Alterations of blood rheology during and after exercise are both consequences and modifiers of body's adaptation to muscular activity

• Published in: Science & sports Vol. 22; no. 6; pp. 251 - 266
• Main Authors: BRUN, J.-F, CONNES, P, VARLET-MARIE, E
• Format: Conference Proceeding Journal Article
• Language: English; French
• Published: Paris Elsevier 01.12.2007
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Vertebrates: blood, hematopoietic organs, reticuloendothelial system; Physical exercise; Human; Viscosity; Sport; Rheology; Interaction; Muscle contraction; Blood; Adaptation
• ISSN: 0765-1597
• DOI: 10.1016/j.scispo.2007.09.010

Objectives: Current knowledge. Exercise has several hemorheological effects that we previously proposed to classify as a triphasic phenomenon: acute effects (hyperviscosity mostly due to hemoconcentration but also to some alterations of erythrocyte properties), delayed effects (hyperhydration resulting in hemodilution and hypoviscosity) and a chronic situation, which can be termed hemorheologic fitness. This presentation focuses on this last stage of hemorheologic effects of exercise. Some recent studies have shown that, according to the training pattern or intensity, it may result in different aspects. In endurance athletes (e.g., cyclists), there is mostly a chronic ''hyperhydration-dilution status'', but some intriguing modifications of red cell properties can also be found, in connection with metabolic and hormonal changes (insulin sensitivity, growth hormone and IGF-I status...). In sports where strength is improved rather than endurance, red cell aggregation and deformability are improved without marked changes in body fluid status and are correlated to body composition (percentage of fat) and the balance of substrate oxidation at exercise. In markedly sedentary obese, insulin resistant patients submitted to a therapeutic protocol of training, the parameter which is mostly improved is plasma viscosity, which appears to reflect in this case the plasma protein pattern related to the metabolic disorders (fibrinogen, lipoproteins...). Finally, overtraining reverses this picture of ''hemorheologic fitness'', mostly by inducing a reversal of the ''hyperhydration-hypoviscosity'' pattern. The physiological and pathophysiological importance of these observations remains unsettled, but there is increasing published evidence that these hemorheologic modifications may interfere with the physiology of the human body at exercise. In addition, exercise appears to be a rather effective ''rheo-fluidifying therapy'' while viscosity mirrors its metabolic effects, which are potentially beneficial on the circulatory level. Conclusion: Muscular activity results in marked hemorheologic alterations that reflect short and long term adaptation of a body submitted to an increase in its load of physical activity.