[Study of the effectiveness of using diets with a varying protein content during physical loads in an experiment on rats].

In experiments on rats subjected for 30 days to perform a graded muscular work (swimming) the influence produced by different levels of protein in the diet (6,18 and 30% by calorific value) on the accretion of body mass, physical work capacity, diurnal passage of total nitrogen, creatinine and creatine with urine was studied. At rest and following the maximum physical efforts the sugar, lactate and pyruvic acids levels were measured in the blood of rats. Food rations with low protein content (6% of the total caloricity), when used in conditions involving physical efforts, exerted an adverse effect on the growth, development and physical work capacity of the animals. The use of a protein-rich diet (30% by caloricity) did not show any substantial advantages over the standard one (18% of protein). In rats fed on diets with 18 and 30% of protein (in terms of caloricity) the body mass gain, physical work capacity and also the nature of changes in the content of lactate, pyruvate and sugar in the blood were the same.