EN
Let w be a non-negative measurable function defined on the positive semi-axis and satisfying the reverse Hölder inequality with exponents 0 < α < β. In the present paper, sharp estimates of the compositions of the power means $𝓟_{α}w(x): = ((1/x) ∫_{0}^{x} w^{α}(t)dt)^{1/α}$, x > 0, are obtained for various exponents α. As a result, for the function w a property of self-improvement of summability exponents is established.