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Red blood cells in sports: effects of exercise and training on oxygen supply by red blood cells.

Mairbäurl H - Front Physiol (2013)

Bottom Line: Trained athletes, particularly in endurance sports, have a decreased hematocrit, which is sometimes called "sports anemia." This is not anemia in a clinical sense, because athletes have in fact an increased total mass of red blood cells and hemoglobin in circulation relative to sedentary individuals.The slight decrease in hematocrit by training is brought about by an increased plasma volume (PV).Together, these adjustments cause a decrease in the average age of the population of circulating red blood cells in trained athletes.

View Article: PubMed Central - PubMed

Affiliation: Medical Clinic VII, Sports Medicine, University of Heidelberg Heidelberg, Germany.

ABSTRACT
During exercise the cardiovascular system has to warrant substrate supply to working muscle. The main function of red blood cells in exercise is the transport of O2 from the lungs to the tissues and the delivery of metabolically produced CO2 to the lungs for expiration. Hemoglobin also contributes to the blood's buffering capacity, and ATP and NO release from red blood cells contributes to vasodilation and improved blood flow to working muscle. These functions require adequate amounts of red blood cells in circulation. Trained athletes, particularly in endurance sports, have a decreased hematocrit, which is sometimes called "sports anemia." This is not anemia in a clinical sense, because athletes have in fact an increased total mass of red blood cells and hemoglobin in circulation relative to sedentary individuals. The slight decrease in hematocrit by training is brought about by an increased plasma volume (PV). The mechanisms that increase total red blood cell mass by training are not understood fully. Despite stimulated erythropoiesis, exercise can decrease the red blood cell mass by intravascular hemolysis mainly of senescent red blood cells, which is caused by mechanical rupture when red blood cells pass through capillaries in contracting muscles, and by compression of red cells e.g., in foot soles during running or in hand palms in weightlifters. Together, these adjustments cause a decrease in the average age of the population of circulating red blood cells in trained athletes. These younger red cells are characterized by improved oxygen release and deformability, both of which also improve tissue oxygen supply during exercise.

No MeSH data available.


Related in: MedlinePlus

Effects of exercise on Hb-O2 affinity. Shifts of the O2-dissociation curves are calculated for an arterial pH = 7.4, a capillary pH = 7.3, and temperature is 37°C rest. Values used to calculate oxygen dissociation curves (ODC) for exercise were an arterial pH = 7.15 at 38.5°C, a capillary pH = 7.0 and temperature = 41°C in working muscle using the equation giving in the text using data from exercise tests (Sun et al., 2000). At rest, assuming a venous PO2 = 40 mmHg, SO2 decreases by 28% (points A and B), while extraction nearly triples in exercise conditions (delta SO2 = 79%) assuming a venous PO2 = 25 mmHg during exercise (points C and D).
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Figure 2: Effects of exercise on Hb-O2 affinity. Shifts of the O2-dissociation curves are calculated for an arterial pH = 7.4, a capillary pH = 7.3, and temperature is 37°C rest. Values used to calculate oxygen dissociation curves (ODC) for exercise were an arterial pH = 7.15 at 38.5°C, a capillary pH = 7.0 and temperature = 41°C in working muscle using the equation giving in the text using data from exercise tests (Sun et al., 2000). At rest, assuming a venous PO2 = 40 mmHg, SO2 decreases by 28% (points A and B), while extraction nearly triples in exercise conditions (delta SO2 = 79%) assuming a venous PO2 = 25 mmHg during exercise (points C and D).

Mentions: Exercising muscle cells release H+, CO2, and lactate into blood capillaries, and there is also a higher temperature in working muscle than in inactive tissues. Blood entering capillaries of exercising muscles is acutely exposed to these changes, which causes a rapid decrease in Hb-O2 affinity. P50 values of ~34–48 mmHg can be estimated from changes in blood gasses (provided e.g., in Sun et al., 2000). Temperature increases from 37°C at rest to 41°C during exercise. Because there is a continuous change in blood composition by admixture of metabolites as new blood enters a capillary, P50 values are lower at the arterial side of the capillaries than at their venous end (Mairbäurl and Weber, 2012) causing an enormous rightward shift of the ODC within the capillaries that increases unloading of O2 from Hb considerably (Berlin et al., 2002). This is also demonstrated by the extensive shift to the right of the ODC in capillary blood in exercise conditions relative to rest (Figure 2; points D and B, respectively). Trained individuals have a higher Bohr effect at low SO2 probably due to elevated 2,3-DPG (Böning et al., 1975; Braumann et al., 1982; Mairbäurl et al., 1983), which might cause an even greater increase in the arterio-to-venous O2 difference.


Red blood cells in sports: effects of exercise and training on oxygen supply by red blood cells.

Mairbäurl H - Front Physiol (2013)

Effects of exercise on Hb-O2 affinity. Shifts of the O2-dissociation curves are calculated for an arterial pH = 7.4, a capillary pH = 7.3, and temperature is 37°C rest. Values used to calculate oxygen dissociation curves (ODC) for exercise were an arterial pH = 7.15 at 38.5°C, a capillary pH = 7.0 and temperature = 41°C in working muscle using the equation giving in the text using data from exercise tests (Sun et al., 2000). At rest, assuming a venous PO2 = 40 mmHg, SO2 decreases by 28% (points A and B), while extraction nearly triples in exercise conditions (delta SO2 = 79%) assuming a venous PO2 = 25 mmHg during exercise (points C and D).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3824146&req=5

Figure 2: Effects of exercise on Hb-O2 affinity. Shifts of the O2-dissociation curves are calculated for an arterial pH = 7.4, a capillary pH = 7.3, and temperature is 37°C rest. Values used to calculate oxygen dissociation curves (ODC) for exercise were an arterial pH = 7.15 at 38.5°C, a capillary pH = 7.0 and temperature = 41°C in working muscle using the equation giving in the text using data from exercise tests (Sun et al., 2000). At rest, assuming a venous PO2 = 40 mmHg, SO2 decreases by 28% (points A and B), while extraction nearly triples in exercise conditions (delta SO2 = 79%) assuming a venous PO2 = 25 mmHg during exercise (points C and D).
Mentions: Exercising muscle cells release H+, CO2, and lactate into blood capillaries, and there is also a higher temperature in working muscle than in inactive tissues. Blood entering capillaries of exercising muscles is acutely exposed to these changes, which causes a rapid decrease in Hb-O2 affinity. P50 values of ~34–48 mmHg can be estimated from changes in blood gasses (provided e.g., in Sun et al., 2000). Temperature increases from 37°C at rest to 41°C during exercise. Because there is a continuous change in blood composition by admixture of metabolites as new blood enters a capillary, P50 values are lower at the arterial side of the capillaries than at their venous end (Mairbäurl and Weber, 2012) causing an enormous rightward shift of the ODC within the capillaries that increases unloading of O2 from Hb considerably (Berlin et al., 2002). This is also demonstrated by the extensive shift to the right of the ODC in capillary blood in exercise conditions relative to rest (Figure 2; points D and B, respectively). Trained individuals have a higher Bohr effect at low SO2 probably due to elevated 2,3-DPG (Böning et al., 1975; Braumann et al., 1982; Mairbäurl et al., 1983), which might cause an even greater increase in the arterio-to-venous O2 difference.

Bottom Line: Trained athletes, particularly in endurance sports, have a decreased hematocrit, which is sometimes called "sports anemia." This is not anemia in a clinical sense, because athletes have in fact an increased total mass of red blood cells and hemoglobin in circulation relative to sedentary individuals.The slight decrease in hematocrit by training is brought about by an increased plasma volume (PV).Together, these adjustments cause a decrease in the average age of the population of circulating red blood cells in trained athletes.

View Article: PubMed Central - PubMed

Affiliation: Medical Clinic VII, Sports Medicine, University of Heidelberg Heidelberg, Germany.

ABSTRACT
During exercise the cardiovascular system has to warrant substrate supply to working muscle. The main function of red blood cells in exercise is the transport of O2 from the lungs to the tissues and the delivery of metabolically produced CO2 to the lungs for expiration. Hemoglobin also contributes to the blood's buffering capacity, and ATP and NO release from red blood cells contributes to vasodilation and improved blood flow to working muscle. These functions require adequate amounts of red blood cells in circulation. Trained athletes, particularly in endurance sports, have a decreased hematocrit, which is sometimes called "sports anemia." This is not anemia in a clinical sense, because athletes have in fact an increased total mass of red blood cells and hemoglobin in circulation relative to sedentary individuals. The slight decrease in hematocrit by training is brought about by an increased plasma volume (PV). The mechanisms that increase total red blood cell mass by training are not understood fully. Despite stimulated erythropoiesis, exercise can decrease the red blood cell mass by intravascular hemolysis mainly of senescent red blood cells, which is caused by mechanical rupture when red blood cells pass through capillaries in contracting muscles, and by compression of red cells e.g., in foot soles during running or in hand palms in weightlifters. Together, these adjustments cause a decrease in the average age of the population of circulating red blood cells in trained athletes. These younger red cells are characterized by improved oxygen release and deformability, both of which also improve tissue oxygen supply during exercise.

No MeSH data available.


Related in: MedlinePlus