TY - JOUR
T1 - Cerebral desaturation during exercise reversed by O2 supplementation
AU - Nielsen, H. B.
AU - Boushel, R.
AU - Madsen, P.
AU - Secher, N. H.
PY - 1999/9
Y1 - 1999/9
N2 - The combined effects of hyperventilation and arterial desaturation on cerebral oxygenation (SC(O2)) were determined using near-infrared spectroscopy. Eleven competitive oarsmen were evaluated during a 6-min maximal ergometer row. The study was randomized in a double-blind fashion with an inspired O2 fraction of 0.21 or 0.30 in a crossover design. During exercise with an inspired O2 fraction of 0.21, the arterial CO2 pressure (35 ± 1 mmHg; 1 mean ± SE) and O2 pressure (77 ± 2 mmHg) as well as the hemoglobin saturation (91.9 ± 0.7%) were reduced (P < 0.05). SC(O2) was reduced from 80 ± 2 to 63 ± 2% (P < 0.05), and the near-infrared spectroscopy-determined concentration changes in deoxy- (ΔHb) and oxyhemoglobin (ΔHbo2) of the vastus lateralis muscle increased 22 ± 3 μM and decreased 14 ± 3 μM, respectively (P < 0.05). Increasing the inspired O2 fraction to 0.30 did not affect ventilation (174 ± 4 l/min), but arterial CO2 pressure (37 ± 2 mmHg), O2 pressure (165 ± 5 mmHg), and hemoglobin O2 saturation (99 ± 0.1%) increased (P < 0.05). SC(O2) remained close to the resting level during exercise (79 ± 2 vs. 81 ± 2%), and although the muscle ΔHb (18 ± 2 μM) and ΔHbO2 (-12 ± 3 μM) were similar to those established without O2 supplementation, work capacity in creased from 389 ± 11 to 413 ± 10 W (P < 0.05). These results indicate that an elevated inspiratory O2 fraction increases exercise performance related to maintained cerebral oxygenation rather than to an effect on the working muscles.
AB - The combined effects of hyperventilation and arterial desaturation on cerebral oxygenation (SC(O2)) were determined using near-infrared spectroscopy. Eleven competitive oarsmen were evaluated during a 6-min maximal ergometer row. The study was randomized in a double-blind fashion with an inspired O2 fraction of 0.21 or 0.30 in a crossover design. During exercise with an inspired O2 fraction of 0.21, the arterial CO2 pressure (35 ± 1 mmHg; 1 mean ± SE) and O2 pressure (77 ± 2 mmHg) as well as the hemoglobin saturation (91.9 ± 0.7%) were reduced (P < 0.05). SC(O2) was reduced from 80 ± 2 to 63 ± 2% (P < 0.05), and the near-infrared spectroscopy-determined concentration changes in deoxy- (ΔHb) and oxyhemoglobin (ΔHbo2) of the vastus lateralis muscle increased 22 ± 3 μM and decreased 14 ± 3 μM, respectively (P < 0.05). Increasing the inspired O2 fraction to 0.30 did not affect ventilation (174 ± 4 l/min), but arterial CO2 pressure (37 ± 2 mmHg), O2 pressure (165 ± 5 mmHg), and hemoglobin O2 saturation (99 ± 0.1%) increased (P < 0.05). SC(O2) remained close to the resting level during exercise (79 ± 2 vs. 81 ± 2%), and although the muscle ΔHb (18 ± 2 μM) and ΔHbO2 (-12 ± 3 μM) were similar to those established without O2 supplementation, work capacity in creased from 389 ± 11 to 413 ± 10 W (P < 0.05). These results indicate that an elevated inspiratory O2 fraction increases exercise performance related to maintained cerebral oxygenation rather than to an effect on the working muscles.
KW - Arterial oxygen pressure
KW - Arterial oxygen saturation
KW - Hyperoxia
KW - Lactate
KW - Near-infrared spectroscopy
KW - pH
UR - http://www.scopus.com/inward/record.url?scp=0032886984&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.1999.277.3.h1045
DO - 10.1152/ajpheart.1999.277.3.h1045
M3 - Journal article
C2 - 10484427
AN - SCOPUS:0032886984
SN - 0363-6135
VL - 277
SP - H1045-H1052
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 3 46-3
ER -