TY - JOUR
T1 - Theoretical predictions of maximal oxygen consumption in hypoxia
T2 - Effects of transport limitations
AU - McGuire, B. J.
AU - Secomb, T. W.
N1 - Funding Information:
This work was supported by National Institutes of Health Grants HL07249 and HL70657 and National Science Foundation Grant 9870659.
PY - 2004/10/12
Y1 - 2004/10/12
N2 - A Krogh-type model for oxygen transport is used to predict maximal oxygen consumption (V̇O2max) of human skeletal muscle under hypoxic conditions. Assumed values of capillary density, blood flow, and hemoglobin concentration are based on measurements under normoxic and hypoxic exercise conditions. Arterial partial pressure of oxygen is assumed to decrease with reductions in inspired partial pressure of oxygen (P IO 2), as observed experimentally. As a result of limitations of convective and diffusive oxygen delivery, predicted V̇O2max values decline gradually as P IO 2 is reduced from 150 mmHg to about 80 mmHg, and more rapidly as P IO 2 is further reduced. At very low levels of P IO 2, V̇O2max is limited primarily by convective oxygen supply. Experimentally observed values of V̇O2max in hypoxia show significant dispersion, with some values close to predicted levels and others substantially lower. These results suggest that maximal oxygen consumption rates in hypoxia are not necessarily determined by oxygen transport limitations and may instead reflect reduced muscle oxygen demand.
AB - A Krogh-type model for oxygen transport is used to predict maximal oxygen consumption (V̇O2max) of human skeletal muscle under hypoxic conditions. Assumed values of capillary density, blood flow, and hemoglobin concentration are based on measurements under normoxic and hypoxic exercise conditions. Arterial partial pressure of oxygen is assumed to decrease with reductions in inspired partial pressure of oxygen (P IO 2), as observed experimentally. As a result of limitations of convective and diffusive oxygen delivery, predicted V̇O2max values decline gradually as P IO 2 is reduced from 150 mmHg to about 80 mmHg, and more rapidly as P IO 2 is further reduced. At very low levels of P IO 2, V̇O2max is limited primarily by convective oxygen supply. Experimentally observed values of V̇O2max in hypoxia show significant dispersion, with some values close to predicted levels and others substantially lower. These results suggest that maximal oxygen consumption rates in hypoxia are not necessarily determined by oxygen transport limitations and may instead reflect reduced muscle oxygen demand.
KW - Hypoxia
KW - Krogh cylinder model
KW - Maximal oxygen consumption
KW - Oxygen transport
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U2 - 10.1016/j.resp.2004.07.001
DO - 10.1016/j.resp.2004.07.001
M3 - Article
C2 - 15477175
AN - SCOPUS:5144222409
VL - 143
SP - 87
EP - 97
JO - Respiratory Physiology and Neurobiology
JF - Respiratory Physiology and Neurobiology
SN - 1569-9048
IS - 1
ER -