[Variations of hematic viscosity due to water-electrolyte disorders induced by muscular stress]

In view of the increasingly widespread tendency of common people to undertake sports activities without adequate athletic preparation, and in consideration of certain cardiovascular alterations detected in subjects cultivating athletic activities of some magnitude for a number of years, the authors set out to explore the effects of severe muscular activity on circulation. More precicely, they measured blood and plasma viscosity at rest and after 50 minutes of intense athletic activity, competitive or otherwise, at the same time looking for possible changes of volemia, blood lipid composition, and hemodynamic parameters. Trained subjects, even if no longer very young, showed viscosity values in the lower range of normal, with no increase following muscular exertion; and likewise no changes of circulating blood volumes. Untrained subjects, conversely, showed more significant increase of both said values, albeit not beyond the limits of norm. The definitely if not dramatically different behavior of the two groups of subjects (trained versus untrained) brings out the value of this simple test. The authors discuss the factors and mechanisms that may be responsible for the observed changes: namely the loss of water and associated changes of electrolyte and protein concentrations, the alterations of blood pH, the changes of paO2, and the increased velocity of blood flow.