The influence of a frustration term in the exchange part of the t-J mo
del onto the dispersion relation of one hole has been investigated. We
have chosen two independent methods, namely, a variational ansatz whi
ch describes a magnetic polaron of minimal size and the exact diagonal
ization method of a 4x4 lattice. It has been found that the frustratio
n shifts the minimum from the point (pi/2, pi/2) to the point (0,pi) i
n k space. It has also been shown that the frustration term alone does
not lead to the correct, experimentally observed Aat dispersion regio
n around (0,pi). A better agreement with the observed, extended saddle
point singularity may be obtained by simulating the decrease of spin
correlations due to a finite temperature.