  We propose a definition of the running coupling constant in a SU(2) lattice
gauge theory with twisted boundary conditions. It is based on the correlation
of Polyakov loops extended in a twisted direction at a distance which is a
fixed fraction of the totale lattice size. We make the perturbative calculation
which connects this definition to standard regularization schemes. We find
Lambda_Twisted-Polyakov/Lambda_MSbar = 1.6136(2).
