Intracellular protein destroying and impairment of their synthesis result in disturbance of cell homeostasis and can lead to cell death. Counteracting these changes the cell induces synthesis of stress proteins among others. Physical exercise has stress attributes, especially if it is a long-lasting and intensive one. It can be assumed that this will bring about an intensification of stress protein expression what was experimentally confirmed. However the significance of this reaction is not fully clear taking into account the variety of functions the stress protein act in the organism.