  We present and discuss the bounds from the energy conditions on a general
f(R) functional form in the framework of metric variational approach. As a
concrete application of the energy conditions to locally homogeneous and
isotropic f(R)-cosmology, the recent estimated values of the deceleration and
jerk parameters are used to examine the bounds from the weak energy condition
on the free parameter of the family of f(R)=\sqrt{R^2 - R_0^2} gravity theory.
