By virtue of convexity of Heinz means, in this paper we derive several refinements of Heinz norm inequalities with the help of the Jensen functional and its properties. In addition, we discuss another approach to Heinz operator means which is more convenient for obtaining the corresponding operator inequalities for positive invertible operators.

We say that the function $f:[a,b]\to ℝ$ is under the chord if $$\frac{\left(b-t\right)f\left(a\right)+\left(t-a\right)f\left(b\right)}{b-a}\ge f\left(t\right)$$ for any $t\in [a,b]$. In this paper we proved amongst other that $${\int }_a^{b}u\left(t\right)df\left(t\right)\ge \frac{f\left(b\right)-f\left(a\right)}{b-a}{\int }_a^{b}u\left(t\right)dt$$ provided that $u:[a,b]\to ℝ$ is monotonic nondecreasing and $f:[a,b]\to ℝ$ is continuous and under the chord. Some particular cases for the weighted integrals in connection with the Fejér inequalities are provided. Applications for continuous functions of selfadjoint operators on Hilbert spaces are also given.