Nutritional status and caloric intake of the mother during pregnancy can profoundly change future morphological, metabolical or mental development of the offspring. With regard to exercise, Arshavsky showed that newborns of hare mothers that swam daily during the last third of pregnancy were born with larger hearts.

Offspring of rat mothers that exercised for 1 hr daily on a treadmill, starting with the 2nd or 3rd day after mating, were therefore studied. Total body weights at birth and during as well as at the end of experiment did not differ. Fifty and 100 day old male offspring were studied from the point of view of the microstructure of the heart muscle, which has an important relationship to the functional capacity of the cardiovascular system.

The impact of exercisd during pregnancy can be manifested in the lipid metabolism of the offspring. When selected parameters were examined, a significant change was found, especially in female offspring of mothers exercised during pregnancy, similar to the type described above. The concentration of total lipids and fatty acids (assessed gravimetrically ) in the liver was significantly increased in female offspring of exercise mothers, together with their decreased synthesis.

In males, such changes were either not apparent or nificantly higher in both female and male offspring of exercised rat mothers. There were also changes in the lipid metabolism in the small intestine as a result of the exercise by the mother. The exercise of the mother during pregnancy also changed the reaction to the adaptation to exercise during postnatal ontogeny of the offspring.

The weights of the hearts in the offspring of exercised mothers were significantly heavier, the number of fibers and capillaries per sq mm was higher, the capillary : fiber ratio was higher, and the diffusion distance was smaller.