Dynamic loads on step ladders are the result of interaction between climber and ladder. The complex dynamical behavior of the climber must be experimentally determined. An analysis of the dynamical response is presented to allow the extrapolation of experimental results to ladders of grossly different structural dynamical parameters from those on which the data are obtained. It is demonstrated that the climber characteristics dominate the dynamical response. Reliable quantitative measures of data applicability are obtained, not withstanding significant uncertainties regarding the details of the mechanics of motion.