Pulmonary gas exchange at maximal exercise in Danish lowlanders during 8 wk of acclimatization to 4,100 m and in high-altitude Aymara natives

We aimed to test effects of altitude acclimatization on pulmonary gas exchange at maximal exercise. Six lowlanders were studied at sea level, in acute hypoxia (AH), and after 2 and 8 wk of acclimatization to 4,100 m (2W and 8W) and compared with Aymara high-altitude natives residing at this altitude. As expected, alveolar Po2 was reduced during AH but increased gradually during acclimatization (61 ± 0.7, 69 ± 0.9, and 72 ± 1.4 mmHg in AH, 2W, and 8W, respectively), reaching values significantly higher than in Aymaras (67 ± 0.6 mmHg). Arterial Po2 (PaO2) also decreased during exercise in AH but increased significantly with acclimatization (51 ± 1.1, 58 ± 1.7, and 62 ± 1.6 mmHg in AH, 2W, and 8W, respectively). PaO2 in lowlanders reached levels that were not different from those in high-altitude natives (66 ± 1.2 mmHg). Arterial O2 saturation (SaO2) decreased during maximum exercise compared with rest in AH and after 2W and 8W: 73.3 ± 1.4, 76.9 ± 1.7, and 79.3 ± 1.6%, respectively. After 8W, SaO2 in lowlanders was not significantly different from that in Aymaras (82.7 ± 1%). An improved pulmonary gas exchange with acclimatization was evidenced by a decreased ventilatory equivalent of O2 after 8W: 59 ± 4, 58 ± 4, and 52 ± 4 l·min·l O2−1, respectively. The ventilatory equivalent of O2 reached levels not different from that of Aymaras (51 ± 3 l·min·l O2−1). However, increases in exercise alveolar Po2 and PaO2 with acclimatization had no net effect on alveolar-arterial Po2 difference in lowlanders (10 ± 1.3, 11 ± 1.5, and 10 ± 2.1 mmHg in AH, 2W, and 8W, respectively), which remained significantly higher than in Aymaras (1 ± 1.4 mmHg). In conclusion, lowlanders substantially improve pulmonary gas exchange with acclimatization, but even acclimatization for 8 wk is insufficient to achieve levels reached by high-altitude natives.

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Training in hypoxia vs. training in normoxia in high-altitude natives

Journal of Applied Physiology ◽

10.1152/jappl.1995.78.6.2286 ◽

1995 ◽

Vol 78 (6) ◽

pp. 2286-2293 ◽

Cited By ~ 22

Author(s):

R. Favier ◽

H. Spielvogel ◽

D. Desplanches ◽

G. Ferretti ◽

B. Kayser ◽

...

Keyword(s):

High Altitude ◽

Sea Level ◽

Maximal Exercise ◽

Work Intensity ◽

Maximal Aerobic Capacity ◽

Trained Subjects ◽

Arterial Ph ◽

High Altitude Natives ◽

Blood Lactate Accumulation ◽

O2 Delivery

To determine the interactions between endurance training and hypoxia on maximal exercise performance, we performed a study on sedentary high-altitude natives who were trained in normoxia at the same relative (n = 10) or at the same absolute (n = 10) intensity of work as hypoxia-trained subjects (n = 10). The training-induced improvement of maximal oxygen uptake (VO2max) in hypoxia-trained subjects was similar to that obtained in normoxia-trained sea-level natives submitted to the same training protocol (H. Hoppeler, H. Howald, K. Conley, S. L. Lindstedt, H. Claassen, P. Vock, and E. W. Weibel. J. Appl. Physiol. 59: 320–327, 1985). Training at the same absolute work intensity in the presence of increased oxygen delivery failed to provide a further increase in VO2max. VO2max was not improved to a greater extent by simultaneously increasing absolute work intensity and O2 delivery during the training sessions. In addition, training in normoxia is accompanied by an increased blood lactate accumulation during maximal exercise, leading to greater drops in arterial pH, bicarbonate concentration, and base excess. We conclude that, in high-altitude natives, 1) training at altitude does not provide any advantage over training at sea level for maximal aerobic capacity, whether assessed in chronic hypoxia or in acute normoxia; 2) VO2max improvement with training cannot be further enhanced by increasing O2 availability alone or in combination with an increased work intensity during the exercising sessions; and 3) training in normoxia in these subjects results in a reduced buffer capacity.

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Ventilatory Response to Acute Hypoxia in Sea Level Natives and in High Altitude Natives*

Acta Physiologica Scandinavica ◽

10.1111/j.1365-201x.1971.tb10952.x ◽

1971 ◽

Vol 81 (S361) ◽

pp. 26-32

Keyword(s):

High Altitude ◽

Sea Level ◽

Ventilatory Response ◽

Acute Hypoxia ◽

High Altitude Natives

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Effects of incomplete pulmonary gas exchange on VO2 max

Journal of Applied Physiology ◽

10.1152/jappl.1989.66.6.2491 ◽

1989 ◽

Vol 66 (6) ◽

pp. 2491-2495 ◽

Cited By ~ 149

Author(s):

S. K. Powers ◽

J. Lawler ◽

J. A. Dempsey ◽

S. Dodd ◽

G. Landry

Keyword(s):

Gas Exchange ◽

Sea Level ◽

Maximal Exercise ◽

Cycle Ergometer ◽

Pulmonary Gas Exchange ◽

Endurance Athletes ◽

Healthy Male ◽

Exercise Tests ◽

Ergometer Exercise ◽

Exercise Induced

Recent evidence suggests that heavy exercise may lower the percentage of O2 bound to hemoglobin (%SaO2) by greater than or equal to 5% below resting values in some highly trained endurance athletes. We tested the hypothesis that pulmonary gas exchange limitations may restrict VO2max in highly trained athletes who exhibit exercise-induced hypoxemia. Twenty healthy male volunteers were divided into two groups according to their physical fitness status and the demonstration of exercise-induced reductions in %SaO2 less than or equal to 92%: 1) trained (T), mean VO2max = 56.5 ml.kg-1.min-1 (n = 13) and 2) highly trained (HT) with maximal exercise %SaO2 less than or equal to 92%, mean VO2max = 70.1 ml.kg-1.min-1 (n = 7). Subjects performed two incremental cycle ergometer exercise tests to determine VO2max at sea level under normoxic (21% O2) and mild hyperoxic conditions (26% O2). Mean %SaO2 during maximal exercise was significantly higher (P less than 0.05) during hyperoxia compared with normoxia in both the T group (94.1 vs. 96.1%) and the HT group (90.6 vs. 95.9%). Mean VO2max was significantly elevated (P less than 0.05) during hyperoxia compared with normoxia in the HT group (74.7 vs. 70.1 ml.kg-1.min-1). In contrast, in the T group, no mean difference (P less than 0.05) existed between treatments in VO2max (56.5 vs. 57.1 ml.kg-1.min-1). These data suggest that pulmonary gas exchange may contribute significantly to the limitation of VO2max in highly trained athletes who exhibit exercise-induced reductions in %SaO2 at sea level.(ABSTRACT TRUNCATED AT 250 WORDS)

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Tolerance to acute anoxia in high altitude natives

Journal of Applied Physiology ◽

10.1152/jappl.1959.14.3.357 ◽

1959 ◽

Vol 14 (3) ◽

pp. 357-362 ◽

Cited By ~ 9

Author(s):

Tulio Velásquez

Keyword(s):

High Altitude ◽

Sea Level ◽

Technical Assistance ◽

Acute Hypoxia ◽

Low Pressure ◽

Pressure Chamber ◽

Relative Influence ◽

Acute Anoxia ◽

High Altitude Natives

Native residents living at an altitude of 14,900 feet were suddenly exposed to simulated higher altitudes, ranging from 30 to 40,000 feet, in a low pressure chamber. The ‘time of consciousness’ and the ceiling breathing air were determined. In addition, observations were made on the respiratory characteristics at these altitudes. Comparing the results with those given by previous investigators using sea level residents, they indicate that a man born and living at an altitude of 14,900 feet has a definitely greater tolerance to acute hypoxia than a man born and residing at sea level. The relative influence of hypoxia and hypocapnia on the symptoms which developed during this test is discussed. Note: (With the Technical Assistance of Edgard Florentini and Melquiades Huayna-Vera) Submitted on June 2, 1958

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AltitudeOmics: impaired pulmonary gas exchange efficiency and blunted ventilatory acclimatization in humans with patent foramen ovale after 16 days at 5,260 m

Journal of Applied Physiology ◽

10.1152/japplphysiol.00879.2014 ◽

2015 ◽

Vol 118 (9) ◽

pp. 1100-1112 ◽

Cited By ~ 15

Author(s):

Jonathan E. Elliott ◽

Steven S. Laurie ◽

Julia P. Kern ◽

Kara M. Beasley ◽

Randall D. Goodman ◽

...

Keyword(s):

Gas Exchange ◽

High Altitude ◽

Sea Level ◽

Patent Foramen Ovale ◽

Acute Mountain Sickness ◽

Cycle Ergometer ◽

Pulmonary Gas Exchange ◽

Foramen Ovale ◽

Ergometer Exercise ◽

High Altitude Acclimatization

A patent foramen ovale (PFO), present in ∼40% of the general population, is a potential source of right-to-left shunt that can impair pulmonary gas exchange efficiency [i.e., increase the alveolar-to-arterial Po2 difference (A-aDO2)]. Prior studies investigating human acclimatization to high-altitude with A-aDO2 as a key parameter have not investigated differences between subjects with (PFO+) or without a PFO (PFO−). We hypothesized that in PFO+ subjects A-aDO2 would not improve (i.e., decrease) after acclimatization to high altitude compared with PFO− subjects. Twenty-one (11 PFO+) healthy sea-level residents were studied at rest and during cycle ergometer exercise at the highest iso-workload achieved at sea level (SL), after acute transport to 5,260 m (ALT1), and again at 5,260 m after 16 days of high-altitude acclimatization (ALT16). In contrast to PFO− subjects, PFO+ subjects had 1) no improvement in A-aDO2 at rest and during exercise at ALT16 compared with ALT1, 2) no significant increase in resting alveolar ventilation, or alveolar Po2, at ALT16 compared with ALT1, and consequently had 3) an increased arterial Pco2 and decreased arterial Po2 and arterial O2 saturation at rest at ALT16. Furthermore, PFO+ subjects had an increased incidence of acute mountain sickness (AMS) at ALT1 concomitant with significantly lower peripheral O2 saturation (SpO2). These data suggest that PFO+ subjects have increased susceptibility to AMS when not taking prophylactic treatments, that right-to-left shunt through a PFO impairs pulmonary gas exchange efficiency even after acclimatization to high altitude, and that PFO+ subjects have blunted ventilatory acclimatization after 16 days at altitude compared with PFO− subjects.

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Cardiorespiratory response to exercise in men repeatedly exposed to extreme altitude

Journal of Applied Physiology ◽

10.1152/jappl.1983.55.5.1379 ◽

1983 ◽

Vol 55 (5) ◽

pp. 1379-1385 ◽

Cited By ~ 12

Author(s):

J. S. Milledge ◽

M. P. Ward ◽

E. S. Williams ◽

C. R. Clarke

Keyword(s):

Heart Rate ◽

High Altitude ◽

Sea Level ◽

Heart Rate Response ◽

Ventilatory Response ◽

Acute Hypoxia ◽

Cardiorespiratory Response ◽

Extreme Altitude ◽

High Altitude Natives ◽

Response To Exercise

The ventilatory and heart rate responses to exercise were studied in four experienced high-altitude climbers at sea level and during a 6-wk period above 4,500 m to discover whether their responses to hypoxia were similar to those of high-altitude natives. Comparison was made with results from four scientists who lacked their frequent exposure to extreme altitude. The climbers had greater Vo2max at sea level and altitude but similar ventilatory responses to increasing exercise. On acute hypoxia at sea level their ventilatory response was less than that of scientists. Their heart rate response did not differ from that of scientists at sea level, but with acclimatization the reduction in response was significantly greater. Alveolar gas concentrations were similar after acclimatization, but climbers achieved these changes more rapidly. The increase in hematocrit was similar in the two groups. It is concluded that these climbers, unlike high-altitude residents, have cardiorespiratory responses to exercise similar to those of other lowlanders except that their ventilatory response was lower and the reduction in their heart rate response was greater.

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Body water metabolism in high altitude natives during and after a stay at sea level

International Journal of Biometeorology ◽

10.1007/bf02184438 ◽

1981 ◽

Vol 25 (1) ◽

pp. 47-52 ◽

Cited By ~ 3

Author(s):

S. C. Jain ◽

Jaya Bardhan ◽

Y. V. Swamy ◽

A. Grover ◽

H. S. Nayar

Keyword(s):

High Altitude ◽

Sea Level ◽

Body Water ◽

Water Metabolism ◽

High Altitude Natives

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Global REACH 2018: renal oxygen delivery is maintained during early acclimatization to 4,330 m

AJP Renal Physiology ◽

10.1152/ajprenal.00372.2020 ◽

2020 ◽

Vol 319 (6) ◽

pp. F1081-F1089

Author(s):

Andrew R. Steele ◽

Michael M. Tymko ◽

Victoria L. Meah ◽

Lydia L. Simpson ◽

Christopher Gasho ◽

...

Keyword(s):

Blood Flow ◽

Renal Function ◽

High Altitude ◽

Renal Blood Flow ◽

Sea Level ◽

Oxygen Delivery ◽

Acid Base ◽

Altitude Acclimatization ◽

High Altitude Acclimatization ◽

Renal Oxygen

Early acclimatization to high altitude is characterized by various respiratory, hematological, and cardiovascular adaptations that serve to restore oxygen delivery to tissue. However, less is understood about renal function and the role of renal oxygen delivery (RDO2) during high altitude acclimatization. We hypothesized that 1) RDO2 would be reduced after 12 h of high altitude exposure (high altitude day 1) but restored to sea level values after 1 wk (high altitude day 7) and 2) RDO2 would be associated with renal reactivity, an index of acid-base compensation at high altitude. Twenty-four healthy lowlander participants were tested at sea level (344 m, Kelowna, BC, Canada) and on day 1 and day 7 at high altitude (4,330 m, Cerro de Pasco, Peru). Cardiac output, renal blood flow, and arterial and venous blood sampling for renin-angiotensin-aldosterone system hormones and NH2-terminal pro-B-type natriuretic peptides were collected at each time point. Renal reactivity was calculated as follows: (Δarterial bicarbonate)/(Δarterial Pco2) between sea level and high altitude day 1 and sea level and high altitude day 7. The main findings were that 1) RDO2 was initially decreased at high altitude compared with sea level (ΔRDO2: −22 ± 17%, P < 0.001) but was restored to sea level values on high altitude day 7 (ΔRDO2: −6 ± 14%, P = 0.36). The observed improvements in RDO2 resulted from both changes in renal blood flow (Δ from high altitude day 1: +12 ± 11%, P = 0.008) and arterial oxygen content (Δ from high altitude day 1: +44.8 ± 17.7%, P = 0.006) and 2) renal reactivity was positively correlated with RDO2 on high altitude day 7 ( r = 0.70, P < 0.001) but not high altitude day 1 ( r = 0.26, P = 0.29). These findings characterize the temporal responses of renal function during early high altitude acclimatization and the influence of RDO2 in the regulation of acid-base balance.

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