Reduced arterial O2 saturation during supine exercise in highly trained cyclists
- 1 December 1996
- journal article
- research article
- Published by Wiley in Acta Physiologica Scandinavica
- Vol. 158 (4) , 325-331
- https://doi.org/10.1046/j.1365-201x.1996.575323000.x
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 (VPO2max) 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 VPO2max averaged 75±1.6 mL O2 min‐1 kg‐1 (±SEM) and it was 10.6±1.7% lower during supine cycling (PP< 0.001) which related to a 0.8±0.1 L lower tidal volume (PPaO2 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; PPO2 difference increased from 6±2 to 37±3 Torr in both body positions. At exhaustion arterial PCO2 was lower in upright than in supine (33.4±0.6 vs. 35.9±0.9 Torr; PVPO2max and supposedly an improved ventilation–perfusion distribution, altering body position from upright to supine does not influence arterial O2 desaturation during intense exercise.Keywords
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