In chronic experiments on rabbits, under the action of maximal physical load ("to the utmost"), the greatest fluctuations of intensity of the local brain blood flow, excitability and pattern of bioelectrical activity in the cortical sensorimotor area, dorsal hippocampus and subcortical formations were observed the first 20 days of the experiment. The nature of intercentral relations of the cortical deep structures changed during the whole period of training. Stabilization of some functional parameters was observed at certain stages of the experiment, which is considered as adaptive reaction to physical load.