On the basis of experimental investigations of Gamov-Teller spin flip β⁺ transitions in neutron deficient nuclei near ¹⁴⁶Gd and theoretical calculations, the renormalization of the weak axial-vector coupling constant G_A in heavy nuclei is derived: |G_A/g_v| = 0.7-1.0 (for a free neutron g_A/g_v = -1.25).