[The effect of physical stress on rheological properties of blood]

The influence of physical load on blood viscosity was observed in the presented study. Three groups of persons were examined: 23 volleyball and football players, 96 employees of a nuclear power plant, and 49 employees of a coal power plant. The values of blood viscosity and hematocrit were determined in the quiescent state before the load, after the performance of 2W.kg-1, and after the maximum performance obtained at a bicycle ergometer. After the data processing the following results were obtained: The average performance of the trained persons was 40% higher compared to the untrained persons (power plants employees). Blood viscosity was lower before the load in the trained persons, and remained on average by 5% lower also after the maximum load. The total relative increase of the value of blood viscosity caused by the maximum load was however approximately the same in all groups (about 15%). The mean value of blood pressure increased with the increased blood viscosity, and therefore also with the increased physical load. The study contains also mathematical expressions of the observed relations.