If F is an exact symplectic map on the{\it d}-dimensional cylinder \(\mathbb{T}^d \times \mathbb{R}^d\), with a generating function h having superlinear growth and uniform bounds on the second derivative, we construct a strictly gradient semiflow \(\phi^*\) on the space of shift-invariant probability measures on the space of configurations \(({\mathbb{R}}^d)^{\mathbb{Z}}\). Stationary points of \(\phi^*\) are invariant measures of F, and the rotation vector and all spectral invariants are invariants of \(\phi^*\). Using \(\phi^*\) and the minimisation technique, we construct minimising measures with an arbitrary rotation vector \(\rho \in \mathbb{R}^d\), and with an additional assumption that F is strongly monotone, we show that the support of every minimising measure is a graph of a Lipschitz function. Using \(\phi^*\) and the relaxation technique, assuming a weak condition on \(\phi^*\) (satisfied e.g. in Hedlund's counter-example, and in the anti-integrable limit) we show existence of double-recurrent orbits of F (and F-ergodic measures) with an arbitrary rotation vector \(\rho \in \mathbb{R}^d\), and action arbitrarily close to the minimal action \(A(\rho)\).