TY JOUR TI TYPOLOGICAL FEATURES OF THE HIGHER NERVOUS ACTIVITY OF EXTREME ATHLETES AT THE PREPARATORY STAGE KW athletes KW extreme sports. heart rate variability KW anxiety JO Scientific Notes of V.I. Vernadsky Crimean Federal University. Biology. Chemistry AU Zhmurova, T.A. AU Ryabcev, S.M. PY 2024 IS 10 PB V.I. Vernadsky Crimean Federal University