Degree of arterial desaturation in normoxia influences VO2max decline in mild hypoxia.
Med Sci Sports Exerc
; 31(5): 658-63, 1999 May.
Article
em En
| MEDLINE
| ID: mdl-10331884
ABSTRACT
PURPOSE:
Elite endurance athletes display varying degrees of pulmonary gas exchange limitations during maximal normoxic exercise and many demonstrate reduced arterial O2 saturations (SaO2) at VO2max--a condition referred to as exercise induced arterial hypoxemia (EIH). We asked whether mild hypoxia would cause significant declines in SaO2 and VO2max in EIH athletes while non-EIH athletes would be unaffected.METHODS:
Nineteen highly trained males were divided into EIH (N = 8) or Non-EIH (N = 6) groups based on SaO2 at VO2max (EIH <90%, Non-EIH >92%). Athletes with intermediate SaO2 values (N = 5) were only included in correlational analyses. Two randomized incremental treadmill tests to exhaustion were completed--one in normoxia, one in mild hypoxia (FIO2 = 0.187; approximately 1,000 m).RESULTS:
EIH subjects demonstrated a significant decline in VO2max from normoxia to mild hypoxia (71.1+/-5.3 vs. 68.1+/-5.0 mL x kg(-1) min(-1), P<0.01), whereas the non-EIH group did not show a significant deltaVO2max (67.2+/-7.6 vs. 66.2+/-8.4 mL x kg(-1) x min(-1)). For all 19 athletes, SaO2 during maximal exercise in normoxia correlated with the change in VO2max from normoxia to mild hypoxia (r = -0.54, P<0.05). However, the change in SaO2 and arterial O2 content from normoxia to mild hypoxia was equal for both EIH and Non-EIH (deltaSaO2 = 5.2% for both groups), bringing into question the mechanism by which changes in SaO2 affect VO2max in mild hypoxia.CONCLUSIONS:
We conclude that athletes who display reduced measures of SaO2 during maximal exercise in normoxia are more susceptible to declines in VO2max in mild hypoxia compared with normoxemic athletes.
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Base de dados:
MEDLINE
Assunto principal:
Consumo de Oxigênio
/
Resistência Física
/
Exercício Físico
/
Mecânica Respiratória
/
Hipóxia
Tipo de estudo:
Clinical_trials
Limite:
Adult
/
Humans
/
Male
Idioma:
En
Ano de publicação:
1999
Tipo de documento:
Article