Role of Maximal Heart Rate and Arterial O2 Saturation on the Decrement of V·O2max in Moderate Acute Hypoxia in Trained and Untrained Men

Abstract We aimed to evaluate 1) the altitude where maximal heart rate (HR max ) decreases significantly in both trained and untrained subjects in moderate acute hypoxia, and 2) if the HR max decrease could partly explain the drop of V·O 2max . Seventeen healthy males, nine trained endurance athlete...

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Bibliographic Details
Published in:International journal of sports medicine 2007-03, Vol.28 (3), p.186-192
Main Authors: Mollard, P., Woorons, X., Letournel, M., Cornolo, J., Lamberto, C., Beaudry, M., Richalet, J.-P.
Format: Article
Language:English
Subjects:
Physiology & Biochemistry
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Summary:Abstract We aimed to evaluate 1) the altitude where maximal heart rate (HR max ) decreases significantly in both trained and untrained subjects in moderate acute hypoxia, and 2) if the HR max decrease could partly explain the drop of V·O 2max . Seventeen healthy males, nine trained endurance athletes (TS) and eight untrained individuals (US) were studied. Subjects performed incremental exercise tests at sea level and at 5 simulated altitudes (1000, 1500, 2500, 3500, 4500 meters). Power output (PO), heart rate (HR), arterial oxygen saturation (SaO 2 ), oxygen uptake (V·O 2 ), arterialized blood pH and lactate were measured. Both groups showed a progressive reduction in V·O 2max . The decrement in HR max (ΔHR max ) was significant from 1000 m for TS and 2500 m for US and more important in TS than US (at 1500 m and 3500 m). At maximal exercise, TS had a greater reduction in SaO 2 (ΔSaO 2 ) at each altitude. ΔHR max observed in TS was correlated with ΔSaO 2 . When the two groups were pooled, simple regressions showed that ΔV·O 2max was correlated with both ΔSaO 2 and ΔHR max . However, a multiple regression analysis demonstrated that ΔSaO 2 alone may account for ΔV·O 2max . Furthermore, in spite of a greater reduction in SaO 2 and HR max in TS, no difference was evidenced in relative ΔV·O 2max between groups. Thus, in moderate acute hypoxia, the reduction in SaO 2 is the primary factor to explain the drop of V·O 2max in trained and untrained subjects.
ISSN:0172-4622
1439-3964
DOI:10.1055/s-2006-924215