta Physiologica Scandinavica·H B NielsenN H Secher
Jul 25, 2000·Sports Medicine·C PrefautC Caillaud
Oct 29, 2021·Frontiers in Cardiovascular Medicine·Xiaohua WanWei Jiang

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