Influence of physical exercises on the content of androstendione, estradiol and testosterone was studied in blood and skeletal muscles. The content of steroids was increased immediately after physical exercises and diminished down to the initial level within 48-72 hrs. Androgen receptors were increased from 0.58 +/- 0.04 to 1.17 +/- 0.17 fmol/mg of protein within 72 hrs after physical exercises in the skeletal muscle cytosol. The increase in the estradiol concentration stimulated the elevation in the androgen receptors content. Effect of estradiol on the content of androgen receptors in skeletal muscles was shown in model experiments using various doses of estradiol-benzoate. Thus, the hormonal status, responsible for metabolism during a body adaptation to physical exercises, depended not only on alterations in the content of steroids but also on the amount of receptors in skeletal muscles within various periods of rests after physical exercises.