Operation Everest III: role of plasma volume expansion on VO(2)(max) during prolonged high-altitude exposure.
J Appl Physiol (1985)
; 89(1): 29-37, 2000 Jul.
Article
em En
| MEDLINE
| ID: mdl-10904032
ABSTRACT
We hypothesize that plasma volume decrease (DeltaPV) induced by high-altitude (HA) exposure and intense exercise is involved in the limitation of maximal O(2) uptake (VO(2)(max)) at HA. Eight male subjects were decompressed for 31 days in a hypobaric chamber to the barometric equivalent of Mt. Everest (8,848 m). Maximal exercise was performed with and without plasma volume expansion (PVX, 219-292 ml) during exercise, at sea level (SL), at HA (370 mmHg, equivalent to 6, 000 m after 10-12 days) and after return to SL (RSL, 1-3 days). Plasma volume (PV) was determined at rest at SL, HA, and RSL by Evans blue dilution. PV was decreased by 26% (P < 0.01) at HA and was 10% higher at RSL than at SL. Exercise-induced DeltaPV was reduced both by PVX and HA (P < 0.05). Compared with SL, VO(2)(max) was decreased by 58 and 11% at HA and RSL, respectively. VO(2)(max) was enhanced by PVX at HA (+9%, P < 0.05) but not at SL or RSL. The more PV was decreased at HA, the more VO(2)(max) was improved by PVX (P < 0.05). At exhaustion, plasma renin and aldosterone were not modified at HA compared with SL but were higher at RSL, whereas plasma atrial natriuretic factor was lower at HA. The present results suggest that PV contributes to the limitation of VO(2)(max) during acclimatization to HA. RSL-induced PVX, which may be due to increased activity of the renin-aldosterone system, could also influence the recovery of VO(2)(max).
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Consumo de Oxigênio
/
Volume Plasmático
/
Altitude
/
Doença da Altitude
Limite:
Adult
/
Humans
/
Male
Idioma:
En
Revista:
J Appl Physiol (1985)
Assunto da revista:
FISIOLOGIA
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
França