Cardiorespiratory response to exercise in men repeatedly exposed to extreme altitude

1983 ◽  
Vol 55 (5) ◽  
pp. 1379-1385 ◽  
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.

Regulation of respiration and heart rate response in exercise during altitude acclimatization

1963 ◽  
Vol 18 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Pierre Dejours ◽  
Ralph H. Kellogg ◽  
Nello Pace
Keyword(s):  
Heart Rate ◽  
Sea Level ◽  
Blood Lactate ◽  
Environmental Conditions ◽  
Heart Rate Response ◽  
Treadmill Exercise ◽  
Ventilatory Response ◽  
Pulmonary Ventilation ◽  
Regulation Of Respiration ◽  
Response To Exercise

In three subjects pulmonary ventilation, alveolar gas, blood lactate, and heart rate were studied at rest and during two grades of treadmill exercise in four environmental conditions: at sea level breathing air or 13% O2 (simulating altitude), and during a sojourn of 3 weeks at an altitude of 3,800 m breathing air or 33% O2 (simulating sea level). At altitude, ventilatory response to exercise was decreased by inhalation of 33% oxygen but remained above that observed at sea level breathing air. Study of the transients at the beginning and end of exercise showed that in all four environmental conditions, the ventilatory response to exercise could be dissected into fast and slow components, interpreted as neurogenic and humoral, respectively, in accordance with the neurohumoral theory. In two subjects, the increased hyperpnea of exercise at altitude represented increases in both the neurogenic and humoral components, while in the third subject only the humoral component was increased. Study of the composition of alveolar gas at the start and end of exercise indicated that pulmonary blood flow as well as ventilation undergoes immediate change at these times. Resting blood lactate concentrations and the increment produced by exercise were higher at altitude and resting heart rate tended to increase throughout the altitude sojourn in these subjects. The increment in pulse rate produced by exercise fell progressively, as expected. Submitted on February 5, 1962

Tolerance to acute anoxia in high altitude natives

1959 ◽  
Vol 14 (3) ◽  
pp. 357-362 ◽  
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

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

2004 ◽  
Vol 287 (5) ◽  
pp. R1202-R1208 ◽  
Author(s):  
Carsten Lundby ◽  
Jose A. L. Calbet ◽  
Gerrit van Hall ◽  
Bengt Saltin ◽  
Mikael Sander
Keyword(s):  
Gas Exchange ◽  
High Altitude ◽  
Sea Level ◽  
Maximal Exercise ◽  
Acute Hypoxia ◽  
Pulmonary Gas Exchange ◽  
Maximum Exercise ◽  
Altitude Acclimatization ◽  
Ventilatory Equivalent ◽  
High Altitude 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.

Selected Contribution: High-altitude natives living at sea level acclimatize to high altitude like sea-level natives

2003 ◽  
Vol 94 (3) ◽  
pp. 1263-1268 ◽  
Author(s):  
Maria Rivera-Ch ◽  
Alfredo Gamboa ◽  
Fabiola León-Velarde ◽  
Jose-Antonio Palacios ◽  
David F. O'Connor ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Time Course ◽  
Ventilatory Response ◽  
Air Breathing ◽  
High Altitude Natives ◽  
End Tidal ◽  
Ventilatory Response To Hypoxia

Sea-level (SL) natives acclimatizing to high altitude (HA) increase their acute ventilatory response to hypoxia (AHVR), but HA natives have values for AHVR below those for SL natives at SL (blunting). HA natives who live at SL retain some blunting of AHVR and have more marked blunting to sustained (20-min) hypoxia. This study addressed the question of what happens when HA natives resident at SL return to HA: do they acclimatize like SL natives or revert to the characteristics of HA natives? Fifteen HA natives resident at SL were studied, together with 15 SL natives as controls. Air-breathing end-tidal Pco 2 and AHVR were determined at SL. Subjects were then transported to 4,300 m, where these measurements were repeated on each of the following 5 days. There were no significant differences in the magnitude or time course of the changes in end-tidal Pco 2 and AHVR between the two groups. We conclude that HA natives normally resident at SL undergo ventilatory acclimatization to HA in the same manner as SL natives.

scholarly journals Spleen contraction elevates hemoglobin concentration at high altitude during rest and exercise

2020 ◽  
Vol 120 (12) ◽  
pp. 2693-2704
Author(s):  
Erika Schagatay ◽  
Alexander Lunde ◽  
Simon Nilsson ◽  
Oscar Palm ◽  
Angelica Lodin-Sundström
Keyword(s):  
High Altitude ◽  
Acute Hypoxia ◽  
Arterial Oxygen Saturation ◽  
Hemoglobin Concentration ◽  
Step Test ◽  
Arterial Oxygen ◽  
Spleen Volume ◽  
Spleen Contraction ◽  
Response To Exercise ◽  
Rest And Exercise

Abstract Purpose Hypoxia and exercise are known to separately trigger spleen contraction, leading to release of stored erythrocytes. We studied spleen volume and hemoglobin concentration (Hb) during rest and exercise at three altitudes. Methods Eleven healthy lowlanders did a 5-min modified Harvard step test at 1370, 3700 and 4200 m altitude. Spleen volume was measured via ultrasonic imaging and capillary Hb with Hemocue during rest and after the step test, and arterial oxygen saturation (SaO2), heart rate (HR), expiratory CO2 (ETCO2) and respiratory rate (RR) across the test. Results Resting spleen volume was reduced with increasing altitude and further reduced with exercise at all altitudes. Mean (SE) baseline spleen volume at 1370 m was 252 (20) mL and after exercise, it was 199 (15) mL (P < 0.01). At 3700 m, baseline spleen volume was 231 (22) mL and after exercise 166 (12) mL (P < 0.05). At 4200 m baseline volume was 210 (23) mL and after exercise 172 (20) mL (P < 0.05). After 10 min, spleen volume increased to baseline at all altitudes (NS). Baseline Hb increased with altitude from 138.9 (6.1) g/L at 1370 m, to 141.2 (4.1) at 3700 m and 152.4 (4.0) at 4200 m (P < 0.01). At all altitudes Hb increased from baseline during exercise to 146.8 (5.7) g/L at 1370 m, 150.4 (3.8) g/L at 3700 m and 157.3 (3.8) g/L at 4200 m (all P < 0.05 from baseline). Hb had returned to baseline after 10 min rest at all altitudes (NS). The spleen-derived Hb elevation during exercise was smaller at 4200 m compared to 3700 m (P < 0.05). Cardiorespiratory variables were also affected by altitude during both rest and exercise. Conclusions The spleen contracts and mobilizes stored red blood cells during rest at high altitude and contracts further during exercise, to increase oxygen delivery to tissues during acute hypoxia. The attenuated Hb response to exercise at the highest altitude is likely due to the greater recruitment of the spleen reserve during rest, and that maximal spleen contraction is reached with exercise.

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

1981 ◽  
Vol 25 (1) ◽  
pp. 47-52 ◽  
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

Heart Rate Response to Exercise

2018 ◽  
pp. 437-445
Author(s):  
Gregory S. Thomas
Keyword(s):  
Heart Rate ◽  
Physical Fitness ◽  
Sample Size ◽  
Older Persons ◽  
Heart Rate Response ◽  
Large Sample Size ◽  
Maximum Heart Rate ◽  
Large Sample ◽  
Response To Exercise

The chapter Heart Rate Response to Exercise reviews the studies performed to estimate a patient’s maximum predicted heart rate. While the commonly used formula (220 – age), developed in 1971, is easy to remember, it underestimates the actual maximum heart rate in older persons. Studies of large sample size have found the maximum heart rate to be relatively independent of sex and physical fitness but to incrementally decline with age. The decrease with age is less than 1 beat per minute per year, however. A more accurate and recommended formula is [(208) – (0.7)(age)] as developed by Tanaka and colleagues.

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