RESUMEN
Effects of exercise on erythrocyte aggregation were investigated in 19 elite athletes. High shear rate viscometry (1000 s(-1) evidenced an increase in blood viscosity explained by an increase in hematocrit (+8% p<0.01) and plasma viscosity (+7% p<0.01). Erythrocyte rigidity index and erythrocyte aggregability measured using the Myrenne erythroaggregometer did not change. However, using the laser backscattering technique (SEFAM erythroaggregometer), we observed significant changes in aggregability and desaggregability after 25 min of exercise. The initial aggregation time (TA) decreased by 33% (p<0.01), while the final aggregation time decreased by 13.6% (p<0.01). TA was correlated with aerobic working capacity (r=0.73; p=0.005), which was negatively correlated with blood viscosity at rest (r=-0.57; p=0.043). A significant relationship was observed between TA and the initial fibrinogen levels (r=0.71; p<0.01). The plasma volume contraction during exercise was found to be statistically explained by the water loss proportional to the total work load. Thus, laser backscattering demonstrates an increase in aggregability and a decrease in disaggregability of red cells during exercise, proportional to baseline fibrinogen values.
Asunto(s)
Agregación Eritrocitaria/fisiología , Ejercicio Físico/fisiología , Adulto , Viscosidad Sanguínea , Agua Corporal , Impedancia Eléctrica , Deformación Eritrocítica , Prueba de Esfuerzo , Tolerancia al Ejercicio , Fibrinógeno/análisis , Hematócrito , Humanos , Masculino , Nefelometría y Turbidimetría , Pletismografía de ImpedanciaRESUMEN
Exercise-induced impairment in blood fluidity has been supposed to increase cardiovascular risk but there is no data to support this hypothesis. We report the case of a 50 yr old marathon runner who underwent a central retinal vein thrombosis after a marathon run. We investigated his rheological response to exercise compared to control subjects of previous studies. During a standardized sub-maximal exercise-test, the increase in blood viscosity (+28%) and hematocrit (+25%) exceeded the control range but the most striking differences were found for red cell aggregation (Myrenne +47%) and disaggregation thresholds (Affibio +37%). Although some of this post-exercise hyperviscosity pattern may be due to the previous vascular event, these findings may also support the hypothesis of a role for hemorheological alterations during exercise in the pathogenesis of this marathon-induced retinal thrombosis, and indicate that after such an event hemorheological adaptation to exercise remains markedly disturbed.
Asunto(s)
Ejercicio Físico/fisiología , Hemorreología , Oclusión de la Vena Retiniana/etiología , Viscosidad Sanguínea , Agregación Eritrocitaria , Hematócrito , Humanos , Masculino , Persona de Mediana Edad , Oclusión de la Vena Retiniana/sangre , Carrera/lesionesRESUMEN
The GH-IGF axis has been recently suggested to modulate blood rheology in trained athletes, via GH effects on body water status and a possible action of IGF-I on erythrocyte deformability and aggregability. Another potential candidate for such a rheologic effect of the GH-IGF axis is insulin-like growth factor binding protein-1 (IGF-BP1) which is increased in trained people and correlated to fitness: IGF-BP1 is elevated in patients with polycythemia vera and stimulates erythroid burst formation in vitro. We investigated the statistical relationships between IGF-BP1 and blood rheology in athletes. 21 soccer players, age 24.5+/-1.13 yr; body mass index 23.7+/-0.38 kg/m(2); VO2max 44.8+/-7 ml.min(-1).kg(-1)). The major statistical determinant of IGFBP1 (measured at rest after overnight fast) was age (r=0.752, p=0.00013) which was not correlated with rheological parameters. IGF BP1 was negatively correlated with blood viscosity eta (high shear rate r=-0.516, p=0.024) and positively correlated with the percentage of extracellular water in total body water (ECW/TBW) (r=0.488, p=0.039). The previously reported correlations between IGF-I and both eta (r=0.637, p=0.003) and red cell rigidity "Tk" (r=0.696, p=0.0137) were observed, but IGF-I and IGF-BP1 were not correlated to each other (r=-0.176 ns) and their correlations with eta and Tk appeared to be independent when studied by multivariate analysis. Consistent with these correlations, subjects in the upper tertile of IGF-BP1 (>23.4 ng/ml) compared to those in the lower (<7.5 ng/ml) had a higher percentage of ECW/TBW (40.8+/-0.4 vs 38+/-0.8%, p=0.033), a lower eta (2.7+/-0.05 vs 2.97+/-0.06 mPa.s, p=0.016), and a lower Tk (0.54+/-0.05 vs 0.63+/-0.01, p=0.027). Thus, beside GH and IGF-I, IGF-BP1, which is reported to act on erythroid progenitors, exhibits statistical relationships with blood fluidity and erythrocyte flexibility that may suggest a physiological role in improving blood rheology.
Asunto(s)
Hemorreología , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Deportes/fisiología , Adulto , Fenómenos Fisiológicos Sanguíneos , Viscosidad Sanguínea , Agua Corporal , Pruebas Hematológicas , Humanos , MasculinoRESUMEN
Exercise training is known (1) to enhance the function of the GH-IGF-I system, which has profound effects on body fluid status; (2) to increase blood fluidity. Thus, we investigated during an exercise-test in 39 male elite sportsmen (age 23.7+/-0.72 years; body mass index 23.7+/-0.28 kg/m2) the possible relationships between GH and IGF-I status and the rheological properties of blood. Two correlations indicate a relationship between body hydration and fitness: isometric handgrip strength is correlated with the percentage of extracellular water in total body water (r = 0.432, p = 0.02) and the aerobic working capacity W170 is negatively correlated with hematocrit (r = -0.341, p = 0.039). Water loss during exercise appears to be inversely related to fitness as evaluated by W170 (r = -0.529, p = 0.05), and is positively correlated with the score of signs of overtraining (r = 0.725, p = 0.003) and with the red blood cell aggregation index (r = 0.584, p = 0.036). Finally, while the GH peak value is correlated with the extracellular water volume (r = 0.393, p = 0.02), IGF-I is correlated with blood viscosity (r = 0.546, p = 0.0003), suggesting that when IGF-I values are within the upper quintile (>340 ng/ml) IGF-I may unfavourably affect blood rheology. Among factors of blood viscosity, IGF-I exhibits a borderline correlation (p = 0.05) with "Tk" and the ratio IGF1/IGFBP3 which reflects free circulating IGF-I is correlated with red cell aggregability measured with the Myrenne "M" (r = 0.485, p = 0.014) and S60 (r = 0.396, p = 0.494). These findings confirm the importance of hydration and dehydration as determinants of both blood rheology and exercise performance. Moreover, they suggest that values of IGF-I within the upper quintile are associated with an impairment of blood fluidity, possibly due to a direct effect of IGF-I on red cell deformability and aggregability.
Asunto(s)
Viscosidad Sanguínea , Ejercicio Físico/fisiología , Factor I del Crecimiento Similar a la Insulina/análisis , Deportes , Adulto , Agua Corporal , Deshidratación/sangre , Agregación Eritrocitaria , Deformación Eritrocítica , Prueba de Esfuerzo , Hemorreología , Humanos , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Masculino , Aptitud FísicaRESUMEN
We investigated relationships among body composition, blood rheology, and exercise performance in 14 rugbymen (19-31 yr, weight 65.8-109.2 kg, height 1.7-1.96 m, body mass index 21.7-33.1 kg/m2) who underwent a standardized submaximal exercise session on cycloergometer corresponding to 225 kJ over 30 min. The rheologic response to exercise was measured with the MT90 viscometer and the Myrenne aggregometer. Dehydration, evaluated by precision weighing, resulted in a loss of 360 to 973 g water, i.e., 1.69 to 4.32 g/kJ. This loss of water is not correlated to plasma volume contraction as assessed by the equation of Greenleaf. Hemorheologic changes are observed, but they are correlated neither to water loss, nor to plasma volume contraction. A 36% increase in blood viscosity (p < 0.01) is mainly explained by a red blood cell rigidification (p < 0.02), although hematocrit and plasma viscosity also increase (p < 0.01). Isometric adductor strength (specific ergometer) is correlated to erythrocyte flexibility (r = 0.680, p < 0.01). Red cell aggregability (Myrenne aggregometer) is correlated to fat mass measured by bioelectrical impedance (r = 0.634, p < 0.02). Aerobic working capacity index W170 is negatively correlated to the increase in plasma viscosity during exercise (r = -0.546, p < 0.05), suggesting that this event is less important in stronger individuals. This study shows that fat mass, even within a physiological range, is a determinant of erythrocyte aggregability, suggesting that training-induced alterations in body composition play a role in the specific hemorheologic profile of athletes. In addition, both erythrocyte flexibility and the magnitude of fluid shifts during exercise appear to be related to fitness in these sportsmen.
Asunto(s)
Composición Corporal , Tolerancia al Ejercicio/fisiología , Fútbol Americano/fisiología , Hemorreología , Tejido Adiposo/anatomía & histología , Adulto , Viscosidad Sanguínea , Constitución Corporal , Índice de Masa Corporal , Agua Corporal , Deshidratación/fisiopatología , Agregación Eritrocitaria , Deformación Eritrocítica , Prueba de Esfuerzo , Fuerza de la Mano , Hematócrito , Humanos , Contracción Isométrica , Masculino , Pletismografía de ImpedanciaRESUMEN
We aimed at investigating relationships between zinc status, blood rheology and blood glucose during exercise. Twenty-one professional football players underwent a triangular maximal exercise test on cycloergometer, with progressively increasing work loads until VO2max. On the whole these subjects had a low serum zinc because nine of them had a hypozincemia (0.54 +/- 0.01 mg/l) which suggested a zinc deficiency. Subjects with low serum zinc were able to perform a lower power output (123 +/- 8.71 vs. 166.27 +/- 14.84 watts, p = 0.029) and exhibited a higher increase in blood lactate during exercise (7.51 +/- 0.81 vs. 5.57 +/- 0.33 mmol/l, p = 0.024) resulting in a lower 2 mmol lactate threshold (44.7 +/- 3.9% vs. 58.9 +/- 4.8% of maximal power output, p = 0.04). They were less able to maintain their plasma glucose and exhibited a tendency towards hypoglycemia (p = 0.0153). Hypozincemia was associated with a higher viscometric RBC rigidity index (p = 0.0009), and this index was negatively correlated to serum zinc (r = -0.68, p = 0.7 x 10(-3)). Blood viscosity at high shear rate (MT90 viscosimeter) corrected for hematocrit (45%) remained higher during exercise in these hypozincemic subjects (p = 0.003). This study suggests that zinc status may influence blood rheology during exercise, either by its direct action on RBC flexibility (demonstrated in vitro) or by its effect on lactate accumulation which may in turn modify erythrocyte fexibility.
Asunto(s)
Viscosidad Sanguínea , Fútbol Americano/fisiología , Zinc/sangre , Adulto , Prueba de Esfuerzo , Humanos , Modelos Lineales , Masculino , Reología , Zinc/deficienciaRESUMEN
Glucose clamp experiments have shown that patients with reactive postprandial hypoglycaemia (PRH) frequently have an increased glucose disposal, but the relative involvement of insulin sensitivity (SI) and glucose effectiveness (Sg) in this process remains unknown. The minimal model approach was used to compare 13 patients in whom moderate reactive hypoglycaemia ( < 3.3 mmol) had been previously diagnosed and 13 matched controls. The intravenous glucose tolerance test (IVGTT, 0.5 g/kg glucose IV) with 0.02 U/kg insulin given at the 19th min and frequent sampling over 180 min shows that PRH patients exhibit a higher glucose tolerance coefficient Kg (2.99 +/- 0.26 vs 2.19 +/- 0.12; P < 0.02), higher SI [22.9 +/- 6.4 vs 7.18 +/- 0.14 min-1/(microU/ml). 10(-4); P < 0.01] and higher Sg (3.84 +/- 0.35 vs 2.92 +/- 0.79 min-1. 10(-2); P < 0.05). The increase in Sg is explained by an increase in its component basal insulin effectiveness (BIE: 1.2 +/- 0.27 min-1.10(-2) in PRH subjects vs 0.58 +/- 0.07; P < 0.05) rather than an increase in Sg at zero insulin. The increase in BIE results from the high values of SI. In 4 PRH subjects SI and Sg were within the normal range, and the increase in Kg evidenced in the 9 others was explained by an increase in SI alone in 3 cases, in Sg alone in 1 case, and both SI and Sg in 5 cases. Thus, in sedentary subjects, the previously reported rise in tissue glucose assimilation is mainly explained by an increased insulin-mediated glucose disposal rather than non-insulin-mediated glucose disposal.
Asunto(s)
Glucemia/metabolismo , Ingestión de Alimentos , Hipoglucemia/fisiopatología , Insulina/farmacología , Adulto , Glucemia/efectos de los fármacos , Femenino , Glucosa/metabolismo , Técnica de Clampeo de la Glucosa , Prueba de Tolerancia a la Glucosa , Humanos , Hipoglucemia/sangre , Masculino , Valores de ReferenciaRESUMEN
The insulin resistance syndrome (or syndrome X) is a cluster of symptoms (dyslipidemia, impaired glucose tolerance, overweight, hypertension) associated with a higher risk of atherosclerosis. It has been suggested that hemorheological abnormalities, often found in association with most of these symptoms, may be a part of this syndrome, and possibly play a role in the circulatory abnormalities. In 22 nondiabetic women (20-54 years) presenting a wide range of body mass index (from 20 to 48 kg/m2), insulin sensitivity was assessed with the minimal model procedure, over a 180 min intravenous glucose tolerance test with frequent sampling. The insulin sensitivity index SI (i.e. the slope of the dose-response relationship between insulin increased above baseline and glucose disposal) ranges between 0.1 and 20.1 x 10(-4) min-1/microU/ml) i.e all the range of insulin sensitivity. SI was negatively correlated with blood viscosity (r = -0.530 p < 0.02), body mass index (r = 0.563 p < 0.01) and baseline insulinemia (r = 0.489 p < 0.05). These correlations were independent of each other and were not explained by relationships between SI and fibrinogen or blood lipids. Thus, blood fluidity is correlated with insulin sensitivity when it is measured with an accurate technique, suggesting that blood hyperviscosity is a symptom of insulin resistance that might be involved in the cardiovascular risk of this syndrome.