  We consider the chiral Lagrangian with nucleon, isobar, and pion degrees of
freedom. The baryon masses and the axial-vector form factor of the nucleon are
derived at the one-loop level. We explore the impact of using on-shell baryon
masses in the loop expressions. As compared to results from conventional chiral
perturbation theory we find significant differences. An application to QCD
lattice data is presented. We perform a global fit to the available lattice
data sets for the baryon masses and the nucleon axial-vector form factor, and
determine the low-energy constants relevant at N$^3$LO for the baryon masses
and at N$^2$LO for the form factor. Partial finite-volume effects are
considered. We point out that the use of on-shell masses in the loops results
in non-analytic behavior of the baryon masses and the form factor as function
of the pion mass, which becomes prominent for larger lattice volumes than
presently used.
