  The Nambu--Jona-Lasino model is modified by the inclusion of a
running-coupling that was obtained by a fractal approach to Quantum
Chromodynamics. The coupling follows a $q$-exponential function and, in the
context of high energy collisions, explains the origin of the Tsallis
non-extensive statistics distributions. The parameter $q$ is completely
determined in terms of the number of colours and the number of quark flavours.
We study several aspects of the extended model and compare our results to the
standard NJL model, where a constant coupling is used in combination with a
sharp cutoff to regularize the gap equation. We show that the modified coupling
regularizes the model like a smooth cutoff and reproduces the pion mass and
decay constant, providing an almost exact Gell-Mann-Oakes-Renner relation at
physical current quark masses.
