On the extreme behaviour of \(g_1(x,Q^2)\) at \(x\to 0\)

On the basis of the U-matrix form of s-channel unitarization, we consider constraints unitarity provides for the spin structure function \(g_1(x,Q^2)\) at \(x\to 0\). Corresponding constraint for the spin structure function \(h_1(x, Q^2)\) is given along.