Operation Everest III: role of plasma volume expansion onV˙o_2maxduring prolonged high-altitude exposure

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).

Physical Activity at Altitude: Challenges for People With Diabetes

“…During the process of acclimatization, the initial increase in heart rate decreases, probably because of decreased cardiac responsiveness to b-adrenergic stimulation (12) and increased vagal tone (13,14). As stroke volume is decreased after prolonged altitude exposure because of a decrease in plasma volume, heart rate remains increased to maintain cardiac output at altitude (15,16). Even after acclimatization, maximum heart rate, maximum cardiac output, and maximum exercise capacity remain suppressed (17,18).…”

Association of anthropometric, physiologycal and physical traits to success of elite male mountain climbers

“…Reported maximal oxygen consumption was 54.4 ml/kg/min, Whereas Oelz (1986) estimated the mean of maximal oxygen consumption of mountain climbers 60 ml/kg/min (Oelz et al, 1986;Wagner, 2010). Robach et al found a 59% decrease in VO 2max at an altitude of 7,000 m by simulating the altitude in special rooms (Robach et al, 2000). Fitness status and type of equipment and tests used may be some possible reasons for these differences.…”

“…Нађена максимална потрошња кисеоника је износила 54.4 ml/kg/min, док је Оелз (1986) про-ценио средњу вредност максималне потрошње кисеоника код алпиниста од 60 ml/kg/min (Oelz, et al,1986;Wagner, 2010). Робах и сарадници су открили смањење од 59% у VO 2max на надморској висини од 7.000 метара, помоћу симулације виси-не у посебним просторијама (Robach, et al, 2000). Стање физичке спремности и врста опреме, као и тестови који су коришћени могу бити неки од мо-гућих разлога ових разлика.…”

Physiological and Kinanthropometrical Parameters of an Elite Climber. Single case study.

“…Also Cerretelli et al [24] concluded that still at an altitude of 2500 m, the VO 2max begins to fall between 5% and 10% comparing with sea level values. Other research works reporting changes after chronic acute HP, like published by Robach et al [25], simulate the ascent of 8 men to Everest with an hypobaric chamber (COMEX). In this study, the VO 2max decreased 59% at 7000 m above sea level.…”