Several studies have suggested that athletes with low hemoglobin saturation during exercise may experience impaired pulmonary blood gas exchange during maximal exercise. Blood viscosity may be implicated in exercise-induced pulmonary hemorrhage in race horses. We hypothesized that blood rheology may contribute to impaired gas exchange and reduced hemoglobin saturation during exercise in humans. A group of 20 highly trained endurance athletes participated in this study, 9 with low hemoglobin saturation during exercise (Low-SpO2 group) and 11 with normal hemoglobin saturation (High-SpO2 group). All subjects performed a progressive exercise test conducted to V·O2max. Venous blood was sampled at rest, 50 % V·O2max and maximal exercise. Blood viscosity (ηb) was measured at very high shear rate (1000 s-1) and 37 °C with a falling ball viscometer. The erythrocyte rigidity coefficient, “Tk”, was calculated using the Dintenfass equation. At rest, no significant difference in ηb was observed between the two groups (3.00 ± 0.08 mPa · s vs. 3.01 ± 0.04 mPa · s for the Low-SpO2 and High-SpO2 group, respectively). At 50 % V·O2max and maximal exercise, ηb was higher in Low-SpO2 (p < 0.01). Tk decreased in High-SpO2 (p < 0.01) but remained unchanged in the other group during testing. The greater increase in ηb in the Low-SpO2 group during exercise may therefore have been due to the lack of reduction in Tk. As suggested by previous studies, the greater increase in blood viscosity in athletes with low hemoglobin saturation may lead to vascular shear stress. Whether this could impair the blood gas barrier and result in exercise-induced hypoxemia requires further study.
Key words
Hypoxemia - red blood cell - hemorheology - endurance
References
1
Aguilaniu B, Flore P, Page E, Maitre J, Lacour J R, Perrault H.
Effects of indomethacin and polyunsaturated fatty acid diet on exercise-induced hypoxaemia in master athletes.
Eur J Appl Physiol Occup Physiol.
1998;
77
81-88
2
Aillaud M F, Poisson C, Buonocore M, Billery M, Lefèvre P, Juhan Vague.
Etude du viscosimètre médical à chute de billes à haut taux de cisaillement: MT 90.
Pharm Biol.
1985;
159
291-294
5
Brun J F, Fons C, Raynaud E, Fedou C, Orsetti A.
Influence of circulating lactate on blood rheology during exercise in professional football players.
Rev Port Hemorrheol.
1991;
5
219-229
6
Brun J F, Fons C, Supparo C, Mallard C, Orsetti A.
Could exercise-induced increase in blood viscosity at high shear rate be entirely explained by hematocrit and plasma viscosity changes?.
Clin Hemorheol.
1993;
13
187-199
7
Brun J F, Micallef J P, Supparo C, Orsetti A.
Effects of a standardized breakfast compared to fasting on the hemorheologic responses to submaximal exercise.
Clin Hemorheol Microcirc.
1995;
15
213-220
11
Doffin J, Perrault R, Garnaud G.
Blood viscosity measurements in both extensional and shear flow by a falling ball viscometer.
Biorheology Suppl.
1984;
1
89-93
12
Fons C, Brun J F, Supparo I, Mallart C, Bardet L, Orsetti A.
Evaluation of blood viscosity at high shear rate with a falling ball viscometer.
Clin Hemorheol.
1993;
13
651-659
13
Godin C, Caprani A.
Effect of blood storage on erythrocyte/wall interactions: implications for surface charge and rigidity.
Eur Biophys J.
1997;
26
175-182
14
Gueguen-Duchesne M, Durand F, Beillot J, Dezier J F, Rochcongar P, LeGoff M C, Pommereuil M, Genetet B.
Could maximal exercise be a hemorheological risk factor?.
Clin Hemorheol.
1987;
7
418
15
Guezennec C Y, Nadaud J F, Satabin P, Leger F, Lafargue P.
Influence of polyunsaturated fatty acid diet on the hemorheological response to physical exercise in hypoxia.
Int J Sports Med.
1989;
10
286-291
16
Hardeman H R, Peters H PF, Goedhart P T.
Low hematocrit and plasma fibrinogen in trained athletes increase hemorheological tolerance for physical stress.
Biorheology.
1995;
32
401
19
Lipovac V, Gavella M, Turk Z, Skrabalo Z.
Influence of lactate on the insulin action on red blood cell filterability.
Clin Hemorheol.
1985;
5
421-428
20
McClay C B, Weiss D J, Smith 2nd C M.
Evaluation of hemorheologic variables as implications for exercise-induced pulmonary hemorrhage in racing thoroughbreds.
Am J Vet Res.
1992;
53
1380-1385
24
Sjogaard G, Adams R P, Saltin B.
Water and ion shifts in skeletal muscle of humans with intense dynamic knee extension.
Am J Physiol.
1985;
248
190-196
25
Smith J A, Telford R D, Kolbuch-Braddon M, Weidemann M J.
Lactate/H+ uptake by red blood cells during exercise alters their physical properties.
Eur J Appl Physiol Occup Physiol.
1997;
75
54-61
27
Vandewalle H, Lacombe C, Lelievre J C, Poirot C.
Blood viscosity after a 1-h submaximal exercise with and without drinking.
Int J Sports Med.
1988;
9
104-107
28
Weiss D J, Geor R J, Burger K.
Effects of pentoxifylline on hemorheologic alterations induced by incremental treadmill exercise in thoroughbreds.
Am J Vet Res.
1996;
57
1364-1368
30
Wood S C, Doyle M P, Appenzeller O.
Effects of endurance training and long distance running on blood viscosity.
Med Sci Sports Exerc.
1991;
23
1265-1269
