Effects of two successive maximal exercise tests on pulmonary gas exchange in athletes

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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Pulmonary gas exchange during exercise in athletes. I. Ventilation-perfusion mismatch and diffusion limitation

Journal of Applied Physiology ◽

10.1152/jappl.1994.77.2.912 ◽

1994 ◽

Vol 77 (2) ◽

pp. 912-917 ◽

Cited By ~ 95

Author(s):

S. R. Hopkins ◽

D. C. McKenzie ◽

R. B. Schoene ◽

R. W. Glenny ◽

H. T. Robertson

Keyword(s):

Gas Exchange ◽

Aerobic Capacity ◽

Maximal Exercise ◽

Cycle Ergometer ◽

Pulmonary Gas Exchange ◽

Inert Gases ◽

Inert Gas ◽

Diffusion Limitation ◽

Maximal Aerobic Capacity ◽

Arterial Blood

To investigate pulmonary gas exchange during exercise in athletes, 10 high aerobic capacity athletes (maximal aerobic capacity = 5.15 +/- 0.52 l/min) underwent testing on a cycle ergometer at rest, 150 W, 300 W, and maximal exercise (372 +/- 22 W) while trace amounts of six inert gases were infused intravenously. Arterial blood samples, mixed expired gas samples, and metabolic data were obtained. Indexes of ventilation-perfusion (VA/Q) mismatch were calculated by the multiple inert gas elimination technique. The alveolar-arterial difference for O2 (AaDO2) was predicted from the inert gas model on the basis of the calculated VA/Q mismatch. VA/Q heterogeneity increased significantly with exercise and was predicted to increase the AaDO2 by > 17 Torr during heavy and maximal exercise. The observed AaDO2 increased significantly more than that predicted by the inert gas technique during maximal exercise (10 +/- 10 Torr). These data suggest that this population develops diffusion limitation during maximal exercise, but VA/Q mismatch is the most important contributor (> 60%) to the wide AaDO2 observed.

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

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00725.2003 ◽

2004 ◽

Vol 287 (5) ◽

pp. R1202-R1208 ◽

Cited By ~ 71

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.

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Effect of prolonged heavy exercise on pulmonary gas exchange in horses

Journal of Applied Physiology ◽

10.1152/jappl.1998.84.5.1723 ◽

1998 ◽

Vol 84 (5) ◽

pp. 1723-1730 ◽

Cited By ~ 33

Author(s):

S. R. Hopkins ◽

W. M. Bayly ◽

R. F. Slocombe ◽

H. Wagner ◽

P. D. Wagner

Keyword(s):

Gas Exchange ◽

Oxygen Uptake ◽

Gas Phase ◽

Maximal Exercise ◽

Treadmill Exercise ◽

Submaximal Exercise ◽

Pulmonary Gas Exchange ◽

Diffusion Limitation ◽

Short Term ◽

Thoroughbred Horses

During short-term maximal exercise, horses have impaired pulmonary gas exchange, manifested by diffusion limitation and arterial hypoxemia, without marked ventilation-perfusion (V˙a/Q˙) inequality. Whether gas exchange deteriorates progressively during prolonged submaximal exercise has not been investigated. Six thoroughbred horses performed treadmill exercise at ∼60% of maximal oxygen uptake until exhaustion (28–39 min). Multiple inert gas, blood-gas, hemodynamic, metabolic rate, and ventilatory data were obtained at rest and 5-min intervals during exercise. Oxygen uptake, cardiac output, and alveolar-arterial[Formula: see text] gradient were unchanged after the first 5 min of exercise. Alveolar ventilation increased progressively during exercise, from increased tidal volume and respiratory frequency, resulting in an increase in arterial[Formula: see text] and decrease in arterial[Formula: see text]. At rest there was minimalV˙a/Q˙inequality, log SD of the perfusion distribution (log SDQ˙) = 0.20. This doubled by 5 min of exercise (log SDQ˙ = 0.40) but did not increase further. There was no evidence of alveolar-end-capillary diffusion limitation during exercise. However, there was evidence for gas-phase diffusion limitation at all time points, and enflurane was preferentially overretained. Horses maintain excellent pulmonary gas exchange during exhaustive, submaximal exercise. AlthoughV˙a/Q˙inequality is greater than at rest, it is less than observed in most mammals and the effect on gas exchange is minimal.

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Cardiac output and pulmonary gas exchange at maximal exercise after atrial redirection for complete transposition

European Heart Journal ◽

10.1053/euhj.1998.1147 ◽

1998 ◽

Vol 19 (12) ◽

pp. 1856-1864 ◽

Cited By ~ 8

Author(s):

T. Gilljam ◽

B.O. Eriksson ◽

R. Sixt

Keyword(s):

Cardiac Output ◽

Gas Exchange ◽

Maximal Exercise ◽

Pulmonary Gas Exchange ◽

Complete Transposition

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Impact of Pharmacologically Left Shifting the Oxygen–Hemoglobin Dissociation Curve on Arterial Blood Gases and Pulmonary Gas Exchange During Maximal Exercise in Hypoxia

High Altitude Medicine & Biology ◽

10.1089/ham.2020.0159 ◽

2021 ◽

Author(s):

Glenn M. Stewart ◽

Troy J. Cross ◽

Michael J. Joyner ◽

Steven C. Chase ◽

Timothy Curry ◽

...

Keyword(s):

Gas Exchange ◽

Maximal Exercise ◽

Blood Gases ◽

Pulmonary Gas Exchange ◽

Dissociation Curve ◽

Arterial Blood Gases ◽

Arterial Blood

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DLCO versus DLCO/VA as predictors of pulmonary gas exchange

Yearbook of Pulmonary Disease ◽

10.1016/s8756-3452(08)70634-0 ◽

2008 ◽

Vol 2008 ◽

pp. 174-175

Author(s):

K.L. Lewis

Keyword(s):

Gas Exchange ◽

Pulmonary Gas Exchange

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Mechanisms of improvement in pulmonary gas exchange during isovolemic hemodilution

Journal of Applied Physiology ◽

10.1152/jappl.1999.87.1.132 ◽

1999 ◽

Vol 87 (1) ◽

pp. 132-141 ◽

Cited By ~ 39

Author(s):

Steven Deem ◽

Richard G. Hedges ◽

Steven McKinney ◽

Nayak L. Polissar ◽

Michael K. Alberts ◽

...

Keyword(s):

Blood Flow ◽

Fractal Dimension ◽

Gas Exchange ◽

Spatial Correlation ◽

Pulmonary Blood Flow ◽

Minute Ventilation ◽

Flow Distribution ◽

Pulmonary Gas Exchange ◽

Normal Lung ◽

Blood Flow Distribution

Severe anemia is associated with remarkable stability of pulmonary gas exchange (S. Deem, M. K. Alberts, M. J. Bishop, A. Bidani, and E. R. Swenson. J. Appl. Physiol. 83: 240–246, 1997), although the factors that contribute to this stability have not been studied in detail. In the present study, 10 Flemish Giant rabbits were anesthetized, paralyzed, and mechanically ventilated at a fixed minute ventilation. Serial hemodilution was performed in five rabbits by simultaneous withdrawal of blood and infusion of an equal volume of 6% hetastarch; five rabbits were followed over a comparable time. Ventilation-perfusion (V˙a/Q˙) relationships were studied by using the multiple inert-gas-elimination technique, and pulmonary blood flow distribution was assessed by using fluorescent microspheres. Expired nitric oxide (NO) was measured by chemiluminescence. Hemodilution resulted in a linear fall in hematocrit over time, from 30 ± 1.6 to 11 ± 1%. Anemia was associated with an increase in arterial [Formula: see text] in comparison with controls ( P < 0.01 between groups). The improvement in O2 exchange was associated with reducedV˙a/Q˙heterogeneity, a reduction in the fractal dimension of pulmonary blood flow ( P = 0.04), and a relative increase in the spatial correlation of pulmonary blood flow ( P = 0.04). Expired NO increased with anemia, whereas it remained stable in control animals ( P < 0.0001 between groups). Anemia results in improved gas exchange in the normal lung as a result of an improvement in overallV˙a/Q˙matching. In turn, this may be a result of favorable changes in pulmonary blood flow distribution, as assessed by the fractal dimension and spatial correlation of blood flow and as a result of increased NO availability.

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