Some consequences of adaptation to increased or restricted activity during ontogenesis

Abstract

In the normal course of ontogenesis the level of the energy turnover changes markedly (i.e. the calorie intake as well as expenditure) which among others is also linked to the level of spontaneous physical activity. The great variability of physical activity depends on internal as well as external factors (Oliverau 1971). As has been mentioned before the differences in experimental animals (Collier 1971) as well as in man (Gapon 1972 etc.) may be as much as tenfold. Physical activity is also associated with the level of excitability of the central nervous system (CNS) which under various set-ups is also evaluated according to the level of physical activity. A high level of excitability of the CNS is tested in experimental animals, for instance in special boxes used to promote a greater exploratory activity i.e. increased movement of the animal (Lát 1963). Although there is a very wide range of interindividual variability it may be said that during growth the mean physical activity is high and during adult life and advanced age it declines. A very similar trend is also displayed by ontogenetic changes in the level of excitability of the CNS (Lát 1963).