  A conformation space kinetic model is constructed to drive the deformation
cycle of a three-sphere swimmer to achieve propulsion at low Reynolds number.
We analyze the effect of an external load on the performance of this kinetic
swimmer, and show that it depends sensitively on where the force is exerted, so
that there is no general force--velocity relation. We discuss how the
conformational cycle of such swimmers should be designed to increase their
performance in resisting forces applied at specific points.
